Cellular communications systems and methods using mobility-characterized registration districts

• US 6,198,927 B1
• Filed: 04/04/1997
• Issued: 03/06/2001
• Est. Priority Date: 04/04/1997
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Chapman, Randy G., Wright, Andrew S.
• Primary Examiner(s): To, Doris H.
• Assistant Examiner(s): Kincaid, Lester G.
• Application Number:
  US08/833,335
• Time in Patent Office: 1,432 Days
• Field of Search: 455/441, 455/443, 455/444, 455/435, 455/432, 455/426, 455/433, 455/434, 455/458, 455/486, 455/422, 455/446
• US Class Current: 455/435.1
• CPC Class Codes: H04W 48/08 Access restriction or access information delivery, e.g. discovery data delivery signalling during connection H04W76/00
• CPC Class Codes: H04W 60/00 Affiliation to network, e.g. registration; Terminating affiliation with the network, e.g. de-registration
• CPC Class Codes: H04W 68/00 User notification, e.g. alerting and paging, for incoming communication, change of service or the like

Abstract

Subscriber units are tracked in a cellular communications system including a plurality of cells which communicate with subscriber units. A cell type is assigned to each cell according to a mobility characteristic of a subscriber unit population of the cell. Each cell is associated with at least one of a plurality of districts based on the cell type of the cell, such that each of the plurality of districts may be characterized according to a mobility characteristic of a subscriber unit population of the district. A subscriber unit is registered with one of the plurality of the districts according to the mobility of the subscriber unit. According to preferred method aspects of the invention, at least one district is defined for each cell, each district having a geographical extent with respect to the cell location of the cell, to thereby associate each cell with at least one district. A respective cell identification message is broadcast in a respective one of said plurality of cells, the cell identification message for a cell identifying the cell location of the cell, the geographical extent of the least one district to which the cell is assigned and a cell type representing a mobility characteristic of a subscriber unit population of the cell. A cell identification message is received at a subscriber unit, and the subscriber unit is registered with one of the districts according to the cell type, the cell location and the district geographical extent identified in the received cell identification message.

Claims

1. A method of tracking subscriber units in a cellular communications system including a plurality of cells, each cell having a cell location, the method comprising the steps of:

defining at least one district for each cell, each district having a geographical extent with respect to the cell location of the cell, to thereby associate each cell with at least one district;

broadcasting a respective cell identification message in a respective one of the plurality of cells, the cell identification message for a cell identifying the cell location of the cell, the geographical extent, with respect to the cell location, of the least one district to which the cell is assigned and a cell type representing a mobility characteristic of a subscriber unit population typically located in the cell;

receiving a cell identification message at a subscriber unit; and

registering the subscriber unit with one of the districts according to the cell type, the cell location and the district geographical extent identified in the received cell identification message.

2. A method according to claim 1:

wherein said step of receiving comprises the step of receiving a first cell identification message identifying a first cell having a first cell location and associated with a first district;

wherein said step of registering comprises the step of registering the subscriber unit with the first district in response to receipt of the first cell identification message;

wherein said step of receiving further comprises the step of receiving a second cell identification message identifying a second cell having a cell location outside of the geographical extent of the first district while the subscriber unit is registered with the first district; and

wherein said step of registering further comprises the step of registering a subscriber unit with the second district in response to receipt of the second cell identification message.

3. A method according to claim 1:

wherein said step of receiving a cell identification message comprises the step of receiving a first cell identification message identifying a first cell having a first cell location and associated with a first district;

wherein said step of registering comprises the step of registering the subscriber unit with the first district in response to receipt of the first cell identification message;

wherein said step of receiving a cell identification message further comprises the step of receiving a second cell identification message identifying a second cell having a cell location within the first geographical extent of the first district while the subscriber unit is registered with the first district; and

wherein said step of registering further comprises the step of continuing registration with the first district in response to receipt of the second cell identification message.

4. A method according to claim 1, wherein the plurality of cells comprises cells of a first cell type characterized as typically having a subscriber unit population located therein dominated by subscriber units of a first aggregate mobility and cells of a second cell type characterized as typically having a subscriber unit population located therein including a subpopulation of subscriber units of a second aggregate mobility higher than the first aggregate mobility, and;

wherein said step of defining a district for each cell comprises the step of defining districts of a first district type for cells of the first and second cell types, and defining districts of a second district type for cells of the second cell type, such that districts of the first type encompass cell locations of at least one of a cell of the first cell type and a cell of the second cell types while districts of the second type encompass cell locations of cells of the second cell type; and

wherein said step of registering comprises the step of registering the subscriber unit with one of a district of the first district type and a district of the second type according to the cell type identified in the received cell identification message.

