Cross-layer resource allocation for downlink access using instantaneous fading and queue length information

Cross-layer algorithms that jointly allocate resources at different layers are known to foster the communication performance in wireless networks. Recent works have shown that fading and queue information are among the most critical parameters to consider in cross-layer designs. Motivated by those findings, this work develops optimal algorithms that use instantaneous fading and queue length information to allocate resources at transport, link and physical layers. Our focus is on the downlink channel of a cellular system where an access point sends different information to several users through a set flat-fading orthogonal channels. The queue stability and the average queuing delay of the developed algorithms are also investigated. Moreover, a simple mechanism to effect delay priorities among users is presented. Finally, methods that reduce the signalling overhead by allocating groups of channels to the same user are discussed at the end of the paper.