Low-Complexity SQR-Based Decoding Algorithm for Quasi-Orthogonal Space-Time Block Codes

— In this paper, we propose a new decoding algorithm for quasi-orthogonal space-time block codes (QOSTBCs) which achieves near Maximum Likelihood (ML) performance while substantially reducing the decoding complexity. We show that for a system with rate r = ns/T, where ns is the number of transmitted symbols per T time slots; the proposed algorithm decomposes the original complex-valued system into a parallel system with ns 2×2 real-valued components, thus allowing for a simple decoding of one real symbol at a time. For a square QAM constellation with L points (L-QAM), this algorithm achieves full diversity by properly incorporating two-dimensional rotation using the optimal rotation angle and the same rotating matrix for any number of transmit antennas (N ≥ 4). We show that the complexity of this algorithm is linear with the number of transmitted symbols ns, and is independent of the constellation size L.

• Type: Conference
• Year: 2008
• Where: GLOBECOM
• Authors: Luay Azzam, Ender Ayanoglu
• Keywords: GLOBECOM 2008, Optimal Rotation Angle, Quasi-orthogonal Space-time Block, Square Qam Constellation, Telecommunications