Retransmission of data in a multiple input multiple output (MIMO) system

1. A method for retransmission of data in a multiple input multiple output (MIMO) system, the method comprising space-time block code (STBC) encoding multiple data streams including one or more retransmission data streams using a STBC matrix, the STBC matrix multiplying at least one of the retransmission data streams with respective variable weighting factors.

2. The method as claimed in claim 1 , wherein the variable weighting factors are selected such that the associated retransmission data streams are given a weight equal to or greater than one in the STBC encoding.

3. The method as claimed in claim 2 , wherein the STBC matrix further multiplies new data streams with respective variable weighting factors, and the variable weighting factors are selected such that the associated new data streams are given a weight less than one in the STBC encoding.

4. The method as claimed in claim 1 , wherein the variable weighting factors associated with the respective retransmission data streams are selected based on link conditions between respective transmitter and receiver antenna pairs of the MIMO system.

5. The method as claimed in claim 4 , wherein the weighting factors associated with the respective retransmission data streams are selected based on measured signal to noise ratios (SNRs) of originally transmitted data streams detected at a receiver.

6. The method as claimed in claim 1 , wherein the STBC encoding comprises a rate one STBC code.

7. The method as claimed in claim 1 , wherein the STBC encoding comprises a rate two STBC code.

8. The method as claimed in claim 1 , wherein the multiple data streams include one or more retransmission data streams and one or more new transmission data streams, and the antennas used to transmit the STBC encoded data streams are selected such that the antennas are least correlated.

9. A method for receiving data in a multiple input multiple output (MIMO) system, the method comprising utilising a retransmission packet processing based on decoding space-time block code (STBC) encoded multiple data streams including one or more retransmission data streams, wherein a STBC matrix used in the STBC encoding multiplies at least one of the retransmission data streams with respective variable weighting factors.

10. A transmitter for retransmitting data in a multiple input multiple output (MIMO) system, the transmitter comprising a transmitter control module utilising space-time block code (STBC) for encoding multiple data streams including one or more retransmission data streams using a STBC matrix, the STBC matrix multiplying at least one of the retransmission data streams with respective variable weighting factors.

11. The transmitter as claimed in claim 10 , wherein the transmitter control module selects the variable weighting factors such that the associated retransmission data streams are given a weight equal to or greater than one in the STBC encoding.

12. The transmitter as claimed in claim 11 , wherein the STBC matrix further multiplies new data streams with respective variable weighting factors, and the variable weighting factors are selected such that the associated new data streams are given a weight less than one in the STBC encoding.

13. The transmitter as claimed in claim 10 , wherein the variable weighting factors associated with the respective retransmission data streams are selected based on link conditions between respective transmitter and receiver antenna pairs of the MIMO system.

14. The transmitter as claimed in claim 13 , wherein the weighting factors associated with the respective retransmission data streams are selected based on measured signal to noise ratios (SNRs) of originally transmitted data streams detected at a receiver.

15. The transmitter as claimed in claim 10 , wherein the STBC encoding comprises a rate one STBC code.

16. The transmitter as claimed in claim 10 , wherein the STBC encoding comprises a rate two STBC code.

17. The transmitter as claimed in claim 10 , wherein the multiple data streams include one or more retransmission data streams and one or more new transmission data streams, and the antennas used to transmit the STBC encoded data streams are selected such that the antennas are least correlated.

18. A receiver for receiving data in a multiple input multiple output (MIMO) system, the receiver comprising a receiver control module for retransmission packet processing based on decoding space-time block code (STBC) encoded multiple data streams including one or more retransmission data streams, wherein a STBC matrix used in the STBC encoding multiplies at least one of the retransmission data streams with respective variable weighting factors.