TCP Reno over Adaptive CSMA

TL;DR

This paper investigates the compatibility of TCP Reno with adaptive CSMA, finding that multi-connection TCP Reno with active queue management can mitigate starvation and realize adaptive CSMA's benefits, facilitating practical deployment.

Contribution

It demonstrates that multi-connection TCP Reno with active queue management enables adaptive CSMA to achieve fair, efficient rate allocation, overcoming starvation issues.

Findings

TCP Reno alone causes starvation over adaptive CSMA

Multi-connection TCP Reno with AQM alleviates starvation

Simulation shows improved fairness and efficiency

Abstract

An interesting distributed adaptive CSMA MAC protocol, called adaptive CSMA, was proposed recently to schedule any strictly feasible achievable rates inside the capacity region. Of particular interest is the fact that the adaptive CSMA can achieve a system utility arbitrarily close to that is achievable under a central scheduler. However, a specially designed transport-layer rate controller is needed for this result. An outstanding question is whether the widely-installed TCP Reno is compatible with adaptive CSMA and can achieve the same result. The answer to this question will determine how close to practical deployment adaptive CSMA is. Our answer is yes and no. First, we observe that running TCP Reno directly over adaptive CSMA results in severe starvation problems. Effectively, its performance is no better than that of TCP Reno over legacy CSMA (IEEE 802.11), and the potentials of adaptive CSMA cannot be realized. Fortunately, we find that multi-connection TCP Reno over adaptive CSMA with active queue management can materialize the advantages of adaptive CSMA. NS-2 simulations demonstrate that our solution can alleviate starvation and achieve fair and efficient rate allocation. Multi-connection TCP can be implemented at either application or transport layer. Application-layer implementation requires no kernel modification, making the solution readily deployable in networks running adaptive CSMA.