Method and apparatus for implementing space frequency block coding in an orthogonal frequency division multiplexing wireless communication system
The present invention is related to a method and apparatus for implementing space frequency block coding (SFBC) in an orthogonal frequency division multiplexing (OFDM) wireless communication system. The present invention is applicable to both a closed loop mode and an open loop mode. In the closed loop mode, power loading and eigen-beamforming are performed based on channel state information (CSI). A channel coded data stream is multiplexed into two or more data streams. Power loading is performed based on the CSI on each of the multiplexed data streams. SFBC encoding is performed on the data streams for each of the paired subcarriers. Then, eigen-beamforming is performed based on the CSI to distribute eigenbeams to multiple transmit antennas. The power loading may be performed on two or more SFBC encoding blocks or on each eigenmodes. Additionally, the power loading may be performed across subcarriers or subcarrier groups for weak eigenmodes.
1. A wireless transmit/receive unit (WTRU) comprising a processor and a receiver, the processor configured to:
receive, via the receiver, an orthogonal frequency division multiplexing (OFDM) signal, wherein the OFDM signal comprises a channel coded data stream that was space frequency block coding (SFBC) encoded in an open loop mode such that the SFBC encoding was performed using a plurality of pairs of OFDM sub-carriers, and wherein a first pair of OFDM sub-carriers of an OFDM symbol is mapped to a first pair of antenna ports and a second pair of OFDM sub-carriers of the OFDM symbol is mapped to a second pair of antenna ports; and
decode the OFDM signal.
2. The WTRU of claim 1 , wherein a portion of the channel coded data stream that is SFBC encoded using the first pair of OFDM sub-carriers of the OFDM symbol is SFBC encoded independently of another portion of the channel coded data stream that is SFBC encoded using the second pair of OFDM sub-carriers of the OFDM symbol.
3. The WTRU of claim 1 , wherein the processor is further configured to send channel quality information (CQI), wherein the CQI is sent on a per group of OFDM sub-carrier basis.
4. The WTRU of claim 3 , wherein a coding rate and modulation type used for the channel coded data stream is selected on a per group of OFDM sub-carrier basis based on the sent CQI.
5. The WTRU of claim 3 , wherein the channel coded data stream was generated based off of the received CQI, and wherein the WTRU does not provide channel state information (CSI) to a transmitter that transmits the OFDM symbol when operating in the open loop mode.
6. The WTRU of claim 5 , wherein the CSI is used for precoding at the transmitter.
7. The WTRU of claim 5 , wherein the transmitter is a base station.
8. The WTRU of claim 1 , wherein each portion of the channel coded data stream that is SFBC encoded using a pair of OFDM sub-carriers is encoded using an Alamouti type SFBC code.
9. A method performed by a wireless transmit/receive unit (WTRU), the method comprising:
receiving an orthogonal frequency division multiplexing (OFDM) signal, wherein the OFDM signal comprises a channel coded data stream that was space frequency block coding (SFBC) encoded in an open loop mode such that the SFBC encoding was performed using a plurality of pairs of OFDM sub-carriers, and wherein a first pair of OFDM sub-carriers of an OFDM symbol is mapped to a first pair of antenna ports and a second pair of OFDM sub-carriers of the OFDM symbol is mapped to a second pair of antenna ports; and
decoding the OFDM signal.
10. The method of claim 9 , wherein a portion of the channel coded data stream that is SFBC encoded using the first pair of OFDM sub-carriers of the OFDM symbol is SFBC encoded independently of another portion of the channel coded data stream that is SFBC encoded using the second pair of OFDM sub-carriers of the OFDM symbol.
11. The method of claim 9 , further comprising sending channel quality information (CQI), wherein the CQI is sent on a per group of OFDM sub-carrier basis.
12. The method of claim 11 , wherein a coding rate and modulation type used for the channel coded data stream was selected on a per group of OFDM sub-carrier basis based on the sent CQI.
13. The method of claim 11 , wherein the channel coded data stream was generated based off of the received CQI, and wherein the WTRU does not provide channel state information (CSI) to a transmitter that transmits the OFDM symbol when operating in the open loop mode.
14. The method of claim 13 , wherein the CSI is used for precoding at the transmitter.
15. The method of claim 13 , wherein the transmitter is a base station.
16. The method of claim 9 , wherein each portion of the channel coded data stream that is SFBC encoded using a pair of OFDM sub-carriers is encoded using an Alamouti type SFBC code.