Reverse-Link Interrogation Range of a UHF MIMO-RFID System in Nakagami- m Fading Channels

In this paper, the reverse-link interrogation range (RIR) of ultrahigh-frequency-band passive radio-frequency identification (RFID) is analyzed for single-input and single-output (SISO) and multiple-input and multiple-output (MIMO) systems with maximal-ratio combining in the pinhole channel, where each channel is modeled as an arbitrarily correlated Nakagami-m distribution. Under the assumptions of perfect channel estimation and no interference, the closed-form expression of average RIR is derived, involving various parameters, such as the number of antennas, correlation, reader structure, and Nakagami- m shaping factor. The results show that the employment of multiple antennas at a reader causes the received SNR to change favorably and contributes to the improvement of the average RIR. Particularly, for the bistatic structure and Rayleigh fading (m = 0 dB), a 3 × 3 MIMO-RFID system can achieve 60% gain in the average RIR compared to the SISO-RFID system. In order to consider more realistic environments, finally, we investigated the influence of interference and imperfect channel estimation on the average RIR of the MIMO-RFID system in the uncorrelated Rayleigh fading channel.