MIMO pre-equalization and DFE for high-speed off-chip communication

In this contribution, we present a multiple-input multiple-output (MIMO) transceiver scheme for high-speed chip-to-chip communication over low-cost electrical interconnects. Linear MIMO pre-equalization at the transmitter is combined with decision feedback equalization (DFE) at the receiver to counteract the adverse effect of inter symbol interference (ISI) and crosstalk (XT). Considering an energy constraint at the transmit side, we derive elegant closed-form expressions for the equalization filters under a minimum mean square error (MMSE) criterion. Numerical analysis shows that the combination of linear MIMO pre-equalization and MIMO DFE allows to significantly improve the reliability of future high-speed off-chip communication

Application of MIMO DF equalization to high-speed off-chip communication

In this contribution, we present a multiple-input multiple-output (MIMO) equalizer with decision feedback (DF) for high-speed chip-to-chip communication. We derive an elegant closed-form expression for the minimum mean square error (MMSE) equalization filters and show that the application of MIMO DF equalization (DFE) allows to significantly improve the reliability of high-speed communication over low-cost electrical interconnects

Performance analysis of pre-equalized multilevel partial response schemes

In order to achieve high speed on electrical interconnects, channel attenuation at high frequencies must be dealt with by proper transceiver design. In this paper we investigate finite-complexity MMSE pre-equalization under an average transmit power constraint, to compensate for channel distortion in the case of both full-response and precoded partial response signaling with L-PAM mapping, and consider the resulting error performance for symbol-by-symbol detection and sequence detection. For a representative electrical interconnect, we point out that the constellation size (2-PAM or 4-PAM), the type of signaling (full response or partial response), the detection method (symbol-by-symbol detection or sequence detection) and the number of pre-equalizer taps should be carefully selected in order to achieve satisfactory error performance at high data rates. For several scenarios, precoded duobinary 4-PAM is found to yield the best error performance for given average transmit power

Robust spatio-temporal partial-response signaling over a frequency-selective fading MIMO channel with imperfect CSI

Partial-response signaling is known to facilitate the equalizer design because a controlled amount of residual interference is permitted. The design of the target impulse response of the partial-response precoder often assumes perfect channel state information, which is unfortunately not available at the transmitter in most practical applications. Consequently, this contribution focuses instead on the robust and joint design of a spatio-temporal target impulse response and the equalization coefficients for a frequency-selective fading multiple-input multiple-output communication channel based on current and/or previous noisy channel estimates. More precisely, the error in the channel estimates is statistically modeled, and robustness is achieved by minimizing the mean-squared estimation error averaged over the joint distribution of the actual channel and the available channel estimates. Numerical results of the bit error rate confirm that the proposed robust partial-response signaling not only provides a significant performance gain compared to traditional full-response signaling, but also outperforms the naive approach, which ignores channel estimation errors

Optimized precoded spatio-temporal partial-response signaling over frequency-selective MIMO channels

Due to the continuous demand for higher bit rates, the management of the spatio-temporal intersymbol interference in frequency-selective multiple-input multiple-output (MIMO) channels becomes increasingly important. For single-input single-output channels, equalized precoded partial-response signaling is capable of handling a large amount of intersymbol interference, but, to date, no equalization scheme with general partial-response signaling has been presented for the frequency-selective MIMO channel. Not only does this contribution extend partial-response signaling to the MIMO channel by proposing a general spatio-temporal partial-response precoder, but it also develops a minimum mean-squared-error optimization framework in which the equalization coefficients and the spatio-temporal target response are jointly optimized. Three iterative optimization algorithms are discussed, which update (part of) a row of the target impulse response matrix in each iteration. In particular, the third algorithm reformulates this row optimization as a lattice decoding problem. Numerical simulations confirm that the general partial-response signaling clearly outperforms the traditional full-response signaling in terms of the mean squared error and the bit error rate. The third optimization algorithm has a better performance but a higher complexity, compared to the first and the second algorithm

Error performance prediction of randomly shortened and punctured LDPC codes

In this contribution, we show that the word error rate (WER) performance in the waterfall region of a randomly shortened and punctured low density parity check code can be accurately predicted from the WER performance of its finitelength mother code. We derive an approximate analytical expression for the mutual information (MI) required by a daughter code to achieve a given WER, based on the MI required by the mother code, which shows that the gap to the capacity of the daughter code grows the more the code is punctured or shortened. The theoretical results are confirmed by simulations (where the random shortening and puncturing pattern is either selected independently per codeword or kept the same for all codewords) for practical codes on both the binary erasure channel and the binary-input additive white Gaussian noise channel

Receiver design for wideband CDMA communication systems

Doctorat en sciences appliquées (FSA 3)--UCL, 200