Cross-Talk Cancellation in Cooperative Wireless Relay Networks

• US 20110044158A1
• Filed: 08/19/2009
• Published: 02/24/2011
• Est. Priority Date: 08/19/2009
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Research Laboratories, Inc. (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Electric Research Laboratories, Inc. (Mitsubishi Electric Corporation)
• Inventors: Orlik, Philip V., Ma, Jun, Li, Ye, Zhang, Jinyun, Tao, Zhifeng
• Granted Patent: US 8,014,263 B2
• Time in Patent Office: Days
• US Class Current: 370/201
• CPC Class Codes: H04B 7/15564 Relay station antennae loop interference reduction
• 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 27/2601 Multicarrier modulation systems

Abstract

Cross-talk is canceled in a cooperative wireless relay network that includes a base station (BS), a relay station (RS), and a mobile station (MS). A coupling channel between a transmit antenna and a receive antenna colocated at the RS is estimated. Cross-talk interference determination is based on a previous transmitted signal by the transmit antenna, and the coupling channel. The cross-talk interference is subtracted from a currently received signal by the receive antenna to obtain a residual signal. The residual signal is then transmitted as a next transmitted signal by the transmit antenna.

Claims

1. A method for canceling cross-talk in a cooperative wireless relay network including a base station (BS), a relay station (RS), and a mobile station (MS), comprising a processor for performing the steps, comprising the steps:

estimating a coupling channel between a transmit antenna and a receive antenna, wherein the transmit antenna and the receive antenna are colocated at the RS;

determining cross-talk interference based on a previous transmitted signal by the transmit antenna, and the coupling channel;

subtracting the cross-talk interference from a currently received signal by the receive antenna to obtain a residual signal; and

transmitting the residual signal as a next transmitted signal by the transmit antenna.

2. The method of claim 1, wherein the RS operates as a frequency-shifted-relay-station (FSRS).

3. The method of claim 1, wherein the RS operates as a frequency-reuse-relay-station (FRRS).

4. The method of claim 1, wherein the RS has a plurality of receive antennas and a plurality of transmit antennas.

5. The method of claim 1, wherein the previous transmitted signal is x(n−

1), and the currently received signal is y(n), the cross-talk interference is i(n), the coupling channel is h_c.

6. The method of claim 1, wherein for K-subcarrier orthogonal frequency-division multiplexing (OFDM), the received signal is represented by OFDM modulation, the received symbol vector over the k^th subcarrier of the n^th OFDM symbol is

y(n, k)=s(n, k)+i(n, k)+w(n, k),

where n represents an OFDM symbol, k represents a subcarrier, s represents a desired signal, i represents the cross-talk interference, and w represents noise.

7. The method of claim 6, in which the estimating of the coupling channel for multiple consecutive OFDM symbols is implemented iteratively.

8. The method of claim 1, wherein the RS operates in amplify-and-forward mode.

9. The method of claim 1, wherein the RS operates in decode-and-forward mode.

10. The method of claim 9, wherein the received signal and the next transmitted signal have identical power.

11. The method of claim 1, wherein the estimating uses a least-square estimate.

12. The method of claim 1, wherein the estimating uses a minimum mean-square error estimate.

13. The method of claim 1, wherein the received signal is transmitted by the BS, and the next transmitted signal is received by the MS.

14. The method of claim 1, wherein the received signal is transmitted by the MS, and the next transmitted signal is received by the BS.

15. A relay station in a cooperative wireless relay network including a base station (BS) and a mobile station (MS), comprising:

means for estimating a coupling channel between a transmit antenna and a receive antenna, wherein the transmit antenna and the receive antenna are colocated at the RS;

means for determining a cross-talk interference based on a previous transmitted signal by the transmit antenna and the coupling channel;

means for subtracting the cross-talk interference from a currently received signal by the receive antenna to obtain a residual signal; and

means for transmitting the residual signal as a next transmitted signal by the transmit antenna.