ON PERFORMANCE ANALYSIS OF DS/SSMA ALOHA USING CHANNEL LOAD SENSING PROTOCOL

Abstract

Packet radio systems based on Code Division Multiple Access (CDMA) have drawn much attention for use in mobile and personal communications because of their capability of random access, the potential for high throughput performance, and the low peak power in the transmitter. Direct Sequence (DS) multiple access radio systems allow multiple access to the channel ' by a wideband averaging technique so that multiple users can send data on a channel simultaneously. A packet CDMA channel is characterised by Aloha like operation with traffic dependent probability of successful packet transmission. Packets which encounter excessive multiuser interference are retransmitted with random delay. In this dissertation throughput performance analysis. of infinite-user DS/SSMA slotted and unslotted ALOHA networks with fixed packet length is presented. The probability of data bit error is calculated by . using Improved Gaussion Approximation. The effect of bit-to-bit error dependence on packet success probability is explained for varying amount of ' block error control employed in a packet. Average delay time is also calculated for conventional slotted ALOHA. The effect of Channel Load Sensing Protocol (CLSP) on throughput performance is studied in case of half-slotted Aloha and unslotted Aloha. An optimum channel threshold is obtained as a function of number of chips per bit. A network model consisting of N users, communicating with each other over a single broadcasting channel is also analysed using the same protocol as above.