Tag read enhancement using unsynchronized signal from adjacent readers in multi-cell RFID system

This paper addresses the interference issue in a passive multi-cell radio frequency identification (RFID) system. Instead of considering the negative effect of interfering RF signals from adjacent readers, we investigate its constructive effect in providing extra RF power to tags in the cell of the desired reader system. Through detailed simulation and experimental analysis, it is found that the unsynchronised signal from neighbouring readers can be utilized to activate marginal tags through enhancing power delivery. This results in improved tag received signal strength indicator (RSSI). In addition, it is found that the overlap zone between two RFID cells is not as vulnerable to interference as one might think. In fact, the adjacent reader may facilitate the desired reader to read more tags in the overlapping zone, although a longer inventory period may be required. We believe these findings might provide a new insight into the interference effect on multi-cell RFID system and be applied to future medium access control (MAC) protocols.