Notice: More than one reissue application has been filed for the reissue of U.S. Pat. No. 6,449,306. The reissue applications are application Ser. Nos. 10/932,227 (this application), which was filed on Sep. 2, 2004 and 11/648,915, a continuation reissue application of 10/932,227, which was filed on Jan. 3, 2007 and is still pending.
This application is a continuation of application Ser. No. 09/162,764, now U.S. Pat. No. 6,222,873.
1. Field of the Invention
The present invention relates to an orthogonal complex spreading method for a multichannel and an apparatus thereof, and in particular, to an improved orthogonal complex spreading method for a multichannel and an apparatus thereof which are capable of decreasing a peak power-to-average power ratio by introducing an orthogonal complex spreading structure and spreading the same using a spreading code, implementing a structure capable of spreading complex output signals using a spreading code by adapting a permutated orthogonal complex spreading structure for a complex-type multichannel input signal with respect to the summed values, and decreasing a phase dependency of an interference based on a multipath component (when there is one chip difference) of a self signal, which is a problem that is not overcome by a permutated complex spreading modulation method, by a combination of an orthogonal Hadamard sequence.
2. Description of the Conventional Art
Generally, in the mobile communication system, it is known that a linear distortion and non-linear distortion affect power amplifier. The statistical characteristic of a peak power-to-average power ratio has a predetermined interrelationship for a non-linear distortion.
The third non-linear distortion which is one of the factors affecting the power amplifier causes an inter-modulation product problem in an adjacent frequency channel. The above-described inter-modulation product problem is generated due to a high peak amplitude for thereby increasing an adjacent channel power (ACP), so that there is a predetermined limit for selecting an amplifier. In particular, the CDMA (Code Division Multiple Access) system requires a very strict condition with respect to a linearity of a power amplifier. Therefore, the above-described condition is a very important factor.
In accordance with IS-97 and IS-98, the FCC stipulates a condition on the adjacent channel power (ACP). In order to satisfy the above-described condition, a bias of a RF power amplifier should be limited.
According to the current IMT-2000 system standard recommendation, a plurality of CDMA channels are recommended. In the case that a plurality of channels are provided, the peak power-to-average power ratio is considered as an important factor for thereby increasing efficiency of the modulation method.
The IMT-2000 which is known as the third generation mobile communication system has a great attention from people as the next generation communication system following the digital cellular system, personal communication system, etc. The IMT-2000 will be commercially available as one of the next generation wireless communication system which has a high capacity and better performance for thereby introducing various services and international loaming services, etc.
Many countries propose various IMT-2000 systems which IC require high data transmission rates adapted for an internet service or an electronic commercial activity. This is directly related to the power efficiency of a RF amplifier.
The CDMA based IMT-2000 system modulation method introduced by many countries is classified into a pilot channel method and a pilot symbol method. Of which, the former is directed to the ETRI 1.0 version introduced in Korea and is directed to CDMA ONE introduced in North America, and the latter is directed to the NTT-DOCOMO and ARIB introduced in Japan and is directed to the FMA2 proposal in a reverse direction introduced in Europe.
Since the pilot symbol method has a single channel effect based on the power efficiency, it is superior compared to the pilot channel method which is a multichannel method. However since the accuracy of the channel estimation is determined by the power control, the above description does not have its logical ground.
In a summing unit 40, the pilot signal multiplied by the channel gain A0 and the fundamental channel signal multiplied by the channel gain A1 are summed by a first adder for thereby obtaining an identical phase information, and the supplemental channel signal multiplied by the channel gain A2 and the control channel signal multiplied by the channel gain A3 are summed by a second adder for thereby obtaining an orthogonal phase information.
The thusly obtained in-phase information and quadrature-phase information are multiplied by a PN1 code and PN2 code by a spreading unit 50, and the identical phase information multiplied by the PN2 code is subtracted from the identical phase information multiplied by the PN1 code and is outputted as an I channel signal, and the quadrature-phase information multiplied by the PN1 code and the in-phase information multiplied by the PN2 code are summed and are outputted through a delay unit as a Q channel signal.
