Real Time Services over Wireless Networks

Research Abstract

Future wireless communication systems are expected to provide a broad range of multimedia services including voice, video, and data. A cellular architecture is envisioned in order to support the service over a wide area. Due to heterogeneity of the traffic, a network based on the packet switching technology may provide a more flexible framework and allow a simpler architecture and significant cost savings. Those have been the experiences with the wireline networks, which have moved recently to such an integrated architecture. By having all data in a packetized form, there is no need to maintain a different type of network for specialized applications, such as a circuit-switched network for voice telephony, which may require different types of equipment and administrative overhead. In addition, there is the possibility of using statistical multiplexing to increase the utilization of often-limited transmission resources. Since network resources are not pre-assigned in a packet-switched network, different users or flows can share the network resources and higher utilization of may be achieved. In particular, networks based on the Internet Protocol (IP) have begun to gain momentum as the platform of choice due to their ubiquity and scalability.
There are significant hurdles to overcome, however, in building a packet-switched wireless network that can serve all types of traffic. Not only must the communication link be shared among many users and flows while providing adequate QoS, the sharing must be done over the wireless channel which is prone to frequent errors and sometimes prolonged outages. Transport of packet data traffic over the wireless channel has received a lot of attention lately due to increasing use of the Internet from wireless devices. However, much of the work has dealt with delay-insensitive data, as most researchers have assumed that delay-sensitive applications such as voice telephony will continue to be served using a separate circuit-switched network dedicated to such applications. To make the idea of extending the packet-switched framework to the wireless network more feasible, there remains much work to be done on how to efficiently serve different types of data over a medium that is relatively scarce and fraught with errors. In this resesarch project, we focus on the transport of real-time packets such as those from voice over IP (VoIP) applications which may make up an important subset of traffic over the future packet-switched wireless networks.