BER Performance of 4x1 Space-Time Parallel Block Coded Two-Path OFDM Systems

In this paper, a 4x1 space-time (ST) orthogonal frequency division multiplexing (OFDM) system is proposed with parallel cancellation (PC) to form a 4x1 STPC-OFDM system. The 4x1 STPC-OFDM system mitigates the inter-carrier interference (ICI) in the mobile channels due to the two-path block coding approach in PC scheme. Furthermore, a generalized STPC architecture can also be designed with multiple receiver antennas. It offers higher diversity and better BER performance. The orthogonal transforms, Zadoff-Chu transform (ZCT) and Walsh–Hadamard transform (WHT) can be employed as a precoder to enhance the BER further. Although the proposed STPC-OFDM systems require two-path transmission, simulations demonstrate that the proposed 4x1 STPC-OFDM full rate systems are more robust to the frequency selective channels and have a better BER performance than that of a half rate ST-OFDM system with the same bandwidth efficiency. Moreover, it regains the bandwidth efficiency and still has a better BER for fair data rate comparison with 4x1 ST-OFDM when using a high modulation index.

I. Introduction

Modern communication systems, including internet of things (IoT), unmanned aerial vehicle (UAV) are required to be robust in a rapidly changing channel environment. Applications such as industrial or smart sensors, wearables, and medical devices are operated in either stationary or mobile fading channels. The interference should be mitigated to maintain quality of service (QoS) in both up and down communication links.