Decoupling multiuser cross-layer adaptive transmission

In wireless data communications, it has been realized that by adapting the transmit power and rate, not only to the channel conditions, but also to higher layer parameters, such as the buffer occupancy and data arrival statistics, the system performance can be significantly improved. However, most of the existing approaches deal only with single user scenarios. In this paper, we consider a multiuser scenario in which N users share a common time-varying wireless channel. During each time slot, a scheduler allows only one user to access the common channel for data transmission. We show that, under certain scheduling policies, the problem of optimal adaptive transmission for this multiuser system can be decoupled into N single-user problems. This allows the use of optimal adaptive single-user policies, where the adaptation is done with respect to each user's effective channel.