Throughput and delay analysis of DS/SSMA unslotted ALOHA by non-perfect capture

Throughput and delay analysis of direct-sequence spread spectrum multiple access (DS/SSMA) unslotted ALOHA is presented. Due to the fluctuation of the levels of multi-user interference during the packet transmission, we calculate the throughput and delay by considering not only the number of overlapped packets but also the amount of time overlap. We consider the case of variable packet length and fixed packet length. As a result, we found that the performance of DS/SSMA unslotted ALOHA with fixed packet length is better than that with variable packet length.