Study of Unique-Word Based GFDM Transmission Systems

TL;DR

This paper introduces a novel UW-based GFDM system that replaces cyclic prefixes with deterministic sequences, enhancing synchronization, channel estimation, and noise reduction, and demonstrates superior performance through simulations.

Contribution

The paper proposes a UW-based GFDM system with an LMMSE receiver, improving synchronization, channel estimation, and noise reduction over traditional methods.

Findings

Outperforms prior GFDM systems in simulations

Uses UW for synchronization and channel estimation

Employs LMMSE smoothing for noise reduction

Abstract

In this paper, we propose the use of a deterministic sequence, known as unique word (UW), instead of the cyclic prefix (CP) in generalized frequency division multiplexing (GFDM) systems. The UW consists of known sequences that, if not null, can be used advantageously for synchronization and channel estimation purposes. In addition, UW allows the application of a highly efficient linear minimum mean squared error (LMMSE) smoother for noise reduction at the receiver. To avoid the conditions of non-orthogonality caused by the insertion of the UW and performance degradation in time varying frequency-selective channels, we use frequency-shift offset quadrature amplitude modulation (FS-OQAM). We present a signal model of a UW-GFDM system considering a single and multiple UWs. We then develop an LMMSE receive filter for signal reception of the proposed UW-GFDM system. Simulations show that the proposed UW-GFDM system outperforms prior work.