The CDMA ONE is implemented using a complex spreading method. The pilot channel and the fundamental channel spread to a Walsh code 1 are summed for thereby forming an in-phase information, and the supplemental channel spread to the Walsh code 2 and the control channel spread to a Walsh code 3 are summed for thereby forming an quadrature-phase information. In addition, the in-phase information and quadrature-phase information are complex-spread by PN codes.
As shown therein, in the CDMA ONE, the left and right information, namely, the in-phase information (I channel) and the upper and lower information, namely, the quadrature-phase information (Q channel) pass through the actual phase shaping filter for thereby causing a peak power, and in the ETRI version 1.0 shown in
In view of the crest factor and the statistical distribution of the power amplitude, in the CDMA ONE, the peak power is generated in vertical direction, so that the irregularity problem of the spreading code and an inter-interference problem occur.
Accordingly, it is an object of the present invention to provide an orthogonal complex spreading method for a multichannel and an apparatus thereof overcome the aforementioned problems encountered in the conventional art.
The CDMA system requires a strict condition for a linearity of a power amplifier, so that the peak power-to-average power ratio is important. In particular, the characteristic of the IMT-2000 system is determined based on the efficiency of the modulation method since multiple channels are provided, and the peak power-to-average power ratio is adapted as an important factor.
It is another object of the present invention to provide an orthogonal complex spreading method for a multichannel and an apparatus thereof which have an excellent power efficiency compared to the CDMA-ONE introduced in U.S.A. and the W-CDMA introduced in Japan and Europe and is capable of resolving a power unbalance problem of an in-phase channel and a quadrature-phase channel as well as the complex spreading method.
It is still another object of the present invention to provide an orthogonal complex spreading method for a multichannel and an apparatus thereof which is capable of stably maintaining a low peak power-to-average power ratio.
It is still another object of the present invention to provide an orthogonal complex spreading method for a multichannel and an apparatus thereof in which a spreading operation is implemented by multiplying a predetermined channel data among data of a multichannel by an orthogonal Hadamard sequence and a gain and, multiplying a data of another channel by an orthogonal Hadamard sequence and a gain, summing the information of two channels in complex type, multiplying the summed information of the complex type by the orthogonal Hadamard sequence of the orthogonal type, obtaining a complex type, summing a plurality of channel information of the complex type in the above-described manner and multiplying the information of the complex type of the multichannel by a spreading code sequence.
It is still another object of the present invention to provide an orthogonal complex spreading method for a multichannel and an apparatus thereof which is capable of decreasing the probability that the power becomes a zero state by preventing the FIR filter input state from exceeding ±90° in an earlier sample state, increasing the power efficiency, decreasing the consumption of a bias power of a back-off of the power amplifier and saving the power of a battery.
It is still another object of the present invention to provide an orthogonal complex spreading method for a multichannel and an apparatus thereof which is capable of implementing a POCQPSK (Permutated Orthogonal Complex QPSK) which is another modulation method and has a power efficiency similar with the OCQPSK (Orthogonal Complex QPSK).
In order to achieve the above objects, there is provided an orthogonal complex spreading method for a multichannel which includes the steps of complex-summing α_{n1}W_{M,n1}X_{n1 }which is obtained by multiplying an orthogonal Hadamard sequence W_{M,n1 }by a first data X_{n1 }of a n-th block and α_{n2}W_{M,n2}X_{n2 }which is obtained by multiplying an orthogonal Hadamard sequence W_{M,n2 }by a second data X_{n2 }of a n-th block; complex-multiplying α_{n1}W_{M,n1}X_{n1}+jα_{n2}W_{M,n2}X_{n2 }which is summed in the complex type and W_{M,n3}+jW_{M,n4 }of the complex type using a complex multiplier and outputting as an in-phase information and quadrature-phase information; and summing only in-phase information outputted from a plurality of blocks and only quadrature-phase information outputted therefrom and spreading the same using a spreading code.
