Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS20070041457 A1
Publication typeApplication
Application numberUS 11/261,823
Publication dateFeb 22, 2007
Filing dateOct 27, 2005
Priority dateAug 22, 2005
Also published asCN101288245A, CN101288245B, CN104601212A, CN104618004A, CN104660316A, CN104660317A, EP1917736A2, EP1917736B1, US20120120925, US20120140798, US20120140838, WO2007024935A2, WO2007024935A3
Publication number11261823, 261823, US 2007/0041457 A1, US 2007/041457 A1, US 20070041457 A1, US 20070041457A1, US 2007041457 A1, US 2007041457A1, US-A1-20070041457, US-A1-2007041457, US2007/0041457A1, US2007/041457A1, US20070041457 A1, US20070041457A1, US2007041457 A1, US2007041457A1
InventorsTamer Kadous, Aamod Khadekar, Dhananjay Gore, Alexei Gorokhov
Original AssigneeTamer Kadous, Aamod Khadekar, Gore Dhananjay A, Alexei Gorokhov
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method and apparatus for providing antenna diversity in a wireless communication system
US 20070041457 A1
Abstract
Transmission schemes that can flexibly achieve the desired spatial multiplexing order, spatial diversity order, and channel estimation overhead order are described. For data transmission, the assigned subcarriers and spatial multiplexing order (M) for a receiver are determined, where M≧1. For each assigned subcarrier, M virtual antennas are selected from among V virtual antennas formed with V columns of an orthonormal matrix, where V≧M. V may be selected to achieve the desired spatial diversity order and channel estimation overhead order. Output symbols are mapped to the M virtual antennas selected for each assigned subcarrier by applying the orthonormal matrix. Pilot symbols are also mapped to the V virtual antennas. The mapped symbols are provided for transmission from T transmit antennas, where T≧V. Transmission symbols are generated for the mapped symbols, e.g., based on OFDM or SC-FDMA. Different cyclic delays may be applied for the T transmit antennas to improve diversity.
Images(15)
Previous page
Next page
Claims(40)
1. An apparatus comprising:
at least one processor configured to select M virtual antennas to use for transmission from among V virtual antennas, to map output symbols to the M virtual antennas, and to provide the mapped output symbols for transmission from T transmit antennas, wherein M is equal to one or greater, V is equal to or greater than M, and T is equal to or greater than V; and
a memory coupled to the at least one processor.
2. The apparatus of claim 1, wherein the at least one processor is configured to select different sets of M virtual antennas for different frequency subcarriers from among the V virtual antennas.
3. The apparatus of claim 1, wherein the at least one processor is configured to select a set of M virtual antennas for each of a plurality of frequency subcarriers by cycling through the V virtual antennas.
4. The apparatus of claim 1, wherein the at least one processor is configured to form a permutation matrix indicative of the M virtual antennas selected from among the V virtual antennas, to apply the permutation matrix to the output symbols, and to applying an orthonormal matrix used to form the V virtual antennas.
5. The apparatus of claim 1, wherein the at least one processor is configured to select one virtual antenna from among the V virtual antennas for a first receiver assigned with a first set of frequency subcarriers, to select more than one virtual antenna from among the V virtual antennas for a second receiver assigned with a second set of frequency subcarriers, to map output symbols for the first receiver to the first set of frequency subcarriers of the one virtual antenna, and to map output symbols for the second receiver to the second set of frequency subcarriers of the more than one virtual antenna.
6. The apparatus of claim 1, wherein the at least one processor is configured to apply T different cyclic delays for the T transmit antennas.
7. The apparatus of claim 1, wherein the at least one processor is configured to scale output symbols for the M virtual antennas with M gains.
8. The apparatus of claim 1, wherein the at least one processor is configured to transmit a first pilot on a first virtual antenna among the V virtual antennas, and to transmit a second pilot on remaining ones of the V virtual antennas.
9. The apparatus of claim 8, wherein the at least one processor is configured to transmit the first pilot on a first set of frequency subcarriers of the first virtual antenna, and to transmit the second pilot on a second set of frequency subcarriers by cycling through the remaining ones of the V virtual antennas.
10. The apparatus of claim 1, wherein the at least one processor is configured to transmit pilot symbols on at least one frequency subcarrier in at least one symbol period selected based on a pilot pattern.
11. The apparatus of claim 1, wherein the at least one processor is configured to select an orthonormal matrix from among a plurality of orthonormal matrices available to form the V virtual antennas.
12. The apparatus of claim 1, wherein the at least one processor is configured to receive feedback selecting an orthonormal matrix from among a plurality of orthonormal matrices available to form the V virtual antennas.
13. The apparatus of claim 1, wherein the at least one processor is configured to generate orthogonal frequency division multiplexing (OFDM) symbols for the T transmit antennas based on the mapped output symbols.
14. The apparatus of claim 1, wherein the at least one processor is configured to generate single-carrier frequency division multiple access (SC-FDMA) symbols for the T transmit antennas based on the mapped output symbols.
15. The apparatus of claim 1, wherein the at least one processor is configured to dynamically select M based on channel conditions.
16. The apparatus of claim 1, wherein the at least one processor is configured to dynamically select V based on channel conditions.
17. The apparatus of claim 1, wherein an orthonormal matrix, used to form the V virtual antennas, is defined such that equal transmit power is used for the T transmit antennas.
18. The apparatus of claim 1, wherein an orthonormal matrix, used to form the V virtual antennas, is based on a Fourier matrix or a Walsh matrix.
19. The apparatus of claim 1, wherein an orthonormal matrix, used to form the V virtual antennas is based upon scaling a Fourier matrix or a Walsh matrix with different random phases.
20. A method comprising:
selecting M virtual antennas to use for transmission from among V virtual antennas, wherein M is one or greater and V is equal to or greater than M;
mapping output symbols to the M virtual antennas; and
providing the mapped output symbols for transmission from T transmit antennas, wherein T is equal to or greater than V.
21. The method of claim 20, further comprising:
selecting different sets of M virtual antennas for different frequency subcarriers from among the V virtual antennas.
22. The method of claim 20, further comprising:
applying T different cyclic delays for the T transmit antennas.
23. The method of claim 20, further comprising:
transmitting a pilot on the M virtual antennas.
24. An apparatus comprising:
means for selecting M virtual antennas to use for transmission from among V virtual antennas, wherein M is one or greater and V is equal to or greater than M;
means for mapping output symbols to the M virtual antennas; and
means for providing the mapped output symbols for transmission from T transmit antennas, wherein T is equal to or greater than V.
25. The apparatus of claim 24, further comprising:
means for selecting different sets of M virtual antennas for different frequency subcarriers from among the V virtual antennas.
26. The apparatus of claim 24, further comprising:
means for applying T different cyclic delays for the T transmit antennas.
27. The apparatus of claim 24, further comprising:
means for transmitting a pilot on the M virtual antennas.
28. An apparatus comprising:
at least one processor configured to select M1 virtual antennas to use for transmission to a first receiver from among V virtual antennas, to select M2 virtual antennas to use for transmission to a second receiver from among the V virtual antennas, to map output symbols for the first receiver to the M1 virtual antennas, to map output symbols for the second receiver to the M2 virtual antennas, to provide the mapped output symbols for the first receiver for transmission on a first frequency subcarrier of T transmit antennas, and to provide the mapped output symbols for the second receiver for transmission on a second frequency subcarrier of the T transmit antennas, wherein M1 and M2 are each equal to one or greater, V is equal to or greater than the larger of M1 and M2, and T is equal to or greater than V; and
a memory coupled to the at least one processor.
29. The apparatus of claim 28, wherein the at least one processor is configured to apply T different cyclic delays for the T transmit antennas.
30. The apparatus of claim 28, wherein M1 is not equal to M2.
31. The apparatus of claim 28, wherein the first and second frequency subcarriers are one frequency subcarrier, and wherein transmissions are sent to the first and second receivers using spatial division multiple access (SDMA).
32. The apparatus of claim 28, wherein the at least one processor is configured to transmit a pilot on each virtual antenna used for transmission.
33. The apparatus of claim 28, wherein the at least one processor is configured to generate transmission symbols for the T transmit antennas based on the mapped output symbols and using orthogonal frequency division multiplexing (OFDM) or single-carrier frequency division multiple access (SC-FDMA) modulation technique.
34. An apparatus comprising:
means for selecting M1 virtual antennas to use for transmission to a first receiver from among V virtual antennas, wherein M1 is equal to one or greater and V is equal to or greater than M1;
means for selecting M2 virtual antennas to use for transmission to a second receiver from among the V virtual antennas, wherein M2 is equal to one or greater and is also less than or equal to V;
means for mapping output symbols for the first receiver to the M1 virtual antennas;
means for mapping output symbols for the second receiver to the M2 virtual antennas;
means for providing the mapped output symbols for the first receiver for transmission on a first frequency subcarrier of T transmit antennas, wherein T is equal to or greater than V; and
means for providing the mapped output symbols for the second receiver for transmission on a second frequency subcarrier of the T transmit antennas.
35. The apparatus of claim 34, further comprising:
means for applying T different cyclic delays for the T transmit antennas.
36. An apparatus comprising:
at least one processor configured to map output symbols to a plurality of antennas based upon at least one mapping pattern selected from among a plurality of mapping patterns, wherein each mapping pattern indicates a specific mapping of an output symbol to the plurality of antennas; and
a memory coupled to the at least one processor.
37. The apparatus of claim 36, wherein the at least one processor is configured to select different mapping patterns for different frequency subcarriers in a symbol period.
38. The apparatus of claim 36, wherein the at least one processor is configured to select different mapping patterns for symbol periods.
39. The apparatus of claim 36, wherein the at least one processor is configured to select different mapping patterns from among the plurality of mapping patterns for different frequency subcarriers or different symbol periods based on a predetermined pattern.
40. The apparatus of claim 36, wherein the at least one processor is configured to apply a different column of an orthonormal matrix for each of a plurality of frequency subcarriers in accordance with a predetermined pattern, wherein the orthonormal matrix includes a plurality of columns for the plurality of mapping patterns.
Description
  • [0001]
    The present application claims priority to provisional U.S. Application Ser. No. 60/710.408, entitled “Method and Apparatus for Antenna Diversity in Multi-input Multi-Output Communication Systems,” filed Aug. 22, 2005, and provisional U.S. Application Ser. No. 60/711,144 entitled “Method and Apparatus for Antenna Diversity in Multi-input Multi-Output Communication Systems,” filed Aug. 24, 2005, both assigned to the assignee hereof and incorporated herein by reference. The present application is further related to commonly assigned U.S. patent application Ser. No. to be determined, entitled “Adaptive Sectorization in Cellular Systems,” filed on the same day herewith, and incorporated herein by reference.
  • BACKGROUND
  • [0002]
    I. Field
  • [0003]
    The present disclosure relates generally to communication, and more specifically to transmission schemes for wireless communication.
  • [0004]
    II. Background
  • [0005]
    In a wireless communication system, a transmitter (e.g., a base station or a terminal) may utilize multiple (T) transmit antennas for data transmission to a receiver equipped with one or more (R) receive antennas. The multiple transmit antennas may be used to increase system throughput by transmitting different data from these antennas and/or to improve reliability by transmitting data redundantly. For example, the transmitter may transmit a given symbol from all T transmit antennas, and the receiver may receive multiple versions of this symbol via the R receive antennas. These multiple versions of the transmitted symbol generally improve the receiver's ability to recover the symbol.
  • [0006]
    Transmission performance may be improved by exploiting the spatial dimension obtained with the multiple transmit antennas and, if present, the multiple receive antennas. A propagation path exists between each pair of transmit and receive antennas. TR different propagation paths are formed between the T transmit antennas and the R receive antennas. These propagation paths may experience different channel conditions (e.g., different fading, multipath, and interference effects) and may achieve different signal-to-noise-and-interference ratios (SNRs). The channel responses for the TR propagation paths may vary from path to path and may further vary across frequency for a dispersive wireless channel and/or over time for a time-variant wireless channel.
  • [0007]
    A major drawback to using multiple transmit antennas for data transmission is that the channel response between each pair of transmit and receive antennas (or each propagation path) typically needs to be estimated in order to properly receive the data transmission. Estimation of the fall channel response for all TR transmit and receive antenna pairs may be undesirable for several reasons. First, a large amount of link resources may be consumed in order to transmit a pilot used for channel estimation, which in turn reduces the link resources available to transmit data. Second, channel estimation for all TR transmit and receive antenna pairs increases processing overhead at the receiver.
  • [0008]
    There is therefore a need in the art for transmission schemes that can ameliorate the need to estimate the fall channel response for all transmit and receive antenna pairs.
  • SUMMARY
  • [0009]
    Transmission schemes that can flexibly achieve the desired spatial multiplexing order, spatial diversity order, and channel estimation overhead order are described herein. The spatial multiplexing order determines the number of symbols to send simultaneously on one subcarrier in one symbol period, the spatial diversity order determines the amount of spatial diversity observed by the transmitted symbols, and the channel estimation overhead order determines the amount of pilot overhead.
  • [0010]
    In an embodiment, for a data transmission from a transmitter to a receiver, the subcarriers assigned to the receiver and the spatial multiplexing order (M) for the receiver are determined, where M≧1. For each assigned subcarrier, M virtual antennas are selected from among V virtual antennas formed with V columns of an orthonormal matrix, where V≧M. V may be selected to achieve the desired spatial diversity order and channel estimation overhead order. The M virtual antennas for each assigned subcarrier may be selected in various manners, as described below. Output symbols for the receiver are mapped to the M virtual antennas selected for each assigned subcarrier by applying the orthonormal matrix. Pilot symbols are also mapped to the V virtual antennas. The mapped output symbols and pilot symbols (or transmit symbols) are provided for transmission from T physical transmit antennas, where T≧V. Transmission symbols (e.g., OFDM symbols or SC-FDMA symbols) are generated for each transmit antenna based on the transmit symbols for that transmit antenna. Different cyclic delays may be applied to the transmission symbols for the T transmit antennas.
