Channel identification and sequential sequence estimation using antenna array for broad-band mobile communications

This paper proposes the joint use of an antenna array and sequential sequence estimation (SSE) technique for the equalization of multipath fading channels suffering from severe intersymbol interference (ISI). It is shown that with the proper use of the multiple stack algorithm (MSA), exploiting the redundant structure of the signal received by multiple antenna array elements can enhance the uniqueness of the sequence estimation, thereby significantly reducing the frame erasure probability. Three new algorithms are derived for vector channel identification, the results of which are used to calculate the Fano metric for SSE. The first algorithm uses just a temporal reference, and others use both temporal and spatial references. Impacts of using the temporal and spatial references are investigated in terms of the channel identification accuracy as well as overall frame erasure rate (ERR) and bit error rate (BER). Results of computer simulations are then presented to compare the performances of the three algorithms for vector channel identification. The propagation scenario assumed in the simulations is equal-power 12-path propagation, in which, even with binary phase shift keying (BPSK), maximum likelihood sequence estimation (MLSE) requires 2048 states. It is shown that even in such a complicated situation, the MSA algorithm can achieve excellent ERR and BER performances with reasonable computational complexity.