ON SPACE-FREQUENCY BLOCK CODES FOR UNEQUAL CHANNELS

After a systematic derivation of space-frequency block codes, the case of two transmitter antennas where unequal channels are applied to the two symbols that belong to two adjacent subcarriers is considered. At the receiver, the coefficients of the linear combiner are calculated and the expressions are given for the signal-to-noise ratios and different approaches. We propose a scheme that gives the same performance as the ML decoding with computationally efficient structure. The performance of proposed scheme is confirmed by simulations with respect to Hiperlan/2 characteristics. The solution improves the BER performance especially at high compared to ZF approach. The channel coefficients that the scheme needs can be directly estimated by using the adaptive filter in a lattice structure. b E / N0

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