A NOVEL PACKET DATA-TRANSMISSION STRATEGY FOR PERSONAL HANDY-PHONE SYSTEM

The demand for data communication over Personal Handy-phone System (PH S) is expected to rapidly increase in the near future. Some applicatio ns based on the circuit-switched services have been recently developed . However, the packet-switched service is better than the circuit-swit ched service for personal data communications in terms of the flexible utilization of radio resources. In this paper, we propose PHS with pa cket data communications system (PHS-PD), which has four system concep ts; (i) to support the Internet access, (ii) to realize compatibility with circuit-switching services, (iii) to share the common radio chann els with circuit-switched calls, and (iv) to utilize idle time slots f or packet data. Moreover, a novel packet channel structure for sharing radio resources with circuit-switched calls is introduced. Although p acket data are transferred using common radio resources, the proposed channel structure prevents any degradation in call loss performance of the circuit-switching service. An evaluation of the maximum packet tr ansmission rate shows that PHS-PD can offer a data communication rate of 20.1 kbps even if circuit-switched calls are in progress. Furthermo re, up to 83.6 kbps is possible if circuit-switched calls are quiescen t. It is also shown that enough capacity for a practical e-mail servic e can be ensured by PHS-PD even if the degradation of throughput perfo rmance due to packet collisions on random access channels is considere d.