Apparatus and method for cooperative relay in a wireless communication system based on relay stations

• US 20090047901A1
• Filed: 08/13/2008
• Published: 02/19/2009
• Est. Priority Date: 08/14/2007
• Status: Active Grant

• Current Assignee: Korea Advanced Institute of Science and Technology, Samsung Electronics Co. Ltd.
• Original Assignee: Korea Advanced Institute of Science and Technology, Samsung Electronics Co. Ltd.
• Inventors: Chung, Sae-Young, Kim, Muryong, Kim, Yung-Soo, Cho, Myeon-Kyun, Yu, Tak-Ki
• Granted Patent: US 8,019,288 B2
• Time in Patent Office: Days
• US Class Current: 455/7
• CPC Class Codes: H04B 7/022 Site diversity; Macro-diversity using two or more spaced independent antennas H04B7/04
• CPC Class Codes: H04B 7/026 Co-operative diversity, e.g. using fixed or mobile stations as relays
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/15592 Adapting at the relay station communication parameters for supporting cooperative relaying, i.e. transmission of the same data via direct - and relayed path cooperative diversity H04B7/024
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/004 by using forward error control H04L1/0618 takes precedence; coding, decoding or code conversion, for error detection or correction H03M13/00
• CPC Class Codes: H04L 1/0656 Cyclotomic systems, e.g. Bell Labs Layered Space-Time [BLAST]
• CPC Class Codes: H04L 2001/0097 Relays
• CPC Class Codes: H04W 52/241 taking into account channel quality metrics, e.g. SIR, SNR, CIR, Eb/lo

Abstract

An apparatus and method for cooperative relay in a multiple-antenna wireless communication system based on relay stations (RSs) are provided. The apparatus includes a serial/parallel converter for dividing data into N number of streams, a channel estimator for calculating a first transmission rate at which a RS performing the cooperative relay can perform decoding and a second transmission rate at which all relay stations performing the cooperative relay can commonly perform decoding, and determining transmission rates for each of the N-number streams, and an adaptive modulation and coding (AMC) unit for encoding and modulating the N-number streams according to their respective transmission rates.

Claims

1. A transmit apparatus for a cooperative relay in a multiple-antenna wireless communication system based on relay stations, the apparatus comprising:

a serial/parallel converter for dividing data into N number of streams;

a channel estimator for calculating a first transmission rate at which a relay station performing the cooperative relay can perform decoding and a second transmission rate at which all relay stations performing the cooperative relay can commonly perform decoding, and determining transmission rates for each of the N-number streams; and

an adaptive modulation and coding (AMC) unit for encoding and modulating the N-number streams according to the transmission rates.

2. The apparatus of claim 1, wherein the channel estimator receives one or more feedback parameters optimizing a signal correlation between the relay stations from the relay stations performing the cooperative relay and calculates the first transmission rate and the second transmission rate.

3. The apparatus of claim 1, further comprising:

a beamforming unit for multiplying an output signal from the AMC unit by a beamforming vector and forming beamforming.

4. A relay reception apparatus for cooperative relay in a multiple-antenna wireless communication system based on relay stations, the apparatus comprising:

a first decoder for decoding a common signal among a received signal that comprises a private signal and the common signal; and

a second decoder for removing the decoded common signal from the received signal and decoding the private signal.

5. The apparatus of claim 4, wherein the private signal is a signal encoded and modulated at a transmission rate at which a relay station performing the cooperative relay can perform decoding, and

wherein the common signal is a signal encoded and modulated at a transmission rate at which all relay stations performing the cooperative relay can commonly perform decoding.

6. A relay receive apparatus for cooperative relay in a multiple-antenna wireless communication system based on relay stations, the apparatus comprising:

an encoder/modulator for re-encoding and re-modulating a decoded private signal and a common signal on the basis of a channel estimation; and

a signal synthesizer for applying a parameter for controlling a multiplexing gain and a diversity gain to the re-encoded and re-modulated private signal and common signal and synthesizing the two signals.

7. The apparatus of claim 6, further comprising:

a gain controller for calculating a parameter for controlling the multiplexing gain and the diversity gain.

8. The apparatus of claim 6, wherein the gain controller calculates the parameter for controlling the multiplexing gain and the diversity gain on the basis of the channel estimation and optimizes a correlation between cooperative relay signals.