  • [0011]
    Various aspects and embodiments of the invention are described in further detail below.
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • [0012]
    The features and nature of the present invention will become more apparent from the detailed description set forth below when taken in conjunction with the drawings in which like reference characters identify correspondingly throughout.
  • [0013]
    FIG. 1 shows a wireless communication system.
  • [0014]
    FIGS. 2A and 2B show MISO and MIMO channels, respectively.
  • [0015]
    FIG. 3 shows a transmission scheme with virtual antennas.
  • [0016]
    FIG. 4 shows a transmission scheme with virtual antennas and cyclic delay diversity.
  • [0017]
    FIG. 5 shows a MIMO transmission by cycling through the virtual antennas.
  • [0018]
    FIGS. 6A, 6B and 6C show three exemplary subcarrier structures.
  • [0019]
    FIG. 7 shows an exemplary frequency hopping scheme.
  • [0020]
    FIG. 8 shows an exemplary pilot scheme for symbol rate hopping.
  • [0021]
    FIG. 9A through 9D show four exemplary pilot schemes for block hopping.
  • [0022]
    FIG. 10 shows a process for transmitting data and pilot to one or more receivers.
  • [0023]
    FIG. 11 shows an apparatus for transmitting data and pilot to one or more receivers.
  • [0024]
    FIG. 12 shows a block diagram of a base station and two terminals.
  • DETAILED DESCRIPTION
  • [0025]
    The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments or designs.
  • [0026]
    FIG. 1 shows a wireless communication system 100 with multiple base stations 110 and multiple terminals 120. A base station is a station that communicates with the terminals. A base station may also be called, and may contain some or all of the functionality of, an access point, a Node B, and/or some other network entity. Each base station 110 provides communication coverage for a particular geographic area 102. The term “cell” can refer to a base station and/or its coverage area depending on the context in which the term is used. To improve system capacity, a base station coverage area may be partitioned into multiple smaller areas, e.g., three smaller areas 104 a, 104 b, and 104 c. Each smaller area is served by a respective base transceiver subsystem (BTS). The term “sector” can refer to a BTS and/or its coverage area depending on the context in which the term is used. For a sectorized cell, the BTSs for all sectors of that cell are typically co-located within the base station for the cell. The transmission techniques described herein may be used for a system with sectorized cells as well as a system with un-sectorized cells. For example, the techniques may be used for the system described in the aforementioned U.S. patent application Ser. No. [Attorney Docket No. 05091]. For simplicity, in the following description, the term “base station” is used generically for a BTS that serves a sector as well as a base station that serves a cell.
  • [0027]
    Terminals 120 are typically dispersed throughout the system, and each terminal may be fixed or mobile. A terminal may also be called, and may contain some or all of the functionality of, a mobile station, a user equipment, and/or some other device. A terminal may be a wireless device, a cellular phone, a personal digital assistant (PDA), a wireless modem card, and so on. Each terminal may communicate with zero, one, or multiple base stations on the downlink and uplink at any given moment. The downlink (or forward link) refers to the communication link from the base stations to the terminals, and the uplink (or reverse link) refers to the communication link from the terminals to the base stations.
  • [0028]
    For a centralized architecture, a system controller 130 couples to base stations 110 and provides coordination and control for these base stations. For a distributed architecture, the base stations may communicate with one another as needed.
  • [0029]
    The transmission techniques described herein may be used for various wireless communication systems such as an orthogonal frequency division multiple access (OFDMA) system, a single-carrier frequency division multiple access (SC-FDMA) system, a frequency division multiple access (FDMA) system, a code division multiple access (CDMA) system, a time division multiple access (TDMA) system, a spatial division multiple access (SDMA) system, and so on. An OFDMA system utilizes orthogonal frequency division multiplexing (OFDM), which is a multi-carrier modulation technique that partitions the overall system bandwidth into multiple (K) orthogonal subcarriers. These subcarriers may also be called tones, bins, and so on. With OFDM, each subcarrier is associated with a respective subcarrier that may be modulated with data. An SC-FDMA system may utilize interleaved FDMA (IFDMA) to transmit on subcarriers that are distributed across the system bandwidth, localized FDMA (LFDMA) to transmit on a block of adjacent subcarriers, or enhanced FDMA (EFDMA) to transmit on multiple blocks of adjacent subcarriers. In general, modulation symbols are sent in the frequency domain with OFDM and in the time domain with SC-FDMA.
  • [0030]
    An OFDM symbol may be generated for one transmit antenna in one symbol period as follows. N modulation symbols are mapped to N subcarriers used for transmission (or N assigned subcarriers) and zero symbols with signal value of zero are mapped to the remaining K−N subcarriers. A K-point inverse fast Fourier transform (IFFT) or inverse discrete Fourier transform (IDFT) is performed on the K modulation symbols and zero symbols to obtain a sequence of K time-domain samples. The last Q samples of the sequence are copied to the start of the sequence to form an OFDM symbol that contains K+Q samples. The Q copied samples are often called a cyclic prefix or a guard interval, and Q is the cyclic prefix length. The cyclic prefix is used to combat intersymbol interference (ISI) caused by frequency selective fading, which is a frequency response that varies across the system bandwidth.
  • [0031]
    An SC-FDMA symbol may be generated for one transmit antenna in one symbol period as follows. N modulation symbols to be sent on N assigned subcarriers are transformed to the frequency domain with an N-point fast Fourier transform (FFT) or discrete Fourier transform (DFT) to obtain N frequency-domain symbols. These N frequency-domain symbols are mapped to the N assigned subcarriers, and zero symbols are mapped to the remaining K−N subcarriers. A K-point IFFT or IDFT is then performed on the K frequency-domain symbols and zero symbols to obtain a sequence of K time-domain samples. The last Q samples of the sequence are copied to the start of the sequence to form an SC-FDMA symbol that contains K+Q samples.
  • [0032]
    A transmission symbol may be an OFDM symbol or an SC-FDMA symbol. The K+Q samples of a transmission symbol are transmitted in K+Q sample/chip periods. A symbol period is the duration of one transmission symbol and is equal to K+Q sample/chip periods.
  • [0033]
    The transmission techniques described herein may be used for the downlink as well as the uplink. For clarity, much of the following description is for downlink transmission from a base station (a transmitter) to one or more terminals (receivers). For each subcarrier, the base station may transmit to one terminal without SDMA or to multiple terminals with SDMA.
  • [0034]
    FIG. 2A shows a multiple-input single-output (MISO) channel formed by multiple (T) transmit antennas 112 a through 112 t at base station 110 and a single receive antenna 122 x at a terminal 120 x. The MISO channel may be characterized by a 1T channel response row vector h(k) for each subcarrier k, which may be given as:
    h (k)=[h 1(k) h 2(k) . . . h T(k)],   Eq (1)
    where hi(k), for i=1, . . . , T, denotes the coupling or complex channel gain between transmit antenna i and the single receive antenna for subcarrier k.
  • [0035]
    FIG. 2B shows a multiple-input multiple-output (MIMO) channel formed by the T transmit antennas 112 a through 112 t at base station 110 and multiple (R) receive antennas 122 a through 122 r at a terminal 120 y. The MIMO channel may be characterized by an RT channel response matrix H(k) for each subcarrier k, which may be given as: H _ ( k ) = [ h 1 , 1 ( k ) h 1 , 2 ( k ) h 1 , T ( k ) h 2 , 1 ( k ) h 2 , 2 ( k ) h 2 , T ( k ) h R , 1 ( k ) h R , 2 ( k ) h R , T ( k ) ] = [ h _ 1 ( k ) h _ 2 ( k ) h _ T ( k ) ] , Eq ( 2 )
    where hj,i (k), for j=1, . . . , R and i=1, . . . , T, denotes the complex channel gain between transmit antenna i and receive antenna j for subcarrier k; and
      • h i (k) is an R1 channel response vector for transmit antenna i, which is the i-th column of H(k).
  • [0037]
    The transmitter may transmit one or more output symbols from the T transmit antennas on each subcarrier in each symbol period. Each output symbol may be a modulation symbol for OFDM, a frequency-domain symbol for SC-FDMA, or some other complex value. The data transmission may be quantified by the following metrics:
      • Spatial multiplexing order (M)—the number of output symbols transmitted via the T transmit antennas on one subcarrier in one symbol period;
      • Spatial diversity order (D)—the amount of spatial diversity observed by the transmitted output symbols; and
      • Channel estimation overhead order (C)—the number of virtual antennas to be estimated by a receiver for each receive antenna.
        In general, M≦min {T, R}, D≦T, and C≦T. The spatial diversity refers to transmit diversity resulting from the use of multiple transmit antennas and does not include receive diversity resulting from the use of multiple receive antennas.
  • [0041]
    If the transmitter transmits output symbols directly from the T transmit antennas, then a receiver typically needs to estimate the full channel response for all T transmit antennas in order to recover the data transmission. The channel estimation overhead order is then C=T. In certain scenarios, it may be desirable to transmit fewer than T output symbols simultaneously, e.g., if the channel conditions are poor. A subset of the T transmit antennas may be used to transmit fewer than T output symbols. However, this is undesirable since the transmit powers available for the unused transmit antennas are not judiciously employed for transmission.
  • [0042]
    The transmission schemes described herein allow for flexible selection of the three metrics M, D and C in order to achieve good performance for data transmission in different conditions. For example, a larger spatial multiplexing order M may be selected for good channel conditions with high SNRs, and a smaller spatial multiplexing order may be selected for poor channel conditions with low SNRs. A lower channel estimation overhead order C may be selected, e.g., in scenarios where low throughput due to low SNRs does not justify a large channel estimation overhead.
  • [0043]
    The transmission schemes described herein can utilize all T transmit antennas for transmission, regardless of the number of output symbols being sent and regardless of which subcarriers are used for transmission. This capability allows the transmitter to utilize all of the transmit power available for the T transmit antennas, e.g. by utilizing the power amplifiers coupled to each of the antennas, for transmission, which generally improves performance. Employing fewer than T transmit antennas for transmission typically results in less than all of the available transmit power being used for the transmission, which would impact performance.
  • [0044]
    The transmission schemes described herein can readily support MIMO, single-input multiple-output (SIMO), and single-input single-output (SISO) transmissions. A MIMO transmission is a transmission of multiple output symbols from multiple virtual antennas to multiple receive antennas on one subcarrier in one symbol period. A SIMO transmission is a transmission of a single output symbol from one virtual antenna to multiple receive antennas on one subcarrier in one symbol period. A SISO transmission is a transmission of a single output symbol from one virtual antenna to one receive antenna on one subcarrier in one symbol period. The transmitter may also send a combination of MIMO, SIMO and/or SISO transmissions to one or more receivers in one symbol period.
  • [0045]
    The transmitter may transmit M output symbols simultaneously from the T transmit antennas on one subcarrier in one symbol period using various transmission schemes. In an embodiment, the transmitter processes the output symbols for transmission, as follows:
    x(k)=UP(k)s(k) ,   Eq (3)
    where s(k) is an M1 vector containing M output symbols to be sent on subcarrier k in one symbol period;
      • P(k) is a VM permutation matrix for subcarrier k;
      • U=[u1 u2 . . . uv] is a TV orthonormal matrix; and
      • x(k) is a T1 vector containing T transmit symbols to be sent from the T transmit antennas on subcarrier k in one symbol period. V is the number of virtual antennas formed with the orthonormal matrix U. In general, 1≦M≦V≦T. V may be a fixed value or a configurable value.
  • [0049]
    The orthonormal matrix U is characterized by the property UHU=I, where “H” He denotes a conjugate transpose and I is the identity matrix. The V columns of U are orthogonal to one another, and each column has unit power. In an embodiment, U is defined such that the sum of the squared magnitude of the V entries in each row is equal to a constant value. This property results in equal transmit power being used for all T transmit antennas. U may also be a unitary matrix that is characterized by the property UHU=UUH=I. Orthonormal and unitary matrices may be formed as described below. The V columns of U are used to form V virtual antennas that may be used to send up to V output symbols on one subcarrier in one symbol period. The virtual antennas may also be called effective antennas or by some other terminology.
  • [0050]
    In an embodiment, a single orthonormal matrix U is used for all K total subcarriers in all symbol periods, so that U is not a function of subcarrier index k or symbol index n. In another embodiment, different orthonormal matrices are used for different subcarrier sets that may be assigned to different receivers. In yet another embodiment, different orthonormal matrices are used for different subcarriers. In yet another embodiment, different orthonormal matrices are used for different time intervals, where each time interval may span one or multiple symbol periods. In yet another embodiment, one or more orthonormal matrices are selected for use from among multiple orthonormal matrices, as described below. In general, data and pilot may be transmitted using one or more orthonormal matrices such that a receiver is able to estimate the channel response based on the pilot and use the channel response estimate to recover the data sent to the receiver.
  • [0051]
    The permutation matrix P(k) selects which M virtual antennas to use for subcarrier k from among the V virtual antennas available for use, or which M of the V columns of U. The permutation matrix P(k) may be defined in various manners, and different permutation matrices may be used for different subcarriers, as described below.
