Transmission considerations for polarization-smart antennas

Field trials in the wireless 1900 MHz band revealed that the averaged-in-time polarization measurements of the received wave is copolarized with the original transmitted polarization of the wave, and is highly correlated over a substantial frequency bandwidth. The polarization smart-antenna transmitter is realized at the base transceiver-station (BTS), and is based on the above trial results. In performing the polarization matching algorithm, the appropriate transmit polarization is matched to the averaged receive polarization, for each individual radio link (i.e. per each mobile station-MS), and is maintained dynamically. This recovers a substantial part of the polarization shadow link losses, and serves to reduce the forward power control variation and the average transmit power of the base station, as well as the induced self-interference. This paper discusses several BTS transmission architectures for the implementation of polarization-matching and presents quantitative power overloading, power efficiency and relative interference performance results per each configuration. Finally, an optimal architecture is presented for a multi-user polarization smart-antenna transmitter.