Importance

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Abstract

A microcellular communications network includes a plurality of base station units and corresponding antenna units. Each includes either conventional transmitters and receivers or all digital transmitter and receiver equipment, and interface circuitry to a mobile telecommunications switching office. The microcell traffic output is applied to a frame generator/multiplexer. The output of the frame generator/multiplexer is applied to a digitally modulated laser and conveyed by fiber to a remote antenna unit, which demultiplexes the microcell traffic signal, applies it to a digital-to-analog converter, and applies it to a power amplifier and a main antenna. The received signals are filtered, digitized, multiplexed together and transmitted over the optical fiber back to the base station. The strongest signal is selected for use. Deployment of an all digital microcellular communications system occurs in two stages. Digital filtering of the digitized RF signal is also provided, and a digital passive handoff system provides for an FFT analysis of all traffic in the cell and passive switching in response thereto.

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First Claim