Delay Optimal Multichannel Opportunistic Access

TL;DR

This paper introduces a new access policy, MS-AT, for multichannel opportunistic access that optimally balances queueing delay and throughput by leveraging risk-sensitive Markov decision processes, outperforming existing policies.

Contribution

It proposes the MS-AT policy based on myopic sensing and adaptive transmission, achieving simultaneous throughput and delay optimality under collision constraints.

Findings

MS-AT achieves delay and throughput optimality.

Effective bandwidth and throughput are piece-wise linear functions of collision constraints.

MS-AT outperforms MS-MT in delay-sensitive scenarios.

Abstract

The problem of minimizing queueing delay of opportunistic access of multiple continuous time Markov channels is considered. A new access policy based on myopic sensing and adaptive transmission (MS-AT) is proposed. Under the framework of risk sensitive constrained Markov decision process with effective bandwidth as a measure of queueing delay, it is shown that MS-AT achieves simultaneously throughput and delay optimality. It is shown further that both the effective bandwidth and the throughput of MS-AT are two-segment piece-wise linear functions of the collision constraint (maximum allowable conditional collision probability) with the effective bandwidth and throughput coinciding in the regime of tight collision constraints. Analytical and simulations comparisons with the myopic sensing and memoryless transmission (MS-MT) policy which is throughput optimal but delay suboptimal in the regime of tight collision constraints.