US 4,144,496 A · Mobile communication system and method employing frequency reuse within a geographical service area

Abstract

A communication method and system for providing two-way radio communication links between fixed stations and mobile units, particularly suitable for use in mobile telephone communications. A geographical service area is sectionalized through the use of omnidirectional and directional antennas resulting in increased call capacity for a given number of available communication channels. An orderly, cost-effective manner for accommodating service area expansion, a dynamic channel assignment technique for accommodating variations in user density and a technique for maintaining an established call as a mobile unit moves throughout the sectionalized service area are also disclosed.

Claims79

Dependent claims

In a mobile telephone communication system having a plurality of frequency communication channels assigned thereto, and a service area comprising both a service zone essentially centrally located therein and a plurality of remote mobile service zones, apparatus for providing service from the central zone to mobile units throughout the entire mobile telephone service area comprising:

a plurality of transmitters and receivers,
a plurality of essentially co-located directional antennas within said central zone, each of said plurality of antennas being connected to at least one of said plurality of transmitters and receivers and each oriented to broadcast and receive wave energy in a different predetermined sector of the service area extending radially beyond said central zone, thereby creating the plurality of remote mobile service zones, and
an omnidirectional antenna within said central zone, said antenna being connected to one of said plurality of transmitters and receivers to omnidirectionally broadcast and receive wave energy from said one of said plurality of transmitters and receivers within said central zone.

A mobile telephone system comprising:

a plurality of directional antennas each oriented to transmit a wave energy carrier signal in a sector of a service area;
a plurality of transmitters each connected to a different one of said plurality of directional antennas and each selectively controllable in output power level and frequency to broadcast a carrier signal at different frequencies in immediately adjacent sectors;
means for generating an idle channel marker signal;
means for generating a control signal;
and,
circuit means for selectively applying said control signal and said idle channel marker signal to said plurality of transmitters, said idle channel marker signal modulating said carrier signal from each of said transmitters and said control signal controlling the output power level of said transmitters at a first predetermined level to a second predetermined level during the modulation of said carrier signals by said idle channel marker signal, said first predetermined level being substantially reduced relative to a second predetermined level normally employed for communicating after a call is established.

3 more elements

In a mobile telephone communication system, a system for providing broadcast coverage of a mobile telephone service area comprising:

first, second and third base stations each including a plurality of transmitters, each of the base stations being spaced approximately equidistantly from each of the other base stations;
and,
a plurality of directional antennas at each of said base stations, each directional antenna at each base station being connected to at least one of said plurality of transmitters directionally to broadcast wave energy in a sector of the service area, one of said plurality of directional antennas at each base station being operable to broadcast wave energy in substantially the same sector of the service area to thereby provide broadcast coverage of said same sector from each of said first, second and third base stations, the remaining ones of said plurality of directional antennas at each of the base stations being oriented to provide broadcast coverage of other sectors of the service area from each of said first, second and third base stations.

A system for providing communications in a mobile telephone service area comprising:

a plurality of directional antennas at a first location, each directional antenna defining a geographical sector of the service area extending radially outwardly from the first location;
means including a plurality of transmitters, a plurality of receivers, and said directional antennas for defining plural two-way radio communication channels serving each of said sectors individually, at least some of the same radio communication channels serving more than one of said sectors,
means for designating one of said plural two-way communication channels in each of said sectors as a mobile monitoring channel;
a plurality of mobile units each including means for monitoring said designated plural two-way communication channels;
and,
means connected to each of said communication channels defining means and to a wireline telephone system for selectively establishing communications between a mobile unit and either another mobile unit or a fixed telephone over one of said plural two-way radio communication channels serving the sector in which said mobile unit is monitoring a designated channel.

3 more elements

A system for providing continuity of communications over a plurality of dual frequency communication channels comprising:

a plurality of base stations spaced throughout a service area, each base station including an array of directional antennas directionally defining a plurality of sectors of the service area extending radially outwardly from said base stations;
means for establishing a call between a fixed communication unit and a mobile communication unit over an available one of said dual frequency communication channels through one of said base stations,
means connected to said array of directional antennas at said one of said base stations for monitoring the signal strength of transmissions from said mobile unit engaged in said established call received over a first one of said directional antennas defining a first one of said sectors designated as a home sector;
means connected to said monitoring means for detecting a drop in monitored signal strength received over said first one of said directional antennas below a predetermined threshold;
means connected to said directional antennas and responsive to said detecting means for monitoring and comparing the signal strength of said transmissions from said mobile unit engaged in said established call received over only three of said directional antennas defining three monitoring sectors, the three monitoring sectors being adjacent to and surrounding said first one of said sectors, two of said three directional antennas defining said three monitoring sectors being at said one of said base stations and the third of said three directional antennas being at another of said base stations;
and,
means responsive to said comparing means for designating one of said three monitoring sectors as a new home sector.

4 more elements

In a mobile telephone communication system having a plurality of frequency communication channels assigned thereto, a service area including a plurality of mobile service sectors, and apparatus for providing service to mobile units throughout the entire mobile telephone service area, comprising:

a plurality of transmitters and receivers,
a plurality of essentially co-located directional antennas at a given location, each of said plurality of antennas being connected to at least one of said plurality of transmitters and receivers and each oriented to broadcast as well as receive wave energy in a different predetermined sector of the service area extending radially beyond said given location, thereby creating a plurality of mobile service sectors.
the frequencies broadcast from first alternate sectors created around said co-located directional antennas being different from the frequencies broadcast from the second alternate or intervening sectors of said antennas, with the latter sectors serving as buffers between the first alternate sectors, and thus permitting non-interfering reuse of frequencies within the entire service area.

In a mobile communication system having a plurality of dual frequency communication channels assigned thereto, apparatus for providing broadcast service from a central location to mobile unit throughout a mobile communication service area comprising:

a plurality of transmitters at a central location;
a plurality of essentially co-located directional atennas at the central locations;
and,
means connecting each of said plurality of antennas to at least one of said plurality of tranmitters;
a plurality of antennas being oriented to broadcast wave energy in predetermined respective sectors of the mobile telephone service area extending radially outwardly from the central location, so as to define a plurality of directionally separate broadcast sectors of the service area;
said connected transmitters being tuned so as to broadcast wave energy in adjacent of said broadcast sectors at differing frequencies and to broadcast wave energy in at least some of the sectors at the same frequency, whereby different communication channels serve adjacent of said broadcast sectors and the same communication channel serves more than one of said broadcast sectors.

3 more elements

Dependencies are inferred from the claim text.

Mobile communication system and method employing frequency reuse within a geographical service area

Life of this patent

Mobile communication system and method employing frequency reuse within a geographical service area

Life of this patent

Abstract

Claims79