Creation of overlapping cells when using multi casting

• US 6,449,482 B1
• Filed: 05/24/1995
• Issued: 09/10/2002
• Est. Priority Date: 05/24/1995
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Andersson, Håkan, Persson, Håkan, Johansson, Bo Christer Vilhelm
• Primary Examiner(s): Kincaid, Lester G.
• Application Number:
  US08/448,854
• Time in Patent Office: 2,666 Days
• Field of Search: 455/33.1, 455/33.3, 455/33.4, 455/53.1, 455/54.1, 455/56.1, 455/14, 455/15, 455/19, 455/33.2, 455/443, 455/422, 455/426, 455/502, 455/503
• US Class Current: 455/443
• CPC Class Codes: H04W 16/12 Fixed resource partitioning
• CPC Class Codes: H04W 16/32 Hierarchical cell structures
• CPC Class Codes: H04W 36/32 by location or mobility data, e.g. speed data
• CPC Class Codes: H04W 36/326 by proximity to another entity

Abstract

A method and apparatus for providing handoffs in a cellular communication system is disclosed wherein cells within the communication system share at least one transceiver unit or transceiver units from different cells are placed in close proximity to each other so as to create a larger overlapping region in which mobile stations can be handed off. The shared transceiver unit is able to transmit and receive radio signals with the communication frequencies assigned to the cells sharing the transceiver unit.

Claims

1. A mobile telecommunication system comprising:

a plurality of cells, each cell being assigned at least one communication frequency containing a plurality of transceiver units and at least one base station for transmitting and receiving radio signals on said at least one frequency, wherein neighboring cells share at least one transceiver unit to create an overlapping region, said shared transceiver unit being able to transmit and receive radio signals on communication frequencies assigned to the cells which are sharing the shared transceiver unit; and

at least one base station controller for controlling the operation of said base stations and connecting said mobile telecommunication system to another communication system.

2. A mobile telecommunication system according to claim 1, wherein transceiver units in different regions of a cell transmit signals using different transmission powers.

3. A mobile telecommunication system according to claim 2, wherein transceiver units located near a cell border transmit signals using a lower transmission power than other transceiver units in the cell.

4. A mobile telecommunication system according to claim 1, wherein transceiver units in different regions offset the signal strength of received signals by an offset value.

5. A mobile telecommunication system according to claim 4, wherein transceiver units located near a cell border subtract the offset value from the signal strength of received signals.

6. A method for handing over a call in a mobile telecommunication system, said mobile telecommunication system being divided into a plurality of cells, each cell having a plurality of transceiver means, wherein neighboring cells share at least one of said transceiver means to create an overlapping region, said shared transceiver means being able to transmit and receive radio signals on frequencies assigned to the cells sharing the transceiver means, said method comprising the steps of:

receiving at a mobile station a list of frequencies used by neighboring cell;

periodically broadcasting from each transceiver means within each cell a base station identification code which is unique for each cell within a defined area, wherein said shared transceiver means broadcasts the identification codes for the cells sharing the transceiver means;

measuring signal strength of signals received from neighboring cells at the mobile station;

decoding said base station identification codes at the mobile station;

reporting any decoded identification codes and signal strength measurements for a neighboring cell identified by the decoded base station identification code to a base station controller;

determining when the mobile station should be handed over to a second cell based on said signal strength measurements; and

handing over the mobile station to said second cell.

7. A method according to claim 6, wherein transceiver means in different regions of a cell transmit signal using different transmission powers.

8. A method according to claim 7, wherein transceiver means located near a cell border transmit signals using a lower transmission power than other transceiver means in the cell.

9. A mobile telecommunication system comprising:

a plurality of cells, each cell being assigned at least one communication frequency and containing a plurality of transceiver units and at least one base station for transmitting and receiving radio signals on said at least one frequency to a plurality of mobile stations, wherein at least one transceiver units of a first cell is placed in close proximity to at least one transceiver units of a neighboring cell to create an overlapping region; and

at least one base station controller for controlling the operation of said base stations in connecting said mobile telecommunication system to another communication system.

10. A mobile telecommunication system according to claim 9, wherein transceiver units in different regions of a cell transmit signals using different transmission powers.

11. A mobile telecommunication system according to claim 10, wherein transceiver units located near a cell border transmit signals using a lower transmission power than other transceiver units in the cell.

12. A mobile telecommunication system according to claim 9, wherein transceiver units in different regions offset the signal strength of received signals by an offset value.

13. A mobile telecommunication system according to claim 12, wherein transceiver units located near a cell border subtract the offset value from the signal strength of received signals.

