The rapid deployment of global wireless voice services, especially the new personal communications services (PCS) networks, has prompted an ever-growing demand for wireless data communications, such as access to the Internet. Various approaches, ranging from simple use of modems to the more dedicated protocol of cellular digital packet data, have been developed by the industrial and research communities. The authors propose a new scheduling policy for the circuit mode data protocol of PCS networks. The new policy, “latest preempted, earliest resumed” (LPER), allocates a circuit mode channel for a data user with a lower priority that can be preempted by a voice channel. That is, if no idle channel is available when a voice request arrives, a latest data channel (if any) will be interrupted for the request; and the earliest interrupted data channel will be resumed when an idle channel becomes available.

The majority of the paper is devoted to an analysis of the performance behavior of the LPER policy using a PCS system model and a waiting (preemption) time model. The major performance results show that when the voice traffic is low (less than 0.3 erlangs), a large number of voice channels can be shared with data requests due to little influence of the voice traffic on the LPER performance and negligible waiting time for data requests. When the voice traffic becomes high (0.3–0.7 erlangs), the optimal number of channels shared between voice and data requests is four, and the performance degrades deeply if the voice traffic increases beyond that range.