  • [0052]
    FIG. 3 shows a model 300 for the transmission scheme given by equation (3). The transmitter receives the data vector s(k) for each subcarrier and symbol period used for transmission. A virtual antenna mapper 310 processes the data vector s(k) and generates the transmit vector x(k). Within virtual antenna mapper 310, a symbol-to-virtual antenna mapping unit 312 multiplies the data vector s(k) with the permutation matrix P(k) and generates a V1 intermediate vector. A spatial spreading unit 314 multiplies the intermediate vector with the orthonormal matrix U and generates the transmit vector x(k). The transmit vector x(k) is transmitted from the T transmit antennas and via a MIMO channel 350 to R receive antennas at a receiver.
  • [0053]
    The received symbols at the receiver may be expressed as: r _ ( k ) = H _ ( k ) x _ ( k ) + n _ ( k ) , = H _ ( k ) U _ P _ ( k ) s _ ( k ) + n _ ( k ) , = H _ eff ( k ) P _ ( k ) s _ ( k ) + n _ ( k ) , = H _ used ( k ) s _ ( k ) + n _ ( k ) , Eq ( 4 )
    where r(k) is an R1 vector containing R received symbols from the R receive antennas on subcarrier k in one symbol period;
      • Heff (k) is an RV effective channel response matrix for subcarrier k;
      • Hused(k) is an RM used channel response matrix for subcarrier k; and
      • n(k) is an R1 noise vector for subcarrier k.
  • [0057]
    The effective and used channel response matrices may be given as: H _ eff ( k ) = H _ ( k ) U _ , = [ H _ ( k ) u _ 1 H _ ( k ) u _ 2 H _ ( k ) u _ V ] , Eq ( 5 ) and H _ used ( k ) = H _ eff ( k ) P _ ( k ) , = [ H _ ( k ) u _ ( 1 ) H _ ( k ) u _ ( 2 ) H _ ( k ) u _ ( M ) ] , Eq ( 6 )
    where {u(1) u(2) . . . u(M)}⊂{u1 u2 . . . uV}.
  • [0058]
    As shown in equation (3) and illustrated in FIG. 3, an effective MIMO channel with V virtual antennas is formed by the use of the orthonormal matrix U. Data is sent on all or a subset of the V virtual antennas. A used MIMO channel is formed by the M virtual antennas used for transmission.
  • [0059]
    For the transmission scheme described above, an RT MIMO system is effectively reduced to an RV MIMO system. The transmitter appears as if it has V virtual antennas rather than T transmit antennas, where V≦T. This transmission scheme decreases the channel estimation overhead order to C=V. However, the spatial multiplexing order is limited to V, or M≦V, and the spatial diversity order is also limited to V, or D≦V.
  • [0060]
    The description above is for one subcarrier k. The transmitter may perform the same processing for each subcarrier used for transmission. The frequency diversity of each virtual antenna across subcarriers is the same as the frequency diversity of the physical transmit antennas. However, the spatial diversity is reduced from T to V.
  • [0061]
    In another embodiment, the transmitter processes the output symbols for transmission, as follows:
    {tilde over (x)}(k)=D(k)UP(k)s(k),   Eq (7)
    where D(k) is a TT diagonal matrix for subcarrier k. D(k) is used to achieve cyclic delay diversity, which improves the frequency selectivity of the virtual antennas and may improve spatial diversity order to somewhere between V and T. Cyclic delay diversity may be achieved in the time domain or the frequency domain.
  • [0062]
    Cyclic delay diversity may be achieved in the time domain by circularly shifting (or cyclically delaying) the sequence of K time-domain samples (obtained from the K-point IDFT or IFFT) for each transmit antenna i by a delay of Ti, for i=1, . . . , T. For example, Ti may be defined as Ti=(i−1)J, where J may be equal to one sample period, a fraction of a sample period, or more than one sample period. J may be selected such that the channel impulse response for each virtual antenna is expected to be shorter than the cyclic prefix length. A cyclic delay of X samples may be achieved by moving the last X samples in the sequence of K time-domain samples to the front of the sequence. The time-domain samples for the T transmits antenna are cyclically delayed by different amounts. A cyclic prefix may be appended after applying the cyclic delay in order to ensure orthogonality among the K total subcarriers.
  • [0063]
    Cyclic delay diversity may also be achieved in the frequency domain by applying a phase ramp (or a progressive phase shift) across the K total subcarriers for each transmit antenna. T different phase ramps are used for the T transmit antennas to achieve K different cyclic delays for these antennas. The diagonal matrix D(k) for each subcarrier k may be defined as follows: D _ ( k ) = [ 1 0 0 0 j2π ( k - 1 ) J / T 0 0 0 j2π ( k - 1 ) ( T - 1 ) J / T ] , for k = 1 , , K , Eq ( 8 )
    As indicated by equation (8), transmit antenna 1 has a phase slope of 0 across the K total subcarriers, transmit antenna 2 has a phase slope of 2πJ/T across the K total subcarriers, and so on, and transmit antenna T has a phase slope of 2π(T−1)J/T across the K total subcarriers. The diagonal matrix D(k) and the orthonormal matrix U may also be combined to obtain a new orthonormal matrix U(k)=D(k)U, where U(k) may be applied to the data vector s(k).
  • [0064]
    The received symbols with cyclic delay diversity may be expressed as: r ~ _ ( k ) = H _ ( k ) x ~ _ ( k ) + n _ ( k ) , = H _ ( k ) D _ ( k ) U _ P _ ( k ) s _ ( k ) + n _ ( k ) , = H ~ _ eff ( k ) P _ ( k ) s _ ( k ) + n _ ( k ) , = H ~ _ used ( k ) s _ ( k ) + n _ ( k ) , Eq ( 9 )
    where {tilde over (r)}(k) is an R1 received vector with cyclic delay diversity;
      • {tilde over (H)}eff(k) is an RV effective channel response matrix with cyclic delay diversity; and
      • {tilde over (H)}used(k) is an RM used channel response matrix with cyclic delay diversity.
  • [0067]
    The effective and used channel response matrices may be given as: H ~ _ eff ( k ) = H _ ( k ) D _ ( k ) U _ , = [ H _ ( k ) D _ ( k ) u _ 1 H _ ( k ) D _ ( k ) u _ 2 H _ ( k ) D _ ( k ) u _ V ] , and Eq ( 10 ) H ~ _ used ( k ) = H ~ _ eff ( k ) P _ ( k ) , = [ H _ ( k ) D _ ( k ) u _ ( 1 ) H _ ( k ) D _ ( k ) u _ ( 2 ) H _ ( k ) D _ ( k ) u _ ( M ) ] . Eq ( 11 )
  • [0068]
    FIG. 4 shows a model 400 for the transmission scheme given by equation (7). Within a virtual antenna mapper 410, a symbol-to-virtual antenna mapping unit 412 multiplies the data vector s(k) with the permutation matrix P(k) and generates a V1 vector. A spatial spreading unit 414 multiplies the V1 vector with the orthonormal matrix U and generates a T1 vector. A cyclic delay diversity unit 416 multiplies the T1 vector with the diagonal matrix D(k) and generates the T1 transmit vector x(k). The transmit vector x(k) is transmitted from the T transmit antennas and via a MIMO channel 450 to R receive antennas at a receiver.
  • [0069]
    As shown in equation (7) and illustrated in FIG. 4, an effective MIMO channel {tilde over (H)}eff(k) with V virtual antennas is formed by the use of the orthonormal matrix U and cyclic delay diversity. A used MIMO channel {tilde over (H)}used(k) is formed by the M virtual antennas used for transmission.
  • [0070]
    Equations (3) and (7) assume that equal transmit power is used for the M output symbols being sent simultaneously on one subcarrier in one symbol period. In general, the transmit power available for each transmit antenna may be uniformly or non-uniformly distributed across the subcarriers used for transmission. The transmit powers available for the T transmit antennas for each subcarrier may be uniformly or non-uniformly distributed to the M output symbols being sent on that subcarrier. Different transmit powers may be used for the M output symbols by scaling the data vector s(k) with a diagonal gain matrix G as follows: x(k)=UP(k)Gs(k) or {tilde over (x)}(k)=D(k)UP(k)Gs(k), where diag {G}={g1 g2 . . . gm} and gi is the gain for output symbol si.
  • [0071]
    Various types of matrices may be used to form the orthonormal matrix U. For example, U may be formed based on a Fourier matrix, a Walsh matrix, or some other matrix. A TT Fourier matrix FTT has element fn,m in the n-th row of the m-th column, which may be expressed as: f n , m = - j2π ( n - 1 ) ( m - 1 ) T , for n = 1 , , T and m = 1 , T . Eq ( 12 )
    Fourier matrices of any square dimension (e.g., 2, 3, 4, 5, 6, and so on) may be formed. A 22 Walsh matrix W22 and larger size Walsh matrix W2N2N may be expressed as: W _ 2 2 = [ 1 1 1 - 1 ] and W _ 2 N 2 N = [ W _ N N W _ N N W _ N N - W _ N N ] . Eq ( 13 )
  • [0072]
    In an embodiment, the orthonormal matrix U is equal to a matrix containing V columns of a TT Fourier matrix or a TT Walsh matrix. In another embodiment, U is formed as follows:
    U=ΛF   Eq (14)
    where F is a TV matrix containing the first V columns of the TT Fourier matrix; and
      • Λ is a TT diagonal matrix containing T scaling values for the T rows of F.
        For example, the diagonal matrix Λ may be defined as Λ=diag{1 e 1 . . . e T }, where θi for i=1, . . . , T may be random phases. Equation (14) multiplies the rows of F with random phases, which changes the spatial directions depicted by the columns of F. In yet another embodiment, U is an orthonormal matrix with pseudo-random elements, e.g., having unit magnitude and pseudo-random phases.
  • [0074]
    The transmitter may send a MIMO, SIMO or SISO transmission to a receiver on a set of subcarriers, which are called the assigned subcarriers. The K total subcarriers may be partitioned into multiple non-overlapping subcarrier sets. In this case, the transmitter may transmit to multiple receivers simultaneously on multiple subcarrier sets. The transmitter may send the same or different types of transmission to these multiple receivers. For example, the transmitter may send a MIMO transmission on a first subcarrier set to a first receiver, a SIMO transmission on a second subcarrier set to a second receiver, a SISO transmission on a third subcarrier set to a third receiver, and so on.
  • [0075]
    A SIMO or SISO transmission may be sent from a single virtual antenna formed with a single column of the orthonormal matrix U. In this case, M=V=1, and the effective MIMO channel becomes an R1 SISO or SIMO channel having a channel response vector of h eff(k)=H(k)u1 or {tilde over (h)} eff(k)=H(k)D(k)u1. The data vector s(k) becomes a 11 vector containing a single output symbol, the permutation matrix P(k) becomes a 11 matrix containing a single ‘1’, and the orthonormal matrix U becomes a T1 matrix containing a single column.
  • [0076]
    A MIMO transmission may be sent from multiple virtual antennas formed with multiple columns of the orthonormal matrix U. If the number of output symbols is less than the number of virtual antennas (or M<S), then M virtual antennas may be selected for use in various manners.
  • [0077]
    FIG. 5 shows an embodiment for transmitting output symbols cyclically from the V virtual antennas. For this embodiment, the first M output symbols are sent from virtual antennas 1 through M on the first assigned subcarrier, the next M output symbols are sent from virtual antennas 2 through M+1 on the next assigned subcarrier, and so on. The assigned subcarriers may be given indices of k=1, 2, . . . . For the embodiment shown in FIG. 5, the M virtual antennas used for subcarrier k+1 are offset by one from the M virtual antennas used for subcarrier k. The selected virtual antennas wrap around to virtual antenna 1 upon reaching the last virtual antenna. Hence, virtual antennas ((k−1) mod V)+1 through ((k+M−2) mod V)+1 are used for assigned subcarrier k, where “mod S” denotes a modulo-S operation and the “−1” and “+1” are due to the index for the assigned subcarriers and the index for the virtual antennas starting with 1 instead of 0. The M columns of the permutation matrix P(k) for each assigned subcarrier k are the ((k−1, k, k+1, . . . , k+M−2).mod V)+1 columns of a VV identify matrix. For example, if M=2 and V=3, then the permutation matrices may be defined as: P ( 1 ) = [ 1 0 0 1 0 0 ] , P ( 2 ) = [ 0 0 1 0 0 1 ] , P ( 3 ) = [ 0 1 0 0 1 0 ] , P ( 4 ) = [ 1 0 0 1 0 0 ] , and so on . Eq ( 15 )
  • [0078]
    In another embodiment, the first M output symbols are sent from virtual antennas 1 through M on the first assigned subcarrier, the next M output symbols are sent from virtual antennas M+1 through ((2M−1) mod V)+1 on the next assigned subcarrier, and so on. For this embodiment, the M virtual antennas used for subcarrier k+1 start after the last virtual antenna used for subcarrier k. In yet another embodiment, the M virtual antennas for each subcarrier are selected in a pseudo-random manner, e.g., based on a pseudo-random number (PN) generator or sequence that is also known to the receiver.
  • [0079]
    In yet another embodiment, the virtual antennas are selected based on feedback from a receiver. For example, the feedback may indicate the specific virtual antennas to use for all assigned subcarriers, the specific virtual antennas to use for each assigned subcarrier, and so on. In yet another embodiment, the transmitter may select the virtual antennas based on a pilot or some other transmission received from the receiver. For example, the transmitter may estimate the uplink channel response based on the received pilot, estimate the downlink channel response based on the uplink channel response estimate, and select the virtual antennas based on the downlink channel response estimate. The downlink and uplink channel responses may be similar, e.g., in a time division duplexed (TDD) system in which downlink and uplink transmissions are sent on the same frequency channel but in different time intervals.
  • [0080]
    In general, the virtual antennas may be selected (1) by the transmitter in a deterministic manner (e.g., cyclically) or a pseudo-random manner without feedback from the receiver, (2) by the transmitter based on feedback from receiver, or (3) by the receiver and sent to the transmitter.