In order to achieve the above objects, there is provided an orthogonal complex spreading apparatus according to a first embodiment of the present invention which includes a plurality of complex multiplication blocks for distributing the data of the multichannel and complex-multiplying α_{n1}W_{M,n1}X_{n1}+jα_{n2}W_{M,n2}X_{n2 }in which α_{n1}W_{M,n1}X_{n1 }which is obtained by multiplying the orthogonal Hadamard sequence W_{M,n1 }with the first data X_{n1 }of the n-th block and the gain α_{n1 }and α_{n2}W_{M,n2}X_{n2 }which is obtained by multiplying the orthogonal Hadamard sequence W_{M,n2 }with the second data X_{n2 }of the n-th block and the gain α_{n2 }and W_{M,n3}+W_{M,n4 }using the complex multiplier; a summing unit for summing only the in-phase information outputted from each block of the plurality of the complex multiplication blocks and summing only the quadrature-phase information; and a spreading unit for multiplying the in-phase information and the quadrature-phase information summed by the summing unit with the spreading code and outputting an I channel and a Q channel.
In order to achieve the above objects, there is provided an orthogonal complex spreading apparatus according to a second embodiment of the present invention which includes first and second Hadamard sequence multipliers for allocating the multichannel to a predetermined number of channels, splitting the same into two groups and outputting α_{n1}W_{M,n1}X_{n1 }which is obtained by multiplying the data X_{n1 }of each channel by the gain α_{n1 }and the orthogonal Hadamard sequence W_{M,n1};
Additional advantages, objects and other features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained as particularly pointed out in the appended claims.
The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:
The complex summing unit and complex multiplier according to the present invention will be explained with reference to the accompanying drawings. In the present invention, two complexes (a+jb) and (c+jd) are used, where a, b, c and d represent predetermined real numbers.
A complex summing unit outputs (a+c)+j(b+d), and a complex multiplier outputs ((a×c)−(b×d))+j((b×c)+(a×d)). Here, a spreading code sequence is defined as SC, an information data is defined as X_{n1}, and X_{n2}, a gain constant is defined as α_{n1 }and α_{n2}, and an orthogonal Hadamard sequence is defined as W_{M,n1}, W_{M,n2}, W_{M,n3}, W_{M,n4}, W_{M,I}, W_{M,Q}, where M represents a M×M Hadamard matrix, and n1, n2, n3 and n4 represents index of a predetermined vector of the Hadamard matrix. For example, n3 represents a Hadamard vector which is a third vector value written into the n-th block like the n-th block 100n of FIG. 4. The Hadamard M represents a Hadamard matrix. For example, if the matrix W has values of 1 and −1, in the W_{T}×W, the main diagonal terms are M, and the remaining products are zero. Here, T represents a transpose.
The data X_{n1}, X_{n2}, W_{M,n1}, W_{M,n2}, W_{M,n3}, W_{M,n4}, W_{M,I}, and W_{M,Q}, and SC are combined data consisting of +1 or −1, and any and α_{n2 }represent real number.
As shown therein, there is provided a plurality of complex multipliers 100 through 100n in which a data of a predetermined channel is multiplied by a gain and orthogonal Hadamard sequence, and a data of another channel is multiplied by the orthogonal Hadamard sequence for thereby complex-summing two channel data, the orthogonal Hadamard sequence of the complex type is multiplied by the complex-summed data, and the data of other two channels are complex-multiplied in the same manner described above. A summing unit 200 sums and outputs the output signals from the complex multipliers 100 through 100n. A spreading unit 300 multiplies the output signal from the summing unit 200 with a predetermined spreading code SC for thereby spreading the signal. A pulse shaping filter 400 filters the data spread by the spreading unit 300. A modulation wave multiplier 500 multiplies the output signal from the filter 400 with a modulation carrier wave and outputs the modulated data through an antenna.
As shown in
In addition, the n-th complex multiplier 100n complex-sums α_{n1}W_{M,n1}X_{n1 }which is obtained by multiplying the orthogonal Hadamard sequence W_{M,n1 }with the data X_{n1 }of another channel and the gain α_{n1 }and α_{n2}W_{M,n2}X_{n2 }which is obtained by multiplying the orthogonal Hadamard sequence W_{M,n2 }with the data X_{n2 }of another channel and the gain α_{n2}, and complex-multiplies α_{n1}W_{M,n1}X_{n1}+jα_{n2}W_{M,n2}X_{n2 }and the complex-type orthogonal sequence W_{M,n3}X_{11}+jW_{M,n4 }using the complex multiplier 100n.