9. The apparatus of claim 7, wherein the gain controller generates the multiplexing gain by allocating almost all power to the private signal when a signal to noise ratio (SNR) is above a threshold or two row vectors of a channel matrix are close to orthogonal, and generates the diversity gain by allocating almost all power to the common signal when the signal to noise ratio is at or below the threshold or the two row vectors are close to parallel.

10. The apparatus of claim 6, wherein the private signal is a signal encoded and modulated at a transmission rate at which a relay station performing the cooperative relay can perform decoding, and

wherein the common signal is a signal encoded and modulated at a transmission rate at which all relay stations performing the cooperative relay can commonly perform decoding.

11. A receive apparatus for cooperative relay in a multiple-antenna wireless communication system based on relay stations, the apparatus comprising:

a first detector for receiving a cooperative relay signal from a plurality of relay stations and detecting a common signal in the cooperative relay signal on the basis of a corresponding channel estimation information;

a first decoder for decoding the detected common signal;

an N^th detector for multiplying the decoded common signal by a corresponding channel matrix and sequentially detecting two or more private signals on the basis of the corresponding channel estimation information in a signal obtained by removing the detected common signal from the cooperative relay signal; and

an N^th decoder for decoding the two or more detected private signals.

12. A transmission method for cooperative relay in a multiple-antenna wireless communication system based on relay stations, the method comprising:

dividing data into N number of streams;

calculating a first transmission rate at which a relay performing the cooperative relay can perform decoding and a second transmission rate at which all relay stations performing the cooperative relay can perform decoding, and determining a transmission rate for each of the N-number streams; and

encoding and modulating each of the N-number streams according to the transmission rates.

13. The method of claim 12, wherein determining the transmission rates comprises:

receiving one or more feedback parameters optimizing a signal correlation between the relay stations from the relay stations performing the cooperative relay; and

calculating the first transmission rate and the second transmission rate.

14. The method of claim 12, further comprising:

multiplying the modulated output signal by a beamforming vector and forming beamforming.

15. A relay reception method for cooperative relay in a multiple-antenna wireless communication system based on relay stations, the method comprising:

decoding a common signal from a received signal that comprises a private signal and the common signal; and

removing the decoded common signal from the received signal and decoding the private signal.

16. The method of claim 15, wherein the private signal is a signal encoded and modulated at a transmission rate at which a relay station performing cooperative relay can perform decoding, and

wherein the common signal is a signal encoded and modulated at a transmission rate at which all relay stations performing the cooperative relay can commonly perform decoding.

17. A relay transmission method for cooperative relay in a multiple-antenna wireless communication system based on relay stations, the method comprising:

re-encoding and re-modulating a decoded private signal and a common signal on the basis of a channel estimation; and

applying a parameter for controlling a multiplexing gain and a diversity gain to the re-encoded and re-modulated private signal and common signal and synthesizing the two signals.

18. The method of claim 17, further comprising:

calculating the parameter for controlling the multiplexing gain and the diversity gain.

19. The method of claim 17, wherein the parameter is calculated on the basis of the channel estimation and optimizes a correlation between cooperative relay signals.

20. The method of claim 17, wherein the parameter generates a multiplexing gain by allocating almost all power to a private signal when a signal to noise ratio is above a threshold or two row vectors of a channel matrix are close to orthogonal, and generates a diversity gain by allocating almost all power to a common signal when the signal to noise ratio is at or below the threshold or the two row vectors are almost close to parallel.

21. The method of claim 17, wherein the private signal is a signal encoded and modulated at a transmission rate at which a relay station performing the cooperative relay can perform decoding, and

wherein the common signal is a signal encoded and modulated at a transmission rate at which all relay stations performing the cooperative relay can commonly perform decoding.

22. A reception method for cooperative relay in a multiple-antenna wireless communication system based on relay stations, the method comprising:

receiving a cooperative relay signal from a plurality of relay stations and detecting a common signal in the cooperative relay signal on the basis of a corresponding channel estimation information;

decoding the detected common signal;

multiplying the decoded common signal by a corresponding channel matrix and sequentially detecting one or more private signals on the basis of the corresponding channel estimation information from a signal obtained by removing the common signal from the cooperative relay signal; and

decoding the detected private signals.