Method and apparatus for correcting errors in a multiple subcarriers communication system using multiple antennas
A method for correcting errors in a multiple antenna system based on a plurality of sub-carriers and a transmitting/receiving apparatus supporting the same are disclosed. The method includes determining a phase shift based precoding matrix phase shifted at a predetermined phase angle, initially transmitting each sub-carrier symbol to a receiver in a packet unit by using the phase shift based precoding matrix, reconstructing the phase shift based precoding matrix to reduce a spatial multiplexing rate if a negative reception acknowledgement (NACK) is received from the receiver, and retransmitting the initially transmitted sub-carrier symbol by using the reconstructed phase shift based precoding matrix or by changing the phase shift based precoding matrix using offset information fed back from the receiver or random offset information.
1. A method for correcting errors in a multiple antenna system, the method comprising:
selecting a phase shift based precoding matrix that is phase shifted at a predetermined phase angle;
transmitting a sub-carrier symbol in at least one packet unit according to the selected phase shift based precoding matrix;
reconstructing the phase shift based precoding matrix to reduce a spatial multiplexing rate if a negative reception acknowledgement (NACK) is received; and
retransmitting the transmitted sub-carrier symbol according to the reconstructed phase shift based precoding matrix,
wherein the reconstructed phase shift based precoding matrix comprises at least one column that is selected from the phase shift based precoding matrix, and
wherein a number of the at least one column corresponds to the reduced spatial multiplexing rate.
2. The method of claim 1 , wherein retransmitting the transmitted sub-carrier symbol includes retransmitting some of the at least one packet unit where errors occur, but not transmitting a new packet unit until retransmission is completed, in the event that errors occur in less than the total number of the transmitted sub-carrier symbols of the at least one packet unit.
3. The method of claim 2 , wherein retransmitting includes retransmitting through antennas other than those through which the at least one packet unit where errors occur was transmitted.
4. The method of claim 2 , wherein retransmitting includes retransmitting through at least one antenna having a channel status that is better than that of other antennas.
5. The method of claim 1 , wherein retransmitting the transmitted sub-carrier symbol includes retransmitting some of the at least one packet unit where errors occur and transmitting a new packet, in the event that errors occur in less than the total number of the at least one transmitted packet unit.
6. The method of claim 5 , wherein retransmitting includes retransmitting through antennas other than those through which the at least one packet unit where errors occur was transmitted.
7. The method of claim 1 , wherein the transmitting and retransmitting are performed using either two transmitting antennas or four transmitting antennas.
8. A transmitter for correcting errors in a multiple antenna system, the transmitter comprising:
a precoder; and
multiple transmitting antennas,
wherein the transmitter is configured to:
select a phase shift based precoding matrix being phase shifted at a predetermined phase angle by using the precoder;
transmit a sub-carrier symbol via the multiple transmitting antennas in at least one packet unit according to the phase shift based precoding matrix;
reconstruct the phase shift based precoding matrix to reduce a spatial multiplexing rate by using the precoder, if a negative reception acknowledgement (NACK) is received; and
retransmit the transmitted sub-carrier symbol via the multiple transmitting antennas according to the reconstructed phase shift based precoding matrix,
wherein the reconstructed phase shift based precoding matrix comprises at least one column that is selected from the phase shift based precoding matrix, and
wherein a number of the at least one column corresponds to the reduced spatial multiplexing rate.
9. The transmitter of claim 8 , wherein the transmitter is further configured to retransmit some of the at least one packet unit in which errors occur but not transmit a new packet until retransmission is completed, if errors occur in less than a total number of transmitted sub-carrier symbols of the at least one packet unit.
10. The transmitter of claim 9 , wherein the transmitter retransmits the some of the at least one packet unit through antennas other than antennas through which the at least one packet unit in which errors occur was transmitted.
11. The transmitter of claim 9 , wherein the multiple transmitting antennas further comprise two antennas or four antennas.
12. The transmitter of claim 8 , wherein the transmitter is further configured to retransmit some of the at least one packet unit in which errors occur and transmit a new packet, if errors occur in less than a total number of the at least one transmitted packet unit.