The complex multiplication data outputted from the n-number of the complex multipliers are summed by the summing unit 200, and the spreading code SC is multiplied and spread it by the spreading unit 300. The thusly spread data are filtered by the pulse shaping filter 600, and the modulation carried e^{/2πfct }is multiplied by the multiplier 700, and then the function Re{*} is processed, and the real data s(t) is outputted through the antenna. Here, Re{*} represents that a predetermined complex is processed to a real value through the Re{*} function.
The above-described function will be explained as follows:
where K represents a predetermined integer greater than or equal to 1, n represents an integer greater than or equal to 1 and less than K and is identical with each channel number of the multichannel.
Each of the complex multipliers 110 through 100n is identically configured so that two different channel data are complex-multiplied.
As shown in
Therefore, the first and-second multipliers 101 and 102 multiply the data X_{11 }by the orthogonal Hadamard sequence W_{M,11 }and the gain α_{11 }for thereby obtaining α_{11}W_{M,11}X_{11 }(−a). In addition, the third and fourth multipliers 103 and 104 multiply the orthogonal Hadamard sequence W_{M,12 }and the gain α_{12 }for thereby obtaining α_{12}W_{M,12}X_{12 }(=b). The fifth and sixth multipliers 105 and 106 multiply α_{11}W_{M,11}X_{11 }(=a) and α_{12}W_{M,12}X_{12 }(=b) by the orthogonal Hadamard sequence W_{M,13 }(=c), respectively, for thereby obtaining α_{11}W_{M,11}X_{11}W_{M,13 }(=ac) and α_{12}W_{M,12}X_{12}W_{M,13 }(=bc), and the fifth and sixth multipliers 105 and 106 multiply α_{11}W_{M,11}X_{11 }(=a) and α_{12}W_{M,12}X_{12 }(=b) by the orthogonal Hadamard sequence W_{M,14 }(=d) for thereby obtaining α_{11}W_{M,11}X_{11}W_{M,14 }(=ad) and α_{12}W_{M,12}X_{12}W_{M,14 }(=bd). In addition, the first adder 109 computes (α_{11}W_{M,11}X_{11}W_{M,13})−(α_{12}W_{M,12}X_{12}W_{M,14}) (=ac−bd), namely, α_{12}W_{M,12}X_{12}W_{M,14 }is subtracted from α_{11}W_{M,11}X_{11}W_{M,13}. In addition, the second adder 110 computes (α_{11}W_{M,11}X_{11}W_{M,14})+(α_{12}W_{M,12}X_{12}W_{M,13}) (ad+bc), namely, α_{11}W_{M,11}X_{11}W_{M,14 }(=ad) is added with α_{12}W_{M,12}X_{12}W_{M,13 }(=bc).
In addition,
As shown therein, the summing unit 200 includes a first summing unit 210 for summing the in-phase information A_{1}(=(ac−bd), . . . , An outputted from a plurality of complex multipliers, and a second summing unit 220 for summing the quadrature-phase information B_{1}(=bc+ad) outputted from the complex multipliers.
The spreading unit 300 includes first and second multipliers 301 and 302 for multiplying the output signals from the first adder 210 and the second adder 220 of the summing unit 200 by the spreading sequence SC, respectively. Namely, the signals are spread to the in-phase signal (I channel signal) and the quadrature-phase signal (Q channel signal) using one spreading code SC.
In addition, as shown in
Namely, in the summing unit 200, the in-phase information and the quadrature-phase information of the n-number of the complex multipliers are summed by the first and second summing units 210 and 220. In the spreading unit 300, the in-phase information summing value (g) and the quadrature phase information summing value (h) from the summing unit 200 are multiplied by the first spreading code SC1 (1) by the first and second multipliers 310 and 320 for thereby obtaining g1 and h1, and the in-phase information summing value (g) and the quadrature phase information summing value (h) from the summing unit 200 are multiplied by the second spreading code SC2(m) by the third and fourth multipliers 330 and 340 for thereby obtaining gm and hm, and the first adder 350 computes gl−hm in which hm is subtracted from gl, and the second adder 360 computes hl+gm in which hl is added by gm.
