Performance Analysis of Single Code Spread ALOHA Systems

Spread ALOHA has become one of the advanced multiple access techniques promising several advantages over existing conventional and spread spectrum based wireless systems. Spread ALOHA is currently recognised as a simplified wireless multiple access system which provides a higher bandwidth and may accommodate high number of users. Over the last decade, several models have been developed to predict and estimate the performance of Spread ALOHA. Various combinations of protocols have been employed to enhance performance. This paper investigates the employment of a unique spreading code in conjunction with Spread ALOHA as opposed to the common method of employing distinct spreading codes for all users on the communication channel. In this paper we have modeled and simulated a Single Code Spread ALOHA (SCSA) system together with a conventional CDMA ALOHA system in order to analyse and compare the performance of both systems. Two types of PN codes were used in the simulation models, namely m-sequence and Gold codes. The simulation results showed comparable performance of both systems, and verified the suitability of m-sequence for SCSA and Gold codes for CDMA respectively.

I. INTRODUCTION

PREAD ALOHA is a novel multiple access protocol, which has lead to the emergence of a new multiple access technology known as Spread ALOHA Multiple Access (SAMA). In its simplest form Spread ALOHA comprises the combination of two known techniques: conventional narrowband ALOHA wireless multiple access and wideband spread spectrum such as Code Division Multiple Access (CDMA).