Omnidirectional Quasi-Orthogonal Space-Time Block Coded Massive MIMO Systems

TL;DR

This paper introduces a novel omnidirectional quasi-orthogonal space-time block coding scheme for massive MIMO systems that ensures constant received power at all angles and achieves higher diversity, applicable to both ULA and UPA configurations.

Contribution

A new consecutive omnidirectional QOSTBC design utilizing orthogonal complementary codes, providing constant power reception and increased diversity in massive MIMO systems.

Findings

Achieves constant received sum power at any angle.

Provides a higher diversity order of 4.

Extends to 2D UPA configurations.

Abstract

Common signals in public channels of cellular systems are usually transmitted omnidirectionally from the base station (BS). In recent years, both discrete and consecutive omnidirectional space-time block codings (STBC) have been proposed for massive multiple-input multiple-output (MIMO) systems with a uniform linear array (ULA) configuration to ensure cell-wide coverage. In these systems, constant received signal power at discrete angles, or constant received signal sum power in a few consecutive time slots at any angle is achieved. In addition, equal-power transmission per antenna and full spatial diversity can be achieved as well. In this letter, by utilizing the property of orthogonal complementary codes (OCCs), a new consecutive omnidirectional quasi-orthogonal STBC (QOSTBC) design is proposed, in which constant received sum power at any angle can be realized with equal-power transmission per antenna through one STBC transmission, and a higher diversity order of 4 can be achieved. In addition, the proposed design can be further extended to the uniform planar array (UPA) configuration with the two-dimensional OCCs.