Performance analysis of separated/combined air interface protocol structure for IMT2000 system

In order to derive the suitable protocol architecture for IMT2000 systems, we evaluate the performance of signaling messages in the separated protocol layer and combined protocol layer recommended by W-CDMA and cdma2000, respectively. Also, we evaluate the performance of combined processing and sequential processing method in the case of handling registration and authentication messages. According to simulation results, in the case that error occurs, separated protocol layer has better performance than combined protocol layer as error rate increases. Because, separated protocol layer retransmits only errored frame, although combined protocol layer retransmits two frames. Also, in registration and authentication message processing, combined processing that transmits two messages simultaneously is better than sequential processing because of reduced retransmission count.