5. A method according to claim 4:

wherein said step of receiving comprises the step of receiving a first cell identification message identifying a first cell having a cell location having a first district of the first district type associated therewith;

wherein said step of registering comprises the step of registering the subscriber unit with the first district in response to receipt of the first cell identification message;

wherein said step of receiving further comprises the step of receiving a cell identification message while the subscriber unit is registered with the first district; and

wherein said step of registering further comprises one of the steps of;

registering with a new district of the second district type in response to receipt, within a predetermined time interval, of a predetermined number of cell identification messages identifying cells of the second type having the new district associated therewith;

registering with a new district of the first district type in response to receipt of a cell identification message identifying a cell having a cell location outside of the geographical extent of the first district and having the new district associated therewith; and

continuing registration with the first district in response to receipt of a cell identification message identifying a cell having a cell location within the geographical extent of the first district.

6. A method according to claim 4:

wherein said step of receiving comprises the step of receiving a first cell identification message identifying a first cell having a first district of the second district type associated therewith;

wherein said step of registering comprises the step of registering with the first district in response to receipt of the first cell identification message;

wherein said step of receiving further comprises the step of receiving a cell identification message while the subscriber unit is registered with the first district; and

wherein said step of registering further comprises one of the following steps;

registering with a new district of the first district type in response to receipt of a cell identification message identifying a cell of the first cell type having a cell location outside of the geographical extent of the first district;

registering with a new district of the second district type in response to receipt of a cell identification message identifying a cell of the second cell type having a cell location outside of the geographical extent of the first district;

registering with the second district of the first type in response to failing to receive, within a predetermined time interval, a cell identification message identifying a new cell of the second cell type having a cell location within the geographical extent of the first district of the second type; and

continuing registration with the first district of the second type in response to receipt, within the predetermined time interval, of a cell identification message identifying a new cell of the second type having a cell location within the geographical extent of the first district of the second type.

7. A method according to claim 4, wherein said step of defining comprises the step of defining a district of the first district type for cells of the first and second cell types.

8. A method according to claim 4, wherein said step of defining comprises the step of defining districts of the second type only for cells of the second cell type.

9. A method according to claim 4, wherein said step of defining comprises the step of defining a district of the first type to a cell such that the district has a geographic extent which encompasses cell locations of cells which surround the cell.

10. A method according to claim 4 wherein said step of defining comprises the step of defining a district of the first district type for cells of the second cell type such that the geographic extent of the district substantially coincides with a transportation corridor.

11. A method according to claim 1, wherein said step of registering comprises the steps of:

communicating a location update message from the subscriber unit to a base station serving a cell identified in the received cell identification message, the location update message identifying the subscriber unit and the district type with which the subscriber unit is to be registered; and

associating the subscriber unit with a district identified in the cell identification message having the district type identified in the location update message to thereby register the subscriber unit with the district.

12. A method according to claim 1:

wherein said step of defining districts is preceded by the steps of;

defining a geographic region served by the cellular communications system in terms of a coordinate reference frame; and

defining the cell location of each cell in terms of the coordinate reference frame; and

wherein said step of defining at least one district comprises the step of defining at least one district for each cell, the district having a geographic extent represented in terms of a plurality of offsets with respect from the cell location in terms of the coordinate reference frame.

13. A method according to claim 12, wherein said step of defining a geographic region in terms of a coordinate reference frame comprises the step of defining the geographic area in terms of a coordinate reference frame which deviates from rectangularity according to a predetermined warping.

14. A method according to claim 1, wherein said step of registering is followed by the step of:

broadcasting a paging message in cells having locations within the district with which the subscriber is registered.

15. A method according to claim 14, wherein said step of broadcasting a paging message is followed by the steps of:

receiving the paging message at the subscriber unit;

acknowledging the paging message to a base station serving one cell associated with the district with which the subscriber unit is registered, from the subscriber unit; and

routing a message addressed to the subscriber unit through a base station serving the one cell.

16. A cellular communications system, the system comprising:

a subscriber unit;

a plurality of cells, each cell having a cell location;

district defining means for defining at least one district for each cell, each district having a geographical extent with respect to the cell location of the cell, to thereby associate each cell with at least one district;

cell identification message broadcasting means, responsive to said district defining means, for broadcasting a respective cell identification message in a respective one of said plurality of cells, the cell identification message for a cell identifying the cell location of the cell, the geographical extent, with respect to the cell location, of the least one district to which the cell is assigned and a cell type representing a mobility characteristic of a subscriber unit population typically located in the cell;

cell identification message receiving means, located at the subscriber unit, for receiving a cell identification message; and

subscriber unit registering means, responsive to the cell identification receiving means, for registering the subscriber unit with one of the districts according to the cell type, the cell location and the district geographical extent identified in the received cell identification message.

