Performance comparison of a slotted ALOHA DS/SSMA network and a multi-channel narrowband slotted ALOHA network

Throughput, delay, and stability for two slotted ALOHA packet radio systems are compared. One system is a direct-sequence spread-spectrum multiple-access (DS/SSMA) network where each user employs a newly chosen random signature sequence for each bit in a transmitted packet. The other system is a multiple-channel, slotted ALOHA network where each packet is transmitted over a randomly selected channel. Accurate packet success probabilities for the CDMA system are computed using an improved Gaussian approximation technique which accounts for bit-to-bit error dependencies. Average throughput and delay results are obtained for the multiple-channel, slotted ALOHA system and CDMA systems using varying levels of block error correction. The first exit time is computed for both systems and used as a measure of the network stability