US20010055966A1 - Method of power control and cells site selection - Google Patents
Method of power control and cells site selection Download PDFInfo
- Publication number
- US20010055966A1 US20010055966A1 US08/870,669 US87066997A US2001055966A1 US 20010055966 A1 US20010055966 A1 US 20010055966A1 US 87066997 A US87066997 A US 87066997A US 2001055966 A1 US2001055966 A1 US 2001055966A1
- Authority
- US
- United States
- Prior art keywords
- cell site
- cell
- power
- path gain
- site
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 238000000034 method Methods 0.000 title claims abstract description 49
- 238000004891 communication Methods 0.000 claims abstract description 29
- 230000010267 cellular communication Effects 0.000 claims abstract description 18
- 238000001228 spectrum Methods 0.000 claims description 12
- 238000005259 measurement Methods 0.000 abstract description 5
- 230000001413 cellular effect Effects 0.000 description 16
- 230000003044 adaptive effect Effects 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 238000010295 mobile communication Methods 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 1
- 230000001427 coherent effect Effects 0.000 description 1
- 238000013016 damping Methods 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005562 fading Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 230000006855 networking Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000010187 selection method Methods 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W48/00—Access restriction; Network selection; Access point selection
- H04W48/20—Selecting an access point
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
- H04W16/14—Spectrum sharing arrangements between different networks
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
- H04W52/04—TPC
- H04W52/18—TPC being performed according to specific parameters
- H04W52/24—TPC being performed according to specific parameters using SIR [Signal to Interference Ratio] or other wireless path parameters
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W24/00—Supervisory, monitoring or testing arrangements
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W28/00—Network traffic management; Network resource management
- H04W28/16—Central resource management; Negotiation of resources or communication parameters, e.g. negotiating bandwidth or QoS [Quality of Service]
- H04W28/18—Negotiating wireless communication parameters
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/08—Reselecting an access point
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/24—Reselection being triggered by specific parameters
- H04W36/30—Reselection being triggered by specific parameters by measured or perceived connection quality data
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W84/00—Network topologies
- H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
- H04W84/04—Large scale networks; Deep hierarchical networks
- H04W84/042—Public Land Mobile systems, e.g. cellular systems
Definitions
- the invention relates to the area of cellular communications.
- the cellular communications concept calls for dividing a geographic service area into a number of cells.
- Each cell has an associated cell site (also called a base station) connected to the public telephone network.
- the cell site establishes a wireless link over radio channels with communication devices (hereinafter “user devices” or “devices”) operated by system users within the cell who wish to send and receive information (e.g. text, audio, speech, video) via the public telephone network.
- user devices hereinafter “user devices” or “devices”
- users of the system may be mobile or stationary, and the communications of mobile users traveling from a first cell to a second cell can be “handed-off” to the cell site in a second cell without an interruption in communications.
- cellular systems have a limited number of radio channels that may be used, and maximizing system capacity through effective utilization of the frequency spectrum is crucial.
- a cellular system must be reliable, and typically cellular systems must assure each user of a quality of service level, i.e. a guaranteed minimum bandwidth (in bits per second) and a guaranteed maximum bit error rate.
- the configuration of users i.e. the number of users and their locations, is dynamic.
- a given user may travel from one cell to another during a single communication, or one user with a certain quality of service requirement may terminate a communication in one cell while another user with another quality of service requirement in another cell initiates a communication.
- Dynamic user configurations thus make it difficult to optimize certain system parameters (e.g. cell site location).
- each cell site transmits a pilot signal.
- the strength of the pilot signal is measured at a user's device.
- the user's device is then assigned to the cell site whose pilot signal is strongest.
- the device controls its transmit power level as a function of the received pilot signal strength in such a way as to achieve a desired nominal required received power at the selected cell site.
- This solution to the power and cell site selection problem has several drawbacks.
- First, the use of a nominal received power level does not allow different users to have different quality of service requirements.
- the procedure of establishing the desired nominal received power level at each cell is centralized (in that a system controller determines the value of the nominal received power level at a cell) and leaves open the problem of adapting these levels to changing traffic patterns.
- one or more operating parameters of a communication device in a cellular communications system are selected based on an interference level measurement at a base station and on the path gain from the communication device to a cell site.
- the operating parameters include the particular cell site to which the communication device is assigned and the transmit power level for the communication device. The invention advantageously reduces interference levels at cell sites thereby increasing system capacity while maintaining quality of service commitments.
- a communication device is assigned to one cell site in a plurality of cell sites in the cellular communications system by receiving a measure of the interference level at each cell site, determining the path gain to each cell cite from the device, and assigning the communication device to a particular cell site as a function of the interference level and the path gain.
- a communication device with an associated quality of service requirement selects a transmit power level for transmitting to a selected cell site by receiving a measure of the interference level at that cell site, determining the path gain to the cell site, and transmitting with a power level determined as a function of the interference level, required quality of service requirement and the path gain.
- the cell site assignment and transmit power level selections may be periodically updated.
- FIG. 1 is a diagram of a cellular communications system in which the inventive method may be practiced.
- FIG. 2 illustrates a cellular system in which one cell is heavily congested.
- FIG. 3 illustrates a cellular system in which a heavily congested cell is contracted.
- FIG. 4 is a flowchart of the inventive method for assigning a communications device to a cell site as a function of an interference level measurement and a path gain.
- FIG. 5 is a flowchart of the inventive method for selecting a transmit power level for a communications device as a function as a function of an interference level measurement, a quality of service requirement and a path gain.
- FIG. 1 illustrates components of a cellular communications system in which the inventive method may be practiced.
- cell site 105 -k which is connected to the public telephone network.
- information i.e. data representing text, speech, video, etc.
- the wireless link between any device 110 k,j and cell site 105 -k is comprised of an uplink U k,j for transmitting information from device 110 k,j to cell site 105 -k and then to the telephone network and of a downlink D k,j for transmitting to device 110 k,j information received by cell site 105 -k via the telephone network.
- the inventive method selects operating parameters for a system user's communication device in a cellular communications system.
- the method selects for the device a cell site and a transmit power level for that device.
- the selection is based on an interference level at the cell site and on the path gain from the device to the cell site. This task is performed for each and every user in the system in a way that maintains a quality of service level for each user.
- the method is advantageous in that it is dynamic (i.e. able to adapt to changing user configurations and to changing quality of service requirements of system users) and decentralized (i.e. each device can determine its own transmit power level and cell site).
