Integrated Design of Hierarchical QAM Modulation and Retransmission Diversity for Multimedia Wireless Networks

The current and future wireless systems need to support a multitude of services with a wide range of data rates and reliability requirements. The limited battery resource at the mobile terminals coupled with the hostile multipath fading channel makes the problem of providing reliable multimedia services challenging. In this article, we develop a novel method to mechanize a prioritized unicast transmission at the physical layer in response to the disparate quality of service requirements for multimedia traffic (imposed by upper layers) and investigate how the unequal bit error protection offered by multiresolution modulation is capitalized at the data link layer to yield a substantial throughput gain and minimize the packet loss probability of the "more important" packets in an integrated voice/data and delay-sensitive applications (especially in poor and moderate channel conditions). However, there exists a slight throughput penalty in the high signal-to-noise ratio regime due to competitive nature of the "optimal reliable signaling rate" in an unknown time-varying channel.