WIRELESS COMMUNICATION APPARATUS, WIRELESS COMMUNICATION METHOD, AND WIRELESS COMMUNICATION SYSTEM

• US 20150009924A1
• Filed: 11/02/2012
• Published: 01/08/2015
• Est. Priority Date: 01/26/2012
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Takano, Hiroaki
• Granted Patent: US 9,571,244 B2
• Time in Patent Office: Days
• US Class Current: 370/329
• CPC Class Codes: H04B 7/024 Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
• CPC Class Codes: H04B 7/063 Parameters other than those covered in groups H04B7/0623 - H04B7/0634, e.g. channel matrix rank or transmit mode selection
• CPC Class Codes: H04B 7/0639 Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection
• CPC Class Codes: H04B 7/065 Variable contents, e.g. long-term or short-short
• CPC Class Codes: H04B 7/066 Combined feedback for a number of channels, e.g. over several subcarriers like in orthogonal frequency division multiplexing [OFDM]
• CPC Class Codes: H04L 5/0035 Resource allocation in a cooperative multipoint environment
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04L 5/006 Quality of the received signal, e.g. BER, SNR, water filling
• CPC Class Codes: H04W 24/10 Scheduling measurement reports ; Arrangements for measurement reports
• CPC Class Codes: H04W 72/563 of the wireless resources

Abstract

An overhead accompanying feedback from a UE terminal is reduced.

The UE terminal selects not only M subbands with high quality but also M subbands with poor quality. Alternatively, the UE terminal selects M subbands to be fed back by increasing a priority of a subband with a high degree to which the quality of the subband is to be improved by the feedback or a subband having a high possibility of unnecessary eNodeB being removed from the CoMP set by the feedback. In addition, the UE terminal performs measurement and feedback in units of subband groups which can be collectively handled.

Claims

1. A wireless communication apparatus comprising:

a reference signal measurement unit that performs measurement of reference signals transmitted from respective base stations in a wideband and respective subbands, under a communication environment in which an entire system bandwidth is used as the wideband and a plurality of subbands obtained by dividing the system bandwidth are used;

a measurement result selection unit that selects measurement results to be fed back in order to determine a cooperative group of the base stations which performs Coordinated Multi Point Transmission/Reception (CoMP) for its own apparatus, among measurement results obtained in the wideband and the respective subbands by the reference signal measurement unit; and

a feedback unit that feeds back the measurement results selected by the measurement result selection unit to the base station.

2. The wireless communication apparatus according to claim 1, further comprising:

a measurement object determination unit that selects a base station which is in use as a transmission point of the cooperative group or is a candidate for the transmission point, as a measurement object, for each wideband and subband,

wherein the reference signal measurement unit performs measurement of a reference signal from the base station selected by the measurement object determination unit in the wideband and the respective subbands.

3. The wireless communication apparatus according to claim 1,

wherein the measurement result selection unit selects the measurement results to be fed back in order to determine the cooperative group such that a set of measurement results of the base station in the wideband is a population and a set of measurement results in the respective subbands is a subset for the population.

4. The wireless communication apparatus according to claim 1,

wherein the measurement result selection unit selects the measurement results to be fed back in order to determine the cooperative group, so as to include the measurement results of base stations other than the set of the measurement results in the respective subbands, in addition to the set of the measurement results of the base station in the wideband.

5. The wireless communication apparatus according to claim 1,

wherein the measurement result selection unit selects the measurement results to be fed back in order to determine the cooperative group, so as to include a measurement result of a base station added to a combination of base stations of the set of the measurement results in the respective subbands, in addition to the set of the measurement results of the base station in the wideband.

6. The wireless communication apparatus according to claim 1,

wherein the measurement result selection unit preferentially selects a measurement result of a subband having a high possibility of the cooperative group being updated when the measurement result is fed back.

7. The wireless communication apparatus according to claim 1,

wherein the measurement result selection unit preferentially selects a measurement result of a subband having a high possibility of a new base station being added to the cooperative group when the measurement result is fed back.

8. The wireless communication apparatus according to claim 1,

wherein the measurement result selection unit preferentially selects a measurement result of a subband having a high possibility of an unnecessary base station being removed from the cooperative group when the measurement result is fed back.

9. The wireless communication apparatus according to claim 1, further comprising:

a measurement result evaluation unit that evaluates measurement results of the respective subbands by the reference signal measurement unit,

wherein the measurement result selection unit selects the measurement results of the subbands to be fed back in order to determine the cooperative group, based on evaluation results of the respective subbands by the measurement result evaluation unit.

10. The wireless communication apparatus according to claim 9,

wherein the measurement result evaluation unit evaluates a quality of the respective subbands, and

wherein the measurement result selection unit selects measurement results of a predetermined number of subbands to be fed back, in order to include measurement results of a predetermined number of subbands with poor quality.

11. The wireless communication apparatus according to claim 9,

wherein the measurement result evaluation unit predicts an expected value of an improvement in quality for the respective subbands by the cooperative group being updated when measurement results are fed back, and

wherein the measurement result selection unit selects measurement results of a predetermined number of subbands to be fed back, based on the predicted expected value.

12. The wireless communication apparatus according to claim 11, further comprising:

a measurement object determination unit that predicts which cooperative group is to be determined by feeding back measurement results and selects a base station which is a measurement object by the reference signal measurement unit based on the predicted result, for the respective subbands,

wherein the measurement result evaluation unit predicts an expected value of an improvement in quality due to the predicted cooperative group.

13. The wireless communication apparatus according to claim 9,

wherein the measurement result evaluation unit evaluates whether or not an unnecessary base station is to be removed from the cooperative group when measurement results are fed back for the respective subbands, and

wherein the measurement result selection unit selects measurement results of a predetermined number of subbands to be fed back, based on a possibility of the unnecessary base station being removed.

14. The wireless communication apparatus according to claim 13, further comprising:

a measurement object determination unit that predicts which cooperative group is to be determined by feeding back measurement results and selects a base station which is a measurement object by the reference signal measurement unit based on the predicted result, for the respective subbands,

wherein the measurement result evaluation unit evaluates how many useless base stations are to be removed by the predicted cooperative group.

15. The wireless communication apparatus according to claim 1,

wherein the measurement result selection unit selects the measurement results such that an assembly of subbands which are consecutive in the frequency direction and have the same combination of the base stations constituting the cooperative group is made into a subband group and is fed back in units of subband groups.

16. A wireless communication apparatus comprising:

a notification unit that notifies a terminal station of information for determining a range for performing measurement and feedback of reference signals transmitted from respective base stations, under a communication environment in which an entire system bandwidth is used as a wideband and a plurality of subbands obtained by dividing the system bandwidth are used; and

a cooperative group determination unit that determines a cooperative group of base stations which performs CoMP for the terminal station in a wideband and the respective subbands, based on information which is fed back from the terminal station.

17. The wireless communication apparatus according to claim 16,

wherein the notification unit notifies the terminal station of information regarding the cooperative group which is determined by the cooperative group determination unit for the respective subbands.

18. The wireless communication apparatus according to claim 16,

wherein the notification unit divides information notified to the terminal station into three types of information indicating a range having a possibility of being measured, information indicating a range which is used most widely, and information indicating a range of a base station which is additionally used for the respective subbands, and notifies the information in different update frequencies for each piece of information.

19. A wireless communication method comprising:

a reference signal measurement step of performing measurement of reference signals transmitted from respective base stations, in a wideband and respective subbands, under a communication environment in which an entire system bandwidth is used as the wideband and a plurality of subbands obtained by dividing the system bandwidth are used;

a measurement result selection step of selecting measurement results to be fed back in order to determine a cooperative group of base stations which performs CoMP for its own apparatus, among measurement results obtained in the wideband and the respective subbands by the reference signal measurement step; and

a feedback step of feeding back the measurement results selected in the measurement result selection step to the base station.

20. A wireless communication method comprising:

a notification step of notifying a terminal station of information for determining a range for performing measurement and feedback of reference signals transmitted from respective base stations, under a communication environment in which an entire system bandwidth is used as a wideband and a plurality of subbands obtained by dividing the system bandwidth are used; and

a cooperative group determination step of determining a cooperative group of base stations which performs CoMP for the terminal station in a wideband and the respective subbands, based on information which is fed back from the terminal station.

21. A wireless communication system comprising:

a plurality of base stations that transmit reference signals; and

a terminal station that receives the reference signals from the base stations and performs measurement for determination of a cooperative group which performs CoMP for its own station,

wherein the terminal station performs measurement of the reference signals transmitted from respective base stations in a wideband and respective subbands, under a communication environment in which an entire system bandwidth is used as the wideband and a plurality of subbands obtained by dividing the system bandwidth are used, and selects and feeds back measurement results necessary for determining a cooperative group of the base stations which performs CoMP for its own apparatus.

22. A wireless communication system comprising:

a plurality of base stations that transmit reference signals; and

a terminal station that receives the reference signals from the base stations and performs measurement and feedback for determination of a cooperative group of the base stations which perform CoMP for its own station,

wherein at least one base station notifies the terminal station of information for determining a range for performing the measurement and the feedback of the reference signals transmitted from respective base stations, under a communication environment in which an entire system bandwidth is used as a wideband and a plurality of subbands obtained by dividing the system bandwidth are used.