- the inventive method is easier to implement than a centralized scheme, and the method is more robust with respect to changes in user demands.
- the cellular communications system utilizes spread spectrum access techniques, then several factors make the inventive method especially advantageous in selecting a cell site and in selecting a transmit power level.
- the C/I ratio i.e. the ratio of the carrier level to interference level at the cell site
- I typically is high because all other system users are transmitting wideband signals that are treated as interference by a particular device.
- the quality of service in these systems for that particular device is very sensitive to changes in I, and the optimal cell site therefore depends on I as well as on the particular device's carrier signal strength C.
- the inventive method is particularly advantageous for spread spectrum systems because it focuses on the interference level as measured at the cell site.
- FIG. 2 illustrates a cellular system comprising, illustratively, two cells, 201 and 220 , with respective cell sites 205 and 225 .
- Cell 201 is heavily congested and operating near capacity, i.e. a large number of devices (indicated by the x's within the cell) are simultaneously accessing the system.
- there are few devices also indicated by x's communicating with cell site 225 in cell 220 .
- a device selects a cell site from among a set of one or more cell sites based on the interference level at each cell site and on the path gain between the device and each cell site.
- the interference level at a cell site is defined as the sum of the received power at the cell site from all other transmitting devices (i.e. not including the power from the device in question) plus external noise power (e.g. atmospheric noise) received at the cell site.
- the path gain is defined as a scale factor that the required received power level at the cell site is divided by in order to determine the required transmit power of the device. As described in detail below, the path gain from the device to the cell site is assumed to be the same as the path gain from the cell site to the device.
- the path gain from the cell site to the device is easily measured, and the measurement is used for the value of the path gain from the device to the cell site.
- the path gain is typically less than unity and represents, primarily, the degradation in signal strength due to distance and shadow fading.
- the inventive method will typically result in some devices in heavily congested cell 201 transmitting instead to the more distant cell site 225 in cell 220 , thereby trading a typically smaller path gain (due to the increased distance to the cell site) for reduced interference at the cell site 225 (by reason of few devices transmitting a lower power level in the cell).
- the method effectively reduces or contracts the area served by heavily congested cell sites, and thus the user configuration of FIG. 2 may, using the inventive method, be transformed into a user configuration akin to the one shown in FIG. 3.
- cell 220 will contract and the neighboring cell will expand—in a sense the method allows the cell to “breathe.”
- each user's communication device i,i 1,2, . . . N, is allocated to cell site S i .
- the signal received at cell site S i from the j th device constitutes interference at the cell site for the signal received from the i th device.
- each user has a performance level or quality of service requirement that corresponds to a particular required carrier to interference ratio (C/I) i at the cell site for the signal received from the i th device.
- the parameter C is the received signal power of the i th device at cell site S i and I is the interference, i.e.
- the interference level I is defined as the received power of all signals, including the signal from a particular device, received at the cell site.
- the required ratio of C/I i is called ⁇ i .
- FIG. 4 illustrates steps for selecting a cell site for the i th device at the next time interval.
- the i th device receives a signal indicating the amount of interference at each cell site.
- each cell site k may transmit to the i th device a measure of the interference level at that cell site.
- the i th device determines the path gain ⁇ i,k to each cell site k.
- One simple method for computing the path gain ⁇ i,k to each cell site is to broadcast a control signal from each cell site (e.g. a pilot signal).
- the path gain to an individual device from a particular cell site (which is advantageously assumed to be the same as the path gain from the individual device to the particular cell site) can readily be determined from the received strength of the control signal from that particular cell site at the device.
- the i th device can determine the power required to transmit to each cell site while maintaining the required quality of service in step 415 .
- the power P i,k required to transmit from the i th device to each of the k cell sites, k 1,2 , . . .
- the i th device will then select in step 420 , at the next point in time when a new cell site can be chosen, the cell site which requires the least amount of power.
- the device may then optionally transmit at that power.
- ⁇ i is common to equations above since ⁇ i remains the same for a particular device during time n, and thus the choice of cell sites is a function only of the interference level and path gain.
- selecting the cell site which requires the least amount of power is the same as selecting the cell site with minimum I k / ⁇ i,k ratio. As discussed below, the quality of service requirement becomes a factor in determining the power level for transmitting to the selected cell site.
- the above method can be simplified by considering only a subset of cell sites in the system, instead of all cell sites, when selecting a cell site to assign to a particular user. For example, only those m cell sites having the greatest path gain need be considered. Alternatively, only those cell sites having a path gain exceeding a given threshold can be considered for cell site assignment.
- the threshold itself can be adaptive to user configurations in the cellular system. Such a restriction in the number of cell sites considered will lead to computational savings and reduced complexity in user equipment. Finally, it may be that selecting a new cell site yields little advantage (e.g. only a minimal reduction in transmit power). To prevent unnecessary changes in cell site assignments and to reduce the rate of change, a damping mechanism can be employed. In this case, the best cell site for the next time interval is considered only as a candidate cell site.
- P i , candidate ⁇ i ⁇ ⁇ I candidate ⁇ i , candidate
- the candidate cell site is chosen as the new cell site only if P i,candidate is sufficiently less than P i,current .
- a threshold ⁇ 1 may be chosen so that a change in cell sites occurs only if P i,candidate ⁇ P i,current .
- the inventive method may also be used to select the transmit power level parameter for a device to communicate to an assigned cell site.
- the allocation of cell sites is fixed for a time interval, e.g. the system updates the transmit power levels more frequently than it updates the cell site assignments.
- FIG. 5 is flowchart of steps in a method for selecting the transmit power for an i th device with quality of service requirement ⁇ i to communicate with an assigned cell site.
- the device first receives a signal indicating the interference level at the assigned cell site.
- the signal may be broadcast from the assigned cell site, or the signal may be provided by other means.
- the path gain ⁇ i is determined next by the device as described in step 410 above.
- the above disclosure describes a method of selecting operating parameters of a device in a cellular system as a function of the interference level at cell sites in the system and of the path gains between the device and the cell sites.
- the selected operating parameters discussed above include the particular cell site to which the device is assigned and the transmit power level for the communication device, it will be understood by those skilled in that art that other operating parameters may be selected.
- the inventive method selects cell sites based only the uplink between users and cell sites. Note that the uplink communication is incoherent in contrast to the coherent downlink—and thus the uplink requires a greater C/I ratio for a given quality of service.
- any cell site selection procedure that works for the uplink will necessarily work for the downlink and less transmit power will be required on the downlink.
