A Cross-Layer Optimization for a LP-Based Multi-Reader Coordination in RFID Systems

In RFID systems, the system performance such as interrogation range and tag recognition rates may suffer from interferences among readers. The reader interference problem can be alleviated by output signal power control and spectral and/or temporal separation among the readers. However, due to the limited wireless resources, the diverse interference effects, and the constraint of user requirements, it is not easy to derive the optimal solution. In this paper, we propose a cross-layer design to optimally schedule spectral and temporal resources, and to allocate appropriate power to each reader in a dense reader environment. The cross-layer design is as a three-stage optimization problem, where in the first stage the reader interrogation interval is minimized, in the second stage the reader utilization is maximized, and in the last stage output power of each reader is minimized. We merge the three-stage problem into a one-stage problem with more concise mathematical form. Numerical results demonstrate the effectiveness of the proposed optimization problems.