  • [0081]
    The orthonormal matrix U may be fixed, and the V virtual antennas formed with U may be selected for use as described above. In another embodiment, one or more orthonormal matrices are selected for use from among a set of orthonormal matrices available for use. The set of orthonormal matrices forms a codebook, and one or more entries of the codebook may be used for transmission. The orthonormal matrices in the set are different (and may be pseudo-random) with respect to each other. For example, the orthonornal matrices may be defined to provide good performance for different channel conditions, e.g., low and high SNR conditions, low and high mobility, and so on. One orthonormal matrix may be selected for all assigned subcarriers, for each assigned subcarrier, and so on. The matrix selection may be made (1) by the transmitter with or without feedback from a receiver or (2) by the receiver and sent back to the transmitter. The matrix selection may be made based on various factors such as, e.g., the channel conditions, mobility, uplink resources, and so on. In general, the particular entry or entries in the codebook to use for transmission may be selected either autonomously by the transmitter or based on feedback from the receiver.
  • [0082]
    The transmission schemes described herein has the following desirable features:
      • Flexibility to easily select the number of virtual antennas;
      • Flexibility to send any number of output symbols up to the number of available virtual antennas; and
      • Utilization of all T transmit antennas for transmission regardless of the number of output symbols being sent and the number of available virtual antennas.
  • [0086]
    The number of virtual antennas (V) may be selected to support the desired spatial multiplexing order (M), to achieve the desired spatial diversity order (D), and to obtain the desired channel estimation overhead order (C). The number of virtual antennas may be selected autonomously by the transmitter or based on a feedback from the receiver. The desired number of virtual antennas may readily be obtained by defining the orthonormal matrix U with the proper number of columns.
  • [0087]
    The spatial multiplexing order is limited by the number of transmit antennas and the number of receive antennas, or M≦min {T, R}. A higher spatial multiplexing order may be desirable in certain scenarios (e.g., high SNR conditions) and if supported by the receiver. A lower spatial multiplexing order (e.g., M=1) may be desirable in other scenarios (e.g., low SNR conditions) or if a higher spatial multiplexing order is not supported by the receiver. The spatial multiplexing order may be dynamically selected based on the channel conditions and/or other factors. For example, the spatial multiplexing order may be set to one if the SNR is less than a first threshold, set to two if the SNR is between the first threshold and a second threshold, set to three if the SNR is between the second threshold and a third threshold, and so on. The number of virtual antennas is selected to be equal to or greater than the spatial multiplexing order, or V≧M.
  • [0088]
    In general, a higher spatial diversity order is desirable in order to improve performance, and a lower channel estimation overhead order is desirable in order to reduce the amount of link resources used to transmit a pilot for channel estimation. The channel estimation overhead order is closely related to the spatial diversity order, and both are determined by the number of virtual antennas. Hence, the number of virtual antennas may be dynamically selected based on the desired spatial diversity order, the desired channel estimation overhead order, the channel conditions, and/or other factors.
  • [0089]
    The number of virtual antennas may be selected in various manners. In an embodiment, the number of virtual antennas is set equal to the spatial multiplexing order, or V=M. In another embodiment, the number of virtual antennas is set to a largest possible value such that the link resources used for pilot transmission is maintained within a predetermined percentage of the total link resources. In yet another embodiment, the number of virtual antennas is set based on the channel conditions. For example, one virtual antenna may be defined if the SNR is less than a first value, two virtual antennas may be defined if the SNR is between the first value and a second value, and so on.
  • [0090]
    The transmission schemes described herein may be used with various subcarrier structures, some of which are described below. The following description assumes that the K total subcarriers are usable for transmission and are given indices of 1 through K.
  • [0091]
    FIG. 6A shows an interlace subcarrier structure 600. For this subcarrier structure, the K total subcarriers are arranged into S non-overlapping interlaces, each interlace contains N subcarriers that are uniformly distributed across the K total subcarriers, and consecutive subcarriers in each interlace are spaced apart by S subcarriers, where K=SN. Interlace u contains subcarrier u as the first subcarrier, where u ∈ {1, . . . , S}.
  • [0092]
    FIG. 6B shows a block subcarrier structure 610. For this subcarrier structure, the K total subcarriers are arranged into S non-overlapping blocks, with each block containing N adjacent subcarriers, where K=SN. Block v contains subcarriers vN+1 through (v+1)N, where v ∈ {1, . . . , S}.
  • [0093]
    FIG. 6C shows a group subcarrier structure 620. For this subcarrier structure, the K total subcarriers are arranged into S non-overlapping groups, each group contains G subgroups that are distributed across the system bandwidth, and each subgroup contains L adjacent subcarriers, where K=SN and N=GL. The K total subcarriers may be partitioned into G frequency ranges, with each frequency range containing SL consecutive subcarriers. Each frequency range is further partitioned into S subgroups, with each subgroup containing L consecutive subcarriers. For each frequency range, the first L subcarriers are allocated to group 1, the next L subcarriers are allocated to group 2, and so on, and the last L subcarriers are allocated to group S. Each group contains G subgroups of L consecutive subcarriers, or a total of N=GL subcarriers.
  • [0094]
    In general, the transmission techniques described herein may be used for any subcarrier structure with any number of subcarrier sets. Each subcarrier set may include any number of subcarriers that may be arranged in any manner. For example, a subcarrier set may be equal to an interlace, a subcarrier block, a subcarrier group, and so on. For each subcarrier set, (1) the subcarriers in the set may be uniformly or non-uniformly distributed across the system bandwidth, (2) the subcarriers in the set may be adjacent to one another in one group, or (3) the subcarriers in the set may be distributed in multiple groups, where each group may be located anywhere within the system bandwidth and may contain one or multiple subcarriers.
  • [0095]
    For all of the subcarrier structures described above, different receivers may be assigned different subcarrier sets, and the transmitter may transmit data to each receiver on its assigned subcarrier set. The transmitter may use the same orthonormal matrix U for all receivers, a different orthonormal matrix for each receiver, a different orthonormal matrix for each subcarrier set, a different orthonormal matrix for each subcarrier, and so on.
  • [0096]
    The transmission techniques described herein may be used with or without frequency hopping. With frequency hopping, the data transmission hops from subcarrier to subcarrier in a pseudo-random or deterministic manner over time, which allows the data transmission to better withstand deleterious channel conditions such as narrowband interference, jamming, fading, and so on. Frequency hopping can provide frequency diversity and interference randomization. A receiver may be assigned a traffic channel that is associated with a hop pattern that indicates which subcarrier set(s), if any, to use in each time slot. A hop pattern is also called a frequency hopping pattern or sequence. A time slot is the amount of time spent on a given subcarrier set and is also called a hop period. The hop pattern may select different subcarrier sets in different time slots in a pseudo-random or deterministic manner.
  • [0097]
    FIG. 7 shows an exemplary frequency hopping scheme 700. In FIG. 7, traffic channel 1 is mapped to a specific sequence of time-frequency blocks. Each time-frequency block is a specific subcarrier set in a specific time slot. In the example shown in FIG. 7, traffic channel 1 is mapped to subcarrier set 1 in time slot 1, subcarrier set 4 in time slot 2, and so on. Traffic channels 2 through S may be mapped to vertically and circularly shifted versions of the time-frequency block sequence for traffic channel 1. For example, traffic channel 2 may be mapped to subcarrier set 2 in time slot 1, subcarrier set 5 in time slot 2, and so on.
  • [0098]
    Frequency hopping may be used with any of the subcarrier structures shown in FIGS. 6A through 6C. For example, a symbol rate hopping scheme may be defined in which each time-frequency block is a specific interlace in one symbol period. For this hopping scheme, the assigned subcarriers span across the entire system bandwidth and change from symbol period to symbol period. As another example, a block hopping scheme may be defined in which each time-frequency block is a specific subcarrier block in a time slot of multiple symbol periods. For this hopping scheme, the assigned subcarriers are contiguous and fixed for an entire time slot but changes from time slot to time slot. For the block hopping scheme, the spatial multiplexing order may be set equal to the number of virtual antennas, so that constant interference may be observed on any given time-frequency block in any sector for a system with synchronous sectors. Other hopping scheme may also be defined.
  • [0099]
    Pilot may be transmitted in various manners with the subcarrier structures described above. Some exemplary pilot schemes for symbol rate hopping and block hopping are described below.
  • [0100]
    FIG. 8 shows an exemplary pilot scheme 800 for symbol rate hopping. For pilot scheme 800, the transmitter transmits a common pilot on one interlace from virtual antenna 1 in each symbol period. The transmitter may transmit the common pilot on different interlaces in different symbol periods, as shown in FIG. 8. Such a staggered pilot allows a receiver to sample the frequency spectrum on more subcarriers and to derive a longer channel impulse response estimate. The transmitter may also transmit an auxiliary pilot on one or more interlaces from the remaining virtual antennas to allow MIMO receivers to estimate the channel response for all virtual antennas used for transmission. For the embodiment shown in FIG. 8, the transmitter transmits the auxiliary pilot on one interlace in each symbol period and cycles through virtual antennas 2 through V in V−1 different symbol periods. For the case with V=4 as shown in FIG. 8, the transmitter transmits the auxiliary pilot from virtual antenna 2 in symbol period n+1, then from virtual antenna 3 in symbol period n+2, then from virtual antenna 4 in symbol period n+3, then from virtual antenna 2 in symbol period n+4, and so on.
  • [0101]
    The transmitter may transmit the common and auxiliary pilots in other manners. In another embodiment, the auxiliary pilot is staggered and sent on different sets of subcarriers. In yet another embodiment, the common pilot is sent on one or more subcarrier sets that are pseudo-random (or have random offsets) with respect to the one or more subcarrier sets used for the auxiliary pilot.
  • [0102]
    The transmitter may transmit the common pilot for MIMO, SIMO and SISO receivers and may transmit the auxiliary pilot only when MIMO receivers are present. The MIMO, SIMO and SISO receivers may use the common pilot to derive a channel estimate for the K total subcarriers of virtual antenna 1. A MIMO receiver may use the auxiliary pilot to derive channel estimates for virtual antennas 2 through V.
  • [0103]
    FIG. 9A shows an exemplary pilot scheme 910 for block hopping. For the embodiment shown in FIG. 9A, a time-frequency block is composed of 16 adjacent subcarriers k+1 through k+16 and further spans 8 symbol periods n+1 through n+8. For pilot scheme 910, the transmitter transmits a dedicated pilot on subcarriers k+3, k+9 and k+15 in each of symbol periods n+1 through n+3 and n+6 through n+8, or six strips of three pilot symbols. Each pilot symbol may be sent from any virtual antenna. For example, if V=3, then the transmitter may transmit the pilot from virtual antenna 1 in symbol periods n+1 and n+6, from virtual antenna 2 in symbol periods n+2 and n+7, and from virtual antenna 3 in symbol periods n+3 and n+8.
  • [0104]
    FIG. 9B shows an exemplary pilot scheme 920 for block hopping. For pilot scheme 920, the transmitter transmits a dedicated pilot on subcarriers k+3, k+9 and k+15 in each of symbol periods n+1 through n+8, or three strips of eight pilot symbols. Each pilot symbol may be sent from any virtual antenna. For example, if V=4, then the transmitter may transmit the pilot from virtual antenna 1 in symbol periods n+1 and n+5, from virtual antenna 2 in symbol periods n+2 and n+6, from virtual antenna 3 in symbol periods n+3 and n+7, and from virtual antenna 4 in symbol periods n+4 and n+8.
  • [0105]
    FIG. 9C shows an exemplary pilot scheme 930 for block hopping. For pilot scheme 930, the transmitter transmits a dedicated pilot on subcarriers k+1, k+4, k+7, k+10, k+13 and k+16 in each of symbol periods n+1, n+2, n+7 and n+8. Each pilot symbol may be sent from any virtual antenna. For example, the transmitter may transmit the pilot from virtual antenna 1 in symbol period n+1, from virtual antenna 2 in symbol period n+2, from virtual antenna 1 or 3 in symbol period n+7, and from virtual antenna 2 or 4 in symbol period n+8.
  • [0106]
    FIG. 9D shows an exemplary pilot scheme 940 for block hopping. For pilot scheme 940, the transmitter transmits a staggered pilot on three subcarriers in each symbol period and on different pilot subcarriers in different symbol periods. Each pilot symbol may be sent from any virtual antenna. For example, the transmitter may transmit the pilot from a different virtual antenna in each symbol period and may cycle through the V virtual antennas in V symbol periods.
  • [0107]
    In general, for the block hopping scheme, the transmitter may transmit a pilot in each time-frequency block such that a receiver is able to derive a channel estimate for each virtual antenna used for transmission. FIGS. 9A through 9D show four exemplary pilot patterns that may be used. Other pilot patterns may also be defined and used for pilot transmission.
  • [0108]
    For both symbol rate hopping and block hopping, the transmitter may transmit the pilot from any number of virtual antennas, may use any number of pilot subcarriers for each virtual antenna, and may use any amount of transmit power for each virtual antenna. If the pilot is sent from multiple virtual antennas, then the transmitter may use the same or different numbers of subcarriers for these virtual antennas and may transmit the pilot at the same or different power levels for the virtual antennas. The transmitter may or may not stagger the pilot for each virtual antenna. The transmitter may transmit the pilot on more subcarriers to allow a receiver to obtain more “look” of the wireless channel in the frequency domain and to derive a longer channel impulse response estimate. The transmitter may transmit the pilot on all pilot subcarriers from one virtual antenna in each symbol period, as described above. Alternatively, the transmitter may transmit the pilot from multiple virtual antennas on multiple subsets of subcarriers in a given symbol period.