As shown in
Here, the orthogonal Hadamard sequences may be used as a Walsh code or other orthogonal code.
For example, from now on, the case that the orthogonal Hadamard sequence is used for the 8×8 Hadamard matrix shown in
Therefore, in order to enhance the efficiency of the present invention, the orthogonal Hadamard sequence which multiplies each channel data is determined as follows.
In the M×M Hadamard matrix, the sequence vector of the k-th column or row is set to W_{k−1}, and W_{M,n1=}W_{0}, W_{M,n2}=W_{2p }(where p represents a predetermined number of (M/2)−1), and W_{M,n3}=W_{2n−2}, W_{M,n4}=W_{2n−1 }(where n represents the number of n-th blocks), and α_{n1}W_{0}X_{n1}+jα_{n2}W_{2p}X_{n2 }and W_{2n−2}+jW_{2n−1}. The case that only first complex multiplier is used in the embodiment of
In the case that two complex multipliers shown in
In addition, as shown in
In order to achieve the objects of the present invention, the orthogonal Hadamard sequence directed to multiplying each channel data may be determined as follows.
The combined orthogonal Hadamard sequence may be used instead of the orthogonal Hadamard sequence for removing a predetermined phase dependency based on the interference generated in the multiple path type of self-signal and the interference generated by other users.
For example, in the case of two channels, when the sequence vector of the k-th column or row is set to W_{k−1 }in the M×M (M=8) Hadamard matrix, and the sequence vector of the m-th column or row is set to W_{m}, the first M/2 or the last M/2 is obtained based on the vector W_{k−1 }and the last M/2 or the first M/2 is obtained based on W_{m−1}, so that the combined orthogonal Hadamard vector is set to W_{k−1//m−1}, and W_{M,11}=W_{0}, W_{M,12}=W_{4//1}, W_{M//}=W_{0}, W_{M,Q=W1/4 }are determined, so that it is possible to complex-multiply α_{11}W_{0}X_{11}+jα_{12}W_{4//1}X_{11 }and W_{0}+jPW_{1//4}.
In the case of three channels, the sequence vector of the k-th column or row is set to W_{k−1 }based on the M×M (M=8) Hadamard matrix, and the sequence vector of the m-th column or row is set to W_{M}, so that the first M/2 or the last M/2 is obtained from the vector W_{k−1}, and the last M/2 or the first M/2 is obtained from W_{m−1}, and the combined orthogonal Hadamard vector is set to W_{k−1//m−1}, and the summed value of α_{11}W_{0}X_{11}+jα_{12}W_{4//1}X_{12 }and α_{21}W_{2}X_{21 }and W_{0}+jPW_{1//4 }are complex multiplied based on W_{M,11}=W_{0}, W_{M,12}=W_{4//1}, W_{M,21}=W_{1}, and W_{M,I}=W_{0}, W_{M,Q}=W_{1//4}.
In addition, in the case of two channels, when the sequence vector of the k-th column or row of the M×M (M=8) Hadamard vector matrix is set to W_{k−1}, and the sequence vector of the m-th column or row is set to W_{m}, the first M/2 or the last M/2 is obtained from the vector W_{k−1}, and the last M/2 or the first M/2 is obtained from W_{m−1}, so that the combined orthogonal Hadamard vector is set to W_{−1//m−1}, and the summed value of α_{11}W_{0}X_{11}+jα_{12}W_{2//1}X_{12 }and W_{0}+jPW_{1//2 }are complex-multiplied based on W_{M,11}=W_{0}, W_{M,12}=W_{2//1}, and W_{M,I}=W_{0}, W_{M,Q}=W_{1//2}.
