Enabling VLSI processing blocks for MIMO-OFDM Communications

Multi-input multi-output (MIMO) systems combined with orthogonal frequency-division multiplexing (OFDM) gained a wide popularity in wireless applications due to the potential of providing increased channel capacity and robustness against multipath fading channels. However these advantages come at the cost of a very high processing complexity and the efficient implementation of MIMO-OFDM receivers is today a major research topic. In this paper, efficient architectures are proposed for the hardware implementation of the main building blocks of a MIMO-OFDM receiver. A sphere decoder architecture flexible to different modulation without any loss in BER performance is presented while the proposed matrix factorization implementation allows to achieve the highest throughput specified in the IEEE 802.11n standard. Finally a novel sphere decoder approach is presented, which allows for the realization of new golden space time trellis coded modulation (GST-TCM) scheme. Implementation cost and offered throughput are provided for the proposed architectures synthesized on a 0.13  CMOS standard cell technology or on advanced FPGA devices

On Maximum Contention-Free Interleavers and Permutation Polynomials over Integer Rings

An interleaver is a critical component for the channel coding performance of turbo codes. Algebraic constructions are of particular interest because they admit analytical designs and simple, practical hardware implementation. Contention-free interleavers have been recently shown to be suitable for parallel decoding of turbo codes. In this correspondence, it is shown that permutation polynomials generate maximum contention-free interleavers, i.e., every factor of the interleaver length becomes a possible degree of parallel processing of the decoder. Further, it is shown by computer simulations that turbo codes using these interleavers perform very well for the 3rd Generation Partnership Project (3GPP) standard.Comment: 13 pages, 2 figures, submitted as a correspondence to the IEEE Transactions on Information Theory, revised versio

Achieving Low-Complexity Maximum-Likelihood Detection for the 3D MIMO Code

The 3D MIMO code is a robust and efficient space-time block code (STBC) for the distributed MIMO broadcasting but suffers from high maximum-likelihood (ML) decoding complexity. In this paper, we first analyze some properties of the 3D MIMO code to show that the 3D MIMO code is fast-decodable. It is proved that the ML decoding performance can be achieved with a complexity of O(M^{4.5}) instead of O(M^8) in quasi static channel with M-ary square QAM modulations. Consequently, we propose a simplified ML decoder exploiting the unique properties of 3D MIMO code. Simulation results show that the proposed simplified ML decoder can achieve much lower processing time latency compared to the classical sphere decoder with Schnorr-Euchner enumeration