Performance Evaluation of Multi-Access Strategies for an Integrated Voice/Data CDMA Packet Radio Network.

Abstract

The problem of voice/data integration in a random access radio network employing the ALOHA protocol in conjunction with recursive retransmission control is investigated. Code-division multiplexing (CDMA) is used as a suitable modulation in a radio environment to decrease the effect of multiple-access interference. Multi-access control strategies are introduced that take advantage of the multipleaccess capability of the CDMA channel to accommodate several voice calls simultaneously, while the data users contend for the remaining (if any) multiple-access capability of the CDMA channel. The retransmission probabilities of the backlogged data users are updated based on estimates of data backlog and number of established voice calls which are obtained from the side information about the state of channel activities. A two-dimensional Markovian model is developed for the voice and data traffic, with the data backlog and number of established voice calls representing the state of the system. Based on this model, the voice-call blocking probability, the throughput of both traffic types, and the delay of the data packets are evaluated and the tradeoffs between the parameters of different traffic types are quantified.