A PSSS Approach for Wireless Industrial Communication Applying Iterative Symbol Detection

Abstract

Wireless industrial communication requires high reliability and low latencies. In order to fulfill both requirements simultaneously, wireless approaches are being developed. One of these technologies is parallel sequence spread spectrum (PSSS). In comparison to direct sequence spread spectrum approaches, which employ a set of appropriate pseudonoise (PN) sequences, PSSS data symbols are spread based on a single cyclically shifted <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</i> -sequence. Each cyclic shift of the chosen <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</i> -sequence is used as an individual PN-sequence. This enables a code division multiple access (CDMA) scheme with simple processing and thus, a fast hardware implementation. In order to investigate the impact of an inaccurate time synchronization, this paper presents a theoretical and simulative PSSS evaluation. Moreover, an iterative symbol detection is introduced, which neutralizes the impact of the nonorthogonal <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</i> -sequences and mitigates the degradation due to inaccurate synchronization. In addition, several reasonable resource allocation schemes are presented, which emphasize the PSSS systems flexibility.