Realizable equalizers for frequency selective MIMO channels with cochannel interference

Abstract

We consider realizable linear and decision feedback equalization (DFE) of frequency selective multiple-input multiple-output (MIMO) channels in the presence of cochannel interference (CCI). Equalizers that are optimal in the minimum mean square error (MMSE) sense are derived with and without zero forcing (ZF) constraint. It is shown that all problems can be reduced to H(sub 2) optimal deconvolution, for which a novel algorithm is presented

Efficient computation of the realizable MIMO DFE

“…In principle, computation of the optimal DFE can be considered as computation of the optimal linear equalizer for a virtual MIMO channel where the feedback-path is modeled as additional noisefree part of the channel [4], [6]. In particular, the inner-outer factorization approach to linear equalization can be employed [11].…”

“…Explicit state-space formulae for implementation will be presented in the following section. We start with the observation that the MSE holds [6] ÂÄ´ µ Þ Ä ÁÔ À Þ Ä ½ ¾ ¾ · ¾ ¾ ¾ · ÀÁ ¾ ¾ (2) Therefore the optimal filters are given by…”

“…In the polynomial approach, the coefficient matrix is a invertible ¾´Ä· ½µ¢¾´Ä· ½ µ block matrix with Õ¢Õ blocks, 6 i.e., the solution exists and is unique. (See [10, Ch.…”

“…The polynomial approach has been established in [3]. Other approaches work with state-space models and utilize the Wiener-Kalman filter [4], [5] or optimal control [6]. The authors of [3, p. 127] claim that the complexity of their approach grows cubically with the decision delay.…”

Novel System Inversion Algorithm With Application to Oversampled Perfect Reconstruction Filter Banks

“…2 Our solution finds the middle ground between these two extremes, i.e., we let the filter bank designer choose a tradeoff between decision delay and norm. Some preliminary results on this case have already been given by the authors in [8]. However, the assumptions on the weight in [8] are more restrictive, and some proofs were left open.…”