A Simplified Tagged MIMO Communications System with Blind Equalization Capability

This paper proposes a signal processing technique for blindly separating constant modulus sources in multiple-input multiple-output (MIMO) wireless communications systems. With the proposed technique, each modulated source is tagged by pre-filtering using an allpass filter (transmit tagging filter: TT-Filter) and scrambling using a BPSK modulated scrambling code (tagging code). Also, the TT-filter is designed without any multipliers. At the receiver, desired signal is generated by descrambling, filtering using an inverse model of the TT-filter, and blindly separating a constant modulus signal from non-constant modulus signals. The proposed technique enables all transmitting sources to use the same kind of TT-filter, hence allowing low cost system implementation. Furthermore, by using the same kind of TT-filter, system´s latency associated with TT-filters becomes independent of the number of tagged transmitting sources. Computer simulations with constant modulus signals verify the effectiveness of the proposed system