Cellular communication system sharing control channels between cells to reduce number of control channels

• US 4,723,266 A
• Filed: 01/21/1987
• Issued: 02/02/1988
• Est. Priority Date: 01/21/1987
• Status: Expired due to Term

• Current Assignee: Ericsson GE Mobile Communications Inc (Telefonaktiebolaget LM Ericsson)
• Original Assignee: General Electric Company
• Inventors: Perry, Fred G.
• Primary Examiner(s): Lev, Robert
• Application Number:
  US07/005,999
• Time in Patent Office: 377 Days
• Field of Search: 379/58, 379/59, 379/60, 379/63, 455/33, 455/59
• US Class Current: 455/446
• CPC Class Codes: H04W 16/00 Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
• CPC Class Codes: H04W 16/32 Hierarchical cell structures
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Unnecessary control channels are eliminated in a mature cellular radio telephone RF communications system by sharing control channel transceivers and control channels between original omni-directional cells and subdivisions of those original cells. A control channel is allocated to the original omni-directional cell, and subdivided cell areas are not provided with their own control channels. One or more voice channels are allocated to the original omni-directional cell, and the subdivided cell areas also have voice channels allocated to them. Calls are initiated between mobile transceivers and the original omni-directional cell. Locating receivers associated with the subdivided cell areas determine which subdivisions particular mobile transceivers are located within. Subsequently, calls are handed off fron the original omni cell to an appropriate subdivision.

Claims

1. Apparatus for maintaining control over mobile cellular radio transceivers in a sub-divided cell environment, said apparatus including:

a single shared control channel transceiving means for using a single shared control channel to transceive control signals to mobile transceivers in each of plural sub-divided cells; and

plural discrete locating receivers, a different receiver being used for each of said sub-divided cells.

2. A cellular radio communications system including:

first fixed RF transceiving means for communicating RF signals with mobile RF transceivers located within a first geographical area over a first RF communication channel;

second fixed RF transceiving means for communicating RF signals with mobile RF transceivers located within a second geographical area different from said first area over a second RF communication channel different from said first channel; and

a single fixed RF control signal transmitting means shared by said first and second areas for transmitting RF control signals so as to control said mobile RF transceivers within both said first and second geographical areas.

3. A system as in claim 2 wherein said second area is contained within said first area.

4. A system as in claim 3 wherein the coverage of said control signal transmitting means is substantially equal to the coverage of said first transceiving means.

5. Apparatus for establishing radio communications with a mobile radio transceiver located within a first cell area and also within a smaller area located substantially within said first area, said apparatus comprising:

first RF transceiving means for communicating RF signals over a control channel associated with said first cell area;

further RF transceiving means for communicating RF signals over a voice channel associated with said first cell area;

directional RF transceiving means for communicating RF signals over a further voice channel associated with said smaller cell area;

locating means for determining whether said mobile transceiver is located within said smaller area; and

control means connected to said first and further RF transceiving means, said directional RF transceiving means, and said locating means, for;

(a) controlling said first RF transceiving means to transmit RF signals over said control channel directing said mobile transceiver to tune to said first-mentioned voice channel, and subsequently for (b) controlling said further RF transceiving means to transmit RF signals over said voice channel directing said mobile transceiver to retune to the further voice channel associated with the smaller cell area if said locating means determines said mobile transceiver is located within said smaller area.

6. Apparatus as in claim 5 wherein said locating means includes directional RF locating receiver means, associated with said smaller areas, for determining the location of said mobile transceiver in response to the received amplitude of signals transmitted by said mobile transceiver.

7. A cellular radio frequency communications fixed transceiving station of the type which communicates with a tunable mobile RF transceiver, said station including:

first RF transceiving means for communicating RF signals with mobile RF transceivers located within a first geographical area over a first RF communication channel;

second RF transceiving means for communicating RF signals with mobile RF transceivers located within a second geographical area contained within said first area over a second RF communication channel different from said first channel;

RF control signal transmitting means shared by said first and second areas for transmitting RF control signals to mobile RF transceivers located anywhere within said first area and to mobile RF transceivers located anywhere within said second area; and

controller means connected to said first and second transceiving means and to said control signal transmitting means and programmed to perform the following functions;

(1) control said control signal transmitting means to transmit control signals directing a predetermined mobile transceiver located within said second area to tune to said first RF channel,

(2) control said first RF transceiving means to communicate RF signals with said mobile transceiver over said first channel, said RF signals including control signals directing said mobile transceiver to retune to said second RF channel, and

(3) control said second RF transceiving means to communicate RF signals with said predetermined mobile transceiver over said second RF channel.