- the power control equations can be modified for the downlink. Further, it has been assumed that each device employs the full spectrum of available bandwidth. If less than the full spectrum of available bandwidth is used, as for example by using a narrowband channel for communicating, the equations above can easily be modified to reflect that the interference level of interest is only the interference in the narrowband channel.
Abstract
A method for use in a cellular communication system is disclosed which dynamically assigns a communication device to a cell site and which dynamically assigns transmit power levels to the communication device. The method is based on measurements of interference levels at cell sites and on the path gain between the communication device and the cell site.
Description
- This application is a continuation of Ser. No. 08/281956 filed on Jul. 28, 1994.
- The invention relates to the area of cellular communications.
- The tremendous growth experienced by wireless communications systems in the past few years has transformed mobile communications from a specialized service for a select few into a service available to everyone. Only a few years ago mobile communications systems used a limited number of narrowband radio channels for transmitting and receiving voice information in a single geographic area whose extent was defined by the range of the mobile transmitter. Today's wireless systems, and in particular present cellular-based systems, are designed to permit an increased number of users to have access to wider bandwidths (to support data communications as well as voice) over a wider geographic area. Despite such advances in wireless technology, there is a constant demand for increased system capacity while maintaining the quality of services to users.
- The cellular communications concept calls for dividing a geographic service area into a number of cells. Each cell has an associated cell site (also called a base station) connected to the public telephone network. The cell site establishes a wireless link over radio channels with communication devices (hereinafter “user devices” or “devices”) operated by system users within the cell who wish to send and receive information (e.g. text, audio, speech, video) via the public telephone network. Note that users of the system may be mobile or stationary, and the communications of mobile users traveling from a first cell to a second cell can be “handed-off” to the cell site in a second cell without an interruption in communications.
- The design of cellular systems and the selection of operating parameters for the system are particularly challenging for several reasons. First, cellular systems have a limited number of radio channels that may be used, and maximizing system capacity through effective utilization of the frequency spectrum is crucial. Second, even with limited spectral resources, a cellular system must be reliable, and typically cellular systems must assure each user of a quality of service level, i.e. a guaranteed minimum bandwidth (in bits per second) and a guaranteed maximum bit error rate. Third, the configuration of users, i.e. the number of users and their locations, is dynamic. For example, a given user may travel from one cell to another during a single communication, or one user with a certain quality of service requirement may terminate a communication in one cell while another user with another quality of service requirement in another cell initiates a communication. Dynamic user configurations thus make it difficult to optimize certain system parameters (e.g. cell site location).
- Despite these challenges, the current, first-generation cellular systems, based on analog FM technology, have proved to be very successful. In these systems, interference between the communications of different users in different cells is kept to minimal levels by permitting each cell to use only a subset of the available radio channels. System capacity is maintained through reuse of radio channels in cells that are far enough apart so as to minimally interfere with each other.
- With the objective of further reducing interference and increasing capacity, second-generation cellular systems—based on digital radio technology and advanced networking principles—are now being developed and deployed worldwide. Because spread spectrum is a useful technique for facilitating communications when large numbers of users wish to communicate simultaneously, spread spectrum has emerged as a leading multiple access technique for these second generation systems. By “spread spectrum” it is meant that each device generates a wideband signal (e.g. by code division multiple access or by very fast frequency hopping) which is treated as noise by other devices in the system. See, K. S. Gilhousen, et al., “On the Capacity of a Cellular CDMA System,”IEEE Trans. Veh. Tech., Vol. 4, No. 2, pp. 303-312, May 1991; A. M. Viterbi and A. J. Viterbi, “Erlang Capacity of a Power Controlled CDMA System,” J. Sel. Areas Comm., Vol. 11, No. 6, pp. 892-900, August 1993.
- In order to fully exploit the advantages of spread spectrum techniques, however, certain device parameters must be properly selected, e.g. transmit power levels and cell site selection or assignment. A device may have access to a number of possible cell sites and a choice as to which cell site it should communicate with must be made based upon some criterion. Similarly, the transmit power of each device must be determined so as to achieve the desired quality of service. One current technique for selecting parameters is described in Blakeney et al., “Mobile Station Assisted Soft Handoff in a CDMA Cellular Communication System,” U.S. Pat. No. 5,267,261 and in Wheatley, “Transmitter Power Control System,” U.S. Pat. No. 5,267,267, which describe an open loop scheme for power control and cell site assignment. In this scheme, each cell site transmits a pilot signal. The strength of the pilot signal is measured at a user's device. The user's device is then assigned to the cell site whose pilot signal is strongest. The device controls its transmit power level as a function of the received pilot signal strength in such a way as to achieve a desired nominal required received power at the selected cell site. This solution to the power and cell site selection problem, however, has several drawbacks. First, the use of a nominal received power level does not allow different users to have different quality of service requirements. Second, the procedure of establishing the desired nominal received power level at each cell is centralized (in that a system controller determines the value of the nominal received power level at a cell) and leaves open the problem of adapting these levels to changing traffic patterns. Thus, there is a need for an improved method to select device operating parameters in a cellular system, e.g. to select cell sites and to control power levels, to take into account the dynamic nature of the traffic in the cellular system and the increasingly diverse range of services to be carried on wireless networks.
- In accordance with the present invention, one or more operating parameters of a communication device in a cellular communications system are selected based on an interference level measurement at a base station and on the path gain from the communication device to a cell site. In preferred embodiments, the operating parameters include the particular cell site to which the communication device is assigned and the transmit power level for the communication device. The invention advantageously reduces interference levels at cell sites thereby increasing system capacity while maintaining quality of service commitments.
- In a first aspect of the invention, a communication device is assigned to one cell site in a plurality of cell sites in the cellular communications system by receiving a measure of the interference level at each cell site, determining the path gain to each cell cite from the device, and assigning the communication device to a particular cell site as a function of the interference level and the path gain. Additionally in preferred embodiments, a communication device with an associated quality of service requirement selects a transmit power level for transmitting to a selected cell site by receiving a measure of the interference level at that cell site, determining the path gain to the cell site, and transmitting with a power level determined as a function of the interference level, required quality of service requirement and the path gain. The cell site assignment and transmit power level selections may be periodically updated.
- Other features and advantages of the invention will become apparent from the following detailed description taken together with the drawings in which:
- FIG. 1 is a diagram of a cellular communications system in which the inventive method may be practiced.
- FIG. 2 illustrates a cellular system in which one cell is heavily congested.
- FIG. 3 illustrates a cellular system in which a heavily congested cell is contracted.
