RFID physical layer collision recovery receivers with spatial filtering

In this paper, we focus on a throughput increase in multiantenna Radio Frequency Identification (RFID) systems. We propose a physical layer collision recovery receiver with spatial filtering. Our goal is to decrease the number of tags involved in a collision by postprocessing received signals and cancelling tags from certain directions of arrival. To achieve this, we divide the reader´s area in sectors and we perform a collision recovery with different angular attenuations in each sector separately. Furthermore, we derive a semi-analytical formula that takes into account properties of a spatial filter and the throughput, and based on that we predict the optimal frame size. The influence of the proposed method on the system performance is analysed by means of simulations and compared with the performance of an EPC standard compliant reader. When comparing with our proposed method, the tag interrogation time is considerably shortened through which a large gain in the system throughput is achieved.