Spread-spectrum channel sounding

  • US 6,269,092 B1
  • Filed: 01/14/1999
  • Issued: 07/31/2001
  • Est. Priority Date: 01/14/1999
  • Status: Expired due to Term
First Claim
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1. An improvement to a spread-spectrum system having a base station and a plurality of remote stations (RS), with said base station (BS) having a BS-spread-spectrum transmitter for transmitting a plurality of BS-spread-spectrum signals at a first frequency and a BS-spread-spectrum receiver for receiving, at a second frequency, a plurality of RS-spread-spectrum signals from said plurality of remote stations, with the plurality of BS-spread-spectrum signals at the first frequency outside a correlation bandwidth of the plurality of RS-spread-spectrum signals at the second frequency, with each of said plurality of remote stations having an RS-spread-spectrum transmitter for transmitting an RS-spread-spectrum signal at the second frequency, the improvement comprising:

  • a BS transmitter, located at said base station, for transmitting a BS-channel-sounding signal at the second frequency, with the BS-channel-sounding signal having a bandwidth no more than twenty per cent of the spread-spectrum bandwidth of the plurality of RS-spread-spectrum signals;

    each of said plurality of remote stations including an RS receiver, for receiving the BS-channel-sounding signal at the second frequency, each RS receiver having, an RS demodulator for tracking the BS-channel-sounding signal, thereby outputting an RS-receiver signal;

    a frequency-adjust circuit, coupled to said RS demodulator and responsive to the RS-receiver signal, for compensating to the second frequency the RS-spread-spectrum signal of said RS-spread-spectrum transmitter located at said remote station;

    each of said plurality of remote stations including an RS-power-level circuit, responsive to the RS-receiver signal, for adjusting an initial RS-power level of said RS-spread-spectrum transmitter located at said remote station; and

    an interference-reduction subsystem, located at said base station and at a front end to said BS-spread-spectrum receiver, for reducing, at the second frequency, the BS-channel-sounding signal from the RS-spread-spectrum signal arriving at said base station.

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