Spread ALOHA-based fast random access scheme for macro cell CDMA systems

The slotted ALOHA-based random access scheme has low throughput and long access delays when used in macro cell Code Division Multiple Access (CDMA) systems. A Spread ALOHA-based Multiple Access (SAMA) scheme was developed to improve performance. A system model is presented which includes the impact of multiple paths on the conflict interval, and the Multiple Access Interference (MAI) from the traffic channels. Theoretical formulas are given for the throughput and average access delay of packets. Simulations show that the SAMA has much better access performance and significantly reduces the average access delay, especially when for heavy loads. Multiple paths and numerous traffic channels significantly impact the SAMA access performance.