Wireless communications using near field coupling

• US 5,437,057 A
• Filed: 12/03/1992
• Issued: 07/25/1995
• Est. Priority Date: 12/03/1992
• Status: Expired due to Term

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Butcher, Lawrence, Richley, Edward A.
• Primary Examiner(s): Urban, Edward F.
• Assistant Examiner(s): SOBUTKA, PHILIP
• Application Number:
  US07/984,821
• Time in Patent Office: 964 Days
• Field of Search: 455/41, 455/33.1, 455/33.4, 455/53.1, 455/54.1, 455/54.2, 455/56.1, 455/66, 370/85.1, 342/742, 342/867
• US Class Current: 455/41.1
• CPC Class Codes: H04B 5/22 Capacitive coupling
• CPC Class Codes: H04B 5/48 Transceivers

Abstract

Near field coupling is employed for transferring data back and forth between base stations and portable stations in cellular communication systems, such as cellular local area networks.

Claims

1. A near field coupled cellular communication system for providing two-way communication services within a predetermined service area that is composed of a plurality of service cells;

said system comprising

a plurality of stationary base stations that are spatially located within respective ones of said service cells, each of said base stations having an antenna for transmitting output signals and for sensing input signals, with the antenna of each of said base stations has two loops that are physically oriented in quadrature relationship with respect to each other, and with each of said base stations including means for driving the loops of its antenna in phase quadrature to transmit said output signals, and means for combining signals sensed by the loops of its antenna in phase quadrature to sense said input signals;

at least one portable station that is transportable from position-to-position and from cell-to-cell within said service area, each portable station having an antenna for transmitting output signals and for sensing input signals;

said base stations being positioned to cause the antenna of each portable station that is within said service area to be near field coupled to the antenna of at least one of said base stations whenever signals are being transferred in either direction between said portable station and said base station, with the near field coupling of said antennae being sufficiently strong to predominantly govern the transfer of said signals;

said signals being modulated carrier signals, with each of said signals having a carrier that has an angular frequency of approximately ω

radians/sec.; and

every point within said service area is located within a distance of approximately r_secondary =c/ω

of the antenna of at least one of said base stations, where c is the speed of light.

2. The communication system of claim 1 wherein said service area is confined to a building.

3. The communication system of claim 2 wherein said modulated carrier signals have a carrier frequency within a range of 5 MHz-15 MHz.

4. The communication system of claim 3 wherein

said building has a plurality of rooms;

and

at least some of said base stations are located in different rooms.

5. A cellular local area network comprising

a relatively broad bandwidth communication medium for distributing data throughout a predetermined service area;

a plurality of narrower bandwidth, spatially stationary base stations that are linked to said communications medium for transferring data from and to said communications medium;

said base stations being spatially distributed within said service area to define respective service cells;

each of said base stations having an antenna for transmitting and sensing data modulated carrier signals;

at least one portable station that is transportable from location-to-location and from cell-to-cell within said service area;

each portable station having an antenna for transmitting and sensing data modulated carrier signals;

said portable station, while it is anywhere within said service area, having its antenna sufficiently proximate the antenna of at least one of said base stations to achieve near field coupling therebetween whenever signals are being transferred in either direction between said portable station and said one base station, with said near field coupling being sufficiently strong to dominate the transfer of said signals;

each of said base stations being further characterized by the antenna thereof being a dual loop antenna that is composed of first and second antenna loops that are spatially oriented in quadrature relationship with respect to each other;

each of said base stations further including means for driving its first and second antenna loops in phase quadrature when said base station is operating in a transmit mode, and means for combining the signals sensed by its first and second antenna loops in phase quadrature while said base station is operating in a receive mode; and

each portable station being further characterized by the antenna thereof being a loop antenna.

6. The local area network of claim 5 wherein

said service area is located within a building having a plurality of rooms;

and

at least some of said rooms are within different ones of said cells.

7. The local area network of claim 6 wherein

said carrier signals have a carrier frequency of 5 MHz-15 MHz and an angular frequency of ω

;

every point within each of said cells is located within a distance of approximately r_boundary =c/ω

of the antenna of at least one of said base stations, where c is the speed of light.

8. The local area network of claim 7 wherein

each of said cells contains the antenna of a respective one of said base stations, such that said base stations are dedicated to different ones of said cells;

and

every point within each of said cells is located within a distance of approximately r_boundary =c/ω

of the antenna of the base station that is dedicated to that cell and at greater distance from the antenna of each base station that is dedicated to a different cell.