  • [0109]
    In an embodiment, the transmitter transmits the pilot from the virtual antennas, as described above for FIGS. 8 through 9D. In another embodiment, the transmitter transmits the pilot from the physical antennas, without applying the orthonormal matrix U or the permutation matrix P(k). For this embodiment, a receiver may estimate the actual channel response based on the pilot and may then derive an effective channel response estimate based on the actual channel response estimate and the orthonormal and permutation matrices.
  • [0110]
    FIG. 10 shows a process 1000 for transmitting data and pilot to one or more receivers. The processing for each receiver may be performed as follows. The set of subcarriers assigned to the receiver and the spatial multiplexing order (M) for the receiver are determined, where M≧1 (block 1012). For each assigned subcarrier, M virtual antennas are selected for use from among V virtual antennas formed with V columns of the orthonormal matrix U, where V≧M (block 1014). The M virtual antennas for each assigned subcarrier may be selected in various manners, as described above. The output symbols for the receiver are mapped to the M virtual antennas selected for each assigned subcarrier by applying the orthonormal matrix (block 1016). The mapped output symbols (or transmit symbols) are provided for transmission from T transmit antennas, where T≧V (block 1018).
  • [0111]
    Pilot symbols are also mapped to the virtual antennas used for transmission (block 1020). For example, pilot symbols for a common pilot may be mapped to the first virtual antenna on a first set of pilot subcarriers, and pilot symbols for an auxiliary pilot may be mapped to the remaining virtual antennas on a second set of pilot subcarriers.
  • [0112]
    If there are multiple receivers, then the same or different spatial multiplexing orders may be used for these receivers. Furthermore, data may be sent simultaneously on different subcarrier sets to multiple receivers. For example, data may be sent from one virtual antenna on a first subcarrier set to a SIMO or SISO receiver, from multiple virtual antennas on a second subcarrier set to a MIMO receiver, and so on. In any case, the transmit symbols for all receivers are demultiplexed to the T transmit antennas (block 1022). For each transmit antenna, the transmit symbols for each receiver are mapped to the subcarriers assigned to that receiver (also block 1022). Transmission symbols are then generated for each transmit antenna based on the transmit symbols for that transmit antenna and using, e.g., OFDM or SC-FDMA (block 1024). Different cyclic delays may be applied for the T transmit antennas, e.g., by circularly delaying the transmission symbols for each transmit antenna by a different amount (block 1026).
  • [0113]
    For block 1016 in FIG. 10, the output symbol(s) for each subcarrier assigned to each receiver are mapped to the T transmit antennas based on M mapping patterns selected from among V mapping patterns available for use. Each mapping pattern indicates a specific mapping of an output symbol to the T transmit antennas. The V mapping patterns may be formed by V columns of an orthonormal matrix or in other manners. Different mapping patterns may be selected for different subcarriers in a given symbol period and/or different symbol periods, e.g., based on a predetermined pattern. The predetermined pattern may be defined by a permutation matrix or in some other manner. The predetermined pattern may cycle through the V available mapping patterns in different subcarriers and/or symbol periods.
  • [0114]
    FIG. 11 shows an embodiment of an apparatus 1100 for transmitting data and pilot to one or more receivers. Apparatus 1100 includes means for determining the set of subcarriers assigned to each receiver and the spatial multiplexing order (M) for each receiver (block 1112), means for selecting M virtual antennas for use from among V virtual antennas for each subcarrier assigned to each receiver (block 1114), means for mapping the output symbols for each receiver to the virtual antennas selected for each subcarrier assigned to the receiver (e.g., by applying selected columns of an orthonormal matrix or selected mapping patterns) (block 1116), means for providing the mapped output symbols (or transmit symbols) for transmission from T transmit antennas (block 1118), means for mapping pilot symbols to the virtual antennas used for transmission (block 1120), means for demultiplexing the transmit symbols for each receiver to the assigned subcarriers of the T transmit antennas (block 1122), means for generating transmission symbols for each transmit antenna, e.g., using OFDM or SC-FDMA (block 1124), and means for applying different cyclic delays for the T transmit antennas (block 1126).
  • [0115]
    FIG. 12 shows a block diagram of an embodiment of base station 110, single-antenna terminal 120 x, and multi-antenna terminal 120 y. At base station 110, a transmit (TX) data processor 1210 receives data for one or more terminals, processes (e.g., encodes, interleaves, and symbol maps) the data based on one or more coding and modulation schemes, and provides modulation symbols. TX data processor 1210 typically processes the data for each terminal separately based on a coding and modulation scheme selected for that terminal. If system 100 utilizes SC-FDMA, then TX data processor 1210 may perform FFT/DFT on the modulation symbols for each terminal to obtain frequency-domain symbols for that terminal. TX data processor 1210 obtains output symbols for each terminal (which may be modulation symbols for OFDM or frequency-domain symbols for SC-FDMA) and multiplexes the output symbols for the terminal onto the subcarriers and virtual antennas used for that terminal. TX data processor 1210 further multiplexes pilot symbols onto the subcarriers and virtual antennas used for pilot transmission.
  • [0116]
    A TX spatial processor 1220 receives the multiplexed output symbols and pilot symbols, performs spatial processing for each subcarrier, e.g., as shown in equation (3) or (7), and provides transmit symbols for the T transmit antennas. A modulator (Mod) 1222 processes the transmit symbols for each transmit antenna, e.g., for OFDM, SC-FDMA, or some other modulation technique, and generates an output sample stream for that transmit antenna. Since TX spatial processor 1220 performs spatial processing for each subcarrier, the SC-FDMA modulation is divided into two parts that are performed by TX data processor 1210 and modulator 1222. Modulator 1222 provides T output sample streams to T transmitter units (TMTR) 1224 a through 1224 t. Each transmitter unit 1224 processes (e.g., converts to analog, amplifies, filters, and frequency upconverts) its output sample stream and generates a modulated signal. T modulated signals from transmitter units 1224 a through 1224 t are transmitted from T antennas 112 a through 112 t, respectively.
  • [0117]
    At each terminal 120, one or multiple antennas 122 receive the modulated signals transmitted by base station 110, and each antenna provides a received signal to a respective receiver unit (RCVR) 1254. Each receiver unit 1254 processes (e.g., amplifies, filters, frequency downconverts, and digitalizes) its receive signal and provides received samples to a demodulator (Demod) 1256. Demodulator 1256 processes the received samples for each receive antenna 122 (e.g., based on OFDM, SC-FDMA, or some other modulation technique), obtains frequency-domain received symbols for the K total subcarriers, provides received symbols for the assigned subcarriers, and provides received pilot symbols for the subcarriers used for pilot transmission.
  • [0118]
    For single-antenna terminal 120 x, a data detector 1260 x obtains received symbols from demodulator 1256 x, derives channel estimates for the assigned subcarriers based on the received pilot symbols, and performs data detection (e.g., equalization) on the received symbols based on the channel estimates to obtain detected symbols, which are estimates of the output symbols transmitted to terminal 120 x. For multi-antenna terminal 120 y, a receive (RX) spatial processor 1260 y obtains received symbols from demodulator 1256 y, derives channel estimates for the assigned subcarriers based on the received pilot symbols, and performs receiver spatial processing on the received symbols based on the channel estimates to obtain detected symbols. RX spatial processor 1260 y may implement a minimum mean square error (MMSE) technique, a zero-forcing (ZF) technique, a maximal ratio combining (MRC) technique, a successive interference cancellation technique, or some other receiver processing technique. For each terminal, an RX data processor 1262 processes (e.g., symbol demaps, deinterleaves, and decodes) the detected symbols and provides decoded data for the terminal. In general, the processing by each terminal 120 is complementary to the processing by base station 110.
  • [0119]
    Each terminal 120 may generate feedback information for the data transmission to that terminal. For example, each terminal 120 may estimate the SNRs for the virtual antennas, e.g., based on the received pilot symbols. Each terminal 120 may select one or more coding and modulation schemes, one or more packet formats, one or more virtual antennas to use for data transmission, one or more orthonormal matrices, and so on based on the SNR estimates and/or other information. Each terminal 120 may also generate acknowledgments (ACKs) for correctly received data packets. The feedback information may include the SNR estimates, the selected coding and modulation schemes, the selected virtual antenna(s), the selected orthonormal matrix(ces), the selected subcarrier(s), ACKs, information used for power control, some other information, or any combination thereof. The feedback information is processed by a TX data processor 1280, further processed by a TX spatial processor 1282 if multiple antennas are present, modulated by a modulator 1284, conditioned by transmitter unit(s) 1254, and transmitted via antenna(s) 122 to base station 110. At base station 110, the modulated signals transmitted by terminals 120 x and 120 y are received by antennas 112, conditioned by receiver units 1224, and processed by a demodulator 1240, an RX spatial processor 1242, and an RX data processor 1244 to recover the feedback information sent by the terminals. A controller/processor 1230 uses the feedback information to determine the data rates and coding and modulation schemes to use for the data transmission to each terminal as well as to generate various controls for TX data processor 1210 and TX spatial processor 1220.
  • [0120]
    Controllers/processors 1230, 1270 x and 1270 y control the operation of various processing units at base station 110 and terminals 120 x and 120 y, respectively. Memory units 1232, 1272 x and 1272 y store data and program codes used by base station 110 and terminals 120 x and 120 y, respectively. Controller/processor 1230 may implement parts of FIGS. 10 and 11 and may (1) assign subcarriers and select the spatial multiplexing order for each terminal (block 1012 in FIG. 10) and (2) select the virtual antennas for each subcarrier assigned to each terminal (block 1214 in FIG. 10). TX data processor 1220 may implement parts of FIGS. 10 and 11 and perform the processing shown in blocks 1116 through 1126 in FIG. 10.
  • [0121]
    For clarity, much of the description above is for a system with K total subcarriers. The transmission techniques described herein may also be used for a system with a single subcarrier. For such a system, k in the description above may be an index for symbol period instead of subcarrier.
  • [0122]
    The transmission techniques described herein may be implemented by various means. For example, these techniques may be implemented in hardware, firmware, software, or a combination thereof. For a hardware implementation, the processing units at a transmitter may be implemented within one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, micro-controllers, microprocessors, electronic devices, other electronic units designed to perform the functions described herein, or a combination thereof. The processing units at a receiver may also be implemented within one or more ASICs, DSPs, processors, and so on.
  • [0123]
    For a software implementation, the transmission techniques may be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. The software codes may be stored in a memory (e.g., memory 1230, 1272 x or 1272 y in FIG. 12) and executed by a processor (e.g., processor 1232, 1270 x or 1270 y). The memory may be implemented within the processor or external to the processor.