In addition, in the case of three channels, when the sequence vector of the k-th column or row of the M×M (M=8) Hadamard vector matrix is set to W_{k−1}, and the sequence vector of the m-th column or row is set to W_{m}, the first M/2 or the last M/2 is obtained from the vector W_{k−1}, and the last M/2 or the first M/2 is obtained from W_{m−1}, so that the combined orthogonal Hadamard vector is set to W_{k−1//m−1}, and the summed value of α_{11}W_{0}X_{11}+jα_{12}W_{2//} 1X_{12 }and α_{21}W_{4}W_{2l }and W_{0}+jPW_{1//2 }are complex-multiplied based on W_{M,11}=W_{0}, W_{M,12}=W_{2//1}, W_{M,21}=W_{4}, and W_{M,I=W0}, W_{M,Q}=W_{1//2}.
Here, so far the cases of two channels and three channels were explained. The cases of two channels and three channels may be selectively used in accordance with the difference of the impulse response characteristic difference of the pulse shaping bandpass filter.
In order to provide the identical conditions, the power level of the control or signal channel is controlled to be the same as the power level of the communication channel (Fundamental channel, supplemental channel or the In-phase channel and the Quadrature channel), and the power level of the pilot channel is controlled to be lower than the power level of the communication channel by 4 dB. In the above-described state, the statistical distributions of the peak power-to-average power are compared.
In the case of OCQPSK according to the present invention, the comparison is implemented using the first complex multiplier 100 and the n-th complex multiplier 100n shown in FIG. 4. The first block 100 is implemented based on W_{M,11}=W_{0}, W_{M,12}=W_{4}, W_{M,13}=W_{0}, and W_{M,14}=W_{1}, and the n-th block 100n is implemented based on W_{M,n1}=W_{0}, W_{M,n2}=W_{4}, W_{M,n3}=W_{2}, and W_{M,n4}=W_{3}. In addition, the SCI is used as the SC1 for the spreading code. In this case, the SC2 is not used.
In the case of OCQPSK, the probability that the instantaneous power exceeds the average power value (0 dB) by 4 dB is 0.03%, and in the case of CDMA ONE, the same is 0.9%, and in the case of the ETRI version 1.0, the same is 4%. Therefore, in the present invention, the system using the CDMA technique has very excellent characteristic in the peak to average power ratio sense, and the method according to the present invention is a new modulation method which eliminates the cross talk problem.
As shown therein, one or a plurality of channels are combined and complex-multiplied by the permutated orthogonal Hadamard code and then are spread by the spreading code.
As shown therein, there are provided first and second Hadamard sequence multipliers 600 and 700 for allocating the multichannel to a predetermined number of channels, splitting the same into two groups and outputting α_{n1}W_{M,n1}X_{n1 }which is obtained by multiplying the data X_{n1 }of each channel by the gain α_{n1 }and the orthogonal Hadamard sequence W_{M,n1}, a first adder 810 for outputtin
which is obtained by summing the output signals from the first Hadamard sequence multiplier 600, a second adder 820 for outputting
which is obtained by summing the output signals from the second Hadamard sequence multiplier 700, a complex multiplier 900 for receiving the output signal from the first adder 810 and the output signal from the second adder 820 in the complex form of
and complex-multiplying W_{M,I}+jPW_{M,Q }which consist of the orthogonal Hadamard code W_{M,I}, and the permutated orthogonal Hadamard code PW_{M,Q }that W_{M,Q }and a predetermined sequence P are complex-multiplied, a spreading unit 300 for multiplying the output signal from the complex multiplier 900 by the spreading code, a filter 400 for filtering the output signal from the spreading unit 300, and a modulator 500 for multiplying and modulating the modulation carrier wave, summing the in-phase signal and the quadrature phase signal and outputting a modulation signal of the real number.
Here, the construction of the spreading unit 300, the filter 400 and the modulator 500 is the same as the embodiment of
The first orthogonal Hadamard sequence multiplier 600 outputs
which is summed by the first adder 810 by summing α_{11}W_{M,11}X_{11 }which is obtained by the first adder 810 by multiplying the orthogonal Hadamard sequence W_{M,11 }by the first data X_{11 }of the first block and the gain α_{11}, respectively, α_{21}W_{M,21}X_{21 }which is obtained by multiplying the orthogonal Hadamard sequence W_{M,21 }by the second data X_{21 }of the first block and the gain α_{21}, respectively, and α_{n1}W_{M,n1}X_{n1 }which is obtained by multiplying the orthogonal Hadamard sequence W_{M,n1 }by the n-th data X_{n1 }of the first block and the gain α_{n1}.
