Direct Sequence Spread Spectrum Simulation in a CDMA with the Conventional Sliding Correlator

Abstract

A relatively new software package has emerged that facilitates the modeling of Direct Sequence Spread Spectrum (DSSS) systems. The Signal Processing Worksystem with Block Oriented Software Simulator (SPW/BOSS) by Comdisco [1] provides the flexibility of an open architecture and the strength of a vast component library. It was used extensively in this paper to generate models and simulate Code Division Multiple Access (CDMA) systems. The upcoming examples feature data sources and spreading mechanisms designed with individual Pseudo-Noise (PN) sequence generators with different polynomial orders, channels containing Additive White Gaussian Noise (AWGN), and receivers made up of Conventional Sliding Correlators (CSC) that are used as test beds to measure model integrity and performance trends. Contained within the CSC is a local PN generator with a sequence that matches the targeted transmitter, except for a possible phase shift. Further complexity is added to the models by studying the "near-far" problem associated with CDMA systems. These effects are simulated in software by altering the amplitudes of the transmitted signals. Simulation results are compared to analytical predications.