An efficient MAC protocol with interference reduction for wideband DS-CDMA systems

Wideband DS-CDMA is one of the RTT (radio transmission technology) proposals considered by ITU International Mobile Telecommunications commission: IMT-2000. For packet transmission over uplink common channels, multi-code spread slotted Aloha was the most popular MAC protocol. However, CDMA systems require more attention in code allocation and interference prevention, which is different for TDMA systems. This paper proposed an improved uplink MAC protocol for efficient common channel access. The new scheme can efficiently prevent unnecessary interference by stopping a transmission if it is bound to collide with others. Furthermore, the proposed protocol is very flexible in code allocation. The simulation result shows that less number of codes is required to achieve the same throughput/delay performance as the original spread slotted Aloha.