Frequency-domain method for joint equalization and decoding of space-time block codes
Space-time block coding is combined with single-carrier, minimum-mean-square-error, frequency-domain equalization for wireless communication through a medium characterized by multi-paths. The transmitter encodes incoming symbols into two or more streams that are transmitted over a corresponding number of transmitting antennas. The encoding employs modulo arithmetic. Decoding in the receiver proceeds by converting received signals to frequency domain, linearly combining the signals to separate contribution of the signals from the two or more transmitting antennas equalizing the separated signals, converting the equalized signals to time domain, and applying the converted signals to a decision circuit.
1. A transmitter comprising:
two antennas for transmitting information to a receiver via a transmission medium of memory ν; and
an encoder handling two blocks of incoming symbols at a time, each block containing N of said incoming symbols, and encoding said N blocks of incoming symbols into two streams of symbols in pairs of output frames k and k+1, yielding output frames x i k and x i k+1 , for i=1, and 2, where each of a the frames includes ν prefix symbols, each being applied to a different one of said two antennas, where said encoding involves modulo arithmetic, and wherein
frame k said encoder generates
a stream of symbols, x 1 k (n), n=0, 1, 2, . . . N−1, that is applied to a first one of said antennas, preceded by a cyclic prefix sequence of symbols to form a steam of symbols x 1 k (−ν);x 1 k (−ν+1), . . . ,x 1 k (0),x 1 k (1), . . . ,x 1 k (N−1) where ν equals to symbol memory of channel through which said transmitter communicates with a receiver, where a cyclic prefix sequence is one where x 1 k (i) in the prefix sequence equals x 1 k (N−i) in the succeeding sequence, and
a stream of symbols, x 2 k (n), n=0, 1, 2, . . . N−1, that is applied to a second one of said antennas, preceded by a cyclic prefix sequence of symbols to form a steam of symbols x 2 k (−ν),x 2 k (−ν+1), . . . ,x 2 k (0), x 2 k (1), . . . ,x 2 k (N−1) and
in frame k+1 said encoder generates
a stream of symbols x 1 k+1 (t) that is equal to − x 2 k ((−n) N ), that is applied to said first one of said antennas, preceded by a cyclic prefix sequence of symbols to form a steam of symbols
x 1 k+1 (−ν), x t k+1 (−ν+1), . . . ,x 1 k+1 (0), x t k+1 (1), . . . ,x 1 k+1 (N−1), and
a second stream of symbols x 2 k+1 (t) that is equal to, x 1 k ((−n), that is applied to said second one of said antennas, preceded by a cyclic prefix sequence of symbols to form a steam of symbols
x 2 k+1 (−ν),x 2 k+1 (−ν+1), . . . ,x 2 k+1 (0),x 2 k+1 (1), . . . ,x 2 k+1 (N−1).