A Multiple Lattice Reduction Based Detector for Space Time Block Codes Based on Cyclotomic Extensions

Full diversity high-rate Space Time Block Codes (STBCs) based on cyclotomic field extensions Q(ωl), where ωl is the complex lth root of unity, can be decoded by Lenstra-Lenstra-Lovász (LLL) lattice reduction-aided linear equalization followed by appropriate zero forcing. LLL lattice reduction-aided linear equalization enables lower complexity decoding compared to sphere decoding, while resulting in a performance loss. In this paper, we propose a new suboptimal detection algorithm which exploits the algebraic structure of this class of STBCs and applies LLL lattice reduction-based detection multiple times on the received space-time symbol to arrive at an estimate of the transmitted codeword matrix. The decoding complexity is still significantly lower than sphere decoding complexity. Using simulations, the proposed scheme is shown to perform better than the conventional LLL reductionbased scheme in terms of bit error rate. We also point out that the computational effort for the multiple lattice reductionbased scheme can be significantly reduced for codes over certain numbers of transmit antennas.