  • [0124]
    The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US5594738 *Jun 23, 1995Jan 14, 1997Motorola, Inc.Time slot allocation method
US5604744 *Oct 31, 1994Feb 18, 1997Telefonaktiebolaget Lm EricssonDigital control channels having logical channels for multiple access radiocommunication
US5726978 *Jun 22, 1995Mar 10, 1998Telefonaktiebolaget L M Ericsson Publ.Adaptive channel allocation in a frequency division multiplexed system
US5870393 *Jul 11, 1996Feb 9, 1999Hitachi, Ltd.Spread spectrum communication system and transmission power control method therefor
US6016123 *Jun 24, 1997Jan 18, 2000Northern Telecom LimitedBase station antenna arrangement
US6038450 *Sep 12, 1997Mar 14, 2000Lucent Technologies, Inc.Soft handover system for a multiple sub-carrier communication system and method thereof
US6169910 *Jun 30, 1999Jan 2, 2001Focused Energy Holding Inc.Focused narrow beam communication system
US6175650 *Jan 26, 1998Jan 16, 2001Xerox CorporationAdaptive quantization compatible with the JPEG baseline sequential mode
US6176550 *Apr 7, 2000Jan 23, 2001Steelcase Development Inc.Adjustable armrest for chairs
US6198775 *Apr 28, 1998Mar 6, 2001Ericsson Inc.Transmit diversity method, systems, and terminals using scramble coding
US6337657 *Mar 9, 2000Jan 8, 2002Topcon Positioning Systems, Inc.Methods and apparatuses for reducing errors in the measurement of the coordinates and time offset in satellite positioning system receivers
US6363060 *Jun 30, 1999Mar 26, 2002Qualcomm IncorporatedMethod and apparatus for fast WCDMA acquisition
US6507601 *Feb 8, 2001Jan 14, 2003Golden Bridge TechnologyCollision avoidance
US6529525 *May 19, 2000Mar 4, 2003Motorola, Inc.Method for supporting acknowledged transport layer protocols in GPRS/edge host application
US6535666 *Jan 18, 2000Mar 18, 2003Trw Inc.Method and apparatus for separating signals transmitted over a waveguide
US6539008 *Nov 2, 1998Mar 25, 2003Samsung Electronics, Co., Ltd.Method for inserting power control bits in the CDMA mobile system
US6539213 *Jun 14, 1999Mar 25, 2003Time Domain CorporationSystem and method for impulse radio power control
US6674787 *May 19, 2000Jan 6, 2004Interdigital Technology CorporationRaising random access channel packet payload
US6675012 *Aug 31, 2001Jan 6, 2004Nokia Mobile Phones, Ltd.Apparatus, and associated method, for reporting a measurement summary in a radio communication system
US6690951 *Dec 20, 1999Feb 10, 2004Telefonaktiebolaget Lm Ericsson (Publ)Dynamic size allocation system and method
US6701165 *Jun 21, 2000Mar 2, 2004Agere Systems Inc.Method and apparatus for reducing interference in non-stationary subscriber radio units using flexible beam selection
US6704571 *Oct 17, 2000Mar 9, 2004Cisco Technology, Inc.Reducing data loss during cell handoffs
US6711400 *Oct 14, 1999Mar 23, 2004Nokia CorporationAuthentication method
US6842487 *Sep 22, 2000Jan 11, 2005Telefonaktiebolaget Lm Ericsson (Publ)Cyclic delay diversity for mitigating intersymbol interference in OFDM systems
US6850481 *Dec 29, 2000Feb 1, 2005Nortel Networks LimitedChannels estimation for multiple input—multiple output, orthogonal frequency division multiplexing (OFDM) system
US6850509 *Feb 1, 2001Feb 1, 2005Samsung Electronics Co., Ltd.Scheduling apparatus and method for packet data service in a wireless communication system
US6985434 *Dec 29, 2000Jan 10, 2006Nortel Networks LimitedAdaptive time diversity and spatial diversity for OFDM
US6985453 *Feb 15, 2001Jan 10, 2006Qualcomm IncorporatedMethod and apparatus for link quality feedback in a wireless communication system
US6985466 *Nov 9, 1999Jan 10, 2006Arraycomm, Inc.Downlink signal processing in CDMA systems utilizing arrays of antennae
US6985498 *Aug 13, 2003Jan 10, 2006Flarion Technologies, Inc.Beacon signaling in a wireless system
US6987746 *Mar 14, 2000Jan 17, 2006Lg Information & Communications, Ltd.Pilot signals for synchronization and/or channel estimation
US7002900 *Sep 29, 2003Feb 21, 2006Qualcomm IncorporatedTransmit diversity processing for a multi-antenna communication system
US7006848 *Sep 18, 2001Feb 28, 2006Qualcomm IncorporatedMethod and apparatus for utilizing channel state information in a wireless communication system
US7157351 *May 20, 2004Jan 2, 2007Taiwan Semiconductor Manufacturing Co., Ltd.Ozone vapor clean method
US7164649 *Nov 2, 2001Jan 16, 2007Qualcomm, IncorporatedAdaptive rate control for OFDM communication system
US7164696 *Jul 23, 2001Jan 16, 2007Mitsubishi Denki Kabushiki KaishaMulti-carrier CDMA communication device, multi-carrier CDMA transmitting device, and multi-carrier CDMA receiving device
US7170937 *May 1, 2003Jan 30, 2007Texas Instruments IncorporatedComplexity-scalable intra-frame prediction technique
US7177297 *Dec 3, 2003Feb 13, 2007Qualcomm IncorporatedFast frequency hopping with a code division multiplexed pilot in an OFDMA system
US7177351 *Jul 21, 2003Feb 13, 2007Qualcomm, IncorporatedData transmission with non-uniform distribution of data rates for a multiple-input multiple-output (MIMO) system
US7181170 *Dec 22, 2003Feb 20, 2007Motorola Inc.Apparatus and method for adaptive broadcast transmission
US7184713 *Jun 20, 2002Feb 27, 2007Qualcomm, IncorporatedRate control for multi-channel communication systems
US7483408 *Jun 26, 2002Jan 27, 2009Nortel Networks LimitedSoft handoff method for uplink wireless communications
US7483719 *Nov 15, 2004Jan 27, 2009Samsung Electronics Co., Ltd.Method for grouping transmission antennas in mobile communication system including multiple transmission/reception antennas
US7483779 *Feb 3, 2005Jan 27, 2009Jungheinrich AktiengesellschaftMethod for the adjustment of the control current of current-controlled hydraulic valves
US7492788 *Jun 26, 2002Feb 17, 2009Nortel Networks LimitedCommunication of control information in wireless communication systems
US7664061 *Sep 5, 2001Feb 16, 2010Nokia CorporationClosed-loop signaling method for controlling multiple transmit beams and correspondingly adapted transceiver device
US7676007 *Mar 9, 2010Jihoon ChoiSystem and method for interpolation based transmit beamforming for MIMO-OFDM with partial feedback
US8095141 *Jan 10, 2012Qualcomm IncorporatedUse of supplemental assignments
US8098568 *Apr 24, 2009Jan 17, 2012Qualcomm IncorporatedSignaling method in an OFDM multiple access system
US8098569 *Apr 24, 2009Jan 17, 2012Qualcomm IncorporatedSignaling method in an OFDM multiple access system
US20020000948 *Mar 8, 2001Jan 3, 2002Samsung Electronics Co., Ltd.Semi-blind transmit antenna array device using feedback information and method thereof in a mobile communication system
US20020015405 *May 31, 2001Feb 7, 2002Risto SepponenError correction of important fields in data packet communications in a digital mobile radio network
US20020018157 *Sep 24, 2001Feb 14, 2002Semiconductor Energy Laboratory Co., Ltd., A Japanese CorporationLiquid crystal display device and method for fabricating thereof
US20030002464 *Feb 15, 2000Jan 2, 2003Ramin RezaiifarChannel structure for communication systems
US20030020651 *Sep 4, 2002Jan 30, 2003Crilly William J.Wireless packet switched communication systems and networks using adaptively steered antenna arrays
US20030036359 *Apr 30, 2002Feb 20, 2003Dent Paul W.Mobile station loop-back signal processing
US20030040283 *Aug 20, 2002Feb 27, 2003Ntt Docomo, Inc.Radio communication system, communication terminal, and method for transmitting burst signals
US20030043732 *Jun 26, 2001Mar 6, 2003Walton Jay R.Method and apparatus for processing data for transmission in a multi-channel communication system using selective channel transmission
US20030043764 *Aug 21, 2002Mar 6, 2003Samsung Electronics Co., Ltd.Method for allocating HARQ channel number for indicating state information in an HSDPA communication system
US20030073464 *May 28, 2002Apr 17, 2003Giannakis Georgios B.Space-time coded transmissions within a wireless communication network
US20040001429 *Apr 4, 2003Jan 1, 2004Jianglei MaDual-mode shared OFDM methods/transmitters, receivers and systems
US20040001460 *Jun 26, 2002Jan 1, 2004Bevan David Damian NicholasSoft handoff method for uplink wireless communications
US20040002364 *Jan 23, 2003Jan 1, 2004Olav TrikkonenTransmitting and receiving methods
US20040048609 *Nov 30, 2001Mar 11, 2004Minoru KosakaRadio communication system
US20040058687 *Sep 8, 2003Mar 25, 2004Samsung Electronics Co., Ltd.Apparatus and method for transmitting CQI information in a CDMA communication system employing an HSDPA scheme
US20050002412 *Nov 15, 2002Jan 6, 2005Mats SagforsMethod and system of retransmission
US20050002440 *Jul 20, 2004Jan 6, 2005Siavash AlamoutiVertical adaptive antenna array for a discrete multitone spread spectrum communications system
US20050002468 *Jul 29, 2004Jan 6, 2005Walton Jay R.Method and apparatus for processing data in a multiple-input multiple-output (MIMO) communication system utilizing channel state information
US20050003782 *Jun 6, 2003Jan 6, 2005Ola WintzellMethods and apparatus for channel quality indicator determination
US20050008091 *May 19, 2004Jan 13, 2005Mitsubishi Denki Kabushiki KaishaSphere decoding of symbols transmitted in a telecommunication system
US20050009486 *Aug 5, 2004Jan 13, 2005Naofal Al-DhahirFinite-length equalization overmulti-input multi-output channels
US20050013263 *Jan 2, 2004Jan 20, 2005Samsung Electronics Co., Ltd.Apparatus and method for transmitting/receiving uplink data retransmission request in a CDMA communication system
US20050030886 *Sep 16, 2003Feb 10, 2005Shiquan WuOFDM system and method employing OFDM symbols with known or information-containing prefixes
US20050034079 *Jul 30, 2004Feb 10, 2005Duraisamy GunasekarMethod and system for providing conferencing services
US20050041618 *Feb 17, 2004Feb 24, 2005Yongbin WeiExtended acknowledgement and rate control channel
US20050041775 *Aug 22, 2003Feb 24, 2005Batzinger Thomas J.High speed digital radiographic inspection of piping
US20050044206 *Sep 7, 2001Feb 24, 2005Staffan JohanssonMethod and arrangements to achieve a dynamic resource distribution policy in packet based communication networks
US20050047517 *Feb 2, 2004Mar 3, 2005Georgios Giannakis B.Adaptive modulation for multi-antenna transmissions with partial channel knowledge
US20050052991 *Mar 15, 2004Mar 10, 2005Tamer KadousIncremental redundancy transmission in a MIMO communication system
US20050053081 *Sep 7, 2004Mar 10, 2005Telefonaktiebolaget Lm Ericsson (Publ)Acceleration dependent channel switching in mobile telecommunications
US20050053151 *Sep 2, 2004Mar 10, 2005Microsoft CorporationEscape mode code resizing for fields and slices
US20060013285 *Jun 15, 2005Jan 19, 2006Takahiro KobayashiRadio communication apparatus, base station and system
US20060018336 *Dec 22, 2004Jan 26, 2006Arak SutivongEfficient signaling over access channel
US20060018347 *Mar 10, 2005Jan 26, 2006Avneesh AgrawalShared signaling channel for a communication system
US20060018397 *Dec 22, 2004Jan 26, 2006Qualcomm IncorporatedCapacity based rank prediction for MIMO design
US20060029289 *Aug 4, 2005Feb 9, 2006Kabushiki Kaisha ToshibaInformation processing apparatus and method for detecting scene change
US20060034173 *Dec 22, 2004Feb 16, 2006Qualcomm IncorporatedMethod of providing a gap indication during a sticky assignment
US20060039332 *Aug 17, 2004Feb 23, 2006Kotzin Michael DMechanism for hand off using subscriber detection of synchronized access point beacon transmissions
US20060039344 *Aug 20, 2004Feb 23, 2006Lucent Technologies, Inc.Multiplexing scheme for unicast and broadcast/multicast traffic
US20060039500 *Aug 17, 2005Feb 23, 2006Samsung Electronics Co., Ltd.Apparatus and method for space-time-frequency block coding for increasing performance
US20060045003 *Aug 26, 2005Mar 2, 2006Samsung Electronics Co., Ltd.Method for detecting initial operation mode in wireless communication system employing OFDMA scheme
US20060050770 *Jan 24, 2005Mar 9, 2006Qualcomm IncorporatedReceiver structures for spatial spreading with space-time or space-frequency transmit diversity
US20070004430 *Jul 5, 2006Jan 4, 2007Samsung Electronics Co., Ltd.Position measuring system and method using wireless broadband (WIBRO) signal
US20070005749 *Jun 9, 2006Jan 4, 2007Qualcomm IncorporatedRobust rank perdiction for a MIMO system
US20070019596 *Jun 13, 2006Jan 25, 2007Barriac Gwendolyn DLink assignment messages in lieu of assignment acknowledgement messages
US20070025345 *Jul 27, 2005Feb 1, 2007Bachl Rainer WMethod of increasing the capacity of enhanced data channel on uplink in a wireless communications systems
US20070041311 *Aug 18, 2005Feb 22, 2007Baum Kevin LMethod and apparatus for pilot signal transmission
US20070110172 *Dec 3, 2004May 17, 2007Australian Telecommunications Cooperative ResearchChannel estimation for ofdm systems
US20090022098 *Oct 23, 2006Jan 22, 2009Robert NovakMultiplexing schemes for ofdma
US20090041150 *Apr 25, 2008Feb 12, 2009Jiann-An TsaiMethod and apparatus of codebook-based single-user closed-loop transmit beamforming (SU-CLTB) for OFDM wireless systems
US20100002570 *Jan 7, 2010Walton J RTransmit diversity and spatial spreading for an OFDM-based multi-antenna communication system
US20120002623 *Jan 5, 2012Qualcomm IncorporatedScalable frequency band operation in wireless communication systems
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US7366249 *Aug 26, 2004Apr 29, 2008Mitsubishi Denki Kabushiki KaishaMethod for transmitting optimally interleaved data in a MIMO telecommunication system
