Delay-Constrained Optimal Link Scheduling in Wireless Sensor Networks

We consider the optimal link scheduling problem in wireless sensor networks. The optimal link scheduler under our consideration is intended to assign time slots to different users to minimize channel usage subject to constraints on data rate, delay bound, and delay bound violation probability; we study the problem under fading channels and a signal-to-interference-plus-noise-ratio (SINR)-based interference model. To the best of our knowledge, this problem has not been studied previously. We use the effective capacity model to formulate the optimal link scheduling as a mixed-integer optimization problem. We first discuss a simple case, namely, the scheduling with a fixed power allocation, and then extend to the case with variable transmit power. Moreover, because the mixed-integer optimization problem is NP-hard, we propose a computationally feasible column-generation-based iterative algorithm to search for a suboptimal solution to the problem. Finally, we design a medium access control (MAC) protocol to implement our optimal link scheduling strategy in practical wireless networks. Simulation results demonstrate that our proposed scheme achieves a larger throughput, a larger admission region, and a higher power efficiency than a benchmark time-division multiple-access (TDMA) system.