Polarization Division Multiple Access on NLoS Wide-Band Wireless Fading Channels

A cellular down-link polarization division multiple access (PDMA) scheme with collaborative transmitter-receiver-polarization adjustment and polarization filtering detection is proposed for polarized wide-band non-line-of-sight (NLoS) wireless fading channels. The fundamental novelty of the proposed scheme is that it can adjust transmit polarization to yield more desirable per-subcarrier complex cross-polarization discrimination (XPD) observed at the receivers. This is a significant difference between the proposed scheme and conventional multiple-input multiple-output (MIMO) systems. The capacity analysis of the proposed PDMA scheme is provided, and the feasibility and satisfactory performance of the scheme are demonstrated even when serious time-variant channel depolarization and polarization mismatch between receivers occurs. The proposed cellular down-link PDMA scheme uses synchronous orthogonal frequency division multiple access (OFDMA) with an equally spaced pilot symbol allocation and a channel estimator. Excellent symbol error rate (SER)/effective signal-to-interference plus noise ratio (SINR) performance is shown despite the presence of substantial channel depolarization. The scheme can be used to extend the capacity of any cellular system that uses uni-polarized antennas and can be extended and applied to MIMO arrays as well.