Abstract
In this letter, we propose the demodulation method to improve the complexity of demodulation in passive MIMO (Multiple-Input Multiple-Output) scheme. This scheme uses the multiple antennas at both reader and RFID (Radio Frequency Identification) tag to increase the data-rate, but the complexity of MLD (Maximum Likelihood Detection), which is used as demodulation algorithm, increases exponentially with the number of antennas. The proposed method divides tag antennas into two groups that do not interfere each other by decoupling tag antenna groups using 180-degree hybrids at tag side and beam-forming at receiver side. Individual demodulation for each group improves the complexity of MLD significantly. Simulation results show the proposed method can reduce the complexity of MLD with degrading slight BER (Bit-Error-Rate) performance. The results reveal the proposed method is effective in reducing demodulation complexity of passive MIMO transmission even when the number of tag antennas is increased.