- FIG. 4 is a flowchart of the inventive method for assigning a communications device to a cell site as a function of an interference level measurement and a path gain.
- FIG. 5 is a flowchart of the inventive method for selecting a transmit power level for a communications device as a function as a function of an interference level measurement, a quality of service requirement and a path gain.
- FIG. 1 illustrates components of a cellular communications system in which the inventive method may be practiced. Cell102-k, k=1, 2, . . . , represents a portion of the
geographic area 100 served by the system. Within each cell is cell site 105-k which is connected to the public telephone network. Cell site 105-k establishes a wireless link over a radio channel withcommunication device 110 k,j, j=1,2, . . . , within cell 102-k for transmitting and receiving information (i.e. data representing text, speech, video, etc.). The wireless link between anydevice 110 k,j and cell site 105-k is comprised of an uplink Uk,j for transmitting information fromdevice 110 k,j to cell site 105-k and then to the telephone network and of a downlink Dk,j for transmitting todevice 110 k,j information received by cell site 105-k via the telephone network. - The inventive method, described below, selects operating parameters for a system user's communication device in a cellular communications system. In the present illustrative embodiments in particular, the method selects for the device a cell site and a transmit power level for that device. In accordance with the invention, the selection is based on an interference level at the cell site and on the path gain from the device to the cell site. This task is performed for each and every user in the system in a way that maintains a quality of service level for each user. The method is advantageous in that it is dynamic (i.e. able to adapt to changing user configurations and to changing quality of service requirements of system users) and decentralized (i.e. each device can determine its own transmit power level and cell site). The inventive method is easier to implement than a centralized scheme, and the method is more robust with respect to changes in user demands.
- If the cellular communications system utilizes spread spectrum access techniques, then several factors make the inventive method especially advantageous in selecting a cell site and in selecting a transmit power level. In particular, in spread spectrum systems the C/I ratio, i.e. the ratio of the carrier level to interference level at the cell site, is low because I typically is high (because all other system users are transmitting wideband signals that are treated as interference by a particular device). Thus, the quality of service in these systems for that particular device is very sensitive to changes in I, and the optimal cell site therefore depends on I as well as on the particular device's carrier signal strength C. In contrast, in a narrowband system, I is very low (typically comprising only thermal noise and co-channel interference) and so the optimal cell site will typically be the cell cite for which C is greatest—making the cell site selection problem trivial. In any case, I varies too rapidly in the narrowband system to make adaptive cell site selection and adaptive power control very effective. Thus, the inventive method is particularly advantageous for spread spectrum systems because it focuses on the interference level as measured at the cell site.
- In a first aspect, the inventive method selects a cell site for a device. FIG. 2 illustrates a cellular system comprising, illustratively, two cells,201 and 220, with
respective cell sites Cell 201 is heavily congested and operating near capacity, i.e. a large number of devices (indicated by the x's within the cell) are simultaneously accessing the system. In contrast, there are few devices (also indicated by x's) communicating withcell site 225 incell 220. In this aspect of the inventive method, presented in detail below, a device selects a cell site from among a set of one or more cell sites based on the interference level at each cell site and on the path gain between the device and each cell site. The interference level at a cell site is defined as the sum of the received power at the cell site from all other transmitting devices (i.e. not including the power from the device in question) plus external noise power (e.g. atmospheric noise) received at the cell site. The path gain is defined as a scale factor that the required received power level at the cell site is divided by in order to determine the required transmit power of the device. As described in detail below, the path gain from the device to the cell site is assumed to be the same as the path gain from the cell site to the device. Advantageously, the path gain from the cell site to the device is easily measured, and the measurement is used for the value of the path gain from the device to the cell site. The path gain is typically less than unity and represents, primarily, the degradation in signal strength due to distance and shadow fading. - Returning to FIG. 2, the inventive method will typically result in some devices in heavily
congested cell 201 transmitting instead to the moredistant cell site 225 incell 220, thereby trading a typically smaller path gain (due to the increased distance to the cell site) for reduced interference at the cell site 225 (by reason of few devices transmitting a lower power level in the cell). The method effectively reduces or contracts the area served by heavily congested cell sites, and thus the user configuration of FIG. 2 may, using the inventive method, be transformed into a user configuration akin to the one shown in FIG. 3. Likewise, if and whencell 220 becomes congested relative to a neighboring cell,cell 220 will contract and the neighboring cell will expand—in a sense the method allows the cell to “breathe.” -
- Consider a particular ith device which, for illustrative purposes, is assigned to a particular cell site at time n. FIG. 4 illustrates steps for selecting a cell site for the ith device at the next time interval. In
step 405 at time n, the ith device receives a signal indicating the amount of interference at each cell site. For example, each cell site k may transmit to the ith device a measure of the interference level at that cell site. In step 410 the ith device determines the path gain Γi,k to each cell site k. One simple method for computing the path gain Γi,k to each cell site is to broadcast a control signal from each cell site (e.g. a pilot signal). Then if all devices know a priori the transmitted power level used by each cell site for the control signal, the path gain to an individual device from a particular cell site (which is advantageously assumed to be the same as the path gain from the individual device to the particular cell site) can readily be determined from the received strength of the control signal from that particular cell site at the device. As a result, the ith device can determine the power required to transmit to each cell site while maintaining the required quality of service instep 415. The power Pi,k required to transmit from the ith device to each of the k cell sites, k=1,2 , . . . M, is - The ith device will then select in
step 420, at the next point in time when a new cell site can be chosen, the cell site which requires the least amount of power. The device may then optionally transmit at that power. Of course, αi is common to equations above since αi remains the same for a particular device during time n, and thus the choice of cell sites is a function only of the interference level and path gain. In short, selecting the cell site which requires the least amount of power is the same as selecting the cell site with minimum Ik/Γi,k ratio. As discussed below, the quality of service requirement becomes a factor in determining the power level for transmitting to the selected cell site. - The above method can be simplified by considering only a subset of cell sites in the system, instead of all cell sites, when selecting a cell site to assign to a particular user. For example, only those m cell sites having the greatest path gain need be considered. Alternatively, only those cell sites having a path gain exceeding a given threshold can be considered for cell site assignment. The threshold itself can be adaptive to user configurations in the cellular system. Such a restriction in the number of cell sites considered will lead to computational savings and reduced complexity in user equipment. Finally, it may be that selecting a new cell site yields little advantage (e.g. only a minimal reduction in transmit power). To prevent unnecessary changes in cell site assignments and to reduce the rate of change, a damping mechanism can be employed. In this case, the best cell site for the next time interval is considered only as a candidate cell site. Let
-
- be the power used to transmit to the currently assigned cell site. Then the candidate cell site is chosen as the new cell site only if Pi,candidate is sufficiently less than Pi,current. For example, a threshold ρ<1 may be chosen so that a change in cell sites occurs only if Pi,candidate<ρPi,current.
