Improved Pair-Wise Detections of Differential Quasi-Orthogonal Space-Time Modulation with Four Transmit Antennas

Hojun Kim,Taejin Jung,Yulong Shang,Seunghyeon Kim

doi:10.3390/electronics10141675

Abstract

In this paper, we propose new complex and real pair-wise detection for conventional differential space–time modulations based on quasi-orthogonal design with four transmit antennas for general QAM. Since the new complex and real pair-wise detections allow the independent joint ML detection of two complex and real symbol pairs, respectively, the decoding complexity is the same as or lower than conventional differential detections. Simulation results show that the proposed detections exhibit almost identical performance with an optimum maximum-likelihood receiver, as well as improved performance compared with conventional pair-wise detections, especially for higher modulation order.

Highlights

-called quasi-orthogonal (QO) design, adopted in coherent space–time codes (STBCs) [1,2,3], enjoys some preferable features of full spatial diversity gain as well as simplified maximum-likelihood (ML) detection based on complex or real pair-wise symbols for any type of signal constellation
In this paper, new complex and real pair-wise detections for the conventional QO-differential space–time modulations (DSTMs) [7,8] with four transmit antennas were proposed for general QAM without additional operation
We note that the proposed detection shows an SNR loss of less than only 0.2 dB compared to the ML decoding for all cases

Summary

Introduction

-called quasi-orthogonal (QO) design, adopted in coherent space–time codes (STBCs) [1,2,3], enjoys some preferable features of full spatial diversity gain as well as simplified maximum-likelihood (ML) detection based on complex or real pair-wise symbols for any type of signal constellation. [9] does not exhibit significant performance loss unlike [7,8], but has a critical disadvantage due to its decoding complexity greatly increasing as the modulation order increases For this reason, in this paper, new complex and real pair-wise detections for the conventional QO-DSTMs [7,8] with four transmit antennas were proposed for general QAM without additional operation. In (4)–(6), ()R and ()I denote real and imaginary parts, respectively

H Vkl ykl

Simulation Results

Conclusions