US7376203 *Dec 1, 2005May 20, 2008Mitsubishi Denki Kabushiki KaishaMethod for transmitting uniformly distributed data in a MIMO telecommunication system
US7729433 *Nov 29, 2006Jun 1, 2010Motorola, Inc.Method and apparatus for hybrid CDM OFDMA wireless transmission
US7729439 *Sep 18, 2007Jun 1, 2010Marvell World Trade Ltd.Calibration correction for implicit beamforming in a wireless MIMO communication system
US7764705 *Jul 27, 2010Nokia CorporationInterference cancellation unit and interference cancellation method
US7782972 *Aug 24, 2010Realtek Semiconductor Corp.Apparatus and method for selecting antennas in MIMO multi-carrier system
US7787554 *Jan 25, 2007Aug 31, 2010Marvell International Ltd.Beamforming to a subset of receive antennas in a wireless MIMO communication system
US7839944 *Nov 23, 2010Lg Electronics, Inc.Method of performing phase shift-based precoding and an apparatus for supporting the same in a wireless communication system
US7881395Feb 1, 2011Lg Electronics, Inc.Method of transmitting using phase shift-based precoding and an apparatus for implementing the same in a wireless communication system
US7885349Sep 23, 2009Feb 8, 2011Lg Electronics Inc.Data transmitting and receiving method using phase shift based precoding and transceiver supporting the same
US7899132Mar 1, 2011Lg Electronics Inc.Data transmitting and receiving method using phase shift based precoding and transceiver supporting the same
US7957483 *Jun 7, 2011Samsung Electronics Co., LtdTransmission/reception apparatus and method for supporting MIMO technology in a forward link of a high rate packet data system
US7961808Jun 14, 2011Lg Electronics Inc.Data transmitting and receiving method using phase shift based precoding and transceiver supporting the same
US7970074Sep 12, 2008Jun 28, 2011Lg Electronics Inc.Data transmitting and receiving method using phase shift based precoding and transceiver supporting the same
US7978781May 21, 2010Jul 12, 2011Marvell World Trade Ltd.Calibration correction for implicit beamforming in a wireless MIMO communication system
US8000401 *Aug 16, 2011Lg Electronics Inc.Signal generation using phase-shift based pre-coding
US8036286 *May 29, 2007Oct 11, 2011Lg Electronics, Inc.Signal generation using phase-shift based pre-coding
US8036297 *Sep 17, 2007Oct 11, 2011Samsung Electronics Co., LtdApparatus and method for space-time coding in multiple-antenna system
US8073068 *Mar 15, 2006Dec 6, 2011Qualcomm IncorporatedSelective virtual antenna transmission
US8135085Dec 16, 2010Mar 13, 2012Lg Electroncis Inc.Method of transmitting using phase shift-based precoding and an apparatus for implementing the same in a wireless communication system
US8139672Mar 27, 2006Mar 20, 2012Qualcomm IncorporatedMethod and apparatus for pilot communication in a multi-antenna wireless communication system
US8151156 *Apr 6, 2007Apr 3, 2012Lg Electronics Inc.Repetitive transmissions in multi-carrier based wireless access techniques
US8208576Jun 26, 2012Lg Electronics Inc.Data transmitting and receiving method using phase shift based precoding and transceiver supporting the same
US8213530Apr 22, 2011Jul 3, 2012Lg Electronics Inc.Method of transmitting using phase shift-based precoding and an apparatus for implementing the same in a wireless communication system
US8284718 *Nov 27, 2008Oct 9, 2012Panasonic CorporationWireless communication system having MIMO communication capability and having multiple receiving antennas to be selected
US8284849 *Sep 16, 2009Oct 9, 2012Lg Electronics Inc.Phase shift based precoding method and transceiver for supporting the same
US8284853 *Oct 9, 2012Samsung Electronics Co., Ltd.Apparatus and method for spatial multiplexing with backward compatibility in a multiple input multiple output wireless communication system
US8284865Oct 9, 2012Lg Electronics Inc.Data transmitting and receiving method using phase shift based precoding and transceiver supporting the same
US8320338Jun 6, 2011Nov 27, 2012Samsung Electronics Co., LtdTransmission/reception apparatus and method for supporting MIMO technology in a forward link of a high rate packet data system
US8325852May 29, 2008Dec 4, 2012Samsung Electronics Co., Ltd.CDD precoding for open loop SU MIMO
US8331464 *May 29, 2007Dec 11, 2012Lg Electronics Inc.Phase shift based precoding method and transceiver for supporting the same
US8355666 *Jan 15, 2013Qualcomm IncorporatedApparatus and method for interference-adaptive communications
US8359510Feb 21, 2012Jan 22, 2013Lg Electronics Inc.Repetitive transmissions in multi-carrier based wireless access techniques
US8391397Mar 5, 2013Marvell World Trade Ltd.Calibration correction for implicit beamforming in a wireless MIMO communication system
US8406333 *Nov 12, 2008Mar 26, 2013Lg Electronics Inc.Method for transmitting signal in multiple antenna system
US8416757 *Apr 9, 2013Sharp Kabushiki KaishaRadio transmission device
US8422478 *Apr 16, 2013Sharp Kabushiki KaishaRadio transmission device
US8446892May 21, 2013Qualcomm IncorporatedChannel structures for a quasi-orthogonal multiple-access communication system
US8462859Jun 11, 2013Qualcomm IncorporatedSphere decoding apparatus
US8477684Nov 20, 2007Jul 2, 2013Qualcomm IncorporatedAcknowledgement of control messages in a wireless communication system
US8503560 *Jul 3, 2007Aug 6, 2013Samsung Electronics Co., LtdSystem and method for performing precoding in a wireless communication system
US8503572 *Feb 1, 2010Aug 6, 2013Qualcomm IncorporatedAntenna virtualization in a wireless communication environment
US8547951Jun 1, 2010Oct 1, 2013Qualcomm IncorporatedChannel structures for a quasi-orthogonal multiple-access communication system
US8553521 *Sep 25, 2006Oct 8, 2013Interdigital Technology CorporationMIMO beamforming-based single carrier frequency division multiple access system
US8553819 *Apr 16, 2012Oct 8, 2013Broadcom CorporationMethod and system for communication in a wireless orthogonal frequency division multiplexing (OFDM) communication system
US8565194Oct 27, 2005Oct 22, 2013Qualcomm IncorporatedPuncturing signaling channel for a wireless communication system
US8582509Oct 27, 2005Nov 12, 2013Qualcomm IncorporatedScalable frequency band operation in wireless communication systems
US8599945Jun 9, 2006Dec 3, 2013Qualcomm IncorporatedRobust rank prediction for a MIMO system
US8599946 *Sep 5, 2007Dec 3, 2013Lg Electronics Inc.Method of transmitting feedback information for precoding and precoding method
US8599950 *Jan 17, 2008Dec 3, 2013Alcatel LucentMethod and device for cyclic delay mapping for the signal in the multi-antenna transmitter
US8605811 *Feb 28, 2012Dec 10, 2013Huawei Technologies Co., Ltd.Method, apparatus, and system for data signal transmission in multi-antenna system
US8611284Mar 7, 2006Dec 17, 2013Qualcomm IncorporatedUse of supplemental assignments to decrement resources
US8644292Oct 27, 2005Feb 4, 2014Qualcomm IncorporatedVaried transmission time intervals for wireless communication system
US8670500May 17, 2011Mar 11, 2014Lg Electronics Inc.Data transmitting and receiving method using phase shift based precoding and transceiver supporting the same
US8681764Nov 22, 2010Mar 25, 2014Qualcomm IncorporatedFrequency division multiple access schemes for wireless communication
US8687480Jun 12, 2009Apr 1, 2014Apple Inc.Systems and methods for SC-FDMA transmission diversity
US8693405Oct 27, 2005Apr 8, 2014Qualcomm IncorporatedSDMA resource management
US8724740Aug 22, 2006May 13, 2014Qualcomm IncorporatedSystems and methods for reducing uplink resources to provide channel performance feedback for adjustment of downlink MIMO channel data rates
US8737506 *Dec 29, 2010May 27, 2014Sprint Communications Company L.P.Determination of transmit diversity transmission delays
US8750913 *Dec 13, 2011Jun 10, 2014Telefonaktiebolaget L M Ericsson (Publ)Asymmetric resource sharing using stale feedback
US8761287Aug 30, 2010Jun 24, 2014Marvell International Ltd.Beamforming to a subset of receive antennas in a wireless MIMO communication system
US8761298Sep 24, 2009Jun 24, 2014Samsung Electronics Co., Ltd.Apparatus and method for transmitting and receiving signal in multiple input multiple output system
US8774137Nov 26, 2012Jul 8, 2014Samsung Electronics Co., LtdTransmission/reception apparatus and method for supporting MIMO technology in a forward link of a high rate packet data system
US8780771 *Feb 5, 2008Jul 15, 2014Qualcomm IncorporatedCyclic delay diversity and precoding for wireless communication
US8787347Feb 19, 2009Jul 22, 2014Qualcomm IncorporatedVaried transmission time intervals for wireless communication system
US8798201Sep 5, 2007Aug 5, 2014Qualcomm IncorporatedCodeword permutation and reduced feedback for grouped antennas
US8811371Sep 22, 2009Aug 19, 2014Qualcomm IncorporatedTransmit diversity scheme for uplink data transmissions
US8831607Jan 4, 2007Sep 9, 2014Qualcomm IncorporatedReverse link other sector communication
US8838051Feb 19, 2009Sep 16, 2014Qualcomm IncorporatedTransmitter beamforming power control
US8842619Jul 7, 2011Sep 23, 2014Qualcomm IncorporatedScalable frequency band operation in wireless communication systems
US8855228Mar 4, 2013Oct 7, 2014Marvell World Trade Ltd.Calibration correction for implicit beamforming in a wireless MIMO communication system
US8862075 *Mar 26, 2010Oct 14, 2014Icera Inc.Adaptive transmission feedback
US8879511Mar 7, 2006Nov 4, 2014Qualcomm IncorporatedAssignment acknowledgement for a wireless communication system
US8885628May 10, 2006Nov 11, 2014Qualcomm IncorporatedCode division multiplexing in a single-carrier frequency division multiple access system
US8917654Nov 18, 2011Dec 23, 2014Qualcomm IncorporatedFrequency hopping design for single carrier FDMA systems
US8934941 *Mar 8, 2010Jan 13, 2015Sharp Kabushiki KaishaChannel reconstruction method, base station and user equipment
US8948704Oct 21, 2009Feb 3, 2015Qualcomm IncorporatedScope of channel quality reporting region in a multi-carrier system
US8989675Jan 26, 2012Mar 24, 2015Qualcomm IncorporatedScope of channel quality reporting region in a multi-carrier system
US8995547Mar 11, 2005Mar 31, 2015Qualcomm IncorporatedSystems and methods for reducing uplink resources to provide channel performance feedback for adjustment of downlink MIMO channel data rates
US9007263Nov 4, 2010Apr 14, 2015Qualcomm IncorporatedPhase rotation techniques in a multi-user wireless communication environment
US9036538Aug 22, 2005May 19, 2015Qualcomm IncorporatedFrequency hopping design for single carrier FDMA systems
US9059755Jun 8, 2009Jun 16, 2015Telefonaktiebolaget L M Ericsson (Publ)Methods and apparatus using precoding matrices in a MIMO telecommunications system
US9065515 *Oct 4, 2011Jun 23, 2015Vodafone Ip Licensing LimitedMethod and system for enhanced transmission in mobile communication networks
US9088384Aug 28, 2006Jul 21, 2015Qualcomm IncorporatedPilot symbol transmission in wireless communication systems
US9130810Aug 16, 2001Sep 8, 2015Qualcomm IncorporatedOFDM communications methods and apparatus
US9136974Apr 10, 2006Sep 15, 2015Qualcomm IncorporatedPrecoding and SDMA support
US9137822Dec 22, 2004Sep 15, 2015Qualcomm IncorporatedEfficient signaling over access channel
US9143219 *Jun 30, 2014Sep 22, 2015Marvell International Ltd.Equal power output spatial spreading matrix for use in a wireless MIMO communication system
US9143305Mar 17, 2005Sep 22, 2015Qualcomm IncorporatedPilot signal transmission for an orthogonal frequency division wireless communication system
US9144060Mar 7, 2006Sep 22, 2015Qualcomm IncorporatedResource allocation for shared signaling channels
US9148256Dec 22, 2004Sep 29, 2015Qualcomm IncorporatedPerformance based rank prediction for MIMO design
US9154211Sep 21, 2005Oct 6, 2015Qualcomm IncorporatedSystems and methods for beamforming feedback in multi antenna communication systems
US9154969Sep 25, 2012Oct 6, 2015Marvell International Ltd.Wireless device calibration for implicit transmit
US9172453Oct 27, 2005Oct 27, 2015Qualcomm IncorporatedMethod and apparatus for pre-coding frequency division duplexing system
US9178584Mar 20, 2014Nov 3, 2015Qualcomm IncorporatedSystem and methods for reducing uplink resources to provide channel performance feedback for adjustment of downlink MIMO channel data rates
US9179319Oct 27, 2005Nov 3, 2015Qualcomm IncorporatedAdaptive sectorization in cellular systems
US9184808 *Oct 7, 2013Nov 10, 2015Interdigital Technology CorporationMimo beamforming-based single carrier frequency division multiple access system
US9184870Oct 27, 2005Nov 10, 2015Qualcomm IncorporatedSystems and methods for control channel signaling
US9209956Oct 27, 2005Dec 8, 2015Qualcomm IncorporatedSegment sensitive scheduling
US9210651Oct 27, 2005Dec 8, 2015Qualcomm IncorporatedMethod and apparatus for bootstraping information in a communication system
US9225414 *Dec 30, 2009Dec 29, 2015Intellectual Discovery Co., Ltd.Transmission device and method using space-frequency transmission diversity
US9225416Oct 27, 2005Dec 29, 2015Qualcomm IncorporatedVaried signaling channels for a reverse link in a wireless communication system
US9225488Oct 27, 2005Dec 29, 2015Qualcomm IncorporatedShared signaling channel
US9240877Feb 18, 2009Jan 19, 2016Qualcomm IncorporatedSegment sensitive scheduling
US9246560Jul 20, 2005Jan 26, 2016Qualcomm IncorporatedSystems and methods for beamforming and rate control in a multi-input multi-output communication systems