The second orthogonal Hadamard sequence multiplier 700 outputs
which is summed by the second adder 820 by summing α_{12}W_{M,12}X_{12 }which is obtained by multiplying the orthogonal Hadamard sequence W_{M,12 }by the first data X_{12 }of the second block and the gain α_{12}, respectively, α_{22}W_{M,22}X_{22 }which is obtained by multiplying the orthogonal Hadamard sequence W_{M,22 }by the second data X_{22 }of the second block and the gain α_{22}, respectively, and α_{n2}W_{M,n2}X_{n2 }which is obtained by multiplying the orthogonal Hadamard sequence W_{M,n2 }by the n-th data X_{n2 }of the second block and the gain α_{n2}. Here, the block represents one group split into 1 group.
The signal outputted from the first adder 810 forms an in-phase data, and the signal outputted from the second adder 820 forms an quadrature phase data and outputs
In addition, the complex multiplier 900 multiplies the complex output signals from the first and second adders 810 and 820 by a complex type signal that is comprised of an orthogonal Harmard code W_{M,I }and PW_{M,Q }which results from the multiplication of the orthogonal Hardmard code W_{M,Q }by the sequence P and outputs an in-phase signal and a quadrature phase signal. Namely, the complex output signals from the first and second adders 810 and 820 are complex-multiplied by the complex type signals of W_{M,I}+jPW_{M,Q }by the complex multiplier.
The spreading unit 300 multiplies the output signal from the complex multiplier 900 by the spreading code SCI and spreads the same. The thusly spread signals are filtered by the pulse shaping filters 410 and 420. The modulation carrier waves of cos(2πf_{c}t) and sin(2πf_{c}t) are summed by the modulation multipliers 510 and 520 and then modulated for thereby outputting s(t).
Namely, the following equation is obtained.
where K represents an integer greater than or equal to 1.
Here, the orthogonal Hadamard sequence multiplier includes a first multiplier 610 for multiplying the first data X_{11 }by the gain α_{11}, a second multiplier 611 for multiplying the output signal from the first multiplier 610 by the orthogonal Hadamard sequence W_{M,11}, a third multiplier 710 for multiplying the second data X_{12 }by the gain α_{12}, and a fourth multiplier 711 for multiplying the output signal from the third multiplier 710 by the orthogonal Hadamard sequence W_{M,12}. At this time, since one channel is allocated to one group, the summing unit is not used.
The complex multiplier 900 includes fifth and sixth multipliers 901 and 902 for multiplying the output signal α_{11}W_{M,11}X_{11 }from the second multiplier 611 and the output signal α_{12}W_{M,12}X_{12 }from the fourth multiplier 711 by the orthogonal Hadamard sequence W_{M,I}, seventh and eighth multipliers 903 and 904 for multiplying the output signal α_{11}W_{M,11}X_{11 }from the second multiplier 611 and the output signal α_{12}W_{M,12}X_{12 }from the fourth multiplier 711 by the permutated orthogonal Hadamard sequence PW_{M,Q}, a first adder 905 for summing the output signal (+ac) from the fifth multiplier 901 and the output signal (−bd) from the seventh multiplier 903 and outputting an in-phase information (ac−bd), and a second adder 906 for summing the output signal (bc) from the sixth multiplier 902 and the output signal (ad) from the eighth multiplier 904 and outputting an quadrature phase information (bc+ad).
Therefore, the first and second multipliers 610 and 611 multiply the data X_{11 }by the orthogonal Hadamard sequence W_{M,11 }and the gain α_{11 }for thereby obtaining α_{11}W_{M,11}X_{11 }(=a). In addition, the third and fourth multipliers 710 and 711 multiply the data X_{12 }by the orthogonal Hadamard sequence W_{M,12 }and the gain α_{12 }for thereby obtaining α_{12}W_{M,12}X_{12 }(=b). The fifth and sixth multipliers 901 and 902 multiply α_{11}W_{M,11}X_{11 }(=a) and α_{12}W_{M,12}X_{12 }(=b) by the orthogonal Hadamard sequence W_{M,I }(=c) for thereby obtaining α_{11}W_{M,11}X_{11}W_{M,I }(=ac) and α_{12}W_{M,12}X_{12}W_{M,i }(=bc).
