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Abstract-We present a simple closed-form expression for the BER of orthogonal space-time block codes (OSTBCs) with MMSE channel estimation, assuming PAM and QAM constellations and flat Rayleigh block fading. The BER expression is exact for a certain class of OSTBCs, and provides a very accurate approximation for other OSTBCs.Index Terms-Bit error rate (BER), channel estimation, Rayleigh fading, multiple-input multiple-output (MIMO), orthogonal space-time block codes (OSTBCs).

Abstract-In this contribution, we present a linear multiple-input multiple-output (MIMO) equalization scheme at the receiver side for high-speed electrical chip-tochip communication. As opposed to traditional single-input single-output (SISO) equalization per lane, this MIMO approach enables cooperating receivers to treat crosstalk (XT) between neighboring channels as an informationbearing signal instead of a disturbing signal, allowing to mitigate both inter symbol interference and XT. Given a simulated 4 × 4 MIMO electrical chip-to-chip interconnect channel, we point out that, for a given total number of equalizer taps, MIMO equalization can outperform SISO equalization. Moreover, by further increasing the total number of equalizer taps, MIMO equalization allows to obtain performance gains that are substantially larger than for SISO equalization.

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Abstract-An analysis of the exact bit error rate (BER) performance of orthogonal space-time block codes (OSTBCs) with maximum-likelihood detection in the presence of channel estimation errors is presented. The possibly correlated coefficients of the multiple-input multiple-output (MIMO) propagation channel are assumed to be affected by flat block fading and the transmitted symbols belong to a pulse amplitude modulation or quadrature amplitude modulation signal constellation. For both square and nonsquare OSTBCs, we derive approximate and exact BER expressions, irrespective of the distribution of the fading. It is also shown how the exact expressions can be efficiently and accurately evaluated using numerical integration techniques. Their application to the arbitrarily correlated Nakagamifading channel is presented and an efficient importance sampling technique is derived. As the high diversity order resulting from the application of OSTBCs gives rise to small BER values, the numerical evaluation of the presented BER expressions is much faster than straightforward Monte Carlo simulations. BER results have shown the impact of both imperfect channel estimation and antenna correlation on the performance of MIMO OSTBC systems. It is also shown that under highly correlated conditions, antenna correlation is the major source of BER degradation.