- In a second aspect, the inventive method may also be used to select the transmit power level parameter for a device to communicate to an assigned cell site. Suppose the allocation of cell sites is fixed for a time interval, e.g. the system updates the transmit power levels more frequently than it updates the cell site assignments. FIG. 5 is flowchart of steps in a method for selecting the transmit power for an ith device with quality of service requirement αi to communicate with an assigned cell site. In
step 505 the device first receives a signal indicating the interference level at the assigned cell site. The signal may be broadcast from the assigned cell site, or the signal may be provided by other means. The path gain Γi is determined next by the device as described in step 410 above. Instep 515 the power level for transmitting from the ith device to the assigned cell site is determined according to: - The theoretical basis for the inventive method is that if the C/I constraints of devices in the cellular system can be satisfied, then at any given time there is an optimal assignment of devices to cell sites in the sense that the power levels (and hence the interference) are at the minimum levels that achieve the required levels of performance. Iterations of the above method will find this minimal solution. In practice, users will move, and the method will track the changes in user configuration.
- The above disclosure describes a method of selecting operating parameters of a device in a cellular system as a function of the interference level at cell sites in the system and of the path gains between the device and the cell sites. Although the selected operating parameters discussed above include the particular cell site to which the device is assigned and the transmit power level for the communication device, it will be understood by those skilled in that art that other operating parameters may be selected.
- The method disclosed herein has been described without reference to specific hardware or software. Instead, the method has been described in such a way that those skilled in the art can readily adapt such hardware or software as may be available or preferable. While the above teaching of the present invention has been in terms of power control and cell site selection in a cellular communications system using spread spectrum access techniques, those skilled in the art will recognize the applicability of these teachings to other specific contexts. For example, the inventive method selects cell sites based only the uplink between users and cell sites. Note that the uplink communication is incoherent in contrast to the coherent downlink—and thus the uplink requires a greater C/I ratio for a given quality of service. Thus, any cell site selection procedure that works for the uplink will necessarily work for the downlink and less transmit power will be required on the downlink. Similarly, the power control equations can be modified for the downlink. Further, it has been assumed that each device employs the full spectrum of available bandwidth. If less than the full spectrum of available bandwidth is used, as for example by using a narrowband channel for communicating, the equations above can easily be modified to reflect that the interference level of interest is only the interference in the narrowband channel.
Claims (14)
1. A method of selecting an operating parameter for a device in a cellular communication system, the cellular communication system comprising one or more cell sites, each cell site having an associated interference level, the method comprising the steps of:
selecting at the device said operating parameter as a function of the interference level at each cell site in the cellular communications system and of the path gain between the device and each cell site.
2. The method of wherein said operating parameter is a transmit power level used by the device when the device communicates with a cell site.
claim 1
3. The method of wherein said operating parameter is a selection of a particular one of the cell sites said device is to be assigned for communication.
claim 1
4. The method of wherein the interference level associated with a particular cell site is a function of the sum of the received power at the particular cell site from other transmitting devices.
claim 1
5. The method of wherein the device communicates with a cell site by transmitting a signal with a transmit power that is received at the cell cite with a required received power and wherein the path gain is a scale factor based on the transmit power of the device and on the required received power at the cell site.
claim 1
6. The method of wherein the function is the ratio of the interference level to the path gain between the device and each cell site.
claim 1
7. The method of wherein the path gain between the device and a particular cell site is determined by a method comprising the steps of:
claim 1
measuring at the device a received signal of known transmitted power from the particular cell site, and
determining the path gain as a function of the known transmitted power and the power of the received signal.
8. An apparatus for selecting an operating parameter for a device in a cellular communication system, the cellular communication system comprising one or more cell sites, each cell site having an associated interference level, the apparatus comprising:
means for transmitting signals from the device to the cells and for receiving signals at the device from said cell sites; and
means for selecting at the device said operating parameter as a function of the interference level at each cell site in the [spread spectrum] cellular communications system and of the path gain between the device and each cell site.
9. The apparatus of wherein said operating parameter is a transmit power level used by the device when the device communicates with a cell site.
claim 8
10. The apparatus of wherein said operating parameter is a selection of a particular one of the cell sites to which the device is assigned for communication.
claim 8
11. The apparatus of wherein said interference level associated with each cell site is a function of the sum of the received power at each cell site from other transmitting devices.
claim 8
12. The apparatus of wherein the device communicates with a cell site by transmitting a signal with a transmit power that is received at the cell cite with a required received power and wherein the path gain is a scale factor based on the transmit power of the device and on the required received power at the cell site.
claim 8
13. The apparatus of wherein the function is the ratio of the interference level to the path gain between the device and each cell site.
claim 8
14. The apparatus of wherein the path gain between the device and a particular cell site is determined by an apparatus comprising:
claim 8
means for measuring at the device a received signal of known transmitted power from the particular cell site, and
means for determining the path gain as a function of the known transmitted power and the power of the received signal.
