DSP Prototype of a Chaos-Based Multi-User Communication System: Design and Performance Analysis

Ljiljana Simic, Stevan Berber

Abstract

This paper presents the implementation of a multi-user chaos-based communication system in DSP (digital signal processor) technology. The system is based on the chaotic phase shift keying (CPSK) digital modulation scheme, where chaotic signals are used as the spreading sequences of a CDMA (code division multiple access) system. Using chaotic signals offers the advantages of increased security and higher system capacity compared with conventional sequences. The aim of this hardware implementation was to enable a comparison against analytical performance results for CPSK. The transceiver prototype was implemented on a 32-bit floating-point TigerSHARC DSP. Its bit error rate (BER) characteristics were measured in the presence of additive white Gaussian noise. The prototype achieves excellent BER performance, matching that of theoretical CPSK. The effects of the limited number precision of the hardware platform are thus negligible. However, due to the limited concurrency of DSP, the multi-user system only supports low data rates. Despite this, the prototype demonstrates that the CPSK scheme is a promising and viable CDMA option for the future.

Keywords

Code-division Multiple Access (CDMA), multi-user communication, chaos based PSK, DSP design

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