The seventh and eighth multipliers 903 and 904 multiply α_{11}W_{M,11}X_{11 }(=a) and α_{12}W_{M,12}X_{12 }(=b) by the permutated orthogonal Hadamard sequence PW_{M,Q }for thereby obtaining α_{11}W_{M,11}X_{11}PW_{M,Q }(=ad) and α_{12}W_{M,12}X_{12}PW_{M,Q }(=bd).
In addition, the first adder 905 obtains (α_{11}W_{M,11}X_{11}W_{M,I})−(α_{12}W_{M,12}X_{12}PW_{M,Q}) (=ac−bd), namely, α_{12}W_{M,12}X_{12PWM,Q}(bd) is subtracted from α_{11}W_{M,11}X_{11}W_{M,I }(=ac), and the second adder 906 obtains (α_{11}W_{M,11}X_{11}PW_{M,Q})+(α_{12}W_{M,12}X_{12}W_{M,I}) (ad+bc), namely, (α_{11}W_{M,11}X_{11}PW_{M,Q}) (=ad) is summed by (α_{12}W_{M,12}X_{12}W_{M,I}) (bc).
The in-phase data and the quadrature phase data are spread by the spreading unit 300 based on the spreading code (for example, PN code). In addition, the I channel signal which is the in-phase information and the Q channel signal which is the quadrature phase information signal are filtered by the first and second pulse shaping filters 410 and 420. The first and second multipliers 510 and 520 multiply the output signals from the first and second pulse shaping filters 410 and 420 by cos(2πf_{c}t) and sin(2πf_{c}t). The output signals from the multipliers 510 and 520 are summed and modulated by the adder 530 which outputs S(t).
In the embodiment as shown in
The orthogonal Hadamard sequence is allocated to each channel based on the above-described operation, and if there remain other channels which are not allocated the orthogonal Hadamard sequence by the above-described operation, and if there remain other channel which are not allocated the orthogonal Hadamard sequence by the above-described operation, then any row or column vector from the Hamard matrix can be selected.
As shown in
As shown therein, when comparing the embodiments of
In order to provide the identical condition, the power level of the signal channel is controlled to be the same as the power level of the communication channel, and the power level of the pilot channel is controlled to be lower than the power level of the communication channel by 4 dB, and then the statistical distribution of the peak power-to-average power ratio is compared.
In the case of the POCQPSK according to the present invention, in the first block 600 of
For example, the probability that the instantaneous power exceeds the average power value (0 dB) by 4 dB is 0.1% based on POCQPSK, and the complex spreading method is 2%. Therefore, in view of the power efficiency, the method adapting the CDMA technique according to the present invention is a new modulation method having excellent characteristic.
As described above, in the OCQPSK according to the present invention, the first data and the second data are multiplied by the gain and orthogonal code, and the resultant values are complex-summed, and the complex summed value is complex-multiplied by the complex type orthogonal code. The method that the information of the multichannel of the identical structure is summed and then spread is used. Therefore, this method statistically reduces the peak power-to-average power ratio to the desired range.
In addition, in the POCQPSK according to the present invention, the data of the first block and the data of the second block are multiplied by the gain and the orthogonal code, respectively, and the permutated orthogonal spreading code of the complex type is complex-multiplied and then spread. Therefore, this method statistically reduces the peak power-to-average power ratio to the desired range, and it is possible to decrease the phase dependency based in the multichannel interference and the multiuser interference using the combined orthogonal Hadamard sequence.
Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, tat additions and substitutions are possible, without departing from the scope and spirit of the invention as recited in the accompanying claims.
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U.S. Classification | 375/141, 375/298, 375/146 |
International Classification | H04B7/26, H04J13/10, H04J11/00, H04J13/00 |
Cooperative Classification | H04J13/0048, H04J13/102, H04B1/7097, H04J2013/0037 |
European Classification | H04J13/10A, H04J13/00B7B |
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