Wireless voice-over-IP and implications for third-generation network design

The recent rise of voice-over-Internet protocol (IP) as an alternative to circuit-based telephony poses some serious questions to the wireless community. Will wireless voice-over-IP and multimedia-over-IP gain momentum over their circuit-based alternatives? Should the design of third-generation (3G) wireless systems take these alternatives into account? In this paper we describe two models of wireless voice-over-IP and discuss additional requirements necessary to support business-grade-quality voice in the face of mobility. The case studies we present assumed an air interface of IS-95 code division multiple access (CDMA) or IS-136 time division multiple access (TDMA). The results of our studies show that business-grade voice-over-IP may not be economical for the licensed cellular and personal communications services (PCS) radio spectrum because the cost of licensing the cellular/PCS radio spectrum is high and the circuit-mode air interface is already efficient. To compete in various markets, however, 3G networks should efficiently support both wireless voice-over-IP and multimedia-over-IP. To do this, 3G networks should meet the challenge of seamless packet data handoffs and deep compression of user data protocol (UDP)/IP headers. Efficient support for wireless multimedia-over-IP may be even more critical (compared to voice-over-IP) for helping packet-based 3G multimedia such as H.323 to compete with its broadband integrated services digital network (B-ISDN) counterpart. As wireless voice and data converge in the 3G world, betting on packet-data mobility in addition to voice mobility may be a key to enabling the wireless industry to fuel the explosive growth of mobile subscribers worldwide.