14. A method for handing over a call in a mobile telecommunication system, said cellular system being divided into a plurality of cells, each cell having a plurality of transceiver means, wherein at least one transceiver means of a first cell is placed in close proximity to at least one transceiver means of a neighboring cell to create an overlapping region, said method comprising the steps of:

receiving at a mobile station a list of frequencies used by neighboring cells;

broadcasting from each transceiver means within each cell a base station identification code which is unique for each cell within a defined area;

measuring signal strength of signals received from neighboring cells at the mobile station;

decoding said base station identification codes at the mobile station;

reporting any decoded identification codes and signal strength measurements for a neighboring cell identified by the decoded base station identification code to a base station controller;

determining when the mobile station should be handed over to a second cell based on said signal strength measurements; and

handing over the mobile station to said second cell.

15. A method according to claim 14, wherein transceiver means in different regions of a cell transmit signals using different transmission powers.

16. A method according to claim 15, wherein transceiver means located near a cell border transmit signals using a lower transmission power than other transceiver means in the cell.

17. A method for handing over a call in a mobile telecommunication system, said mobile telecommunication system being divided into a plurality of cells, each cell having a plurality of transceiver means, wherein neighboring cells share at least one of said transceiver means to create an overlapping region, said shared transceiver means being able to transmit and receive radio signals on frequencies assigned to the cells sharing the transceiver means, said method comprising the steps of:

periodically broadcasting control signals from each transceiver means within each cell, wherein said shared transceiver means broadcast control signals of the cells sharing the transceiver means;

measuring signal strength of control signals received at a mobile station;

reporting said signal strength measurements to a base station controller;

determining when the mobile station should be handed off to a second cell based on the signal strength measurements; and

handing over the mobile station to the second cell.

18. A method according to claim 17, wherein transceiver means in different regions of a cell transmit signals using different transmission powers.

19. A method according to claim 18, wherein transceiver means located near a cell border transmit signals using a lower transmission power than other transceiver means in the cell.

20. A method for handing over a call in a mobile telecommunication system, said mobile telecommunication system being divided into a plurality of cells, each cell having a plurality of transceiver means, wherein at least one transceiver means of a first cell is placed in close proximity to at least one transceiver means of a neighboring cell to create an overlapping region, said method comprising the steps of:

periodically broadcasting control signals from each transceiver means within each cell;

measuring signal strength of control signals received at a mobile station;

reporting said signal strength measurements to a base station controller;

determining when the mobile station should be handed off to a second cell based on the signal strength measurements; and

handing over the mobile station to the second cell.

21. A method according to claim 20, wherein transceiver means in different regions of a cell transmit signals using different transmission powers.

22. A method according to claim 21, wherein transceiver means located near a cell border transmit signals using a lower transmission power than other transceiver means in the cell.

23. A method for handing over a call in a mobile telecommunication system, said mobile telecommunication system being divided into a plurality of cells, each cell having a plurality of transceiver means, wherein neighboring cells share at least one of said transceiver means to create an overlapping region, said shared transceiver means being able to transmit and receive radio signals on frequencies assigned to the cells sharing the transceiver means, said method comprising the steps of:

periodically broadcasting control signals from each transceiver means within each cell, wherein said shared transceiver means broadcast control signals of the cells sharing the transceiver means;

measuring signal strength of control signals received at a mobile station;

evaluating whether the mobile station should be handed off to a second cell using a handover algorithm and said signal strength measurements at said mobile station;

reporting a handover request to a base station controller based upon said evaluation;

determining whether the handover request should be granted based upon system information; and

handing over the mobile station to the second cell when the handover request is granted.

24. A method according to claim 23, wherein system information comprises the type and capacity of the second cell to handle the call.

25. A method according to claim 24, wherein said signal strength measurements are reported to the base station controller with said handover request.

26. A method according to claim 24, wherein transceiver means in different regions of a cell transmit signals using different transmission powers.

27. A method according to claim 24, wherein transceiver means located near a cell border transmit signals using a lower transmission power than other transceiver means in the cell.

28. A method for handing over a call in a mobile telecommunication system, said mobile telecommunication system being divided into a plurality of cells, each cell having a plurality of transceiver means, wherein at least one transceiver means of a first cell is placed in close proximity to at least one transceiver means of a neighboring cell to create an overlapping region, said method comprising the steps of:

periodically broadcasting control signals from each transceiver means within each cell;

measuring signal strength of control signals received at a mobile station;

evaluating whether the mobile station should be handed off to a second cell using a handover algorithm and said signal strength measurements at said mobile station;

reporting a handover request to a base station controller based upon said evaluation;

determining whether the handover request should be granted based upon system information; and

handing over the mobile station to the second cell when the handover request is granted.

29. A method according to claim 28, wherein system information comprises the type and capacity of the second cell to handle the call.

30. A method according to claim 28, wherein said signal strength measurements are reported to the base station controller with said handover request.

31. A method according to claim 28, wherein transceiver means in different regions offset the signal strength of received signals by an offset value.

32. A method according to claim 28, wherein transceiver means located near a cell border subtract the offset value from the signal strength of received signals.