8. A cellular radio RF transceiving station including:

first RF transceiving means for communicating RF signals with mobile RF transceivers located within a first predefined geographical area over a first radio frequency communications channel;

second RF transceiving means for communicating RF signals with mobile RF transceivers located within a second predefined geographical area smaller than and contained within said first area over a second radio frequency communications channel different from said first channel;

RF locating receiver means for measuring the amplitudes of RF signals transmitted by mobile RF transceivers located within said second area; and

control signal generating means connected to said RF locating receiver means and said first and second RF transceiving means for controlling said first RF transceiving means to transmit RF control signals over said first radio frequency communications channel directing a mobile RF transceiver within said second area to tune from said first radio frequency communications channel to said second radio frequency communications channel in response to said measured amplitudes.

9. A cellular radio RF transceiving station including:

first RF transceiving means for transmitting RF signals to and receiving RF signals transmitted by mobile RF transceivers located within a first geographical area over a first radio frequency communications channel;

first RF locating receiver means for measuring the amplitude of RF signals transmitted by mobile RF transceivers located within said first area;

second RF transceiving means for transmitting RF signals to and receiving RF signals transmitted by mobile RF transceivers located within a second geographical area larger than and including said first area over a second radio frequency communications channel different from said first channel;

RF control signal transmitting means shared between said first and second areas for transmitting RF control signals over a radio frequency control channel to mobile RF transceivers located within said second area; and

controller means, connected to said first and second transceiving means, said locating receiver means and said transmitting means, for;

controlling said control signal transmitting means to transmit RF control signals over said control channel directing a mobile transceiver located within said second area to communicate RF signals with said second RF transceiving means over said second channel,

controlling said locating receiver means to measure the amplitude of RF signals transmitted by said mobile transceiver,

testing said measured amplitude, and

if said testing reveals said mobile transceiver is within said first area, controlling said second RF transceiving means to transmit RF control signals over said second RF channel directing said mobile transceiver to cease communicating RF signals with said second transceiving means and to begin communicating RF signals with said first transceiving means over said first channel.

10. A cellular radio RF transceiving station including:

first RF transceiving means for transmitting RF signals to and receiving RF signals transmitted by mobile RF transceivers located within a first geographical area over a first radio frequency communications channel;

first RF locating receiver means for measuring the amplitude of RF signals transmitted by mobile RF transceivers;

second RF transceiving means for transmitting RF signals to and receiving RF signals transmitted by mobile RF transceivers located within a second geographical area larger than and including said first area over a second radio frequency communications channel different from said first channel;

RF control signal transmitting means shared between said first and second areas for transmitting RF control signals over a radio frequency control channel to mobile RF transceivers located within said first area and to mobile RF transceivers located within said second area; and

controller means, connected to said first and second transceiving means, said locating receiver means and said transmitting means, for;

setting up a call by controlling said control signal transmitting means to transmit RF control signals over said control channel, said control signals directing a mobile transceiver located within said first area to communicate RF signals with said second transceiving means over said second channel,

controlling said locating receiver means to measure the amplitude of RF signals transmitted by said mobile transceiver,

testing said measured amplitude, and

if said testing reveals said mobile transceiver is within said first area, handing off said call by controlling said second transceiving means to transmit RF control signals over said second channel directing said mobile transceiver to cease communicating RF signals with said second transceiving means and to begin communicating RF signals with said first transceiving means over said first channel.

11. A method for maintaining control over mobile cellular radio transceivers in a sub-divided cell environment, said method comprising the steps of:

using a single shared control channel for communicating control signals to mobile units in each of plural sub-divided cells; and

using a separate locating receiver for determining which of said sub-divided cells mobile transceivers are located within.

12. A process for establishing radio communications with a mobile radio transceiver located within a first cell area and also within a smaller area located substantially within said first area, said process comprising:

(a) transmitting signals with a base transceiver over a control channel associated with said first cell area;

(b) tuning to and monitoring said control channel with said mobile transceiver;

(c) communicating further signals between said base transceiver and said mobile transceiver over said control channel;

(d) retuning said mobile transceiver to a voice channel associated with said first cell area in response to said further signals;

(e) determining if the mobile transceiver is located within said smaller area; and

(f) if said determining step reveals said mobile transceiver is located within said smaller area, retuning said mobile transceiver to a further voice channel associated with said smaller area.

13. A process as in claim 12 wherein said determining step (e) includes the step of measuring the amplitude of signals transmitted by said mobile transceiver with a locating receiver associated with said smaller area.

