Patent ID: 6075808
Filing Date: 2000-06-13
Classification: H04B,H04J

Abstract:
A radio communications system comprising:a multiplexer circuit for producing a plurality of quadrature-modulated spread spectrum information-bearing signals using quadrature carriers of single frequency and a plurality of spreading codes, and combining the quadrature-modulated spread spectrum information-bearing signals to produce a code division multiplex signal, there being a predetermined inter-signal time delay between said quadrature-modulated spread spectrum information-bearing signals;a transmitter for up-converting the code division multiplex signal to a radio-frequency signal;a transmit antenna for transmitting the radio-frequency signal;a receive antenna for receiving the transmitted signal;a receiver for down-converting the received signal to recover said code division multiplex signal;a demultiplexer circuit for converting a plurality of quadrature-modulated component signals contained in the recovered multiplex signal to a plurality of information-bearing signals using quadrature carriers of said single frequency and a plurality of despreading codes respectively identical to the spreading codes;a first combiner for combining said plurality of information-bearing signals into a combined information-bearing signal;a delay line having a plurality of successive taps for receiving the combined information-bearing signal, the delay time between the successive taps corresponding to said predetermined inter-signal time delay;a plurality of complex multipliers for respectively weighting tap signals from the taps of the delay line by complex weighting factors;a second combiner for combining the weighted tap signals to produce a combined weighted signal;an adaptive equalizer for producing a decision output from the combined weighted signal; anda plurality of correlation detectors for respectively deriving said plurality of complex weighting factors from correlations between the decision output of the adaptive equalizer and a plurality of delayed versions of tap signals at the taps of the delay line, one of the delayed versions being time coincident with said decision output.