Error propagation analysis of V-BLAST with channel-estimation errors

In this letter, expressions are given for the symbol-error rate (SER) of the Vertical Bell Laboratories Layered Space-Time (V-BLAST) system, taking into account error propagation due to channel-estimation errors. In addition to error propagation, suboptimal substream ordering due to imperfect channel estimates is accounted for. First, the conditional SER is determined using the distribution of the signal-to-interference-plus-noise ratio of each substream, conditioned on the channel estimate. Then, the average SER as a function of the channel estimation error-to-signal ratio (ESR) is upper bounded by averaging over the distribution of the channel estimates. The upper bound on the SER is tighter than previous bounds in the literature. Comparisons with exact simulations demonstrate the accuracy of the SER expressions for a large range of ESRs.