Abstract:
The complexity gains of sphere decoders (SDs) with Schnorr–Euchner enumeration and nonconstant amplitude constellations are limited by the required node ordering. Aiming ...Show MoreMetadata
Abstract:
The complexity gains of sphere decoders (SDs) with Schnorr–Euchner enumeration and nonconstant amplitude constellations are limited by the required node ordering. Aiming at improving the implementation efficiency of SD without compromising optimality, this paper proposes a novel tree traversal for soft-output SDs providing the exact max-log MAP decoder performance. It consists of a predefined visiting order that approximates the exact Schnorr–Euchner enumeration (SEE) and a modified pruning metric that preserves the exact max-log MAP despite the approximate ordering. The proposed approach significantly improves both the computational complexity and the implementation cost of exact soft-output SDs compared with previous techniques. In particular, simulations show gains of 30%–56% in the required calculations for a 4 \!\times\! 4 multiple-input multiple-output system with 16-quadrature amplitude modulation (QAM), and field-programmable gate array (FPGA) implementations show an average power reduction of 34%–50%.
Published in: IEEE Transactions on Vehicular Technology ( Volume: 64, Issue: 6, June 2015)