17. A system according to claim 16 wherein said subscriber unit registering means comprises:

means for registering the subscriber unit with a first district in response to receipt of a first cell identification message identifying a first cell having a first cell location and associated with a first district and for registering the subscriber unit with a second district in response to receipt, while the subscriber unit is registered with the first district, of a second cell identification message identifying a second cell having a cell location outside of the geographical extent of the first district.

18. A system according to claim 16 wherein said subscriber unit registering means further comprises:

means for registering the subscriber unit with a first district in response to receipt of a first cell identification message identifying a first cell having a first cell location and associated with a first district and for continuing registration of the subscriber unit with the first district in response to receipt, while the subscriber unit is registered with the first district, of a second cell identification message identifying a second cell having a cell location within the geographical extent of the first district.

19. A system according to claim 16:

wherein said plurality of cells comprises cells of a first cell type characterized as typically having a subscriber unit population located therein dominated by subscriber units of a first aggregate mobility and cells of a second cell type characterized as typically having a subscriber unit population located therein including a subpopulation of subscriber units of a second aggregate mobility higher than the first mobility;

wherein said district defining means comprises means for defining districts of a first district type for cells of the first and second cell types and for defining a districts of a second district type only for cells of the second cell type, such that districts of the first type encompass cell locations of at least one of a cell of the first cell type and a cell of the second cell types while districts of the second type encompass cell locations of cells of the second cell type; and

wherein said subscriber unit registering means comprises means for registering the subscriber unit with one of a district of the first district type and a district of the second district type according to the cell type identified in the received cell identification message.

20. A system according to claim 19 wherein said subscriber unit registering means comprises:

means for registering the subscriber unit with a first district of the first district type in response to receipt of a first cell identification message identifying a first cell having a cell location and the first district associated therewith;

means for registering with a new district of the second district type in response to receipt, while the subscriber unit is registered with the first district, of a predetermined number of cell identification messages identifying cells of the second type having the new district associated therewith, within a predetermined time interval;

means for registering with a new district of the first district type in response to receipt, while the subscriber unit is registered with the first district, of a cell identification message identifying a cell having a cell location outside of the geographical extent of the first district of the first type and having the new district associated therewith; and

means for continuing registration with the first district in response to receipt, while the subscriber is registered with the first district, of a cell identification message identifying a cell having a cell location within the geographical extent of the first district.

21. A system according to claim 20:

wherein said subscriber unit registering means comprises means for registering the subscriber unit with a first district of the second district type, in response to receipt of a first cell identification message identifying a first cell having the first district associated therewith;

means for registering with a new district of the first district type in response to receipt, while the subscriber unit is registered with the first district, of a cell identification message identifying a cell of the first cell type having a cell location outside of the geographical extent of the first district;

means for registering with a new district of the second district type in response to receipt, while the subscriber unit is registered with the first district, of a cell identification message identifying a cell of the second cell type having a cell location outside of the geographical extent of the first district;

means for registering with a new district of the first type in response to failure to receive, during a predetermined time interval while the subscriber unit is registered with the first district, a cell identification message identifying a new cell of the second cell type having a cell location within the geographical extent of the first district; and

means for continuing registration with the first district in response to receipt, within the predetermined time interval, of a cell identification message identifying a second cell of the second type having a cell location within the geographical extent of the first district.

22. A system according to claim 19, wherein said district defining means comprises means for defining said districts of the first district type for cells of the first and second cell types.

23. A system according to claim 19, wherein said district defining means comprises means for defining said districts of second type only for cells of the second cell type.

24. A system according to claim 19, wherein said district defining means comprises means for defining said districts of the first district type for each respective cell such that the district associated with a respective cell has a geographic extent which encompasses cell locations of cells which surround the cell.

25. A system according to claim 19 wherein said step of defining comprises the step of defining a district of the first district type for cells of the second cell type such that the geographic extent of the district substantially coincides with a transportation corridor.

26. A system according to claim 19:

paging message receiving means, responsive to said paging message broadcasting means, for receiving the paging message at the subscriber unit;

paging message acknowledgment means, responsive to said paging message receiving means, for acknowledging the paging message to a base station serving one cell associated with the district with which the subscriber unit is registered, from the subscriber unit; and

means, responsive to said paging message acknowledgment means, for routing a message addressed to the subscriber unit through a base station serving the one cell.

27. A system according to claim 16, wherein subscriber unit registering means comprises:

location update message communicating means for communicating a location update message from the subscriber unit to a base station serving a cell identified in the received cell identification message, the location update message identifying the subscriber unit and the district type with which the subscriber unit is to be registered; and

means, responsive to said location update message communicating means, for associating the subscriber unit with a district identified in the cell identification message having the district type identified in the location update message to thereby register the subscriber unit with the district.

