QoS and channel aware packet bundling for VoIP traffic in cellular networks

We study the problem of multiple packet bundling to improve spectral efficiency in cellular networks. The packet size of real-time data, such as VoIP, is often very small. However, the use of time division multiplexing (TDM) limits the number of VoIP users supported, because a packet has to wait until it receives a time slot. Packet bundling can alleviate such a problem by sharing a time slot among multiple users. A recent revision of cdma2000 1xEV-DO introduces the concept of the multi-user packet (MUP) in the downlink to overcome limitations on the number of time slots. However, the efficacy of packet bundling is not well understood, particularly in the presence of time varying channels. We propose a novel QoS and channel aware packet bundling algorithm that uses adaptive modulation and coding. We show that channel utilization can be significantly increased by delaying some real-time packets slightly within their QoS requirements. We validate our study through OPNET simulation with a complete EV-DO implementation.