In this talk we study the issue of cross-layer design for rate control in multihop wireless networks. We have developed an optimal cross-layered rate control scheme that jointly computes both the rate allocation and the stabilizing schedule that controls the resources at the underlying layers. However, the scheduling component in this optimal cross-layered rate control scheme has to solve a complex global optimization problem at each time, and is hence too computationally expensive for online implementation. Thus, we study the impact on the performance of cross-layer rate control if the network can only use an imperfect (and potentially distributed) scheduling component that is easier to implement. We study scenarios with both fixed number of users as well as when the number of users change due to arrivals and departures in the system. In each case, we establish desirable results on the performance bounds of cross-layered rate control with imperfect scheduling. Our cross-layered approach provides provably better performance bounds when compared with a layered approach (that does not design rate control and scheduling together). The insights drawn from our analyses also enable us to design a fully distributed cross-layered rate control and scheduling algorithm under a restrictive interference model.
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