Throughput of CDM-Based Random Access With SINR Capture

Code division multiplexing (CDM)-based random access, wherein a set of sequences is reserved for random access and a remote station transmits a random access packet using a sequence randomly selected from this set, is employed in numerous practical wireless systems. If multiple remote stations simultaneously transmit random access packets using the same sequence, the performance degrades owing to sequence collision. In addition, the performance is degraded because of interference if multiple remote stations simultaneously transmit random access packets using different sequences. Therefore, the performance of CDM-based random access is dependent on both sequence collision and interference. There have been no previous studies on analyzing the performance of CDM-based random access considering both sequence collision and interference. In this paper, the throughput of CDM-based random access is investigated considering both sequence collision and interference based on a signal-to-interference-plus-noise ratio (SINR) capture model. Analyses and numerical simulations are performed to compare the throughputs of several random access schemes, including conventional and channel-adaptive random access. The results show that channel-adaptive random access can achieve significantly higher throughput than that achieved by conventional random access. Moreover, the results demonstrate that it is possible to analyze the trade-off between the throughput and implementation complexity with the increased the number of sequences.