Throughput-optimal multihop wireless network operation entails a key physical-layer optimization problem: maximizing a weighted sum of link rates, with weights given by the differential queue backlogs. This emerges in joint back-pressure routing and power control, which is central in cross-layer wireless networking. We begin by showing that the core problem is not only nonconvex, but also NP-hard. This is a negative result, which however comes with a positive flip side: drawing from related developments in the digital subscriber line (DSL) literature, we propose effective ways to approximate it. Exploiting quasi-periodicity of the power allocation in stable setups due to the push-pull nature of the solution, we derive two custom algorithms that offer excellent throughput performance at reasonable, worst-case polynomial complexity. Judicious simulations illustrate the merits of the proposed algorithms.
Bibliographical noteFunding Information:
Manuscript received October 20, 2010; revised April 28, 2011 and November 27, 2011; accepted December 18, 2011. Date of publication January 12, 2012; date of current version March 06, 2012. The associate editor coordinating the review of this manuscript and approving it for publication was Dr. Josep Vidal. This work was co-financed by the European Union (European Social Fund—ESF) and Greek National Funds through the Operational Program “Education and Lifelong Learning” of the National Strategic Reference Framework (NSRF)—Research Funding Program: Heracleitus II, investing in knowledge society through the European Social Fund. This work was also supported in part by ARL/ERO, under contract W911NF-09-1-0004 and EC FP7 project N-CRAVE. Part of this work has appeared in Proc. IEEE ICASSP 2011 Conference.
- Back-pressure routing
- NP-hard problems
- convex approximation
- cross-layer design
- digital subscriber line (DSL)
- dynamic spectrum management
- network optimization
- power control
- utility maximization