Systems and methods for wireless communication using SDMA

• US 8,310,995 B2
• Filed: 05/02/2007
• Issued: 11/13/2012
• Est. Priority Date: 05/29/2006
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Murai, Shinji, Ishifuji, Tomoaki, Yano, Takashi, Shida, Masaaki, Hayase, Shigenori
• Primary Examiner(s): Appiah, Charles
• Assistant Examiner(s): Sabouri, Mazda
• Application Number:
  US11/797,321
• Publication Number:
  US 20070274256A1
• Time in Patent Office: 2,022 Days
• Field of Search: 370/328, 370/329
• US Class Current: 370/329
• CPC Class Codes: H04W 28/18 Negotiating wireless communication parameters
• CPC Class Codes: H04W 72/046 the resource being in the space domain, e.g. beams
• CPC Class Codes: H04W 72/542 using measured or perceived quality

Abstract

In a wireless communication system for communicating with a plurality of stations at the same point of time with the same frequency using a Space Division Multiple Access (SDMA), wireless resources are allocated by a first decision unit which evaluates performance of each station obtained when the SDMA is used and which determines periods of time to be allocated to groups of stations formed according to the SDMA technique. Using a first evaluation unit and a second evaluation unit to evaluate performance required by each station and each application, the first decision unit allocates the wireless resources to the stations. It is therefore possible that the wireless resources are efficiently allocated to the stations while preventing an event in which the wireless resources are excessive or insufficient for required quality of service.

Claims

1. A wireless communication apparatus for communicating with a plurality of stations using Space Division Multiple Access (SDMA), comprising:

a channel state information collecting unit which collects channel state information from each channel between the wireless communication apparatus and each station of the plurality of stations;

a wireless resource allocating unit which generates a plurality of SDMA station combinations as SDMA group candidates from which a plurality of SDMA groups for conducting SDMA for the plurality of stations are selected such that at least one station of the plurality of stations may belong to multiple SDMA groups of the plurality of SDMA groups for conducting SDMA, estimates a communication performance for each of the stations belonging to the SDMA group candidates by using the channel state information, performs an optimization of an evaluation value of an objective function used to evaluate a degree of achieving an object of a system under conditions of constraint that include the communication performance estimated for each station and a communication performance required for each station or a communication performance required for an application provided to the stations, and determines, in accordance with a result of the optimization, periods of time to be respectively allocated to the plurality of SDMA groups selected from the SDMA group candidates to thereby allocate wireless resources to the plurality of stations; and

a signal processing unit which communicates with the plurality of stations according to the wireless resources thus allocated.

2. A wireless communication apparatus according to claim 1, wherein the channel state information collecting unit collects, as the channel state information of each channel, a Signal to Noise power Ratio (SNR) or a Signal to Interference power Ratio (SIR).

3. A wireless communication apparatus according to claim 1, wherein the communication performance required for each channel or the application includes information regarding channel capacity required for the station corresponding to the channel or the application or information regarding delay allowed therefor.

4. A wireless communication apparatus according to claim 1, wherein the wireless resource allocating unit determines the plurality of SDMA station combinations as the SDMA group candidates according to a correlation of the channel state information.

5. A wireless communication apparatus according to claim 1, wherein the wireless resource allocating unit optimizes a period of time required for data communication with the plurality of stations as an evaluation value of an objective function under the conditions of constraint, and wherein the wireless resource allocating unit selects the SDMA groups and determines the allocation of the periods of time to the SDMA groups in accordance with the result of the optimization.

6. A wireless communication apparatus according to claim 1, wherein the wireless resource allocating unit optimizes a total of channel capacity for the plurality of stations as an evaluation value of an objective function under the conditions of constraint, and wherein the wireless resource allocating unit selects the SDMA groups and determines the allocation of the periods of time to the SDMA groups in accordance with the result of the optimization.

7. A wireless communication apparatus according to claim 1, wherein if the communication performance thus required includes transmission data of an absolute guarantee type and transmission data of a relative guarantee type, an evaluation index of the optimization calculation is a maximization of a total of channel capacity for communication of the transmission data of the relative guarantee type while satisfying a requirement of the communication performance for the transmission data of the absolute guarantee type.

8. A wireless communication apparatus according to claim 1, wherein if the communication performance thus required includes transmission data of an absolute guarantee type and transmission data of a relative guarantee type, an evaluation index of the optimization calculation is an operation to equally allocate channel capacity of the transmission data of the relative guarantee type to the respective stations of the plurality of SDMA groups while satisfying a requirement of the communication performance for the transmission data of the absolute guarantee type.

9. A wireless resource allocation method implemented by a wireless communication apparatus for communicating with a plurality of stations using Space Division Multiple Access (SDMA), comprising:

a first step of collecting channel state information from each channel between the wireless communication apparatus and each station of the plurality of stations;

a second step of generating a plurality of SDMA station combinations as SDMA group candidates from which a plurality of SDMA groups for conducting SDMA for the plurality of stations are selected such that at least one station of the plurality of stations may belong to multiple SDMA groups of the plurality of SDMA groups for conducting SDMA;

a third step of estimating a communication performance for each of the stations belonging to the SDMA group candidates by using the channel state information, performing an optimization of an evaluation value of an objective function used to evaluate a degree of achieving an object of a system under conditions of constraint that include the communication performance estimated for each station and a communication performance required for each station or a communication performance required for an application provided to the stations, and determining, in accordance with a result of the optimization, periods of time to be respectively allocated to the plurality of SDMA groups selected from the SDMA group candidates to thereby allocate wireless resources to the plurality of stations; and

a fourth step of communicating with the plurality of stations according to the allocated wireless resources.

10. A wireless resource allocation method according to claim 9, further comprising a step of collecting, as the channel state information of each channel, a Signal to Noise power Ratio (SNR) or a Signal to Interference power Ratio (SIR).

11. A wireless resource allocation method according to claim 9, wherein the communication performance required for each channel or the application includes information regarding channel capacity required for the station corresponding to the channel or the application or information regarding delay allowed therefor.

12. A wireless resource allocation method according to claim 9, wherein the second step further comprises determining the plurality of SDMA station combinations as the SDMA group candidates according to a correlation of the channel state information.

13. A wireless resource allocation method according to claim 9, wherein the wireless resource allocating unit optimizes a period of time required for data communication with the plurality of stations as an evaluation value of an objective function under the conditions of constraint, and wherein the wireless resource allocating unit selects the SDMA groups and determines the allocation of the periods of time to the SDMA groups in accordance with the result of the optimization.

14. A wireless resource allocation method according to claim 9, wherein the wireless resource allocating unit optimizes a total of channel capacity for the plurality of stations as an evaluation value of an objective function under the conditions of constraint, and wherein the wireless resource allocating unit selects the SDMA groups and determines the allocation of the periods of time to the SDMA groups in accordance with the result of the optimization.

15. A wireless resource allocation method according to claim 9, wherein if the communication performance thus required includes transmission data of an absolute guarantee type and transmission data of a relative guarantee type, an evaluation index of the optimization calculation is a maximization of a total of channel capacity for communication of the transmission data of the relative guarantee type while satisfying a requirement of the communication performance for the transmission data of the absolute guarantee type.

16. A wireless resource allocation method according to claim 9, wherein if the communication performance thus required includes transmission data of an absolute guarantee type and transmission data of a relative guarantee type, an evaluation index of the optimization calculation is an operation to equally allocate channel capacity of the transmission data of the relative guarantee type to the respective stations of the plurality of SDMA groups while satisfying a requirement of the communication performance for the transmission data of the absolute guarantee type.