An Improved Soft Decision Based MIMO Detection Using Lattice Reduction

Abstract

Abstract-This paper presents a performance analysis of soft decision based Lattice Reduction (LR) aided Schnorr-Euchner (SE) multiple-input-multiple-output (MIMO) detection algorithm with that of a hard one. We develop an advanced soft decoding scheme, for 4×4 MIMO with different modulation schemes and it provides 1.3 to 1.5 dB improvement compared to the LR-aided hard decision based detection method. The optimum parameters for K and saturation limit are further derived using extensive simulation. In the conventional K-best algorithm limiting the LLR values is not beneficiary in reducing the optimum size of candidate list, whereas applying the saturation limit on the LLR values in LR-aided algorithm will result in more than 8x reduction in list size as well as in the complexity of detector and LLR calculation unit.Index Terms-MIMO, soft decoding, lattice reduction, and k-best detector.

An iterative LR-aided MMSE extended soft MIMO decoding algorithm

“…But the proposed NLD does not generally have good diversity-multiplexing tradeoff (DMT) optimally, even with the K-best search [15]. To achieve DMT, the following modifications are proposed in [5] and [11]: s == arg min (IIY -H sll + 2N~Ilsll) , sE11 2N T as S == arg min Ilv -Hs112. (6) sE11 2N T Here, 11.…”

“…We have used algorithm in [11] to perform the list calculation and then the chosen K paths are passed to the iterative soft input soft output (SISO) decoder.…”

“…LDPC soft decoder can calculate the approximate LLRs from a list of possible candidates using (11), as described in [3].…”

“…In this paper, we have compared the result of our algorithm with that of a depth first search least sphere decoder (DFS-LSD), which is closest in performance to ML. As the candidate list is a subset of the search tree, further optimization on list size is proved to be possible by limiting the LLR values [8], [11]. A saturation of plus and minus eight is applied to limit the over confident LLRs that are the result of lack of hypothesis in candidate list.…”

Cooperative transmission over Rician fading channels for geostationary orbiting satellite collocation system

“…Over the past two decades, multiple‐input–multiple‐output (MIMO) technology has been widely acclaimed due to its high throughput, spatial gain, diversity, and interference reduction with no additional cost from the perspectives of transmission power and bandwidth [9, 10]. Since the last decade, the possible use of MIMO in GEO satellite collocation (GEOSC) systems has been considered in the literatures [11–24].…”