A High Throughput Reader Scheduling Algorithm for Large RFID Systems in Smart Environments

Radio Frequency IDentification (RFID) plays a vital role in smart computing applications. Due to the limited communication range of individual RFID readers, large RFID systems deployed in real applications usually contain multiple readers. Existing reader scheduling algorithms either disallow adjacent readers to simultaneously work in order to avoid collisions among them, or simply activate all the readers to work together to exploit the parallel working of readers to increase identification throughput. In this paper, we propose a reader scheduling algorithm that tolerates collisions among readers but selects an optimal set of readers that can maximize tag identification throughput to work in parallel. The proposed algorithm thus achieves much higher tag identification throughput than existing solutions. Experiment results in a small testbed containing three readers show that, compared with the state-of-the-art solution, the proposed algorithm enhances tag identification throughput by 40%. Results from extensive simulation experiments further demonstrate that the proposed algorithm performs much better than existing solutions in large RFID systems. For example, the proposed algorithm achieves 132% higher identification throughput than previous best solution in systems containing more than one hundred readers when the readers are randomly deployed, meanwhile achieves much smaller identification delay.