14. A process as in claim 12 wherein said retuning step includes:

(1) transmitting control signals from said base transceiver to said mobile transceiver over said first-mentioned voice channel, said control signals specifying said further voice channel; and

(2) retuning said mobile transceiver to operate on said further voice channel in response to said control signals transmitted by said transmitting step (1).

15. In a cellular radio communications system, a method of establishing communications with a mobile radio transceiver comprising the steps of:

(1) transmitting first RF control signals over a first predefined coverage area via a RF control channel, said control signals directing said mobile transceiver to tune to a first RF communication channel in response thereto;

(2) receiving RF signals transmitted by said mobile transceiver over said first communication channel with a first transceiver having said first coverage area;

(3) determining, in response to the amplitude of said received signals, whether said mobile transceiver is located within a predefined further coverage area smaller than and contained within said first coverage area; and

(4) if said determining step reveals said mobile transceiver is located within said further coverage area, performing the following steps;

(a) transmitting further RF control signals directing said mobile transceiver to retune to a further RF communication channel different from said first channel, and

(b) transmitting RF signals to said mobile transceiver over said further channel with a further transceiver having said further coverage area.

16. In a cellular radio communications system, a method of controlling the operation of a mobile radio transceiver comprising the steps of:

(1) monitoring the one of plural RF control channels carrying signals with the highest received amplitude;

(2) receiving first RF control signals present on said control channel;

(3) tuning to a first RF communication channel in response to said first control signals;

(4) transmitting RF signals over said first channel to a first fixed transceiver having a first predefined coverage area and/or receiving RF signals transmitted by said first transceiver over said first channel;

(5) receiving further RF control signals present on said first channel if said mobile transceiver is located within a further coverage area smaller than and within said first coverage area;

(6) retuning to a further RF communication channel different from said first channel in response to said received further control signals; and

(7) subsequently to said retuning step (6), transmitting RF signals over said further channel to a further fixed transceiver having said further coverage area and/or receiving RF signals transmitted by said further transceiver over said second channel.

17. In a cellular radio communications system, a method of establishing communications with a mobile radio transceiver comprising the steps of:

(1) monitoring a first RF control channel with said mobile transceiver;

(2) transmitting first RF control signals over said control channel with a RF control channel transmitter having a first coverage area;

(3) tuning said mobile transceiver to a first RF communication channel in response to said first control signals;

(4) transmitting RF signals to said mobile transceiver over said first channel with a first transmitter having approximately said first coverage area;

(5) determining whether said mobile transceiver is located within a predefined further coverage area smaller than and contained within said first coverage area; and

(6) if said determining step reveals said mobile transceiver is located within said further coverage area, performing the following steps;

(a) transmitting further RF control signals over said first RF communication channel,

(b) tuning said mobile transceiver to a further RF communication channel different from said first channel in response to said further control signals, and

(c) transmitting RF signals to said mobile transceiver over said further channel with a further transmitter having said further coverage area.

18. A method of subdividing an omni-directional cell of a cellular radio system, said cell being served by a RF transceiving station, said transceiving station including first RF transceiving means and an associated omni-directional RF antenna for communicating RF signals over a first RF communications channel with mobile RF transceivers located within said omni-directional cell and further including RF control signal transmitting means connected to the same or different omni-directional RF antenna for transmitting RF control signals over a radio frequency control channel to mobile RF transceivers within said cell, said method comprising:

providing a second RF transceiving means and associated directional RF antenna for communicating RF signals with mobile RF transceivers located within a predefined geographical subdivision of said cell smaller than and substantially contained within said cell, said second transceiving means operating on a second radio frequency communications channel different from said first channel;

providing a RF locating receiver means connected to said directional RF antenna for determining whether mobile RF transceivers are located within said subdivision; and

sharing said control signal transmitting means between mobile transceivers within said cell and mobile transceivers within said subdivision.

19. In a cellular radio communications system, a method of establishing communications with a mobile radio transceiver comprising the steps of:

(1) transmitting first RF control signals over a RF control channel;

(2) tuning said mobile transceiver to transmit RF signals over a first RF communication channel in response to said first control signals;

(3) receiving said RF signals transmitted by said mobile transceiver over said first communications channel;

(4) transmitting RF signals to said mobile transceiver over said first channel with a first transmitter having a predefined first coverage area;

(5) determining, in response to the amplitude of said received signals, whether said mobile transceiver is located within a predefined further coverage area smaller than and contained within said first coverage area; and

(6) if said determining step reveals said mobile transceiver is located within said further coverage area, transmitting further RF control signals to said mobile transceiver, retuning said mobile transceiver to transmit RF signals over a further RF communication channel different from said first channel in response to said further control signals, and transmitting RF signals to said mobile transceiver over said further channel with a further transmitter having said further coverage area.