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 transmitter comprising:
a plurality of transmit antennas; and
circuitry configured to generate a channel coded data stream;
wherein the circuitry is further configured to perform space frequency block coding (SFBC) encoding on the channel coded data stream in an open loop mode such that the SFBC encoding is performed using a plurality of pairs of orthogonal frequency division multiplexing (OFDM) sub-carriers, 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
wherein the circuitry is further configured to transmit the SFBC encoded data over the plurality of pairs of OFDM sub-carriers using the plurality of transmit antennas as an OFDM signal.
2. The transmitter 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 transmitter of claim 1 , wherein the circuitry is further configured to receive channel quality information (CQI), wherein the CQI is received on a per group of OFDM sub-carrier basis.
4. The transmitter of claim 3 , wherein the circuitry is further configured to select a coding rate and modulation type used for the channel coded data stream on a per group of OFDM sub-carrier basis based on the received CQI.
5. The transmitter of claim 3 , wherein the circuitry is further configured to generate a channel coded data stream based on the received CQI, and wherein channel state information (CSI) is not provided to the transmitter by a receiver device that receives the OFDM symbol when operating in the open loop mode.
6. The transmitter of claim 5 , wherein the CSI is used for precoding at the transmitter.
7. The transmitter 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.
8. The transmitter of claim 1 , wherein the transmitter is a base station.
9. A method comprising:
generating a channel coded data stream;
performing space frequency block coding (SFBC) encoding on the channel coded data stream in an open loop mode such that the SFBC encoding is performed using a plurality of pairs of orthogonal frequency division multiplexing (OFDM) sub-carriers, 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
transmitting the SFBC encoded data over the plurality of pairs of OFDM sub-carriers using the plurality of transmit antennas as an 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 , wherein the circuitry is further configured to receive channel quality information (CQI), wherein the CQI is received on a per group of OFDM sub-carrier basis.
12. The method of claim 11 , wherein the circuitry is further configured to select a coding rate and modulation type used for the channel coded data stream on a per group of OFDM sub-carrier basis based on the received CQI.
13. The method of claim 11 , wherein the circuitry is further configured to generate a channel coded data stream based on the received CQI, and wherein channel state information (CSI) is not provided to the transmitter by a receiver device that receives the OFDM symbol when operating in the open loop mode.
14. The method of claim 13 , wherein the CSI is used for precoding.
15. 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.