Spread ALOHA based random access scheme for macro cell CDMA systems

The slotted ALOHA based random access faces the low throughput and long access delay problems when used in macro cell CDMA systems. This paper proposes the spread ALOHA based random access scheme as a solution. In our physical layer model, we studied the impact of multi-path on conflict interval and the multiple access interference (MAI) from both the traffic channels and the request channel. Based on this model, the close-form theoretical results of throughput and average access delay are derived. Numerical results show that the proposed scheme has much better access performance, which is much higher throughput and much shorter access delay than the slotted ALOHA based scheme. The improvement is enhanced as the load gets heavier.