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/870,669 US20010055966A1 (en) | 1994-07-28 | 1997-06-06 | Method of power control and cells site selection |
US10/141,858 US6873845B2 (en) | 1994-07-28 | 2002-05-10 | Method of power control and cell site selection based upon path gain and interference level |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/281,956 US5697053A (en) | 1994-07-28 | 1994-07-28 | Method of power control and cell site selection |
US08/870,669 US20010055966A1 (en) | 1994-07-28 | 1997-06-06 | Method of power control and cells site selection |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US08/281,956 Continuation US5697053A (en) | 1994-07-28 | 1994-07-28 | Method of power control and cell site selection |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/141,858 Continuation US6873845B2 (en) | 1994-07-28 | 2002-05-10 | Method of power control and cell site selection based upon path gain and interference level |
Publications (1)
Publication Number | Publication Date |
---|---|
US20010055966A1 true US20010055966A1 (en) | 2001-12-27 |
Family
ID=23079483
Family Applications (3)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US08/281,956 Expired - Lifetime US5697053A (en) | 1994-07-28 | 1994-07-28 | Method of power control and cell site selection |
US08/870,669 Abandoned US20010055966A1 (en) | 1994-07-28 | 1997-06-06 | Method of power control and cells site selection |
US10/141,858 Expired - Fee Related US6873845B2 (en) | 1994-07-28 | 2002-05-10 | Method of power control and cell site selection based upon path gain and interference level |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US08/281,956 Expired - Lifetime US5697053A (en) | 1994-07-28 | 1994-07-28 | Method of power control and cell site selection |
Family Applications After (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/141,858 Expired - Fee Related US6873845B2 (en) | 1994-07-28 | 2002-05-10 | Method of power control and cell site selection based upon path gain and interference level |
Country Status (1)
Country | Link |
---|---|
US (3) | US5697053A (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20010031638A1 (en) * | 1999-12-07 | 2001-10-18 | Nokia Mobile Phones Limited | Methods and apparatus for performing cell reselection for supporting efficiently hierarchical cell structures |
US20040162074A1 (en) * | 2003-02-13 | 2004-08-19 | Rex Huan-Yueh Chen | Penalty of cell reselection for a wireless device |
US7359424B2 (en) * | 2000-06-28 | 2008-04-15 | Nec Corporation | Spread spectrum communication system and method therefor |
US20080170512A1 (en) * | 2007-01-12 | 2008-07-17 | Samsung Electoronics Co., Ltd. | Method and apparatus for controlling power in a decode-and-forward relay system |
US20190053144A1 (en) * | 2016-02-12 | 2019-02-14 | Vodafone Ip Licensing Limited | Cellular device cell selection |
Families Citing this family (60)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5697053A (en) | 1994-07-28 | 1997-12-09 | Lucent Technologies Inc. | Method of power control and cell site selection |
FR2747874B1 (en) * | 1996-04-18 | 1998-07-03 | France Telecom | METHOD FOR ANALYZING TRAFFIC LOCATION IN A CELLULAR RADIO COMMUNICATION NETWORK |
KR100199025B1 (en) * | 1996-04-24 | 1999-06-15 | 정선종 | Call allocation method of base station in cdma system |
US5867485A (en) * | 1996-06-14 | 1999-02-02 | Bellsouth Corporation | Low power microcellular wireless drop interactive network |
US6067446A (en) * | 1996-07-11 | 2000-05-23 | Telefonaktiebolaget Lm Ericsson | Power presetting in a radio communication system |
USRE39177E1 (en) * | 1997-01-29 | 2006-07-11 | Qualcomm, Inc. | Method and apparatus for performing soft hand-off in a wireless communication system |
US6151502A (en) * | 1997-01-29 | 2000-11-21 | Qualcomm Incorporated | Method and apparatus for performing soft hand-off in a wireless communication system |
JP2000509950A (en) * | 1997-03-03 | 2000-08-02 | セレトラ・リミテッド | Method and system for improving communication |
US6900775B2 (en) | 1997-03-03 | 2005-05-31 | Celletra Ltd. | Active antenna array configuration and control for cellular communication systems |
US5946612A (en) * | 1997-03-28 | 1999-08-31 | Telefonaktiebolaget L M Ericsson (Publ) | Method and apparatus for performing local traffic measurements in a cellular telephone network |
US6754497B1 (en) * | 1997-10-09 | 2004-06-22 | Interdigital Technology Corporation | Seamless handoff system and method |
US7184426B2 (en) | 2002-12-12 | 2007-02-27 | Qualcomm, Incorporated | Method and apparatus for burst pilot for a time division multiplex system |
US9118387B2 (en) | 1997-11-03 | 2015-08-25 | Qualcomm Incorporated | Pilot reference transmission for a wireless communication system |
JP3013822B2 (en) * | 1997-11-20 | 2000-02-28 | 日本電気株式会社 | Spread spectrum communication system |
US6175745B1 (en) * | 1997-12-24 | 2001-01-16 | Telefonaktiebolaget Lm Ericsson | Initial transmit power determination in a radiocommunication system |
DE69925800T2 (en) * | 1998-02-19 | 2006-05-04 | Qualcomm, Inc., San Diego | METHOD AND DEVICE FOR MAXIMIZING THE REST PERIOD USING A QUICK RUN CHANNEL |
US6163698A (en) * | 1998-05-04 | 2000-12-19 | Motorola | Link setup method for a narrowband cellular communication system |
US6081713A (en) * | 1998-05-18 | 2000-06-27 | Telefonaktiebolaget Lm Ericsson | Method of selectively directing a mobile station to retry system access in a radio telecommunication system |
US6285663B1 (en) | 1998-06-05 | 2001-09-04 | Telefonaktiebolaget Lm Ericsson (Publ) | Increasing performance in communications by embedding one signal in another signal |
US6553010B1 (en) * | 1998-10-16 | 2003-04-22 | Telefonaktiebolaget L M Ericsson | Coverage detection and indication in multimedia radiocommunication system |
US6587690B1 (en) * | 1999-02-12 | 2003-07-01 | Lucent Technologies Inc. | Method for allocating downlink electromagnetic power in wireless networks |
US7076264B2 (en) * | 1999-02-19 | 2006-07-11 | Qualcomm, Inc. | Power control in a cellular system using ES/IO and NT/I0 values |
EP1039662A1 (en) * | 1999-03-25 | 2000-09-27 | Alcatel | Improvements to a telecommunication system using code division multiple access (CDMA) |
US6795426B1 (en) | 1999-07-06 | 2004-09-21 | Cisco Technology, Inc. | Realtime power control in OFDM systems |
US8064409B1 (en) | 1999-08-25 | 2011-11-22 | Qualcomm Incorporated | Method and apparatus using a multi-carrier forward link in a wireless communication system |