28. A system according to claim 16, further comprising:

means for defining a geographic region served by the cellular communications system in terms of a coordinate reference frame; and

means for defining the cell location of each cell in terms of the coordinate reference frame; and

wherein said district defining means comprises means for defining at least one district for each cell, the district having a geographic extent represented in terms of a plurality of offsets with respect from the cell location in terms of the coordinate reference frame.

29. A system according to claim 28, wherein said means for defining a geographic region in terms of a coordinate reference frame comprises means for defining the geographic area in terms of a coordinate reference frame which deviates from rectangularity according to a predetermined warping.

30. A system according to claim 16, further comprising:

paging message broadcasting means for broadcasting a paging message for the subscriber unit in cells having locations within the district with which the subscriber is registered.

31. A subscriber unit for communicating with a cellular communications system including a plurality of cells, each cell having a cell location and associated with at least one district, the cellular communications system broadcasting a respective cell identification message in a respective one of the plurality of cells, the cell identification message for a cell identifying the cell location of the cell, the geographical extent, with respect to the cell location, of at least one district with which the cell is associated and a cell type representing a mobility characteristic of a subscriber unit population typically located in the cell, the subscriber unit comprising:

cell identification message receiving means for receiving a cell identification message; and

location update message transmitting means, responsive to said cell identification message receiving means, for transmitting a location update message identifying the subscriber unit and a district type with which the subscriber unit is to be identified according to the cell type, the cell location and the district geographical extent identified in the received cell identification message, to thereby register the subscriber unit with the district identified in the location update message.

32. A system according to claim 31 wherein said location update message transmitting means comprises:

means for transmitting a first location update message which registers the subscriber unit with a first district in response to receipt of a first cell identification message identifying a first cell having a first cell location and associated with the first district; and

means for transmitting a second location update message which registers the subscriber unit with a second district in response to receipt, while the subscriber unit is registered with the first district, of a second cell identification message identifying a second cell associated with the second district and having a cell location outside of the geographical extent of the first district.

33. A subscriber unit according to claim 31, wherein the plurality of cells includes cells of a first cell type characterized as typically having a subscriber unit population located therein dominated by subscriber units of a first aggregate mobility and cells of a second cell type characterized as typically having a subscriber unit population located therein including a subpopulation of subscriber units of the first aggregate mobility and a subpopulation of subscriber units of a second aggregate mobility higher than the first mobility, wherein the cellular communications system includes districts of a first district type associated with cells of the first and second cell types and districts of a second district type associated only with cells of the second cell type, such that districts of the first type encompass cell locations of at least one of a cell of the first cell type and a cell of the second cell types while districts of the second type encompass cell locations of cells of the second cell type, and wherein said location update transmitting means comprises:

means for transmitting a location update message identifying one of the first and second district types according to the cell type identified in the received cell identification message.

34. A subscriber unit according to claim 33 wherein said location update message transmitting means comprises:

means for transmitting a location update message which registers the subscriber unit with a first district of the first district type in response to receipt of a first cell identification message identifying a first cell having a cell location and the first district associated therewith;

means for transmitting a location update message which registers the subscriber unit with a new district of the second district type in response to receipt, while the subscriber unit is registered with the first district, of a predetermined number of cell identification messages identifying cells of the second type having the new district associated therewith, within a predetermined time interval;

means for transmitting a location update message which registers the subscriber unit with a new district of the first district type in response to receipt, while the subscriber unit is registered with the first district, of a cell identification message identifying a cell having a cell location outside of the geographical extent of the first district of the first type and having the new district associated therewith; and

means for transmitting a location update message which registers the subscriber unit with the first district in response to receipt, while the subscriber is registered with the first district, of a cell identification message identifying a cell having a cell location within the geographical extent of the first district.

35. A subscriber unit according to claim 33, wherein said location update message transmitting means comprises:

means for transmitting a location update message which registers the subscriber unit with a first district of the second district type, in response to receipt of a first cell identification message identifying a first cell having the first district associated therewith;

means for transmitting a location update message which registers the subscriber unit with a new district of the first district type in response to receipt, while the subscriber unit is registered with the first district, of a cell identification message identifying a cell of the first cell type having a cell location outside of the geographical extent of the first district;

means for transmitting a location update message which registers the subscriber unit with a new district of the second district type in response to receipt, while the subscriber unit is registered with the first district, of a cell identification message identifying a cell of the second cell type having a cell location outside of the geographical extent of the first district;

means for transmitting a location update message which registers the subscriber unit with a new district of the first type in response to failure to receive, during a predetermined time interval while the subscriber unit is registered with the first district, a cell identification message identifying a new cell of the second cell type having a cell location within the geographical extent of the first district; and

means for transmitting a location update message which registers the subscriber unit with the first district in response to receipt, within the predetermined time interval, of a cell identification message identifying a second cell of the second type having a cell location within the geographical extent of the first district.