×

Cellular communications system having passive handoff

  • US 5,621,786 A
  • Filed: 08/23/1994
  • Issued: 04/15/1997
  • Est. Priority Date: 09/17/1992
  • Status: Expired due to Term
First Claim
Patent Images

1. A cellular communications system including a cell divided into a plurality of zones, wherein a plurality of telephone signals are transmitted to and received from a plurality of mobile units in the zones using RF transmission, comprising:

  • a cell base station unit connected by transmission means to a plurality of antenna units, at least one antenna unit located in each zone, each antenna unit having an antenna located for broadcast and reception of signals in the associated zone, the base station unit including;

    analog RF signal generation means for generating a plurality of separate RF signals on different channels for carrying telephone signals to mobile units in the cell;

    first switch means responsive to a first control signal for switching and combining the RF signals to form a composite RF signal for each zone, the composite analog signal for each zone containing multiple selected channels;

    analog-to-digital conversion means for convening the composite analog signal for each zone directly to a corresponding digitized stream of samples; and

    means for applying the digitized stream of samples to the transmission means for transmission to each corresponding antenna unit;

    wherein each antenna unit further includes;

    digital-to-analog means for receiving the digitized stream of samples from the base station unit, reconstructing a corresponding composite analog RF signal representing all the multiple selected channels;

    means for amplifying the composite analog RF signal; and

    means for applying the amplified signal to the antenna so that it is broadcast into the zone associated with the antenna unit;

    analog-to-digital means for receiving an RF signal received at the antenna, convening the received RF signal to a digitized stream of samples; and

    means for applying the digitized stream of samples to the transmission means for transmission to the base station unit;

    wherein each base station unit further includes;

    digital-to-analog converter means for receiving the digitized stream of samples from each antenna unit, and reconstructing a single analog RF signal representing multiple channels received at each antenna unit;

    second switch means responsive to a second control signal for selectively combining the analog RF signals from the antenna units to form a plurality of composite analog signals for application to receivers of the base station, each of the composite signals comprising one or more of the RF signals from the antenna units; and

    control means for monitoring the digitized streams of samples from all of the antenna units and digitally analyzing the energy level of each channel in each zone, and in response thereto generating the first and second control signals to selectively control the zones in which each channel is broadcast and the zone from which each channel is received.

View all claims
  • 0 Assignments
Timeline View
Assignment View
    ×
    ×