US6621804B1 (en) | 1999-10-07 | 2003-09-16 | Qualcomm Incorporated | Method and apparatus for predicting favored supplemental channel transmission slots using transmission power measurements of a fundamental channel |
US6487420B1 (en) * | 1999-10-15 | 2002-11-26 | Telefonaktiebolaget Lm Ericsson (Publ) | Adaptive rach power determination for mobile telecommunications user equipment unit |
US6735447B1 (en) | 1999-12-08 | 2004-05-11 | Telefonaktiebolaget Lm Ericsson (Publ) | Transmission power control of a mobile station |
US6512933B1 (en) * | 2000-02-29 | 2003-01-28 | Verizon Laboratories Inc. | Iterative system and method for optimizing CDMA load distribution using reverse interference measurements |
US6973098B1 (en) | 2000-10-25 | 2005-12-06 | Qualcomm, Incorporated | Method and apparatus for determining a data rate in a high rate packet data wireless communications system |
US7068683B1 (en) | 2000-10-25 | 2006-06-27 | Qualcomm, Incorporated | Method and apparatus for high rate packet data and low delay data transmissions |
US7493143B2 (en) * | 2001-05-07 | 2009-02-17 | Qualcomm Incorporated | Method and system for utilizing polarization reuse in wireless communications |
US20040092233A1 (en) * | 2002-11-08 | 2004-05-13 | Rudrapatna Ashok N. | Variable rate closed loop power control for wireless communication systems |
US7133686B2 (en) * | 2003-01-08 | 2006-11-07 | Vtech Telecommunication Limited | System and method for identifying interferes in a communication spectrum |
US8023950B2 (en) * | 2003-02-18 | 2011-09-20 | Qualcomm Incorporated | Systems and methods for using selectable frame durations in a wireless communication system |
US8081598B2 (en) | 2003-02-18 | 2011-12-20 | Qualcomm Incorporated | Outer-loop power control for wireless communication systems |
US7660282B2 (en) | 2003-02-18 | 2010-02-09 | Qualcomm Incorporated | Congestion control in a wireless data network |
US8150407B2 (en) | 2003-02-18 | 2012-04-03 | Qualcomm Incorporated | System and method for scheduling transmissions in a wireless communication system |
US8391249B2 (en) | 2003-02-18 | 2013-03-05 | Qualcomm Incorporated | Code division multiplexing commands on a code division multiplexed channel |
US20040160922A1 (en) | 2003-02-18 | 2004-08-19 | Sanjiv Nanda | Method and apparatus for controlling data rate of a reverse link in a communication system |
US7155236B2 (en) | 2003-02-18 | 2006-12-26 | Qualcomm Incorporated | Scheduled and autonomous transmission and acknowledgement |
JP4178055B2 (en) * | 2003-02-25 | 2008-11-12 | 株式会社エヌ・ティ・ティ・ドコモ | Wireless packet communication system, wireless packet communication method, base station, and mobile station |
US8705588B2 (en) | 2003-03-06 | 2014-04-22 | Qualcomm Incorporated | Systems and methods for using code space in spread-spectrum communications |
US7215930B2 (en) | 2003-03-06 | 2007-05-08 | Qualcomm, Incorporated | Method and apparatus for providing uplink signal-to-noise ratio (SNR) estimation in a wireless communication |
US8477592B2 (en) | 2003-05-14 | 2013-07-02 | Qualcomm Incorporated | Interference and noise estimation in an OFDM system |
US8489949B2 (en) | 2003-08-05 | 2013-07-16 | Qualcomm Incorporated | Combining grant, acknowledgement, and rate control commands |
US20050135313A1 (en) * | 2003-12-23 | 2005-06-23 | Gandhi Asif D. | Method for determining when to increase capacity in a wireless communications system |
JP4448403B2 (en) * | 2004-08-16 | 2010-04-07 | 富士通株式会社 | Power level measuring apparatus and mobile station |
US20060068827A1 (en) * | 2004-09-28 | 2006-03-30 | Lucent Technologies, Inc. | Measuring power of a pilot channel of a transmit signal |
US7587218B2 (en) * | 2004-09-28 | 2009-09-08 | Alcatel-Lucent Usa Inc. | Using power of a pilot channel to control output power from a transmitter |
US7577456B2 (en) * | 2005-02-28 | 2009-08-18 | Telefonaktiebolaget Lm Ericsson (Publ) | Using uplink relative path gain related measurements to support uplink resource management |
US7729704B2 (en) * | 2005-03-31 | 2010-06-01 | Alcatel-Lucent Usa Inc. | Power load balancing in cellular networks employing shadow prices of base stations |
US7644587B2 (en) * | 2005-12-21 | 2010-01-12 | Rentech, Inc. | Method for providing auxiliary power to an electric power plant using fischer-tropsch technology |
WO2007129941A1 (en) * | 2006-05-04 | 2007-11-15 | Telefonaktiebolaget Lm Ericsson (Publ) | Method, apparatus and computer readable medium for obtaining efficient downlink power transmission |
WO2008060236A2 (en) * | 2006-11-17 | 2008-05-22 | Telefonaktiebolaget Lm Ericsson (Publ) | Transmission of special neighbor cell lists |
US8228853B2 (en) * | 2008-02-01 | 2012-07-24 | Qualcomm Incorporated | Serving base station selection in a wireless communication network |
GB2460819A (en) * | 2008-05-28 | 2009-12-16 | Vodafone Plc | Controlling reselection from access points in a telecommunications network |
US8385832B2 (en) * | 2009-03-13 | 2013-02-26 | Telefonaktiebolaget Lm Ericsson (Publ) | Inter-cell interference control in an uplink multi-carrier radio communications system |
US8811200B2 (en) | 2009-09-22 | 2014-08-19 | Qualcomm Incorporated | Physical layer metrics to support adaptive station-dependent channel state information feedback rate in multi-user communication systems |
US20120099449A1 (en) * | 2010-09-27 | 2012-04-26 | Qual Comm Incorporated | Spatial resuse in a wireless network |
Family Cites Families (22)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4613990A (en) * | 1984-06-25 | 1986-09-23 | At&T Bell Laboratories | Radiotelephone transmission power control |
US5267262A (en) * | 1989-11-07 | 1993-11-30 | Qualcomm Incorporated | Transmitter power control system |
US5101501A (en) * | 1989-11-07 | 1992-03-31 | Qualcomm Incorporated | Method and system for providing a soft handoff in communications in a cdma cellular telephone system |
US5056109A (en) * | 1989-11-07 | 1991-10-08 | Qualcomm, Inc. | Method and apparatus for controlling transmission power in a cdma cellular mobile telephone system |
US5265119A (en) * | 1989-11-07 | 1993-11-23 | Qualcomm Incorporated | Method and apparatus for controlling transmission power in a CDMA cellular mobile telephone system |
US5257283A (en) * | 1989-11-07 | 1993-10-26 | Qualcomm Incorporated | Spread spectrum transmitter power control method and system |
US5109390A (en) * | 1989-11-07 | 1992-04-28 | Qualcomm Incorporated | Diversity receiver in a cdma cellular telephone system |
