Low-Complexity Lattice Reduction Aided Schnorr Euchner Sphere Decoder Detection Schemes with MMSE and SIC Pre-processing for MIMO Wireless Communication Systems

© 2021, IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. This is the accepted manuscript version of a conference paper which has been published in final form at https://doi.org/10.1109/IUCC-CIT-DSCI-SmartCNS55181.2021.00045The LRAD-MMSE-SIC-SE-SD (Lattice Reduction Aided Detection - Minimum Mean Squared Error-Successive Interference Cancellation - Schnorr Euchner - Sphere Decoder) detection scheme that introduces a trade-off between performance and computational complexity is proposed for Multiple-Input Multiple-Output (MIMO) in this paper. The Lenstra-Lenstra-Lovász (LLL) algorithm is employed to orthogonalise the channel matrix by transforming the signal space of the received signal into an equivalent reduced signal space. A novel Lattice Reduction aided SE-SD probing for the Closest Lattice Point in the transformed reduced signal space is hereby proposed. Correspondingly, the computational complexity of the proposed LRAD-MMSE-SIC-SE-SD detection scheme is independent of the constellation size while it is polynomial with reference to the number of antennas, and signal-to-noise-ratio (SNR). Performance results of the detection scheme indicate that SD complexity is significantly reduced at only marginal performance penalty

Widely Linear Sphere Decoder in MIMO Systems by Exploiting the Conjugate Symmetry of Linearly Modulated Signals

International audienceThis paper investigates the widely linear processing(WLP) for the detection of circular signals such as M-aryphase shift keying (MPSK) signals, M-ary quadrature amplitudemodulation (MQAM) signals. Firstly, a unified mathematicalmodel is derived to describe the conjugate symmetry of generalMPSK/MQAM signals. In the unified model, a phase-rotation matrix(PRM) is introduced to partition the constellation of multipleinputmultiple-output (MIMO) signals into subsets. Signals in asubset share the same PRM. Secondly, a widely linear receiver isproposed in each subset for MIMO detection. To avoid repetitiveWLP in each subset, a widely linear sphere decoder (WLSD)is further proposed for MIMO systems. WLSD transforms thetraditional SD searching for a true transmitted vector into ashrunk one by searching for the corresponding phase-rotationvector