We study the cross-layer design of congestion control and power allocation with outage constraint in an interference-limited multihop wireless networks. Using a complete-convexification method, we first propose a message-passing distributed algorithm that can attain the global optimal source rate and link power allocation. Despite the attractiveness of its optimality, this algorithm requires larger message size than that of the conventional scheme, which increases network overheads.
Using the bounds on outage probability, we map the outage constraint to an SIR constraint and continue developing a practical near-optimal distributed algorithm requiring only local SIR measurement at link receivers to limit the size of the message. Due to the complicated complete-convexification method, however the congestion control of both algorithms no longer preserves the existing TCP stack. To take into account the TCP stack preserving property, we propose the third algorithm using a successive convex approximation method to iteratively transform the original nonconvex problem into approximated convex problems, and then the global optimal solution can converge distributively with message passing.
Our numerical results show that the gap between three algorithms is almost indistinguishable. Despite the same type of the complete-convexification method, the numerical comparison shows that the second near-optimal scheme has a faster convergence rate than that of the first optimal one, which makes the near-optimal scheme more favorable and applicable in practice. Meanwhile, the third optimal scheme also has a faster convergence rate than that of a previous work using logarithm successive approximation method. Cross-Layer Design of Congestion Control and Power Control in Fast-Fading Wireless Networks
Existing problem in a multi-hop random access wireless network, with the objective of achieving proportional fairness amongst the end-to-end sessions, the problem is considered in the framework of nonlinear optimization. Compared to its counterpart in a wired network where link capacities are assumed to be fixed, rate control in a multi-hop random access network is much more complex and requires joint optimization at both the transport layer and the link layer. This is due to the fact that the attainable throughput on each link in the network is `elastic’ and is typically a non-convex and non-separable function of the transmission attempt rates. Two cross-layer algorithms, a dual based algorithm and a primal based algorithm, are proposed in this paper to solve the rate control problem in a multi-hop random access network.
We aim to design a resource allocation scheme that does not have to keep track of the instantaneous fading state of the wireless channel. Instead, we allow outages to occur between successive updates; as a result, the updates can proceed on a much slower time scale (i.e., the same time scale as log-normal shadowing variations).
We explicitly include the fading induced outage constraint into the underlying cross-layer NUM problem, where we account for the statistical variation in each link’s SIR and allow the SIR to drop below a prescribed threshold with a predetermined probability.