US9246659Feb 18, 2009Jan 26, 2016Qualcomm IncorporatedSegment sensitive scheduling
US9307544Mar 14, 2013Apr 5, 2016Qualcomm IncorporatedChannel quality reporting for adaptive sectorization
US9319904Oct 5, 2015Apr 19, 2016Marvell International Ltd.Wireless device calibration for implicit transmit beamforming
US20050078764 *Aug 26, 2004Apr 14, 2005Mitsubishi Denki Kabushiki KaishaMethod for transmitting optimally interleaved data in a MIMO telecommunication system
US20060018336 *Dec 22, 2004Jan 26, 2006Arak SutivongEfficient signaling over access channel
US20060188036 *Dec 1, 2005Aug 24, 2006Mitsubishi Denki Kabushiki KaishaMethod for transmitting uniformly distributed data in a MIMO telecommunication system
US20060203708 *Sep 21, 2005Sep 14, 2006Hemanth SampathSystems and methods for beamforming feedback in multi antenna communication systems
US20060203891 *Jul 20, 2005Sep 14, 2006Hemanth SampathSystems and methods for beamforming and rate control in a multi-input multi-output communication systems
US20060205357 *Mar 11, 2005Sep 14, 2006Byoung-Hoon KimSystems and methods for reducing uplink resources to provide channel performance feedback for adjustment of downlink MIMO channel data rates
US20060209670 *Mar 17, 2005Sep 21, 2006Alexei GorokhovPilot signal transmission for an orthogonal frequency division wireless communication system
US20060209732 *Oct 27, 2005Sep 21, 2006Qualcomm IncorporatedPilot signal transmission for an orthogonal frequency division wireless communication system
US20060209754 *May 13, 2005Sep 21, 2006Ji TingfangChannel structures for a quasi-orthogonal multiple-access communication system
US20060223449 *Oct 27, 2005Oct 5, 2006Qualcomm IncorporatedSystems and methods for control channel signaling
US20060233124 *Aug 22, 2005Oct 19, 2006Qualcomm IncorporatedFrequency hopping design for single carrier FDMA systems
US20060233131 *Oct 27, 2005Oct 19, 2006Qualcomm IncorporatedChannel quality reporting for adaptive sectorization
US20060274836 *May 31, 2006Dec 7, 2006Hemanth SampathSphere decoding apparatus
US20070041404 *May 10, 2006Feb 22, 2007Ravi PalankiCode division multiplexing in a single-carrier frequency division multiple access system
US20070041464 *Mar 15, 2006Feb 22, 2007Byoung-Hoon KimSelective virtual antenna transmission
US20070047485 *Oct 27, 2005Mar 1, 2007Qualcomm IncorporatedVaried transmission time intervals for wireless communication system
US20070049218 *Apr 10, 2006Mar 1, 2007Qualcomm IncorporatedPrecoding and SDMA support
US20070071127 *Mar 27, 2006Mar 29, 2007Qualcomm IncorporatedMethod and apparatus for pilot communication in a multi-antenna wireless communication system
US20070097853 *Oct 27, 2005May 3, 2007Qualcomm IncorporatedShared signaling channel
US20070097909 *Oct 27, 2005May 3, 2007Aamod KhandekarScalable frequency band operation in wireless communication systems
US20070097927 *Oct 27, 2005May 3, 2007Alexei GorokhovPuncturing signaling channel for a wireless communication system
US20070097942 *Oct 27, 2005May 3, 2007Qualcomm IncorporatedVaried signaling channels for a reverse link in a wireless communication system
US20070105503 *Aug 22, 2006May 10, 2007Byoung-Hoon KimSystems and methods for reducing uplink resources to provide channel performance feedback for adjustment of downlink MIMO channel data rates
US20070206698 *Jan 25, 2007Sep 6, 2007Samsung Electronics Co., Ltd.Transmission/reception apparatus and method for supporting MIMO technology in a forward link of a high rate packet data system
US20070211616 *Mar 7, 2006Sep 13, 2007Aamod KhandekarResource allocation for shared signaling channels
US20070211619 *Nov 29, 2006Sep 13, 2007Motorola, Inc.Method and apparatus for hybrid cdm ofdma wireless transmission
US20070211668 *Mar 7, 2006Sep 13, 2007Avneesh AgrawalUse of supplemental assignments to decrement resources
US20070249298 *Sep 28, 2006Oct 25, 2007Fujitsu LimitedCommunication apparatus based on multi-carrier modulation system
US20070274411 *May 29, 2007Nov 29, 2007Lg Electronics Inc.Signal generation using phase-shift based pre-coding
US20070280373 *May 29, 2007Dec 6, 2007Lg Electronics Inc.Phase shift based precoding method and transceiver for supporting the same
US20080025200 *Jun 13, 2007Jan 31, 2008Nokia CorporationInterference cancellation unit and interference cancellation method
US20080075190 *Sep 25, 2007Mar 27, 2008Realtek Semiconductor Corp.Apparatus and method for selecting antennas in MIMO multi-carrier system
US20080080637 *Jul 3, 2007Apr 3, 2008Samsung Electronics Co., Ltd.System and method for performing precoding in a wireless communication system
US20080080641 *Sep 5, 2007Apr 3, 2008Qualcomm IncorporatedCodeword permutation and reduced feedback for grouped antennas
US20080089396 *Sep 18, 2007Apr 17, 2008Hongyuan ZhangCalibration Correction for Implicit Beamforming in a Wireless MIMO Communication System
US20080089442 *Sep 19, 2007Apr 17, 2008Lg Electronics Inc.method of performing phase shift-based precoding and an apparatus for supporting the same in a wireless communication system
US20080195917 *Feb 8, 2008Aug 14, 2008Interdigital Technology CorporationMethod and apparatus for low complexity soft output decoding for quasi-static mimo channels
US20080198946 *Feb 12, 2008Aug 21, 2008Lg Electronics Inc.Data transmitting and receiving method using phase shift based precoding and transceiver supporting the same
US20080205533 *Sep 19, 2007Aug 28, 2008Lg Electronics Inc.Method of transmitting using phase shift-based precoding and apparatus for implementing the same in a wireless communication system
US20080219375 *Mar 5, 2008Sep 11, 2008Samsung Electronics Co. Ltd.Apparatus and method for spatial multiplexing with backward compatibility in a multiple input multiple output wireless communication system
US20080247364 *Feb 5, 2008Oct 9, 2008Qualcomm IncorporatedCyclic delay diversity and precoding for wireless communication
US20080303701 *May 29, 2008Dec 11, 2008Jianzhong ZhangCDD precoding for open loop su mimo
US20090135939 *Sep 17, 2007May 28, 2009Samsung Electronics Co., Ltd.Apparatus and method for space-time coding in multiple-antenna system
US20090180459 *Jul 16, 2009Orlik Philip VOFDMA Frame Structures for Uplinks in MIMO Networks
US20090276672 *Apr 6, 2007Nov 5, 2009Moon-Il LeeRepetitive transmissions in multi-carrier based wireless access techniques
US20090323863 *Dec 31, 2009Moon-Il LeeSignal generation using phase-shift based pre-coding
US20100014608 *Jan 21, 2010Moon Il LeeData transmitting and receiving method using phase shift based precoding and transceiver supporting the same
US20100062705 *Mar 11, 2010Qualcomm IncorporatedApparatus and method for interference-adaptive communications
US20100074309 *Sep 16, 2009Mar 25, 2010Moon Il LeePhase shift based precoding method and transceiver for supporting the same
US20100074360 *Sep 4, 2009Mar 25, 2010Moon-Il LeeSignal generation using phase-shift based pre-coding
US20100074362 *Mar 25, 2010Jong Bu LimApparatus and method for transmitting and receiving signal in multiple input multiple output system
US20100085955 *Apr 8, 2010Qualcomm IncorporatedTransmit diversity for sc-fdma
US20100091641 *Sep 22, 2009Apr 15, 2010Qualcomm IncorporatedTransmit diversity scheme for uplink data transmissions
US20100113078 *Oct 21, 2009May 6, 2010Qualcomm IncorporatedScope of channel quality reporting region in a multi-carrier system
US20100202500 *Sep 12, 2008Aug 12, 2010Bin Chul IhmData transmitting and receiving method using phase shift based precoding and transceiver supporting the same
US20100202560 *Feb 1, 2010Aug 12, 2010Qualcomm IncorporatedAntenna virtualization in a wireless communication environment
US20100220797 *Aug 28, 2008Sep 2, 2010Hideo NambaCommunication apparatus
US20100226417 *Sep 9, 2010Bin Chul IhmData transmitting and receiving method using phase shift based precoding and transceiver supporting the same
US20100232384 *Mar 11, 2010Sep 16, 2010Qualcomm IncorporatedChannel estimation based upon user specific and common reference signals
US20100232483 *May 21, 2010Sep 16, 2010Hongyuan ZhangCalibration Correction for Implicit Beamforming in a Wireless MIMO Communication System
US20100238902 *Jun 1, 2010Sep 23, 2010Qualcomm IncorporatedChannel Structures for a Quasi-Orthogonal Multiple-Access Communication System
US20100246377 *Sep 25, 2006Sep 30, 2010Interdigital Technology CorporationMimo beamforming-based single carrier frequency division multiple access system
US20100246496 *Nov 27, 2008Sep 30, 2010Hiroyuki YurugiWireless communication system having mimo communication capability and having multiple receiving antennas to be selected
US20100273438 *Jun 5, 2007Oct 28, 2010Panasonic CorporationRadio communication apparatus and radio communication method in multi-carrier communication
US20100284477 *Nov 12, 2008Nov 11, 2010Lg Electronics Inc.Method for transmitting signal in multiple antenna system
US20100309999 *Jan 17, 2008Dec 9, 2010Hongwei YangMethod and device for cyclic delay mapping for the signal in the multi-antenna transmitter
US20100322336 *Aug 30, 2010Dec 23, 2010Nabar Rohit UBeamforming to a Subset of Receive Antennas in a Wireless MIMO Communication System
US20100329370 *Apr 22, 2010Dec 30, 2010Beceem Communications Inc.Selection of a Subset of Antennas for Transmission
US20110009079 *Jan 13, 2011Naoki OkamotoRadio transmission device
US20110064156 *Sep 5, 2007Mar 17, 2011Lg Electronics Inc.Method of transmitting feedback information for precoding and precoding method
US20110075651 *Jun 12, 2009Mar 31, 2011Nortel Networks LimitedSystems and methods for sc-fdma transmission diversity
US20110110403 *Jun 8, 2009May 12, 2011Telefonaktiebolaget L M Ericsson (Publ)Methods and apparatus using precoding matrices in a mimo telecommunications system
US20110110405 *May 12, 2011Moon Il LeeData transmitting and receiving method using phase shift based precoding and transceiver supporting the same
US20110149857 *Dec 16, 2010Jun 23, 2011Moon Il LeeMethod of transmitting using phase shift-based precoding and an apparatus for implementing the same in a wireless communication system
US20110194650 *Aug 11, 2011Moon Il LeeMethod of transmitting using phase shift-based precoding and an apparatus for implementing the same in a wireless communication system
US20110235540 *Sep 29, 2011Samsung Electronics Co., Ltd.Transmission/reception apparatus and method for supporting mimo technology in a forward link of a high rate packet data system
US20110255503 *Oct 20, 2011Naoki OkamotoRadio transmission device
US20110261841 *Dec 30, 2009Oct 27, 2011Seah Networks Co., Ltd.Transmission device and method using space-frequency transmission diversity
US20120004014 *Mar 8, 2010Jan 5, 2012Ming DingChannel reconstruction method, base station and user equipment
US20120113840 *Oct 4, 2011May 10, 2012Vodafone Ip Licensing LimitedMethod and system for enhanced transmission in mobile communication networks
US20120122407 *Mar 26, 2010May 17, 2012Icera Inc.Adaptive transmission feedback
US20120155571 *Feb 28, 2012Jun 21, 2012Huawei Technologies Co., LtdMethod, apparatus, and system for data signal transmission in multi-antenna system
US20120201281 *Apr 16, 2012Aug 9, 2012Broadcom CorporationMethod and System For Communication In A Wireless Orthogonal Frequency Division Multiplexing (OFDM) Communication System
US20130148634 *Dec 13, 2011Jun 13, 2013Telefonaktiebolaget L M Ericsson (Publ)Asymmetric Resource Sharing Using Stale Feedback
US20140036655 *Oct 7, 2013Feb 6, 2014Interdigital Technology CorporationMimo beamforming-based single carrier frequency division multiple access system
EP2156588A2 *Jun 9, 2008Feb 24, 2010Samsung Electronics Co., Ltd.Cdd precoding for open loop su mimo
EP2156588A4 *Jun 9, 2008Oct 2, 2013Samsung Electronics Co LtdCdd precoding for open loop su mimo
EP2234286A1 *Jan 17, 2008Sep 29, 2010Alcatel LucentMethod and apparatus for performing cyclic delay mapping to signals in multiple antenna transmitters
EP2234286A4 *Jan 17, 2008Oct 17, 2012Alcatel LucentMethod and apparatus for performing cyclic delay mapping to signals in multiple antenna transmitters
EP2286530A1 *Jun 12, 2009Feb 23, 2011Nortel Networks LimitedSystems and methods for sc-fdma transmission diversity
EP2385635A2 *Jan 29, 2010Nov 9, 2011LG Electronics Inc.Apparatus and method for transmitting a reference signal in a radio communication system
EP2465208A4 *Dec 15, 2009May 13, 2015Ericsson Telefon Ab L MAntenna device
WO2008150148A2 *Jun 9, 2008Dec 11, 2008Samsung Electronics Co., Ltd.Cdd precoding for open loop su mimo
WO2008150148A3 *Jun 9, 2008Jan 29, 2009Samsung Electronics Co LtdCdd precoding for open loop su mimo
WO2009098532A1 *Feb 7, 2008Aug 13, 2009Nokia CorporationApparatus, methods, and computer program products providing improved spatial multiplexing for mimo communication
WO2009149561A1 *Jun 12, 2009Dec 17, 2009Nortel Networks LimitedSystems and methods for sc-fdma transmission diversity
Classifications
U.S. Classification375/260
International ClassificationH04K1/10
Cooperative ClassificationH04L5/0023, H04B7/0671, H04B7/0691, H04B7/0697, H04L27/2602
European ClassificationH04L5/00A3C, H04L27/26M1, H04B7/06C2D, H04B7/06H2, H04B7/06M
Legal Events
DateCodeEventDescription
Mar 17, 2006ASAssignment
Owner name: QUALCOMM INCORPORATED, CALIFORNIA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:KADOUS, TAMER;KHANDEKAR, AAMOD;GORE, DHANANJAY ASHOK;ANDOTHERS;REEL/FRAME:017350/0865;SIGNING DATES FROM 20060227 TO 20060312