Effect of Word-length Precision on the Performance of MIMO Systems

In this paper, we investigate the effect of quantization noise and roundoff errors involved in finite-precision (FP) signal processing on the performance of multiple-input multiple-output (MIMO) receivers under flat-fading channel conditions. We simulated the performance degradation with FP for six transmission schemes, namely the Alamouti transmit diversity scheme, Spatial Multiplexing (SM) under maximum-likelihood (ML) detection, SM under Ordered Successive Interference Cancellation (OSIC) for (2×2) MIMO, Orthogonal Space-Time Block Code (STBC), Quasi-Orthogonal STBC for (4×2) MIMO and interference cancellation with two (2×2) Alamouti scheme. We also provide a procedure to analyze roundoff errors in FP MIMO receivers and quantify the effective decision-point SNR. The quantified variance of accumulated quantization noise and decision-point SNR for FP Alamouti Scheme corroborates the simulation result. Finally, we provide the minimum word-length precision requirements for these schemes.