US5446756A (en) * | 1990-03-19 | 1995-08-29 | Celsat America, Inc. | Integrated cellular communications system |
SE467332B (en) * | 1990-06-21 | 1992-06-29 | Ericsson Telefon Ab L M | PROCEDURE FOR POWER CONTROL IN A DIGITAL MOBILE PHONE SYSTEM |
US5103459B1 (en) * | 1990-06-25 | 1999-07-06 | Qualcomm Inc | System and method for generating signal waveforms in a cdma cellular telephone system |
SE9003913D0 (en) * | 1990-12-07 | 1990-12-07 | Ericsson Telefon Ab L M | A METHOD OF LOCATING A MOBILE STATION IN A CELLULAR MOBILE RADIO SYSTEM |
US5241685A (en) * | 1991-03-15 | 1993-08-31 | Telefonaktiebolaget L M Ericsson | Load sharing control for a mobile cellular radio system |
US5287544A (en) * | 1991-10-17 | 1994-02-15 | Motorola, Inc. | Method of channel assignment by matching channel interference with channel link loss |
AU2869892A (en) * | 1991-12-11 | 1993-07-19 | Motorola, Inc. | Handover decision algorithm using power budget values |
US5267261A (en) * | 1992-03-05 | 1993-11-30 | Qualcomm Incorporated | Mobile station assisted soft handoff in a CDMA cellular communications system |
US5574982A (en) | 1993-05-14 | 1996-11-12 | Telefonaktiebolaget Lm Ericsson | Method and apparatus for regulating a power level of a transmitted radio signal |
US5490165A (en) | 1993-10-28 | 1996-02-06 | Qualcomm Incorporated | Demodulation element assignment in a system capable of receiving multiple signals |
US5469471A (en) * | 1994-02-01 | 1995-11-21 | Qualcomm Incorporated | Method and apparatus for providing a communication link quality indication |
WO1995022857A1 (en) * | 1994-02-17 | 1995-08-24 | Motorola Inc. | Method and apparatus for controlling encoding rate in a communication system |
US5551057A (en) * | 1994-06-08 | 1996-08-27 | Lucent Technologies Inc. | Cellular mobile radio system power control |
US5697053A (en) | 1994-07-28 | 1997-12-09 | Lucent Technologies Inc. | Method of power control and cell site selection |
FI100575B (en) * | 1995-05-17 | 1997-12-31 | Nokia Mobile Phones Ltd | Method for improving handover and connection reliability and cellular radio system |
-
1994
- 1994-07-28 US US08/281,956 patent/US5697053A/en not_active Expired - Lifetime
-
1997
- 1997-06-06 US US08/870,669 patent/US20010055966A1/en not_active Abandoned
-
2002
- 2002-05-10 US US10/141,858 patent/US6873845B2/en not_active Expired - Fee Related
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20010031638A1 (en) * | 1999-12-07 | 2001-10-18 | Nokia Mobile Phones Limited | Methods and apparatus for performing cell reselection for supporting efficiently hierarchical cell structures |
US6751460B2 (en) * | 1999-12-07 | 2004-06-15 | Nokia Corporation | Methods and apparatus for performing cell reselection for supporting efficiently hierarchical cell structures |
US7359424B2 (en) * | 2000-06-28 | 2008-04-15 | Nec Corporation | Spread spectrum communication system and method therefor |
US20040162074A1 (en) * | 2003-02-13 | 2004-08-19 | Rex Huan-Yueh Chen | Penalty of cell reselection for a wireless device |
US7127253B2 (en) * | 2003-02-13 | 2006-10-24 | Asustek Computer Inc. | Penalty of cell reselection for a wireless device |
US20080170512A1 (en) * | 2007-01-12 | 2008-07-17 | Samsung Electoronics Co., Ltd. | Method and apparatus for controlling power in a decode-and-forward relay system |
US8199693B2 (en) * | 2007-01-12 | 2012-06-12 | Samsung Electronics Co., Ltd. | Method and apparatus for controlling power in a decode-and-forward relay system |
US20190053144A1 (en) * | 2016-02-12 | 2019-02-14 | Vodafone Ip Licensing Limited | Cellular device cell selection |
Also Published As
Publication number | Publication date |
---|---|
US20020160767A1 (en) | 2002-10-31 |
US6873845B2 (en) | 2005-03-29 |
US5697053A (en) | 1997-12-09 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US6873845B2 (en) | Method of power control and cell site selection based upon path gain and interference level | |
US6108321A (en) | Interference based dynamic channel assignment | |
KR100635690B1 (en) | Monitoring of cdma load and frequency reuse based on reverse link signal-to-noise ratio | |
EP0863619B1 (en) | Method for power control in wireless networks for communicating multiple information classes | |
US5732353A (en) | Automatic control channel planning in adaptive channel allocation systems | |
KR100236811B1 (en) | Channel assigning method in mobile terminal | |
US7130635B2 (en) | Mobile radio system and a method for channel allocation in a mobile radio system | |
US6580899B1 (en) | Adaptive forward power management algorithm for traffic hotspots | |
JP2003529962A (en) | Method and apparatus for beamforming in a wireless communication system | |
EP0941003A2 (en) | Flexible channel allocation for a cellular system based on a hybrid of measurement-based dynamic channel assignment and a reuse-distance criterion algorithm | |
JP2002533987A (en) | Method in a communication system | |
JPH09500778A (en) | Channel allocation method and system using power control and mobile assisted switching measurements | |
KR19990087406A (en) | Adaptive frequency allocation in telecommunication systems | |
US6405036B1 (en) | Method and arrangement in a telecommunication system | |
US6381462B1 (en) | Method and communications system with dynamically adaptable subscriber units | |
EP0819364B1 (en) | Stabilized control channel planning using loosely coupled dedicated traffic channels | |
US6570862B2 (en) | Method for selecting the way to perform a handover, and a cellular radio system | |
US20040185864A1 (en) | Channel rate and physical channel selection in wireless communications networks | |
EP1576742B1 (en) | Method and apparatus for determining a transmit power | |
US6804522B2 (en) | Handover in cellular system utilizing narrow and wide beam antennas | |
JP2921739B2 (en) | Call admission control method and apparatus | |
US6618598B1 (en) | Forward rate determination of high data rate channels in CDMA air interface | |
GB2285724A (en) | Selecting a channel in a TDMA system according to a variable threshold value | |
EP1131963B1 (en) | Method and communications system with dynamically adaptable subscriber units | |
JP3207135B2 (en) | Dynamic channel assignment method |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: LUCENT TECHNOLOGIES, INC., NEW JERSEY Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:HANLY, STEPHE VAUGHAN;REEL/FRAME:008591/0877 Effective date: 19970513 |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |