Method and apparatus for coordinated multi-point communication for each sub-band based on long-term channel state information

• US 9,065,493 B2
• Filed: 02/25/2011
• Issued: 06/23/2015
• Est. Priority Date: 07/27/2010
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd., SNU R&DB Foundation (Seoul National University)
• Original Assignee: Samsung Electronics Co. Ltd., SNU R&D Foundation
• Inventors: Hong, Young Jun, Clerckx, Bruno, Choi, Sung Hyun, Lee, Hye Won, Je, Hui Won
• Primary Examiner(s): KASSIM, KHALED M
• Application Number:
  US13/034,836
• Publication Number:
  US 20120027108A1
• Time in Patent Office: 1,579 Days
• Field of Search: 370/329, 370/280, 370351-356, 455/423, 455/509, 455/91, 455/130, 455/450
• US Class Current: 1/1
• 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 7/065 Variable contents, e.g. long-term or short-short
• CPC Class Codes: H04W 52/143 Downlink power control
• CPC Class Codes: H04W 52/40 during macro-diversity or soft handoff

Abstract

Provided is a coordinated communication method and apparatus that may perform coordinated communication based on long-term channel information, for each sub-band. Base stations may exchange scheduling information of each sub-band with each other to determine a priority among the base stations, and may perform rescheduling for each sub-band based on the determined priority. The base stations may obtain the long-term channel information, and thus may reduce overhead occurring with exchanging of information between a base station and a terminal or between base stations, and may decrease damage due to a delay of channel information associated with a terminal.

Claims

1. A communication method of a target base station in a multi-cell communication system, the communication method comprising:

obtaining long-term channel information associated with a long-term channel between the target base station and at least one target terminal served by the target base station;

generating, based on the long-term channel information, scheduling information associated with the target base station by scheduling sub-bands of the target base station;

transmitting scheduling information associated with the target base station to at least one neighbor base station and receiving scheduling information associated with the at least one neighbor base station, wherein the transmitting and the receiving are based on a predetermined period; and

re-scheduling a plurality of sub-bands, the re-scheduling comprising assigning a terminal and a multiple-input multiple-output (MIMO) transmission scheme, from among a plurality of MIMO transmission schemes, to each individual sub-band, from among the plurality of sub-bands, based on the scheduling information associated with the target base station and based on the scheduling information associated with the at least one neighbor base station received from the at least one neighbor base station,

wherein the long-term channel information is channel information associated with a long-term period that includes at least two predetermined short-term periods, and comprises at least one of information associated with a signal to interference and noise ratio (SINR) of a wideband, information associated with a correlation coefficient matrix of a transmission antenna of the target base station and a reception antenna of the at least one target terminal, information associated with channel quality information (CQI) with respect to each sub-band and information associated with a channel direction information (CDI) with respect to each sub-band, information associated with a moving speed of the at least one target terminal, and synchronization information between the at least one neighbor base station and the target base station with respect to the at least one target terminal.

2. The communication method of claim 1, wherein the obtaining comprises:

receiving, from the at least one target terminal, the long-term channel information based on the long-term period.

3. The communication method of claim 1, wherein the obtaining comprises:

receiving, from the at least one target terminal, short-term channel information associated with a short-term channel between the target base station and the at least one target terminal, based on a short-term period; and

calculating the long-term channel information based on the short-term channel information received during the long-term period.

4. The communication method of claim 1, wherein the obtaining comprises:

receiving a pilot from the at least one target terminal; and

calculating the long-term channel information based on the pilot.

5. The communication method of claim 1, wherein the generating comprises:

generating the scheduling information associated with the target base station, and the scheduling information comprises information associated with at least one of an index of each sub-band, a terminal group temporarily selected by the target base station for each sub-band, a transmission power allocated to each sub-band, a multiple-input multiple-output (MIMO) transmission scheme for the temporarily selected terminal group, transmission beamforming matrices recommended for the target base station and the at least one neighbor base station to provide a service to the temporarily selected terminal group based on the MIMO transmission scheme, and a performance metric associated with the terminal group temporarily selected for each sub-band.

6. The communication method of claim 1, wherein the transmitting and receiving comprise:

transmitting, to the at least one neighbor base station, scheduling information associated with the target base station and receiving the scheduling information associated with the at least one neighbor base station, and the transmitting and the receiving are based on the long-term period including at least two predetermined short-term periods.

7. The communication method of claim 1, wherein the re-scheduling comprises:

determining, for each sub-band, at least one of a target terminal for a service, an allocated power, a MIMO transmission scheme, and a transmission beamforming matrix, based on the scheduling information associated with the at least one neighbor base station and the scheduling information associated with the target base station.

8. The communication method of claim 1, wherein the re-scheduling comprises:

re-scheduling a leading sub-band in which a performance metric of the target base station with respect to the corresponding band is higher than a performance metric of the at least one neighbor base station, based on the scheduling information associated with the target base station; and

re-scheduling a following sub-band in which a performance metric of the target base station with respect to the corresponding band is lower than the performance metric of the at least one neighbor base station, based on scheduling information associated with a neighbor base station having a highest performance metric in the following sub-band.

9. The communication method of claim 8, wherein the re-scheduling based on the scheduling information that is associated with the neighbor base station having the highest performance metric comprises:

re-scheduling the following sub-band based on the scheduling information associated with the target base station, when a MIMO transmission scheme of the neighbor base station having the highest performance metric is a single cell MIMO transmission scheme.

10. The communication method of claim 8, wherein the re-scheduling based on the scheduling information that is associated with the neighbor base station having the highest performance metric comprises:

selecting a target terminal for a service in the following sub-band, based on a transmission beamforming matrix of the neighbor base station having the highest performance metric in the following sub-band, when a MIMO transmission scheme of the neighbor base station having the highest performance metric is a coordinated beamforming (CB) scheme.

11. The communication method of claim 8, wherein the re-scheduling based on the scheduling information that is associated with the neighbor base station having the highest performance metric comprises:

determining a transmission beamforming matrix in the following sub-band, based on a transmission beamforming matrix of the neighbor base station having the highest performance metric in the following sub-band, to transmit data to the terminal selected by the neighbor base station having the highest performance metric in the following sub-band, when an MIMO transmission scheme of the neighbor base station having the highest performance metric is a joint processing (JP) scheme.

12. The communication method of claim 1, further comprising:

performing precoding based on a result of the re-scheduling performed with respect to each sub-band.

13. The communication method of claim 1, further comprising:

updating, based on a predetermined period, the scheduling information associated with the target base station, using the long-term channel information associated with a long-term channel between the target base station and the at least one target terminal served by the target base station.

21. The communication method of claim 1, wherein a neighboring base station, from among the at least one neighboring base stations, comprises a leading base station for respective a sub-band, and the target base station reschedules the respective sub-band based on a transmission from the leading base station for the respective sub-band.

14. A target base station in a multi-cell communication system, the target base station comprising:

a channel information obtaining unit configured to obtain long-term channel information associated with a long-term channel between the target base station and at least one target terminal served by the target base station;

a scheduler configured to generate, based on the long-term channel information, scheduling information associated with the target base station by scheduling sub-bands of the target base station;

an information exchanging unit configured to transmit scheduling information associated with the target base station to at least one neighbor base station and to receive scheduling information associated with the at least one neighbor base station, based on a predetermined period; and

a re-scheduler configured to re-schedule a plurality of sub-bands, the re-scheduling comprising assigning a terminal and a multiple-input multiple-output (MIMO) transmission scheme, from among a plurality of MIMO transmission schemes, to each individual sub-band, from among the plurality of sub-bands, based on the scheduling information associated with the target base station and based on scheduling information associated with the at least one neighbor base station received from the at least one neighbor base station

wherein the long-term channel information is channel information associated with a long-term period including at least two predetermined short-term periods, and comprises at least one of information associated with a signal to interference and noise ratio (SINR) of a wideband, information associated with a correlation coefficient matrix of a transmission antenna of the target base station and a reception antenna of the at least one target terminal, information associated with channel quality information (CQI) with respect to each sub-band and information associated with a channel direction information (CDI) with respect to each sub-band, information associated with a moving speed of at least one target terminal, and synchronization information between the at least one neighbor base station and the target base station with respect to the at least one target terminal.

15. The target base station of claim 14, wherein the scheduler generates the scheduling information associated with the target base station, and the scheduling information comprises information associated with at least one of an index of each of the sub-bands, a terminal group temporarily selected by the target base station for each sub-band, a transmission power allocated to each sub-band, a multiple input multiple output (MIMO) transmission scheme for the temporarily selected terminal group, transmission beamforming matrices recommended for the target base station and the at least one neighbor base station to provide a service to the temporarily selected terminal group based on the MIMO transmission scheme, and a performance metric associated with the terminal group temporarily selected for each sub-band.

16. The target bases station of claim 14, wherein the information exchanging unit transmits, to the at least one neighbor base station, scheduling information associated with the target base station and receives the scheduling information associated with the at least one neighbor base station, based on the long-term period including at least two predetermined short-term periods.

17. The target base station of claim 14, wherein the re-scheduler determines, for each sub-band, at least one of a target terminal for a service, an allocated power, a MIMO transmission scheme, and a transmission beamforming matrix, based on the scheduling information associated with the at least one neighbor base station and the scheduling information associated with the target base station.

18. The target base station of claim 14, wherein the re-scheduler performs re-scheduling of a leading sub-band in which a performance metric of the target base station with respect to the corresponding band is higher than a performance metric of the at least one neighbor base station, based on the scheduling information associated with the target base station, and performs re-scheduling of a following sub-band in which the performance metric of the target base station with respect to the corresponding band is lower than the performance metric of the at least one neighbor base station, based on scheduling information associated with a neighbor base station having a highest performance metric in the following sub-band.

19. The target base station of claim 14, further comprising:

a precoder to perform precoding based on a result of the re-scheduling performed with respect to each sub-band.

20. The target base station of claim 14, wherein the scheduler is configured to update, based on a predetermined period, the scheduling information associated with the target base station, using the long-term channel information associated with a long-term channel between the target base station and the at least one target terminal corresponding to the target base station.