Method and apparatus for locating a digital control channel in a radiocommunication system

• US 6,058,108 A
• Filed: 10/31/1994
• Issued: 05/02/2000
• Est. Priority Date: 11/01/1993
• Status: Expired due to Term

• Current Assignee: Optis Wireless Technology, LLC (Brevet Capital)
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Raith, Alex Krister, Sawyer, Francois, Henry, Ray
• Primary Examiner(s): Patel, Ajit
• Application Number:
  US08/331,711
• Time in Patent Office: 2,010 Days
• Field of Search: 370/95.1, 370/95.2, 370/95.3, 370/85.7, 370/337, 370/347, 370/328, 455/32.1, 455/33.1, 455/33.2, 455/226.2, 455/33.4, 455/226.3, 455/54.1, 455/54.2, 455/56.1, 455/62, 455/65, 455/422, 455/434, 455/513, 455/59, 455/101, 455/102 , 455/103, 379/59, 379/60, 379/58
• US Class Current: 370/337
• CPC Class Codes: H04B 7/2643 using time-division multiple access [TDMA] H04B7/2615, H04B7/2618 take precedence
• CPC Class Codes: H04B 7/2656 for structure of frame, burst
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 1/0046 Code rate detection or code type detection H04L1/0038 takes precedence; detection of the data rate H04L25/0262; for packet format H04L1/0091
• CPC Class Codes: H04L 1/0056 Systems characterized by the type of code used H04L1/08 takes precedence
• CPC Class Codes: H04L 1/0057 Block codes H04L1/0061, H04L1/0064 take precedence
• CPC Class Codes: H04L 1/0059 Convolutional codes
• CPC Class Codes: H04L 1/0061 Error detection codes
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 1/0072 Error control for data other than payload data, e.g. control data
• CPC Class Codes: H04L 1/0083 Formatting with frames or packets; Protocol or part of protocol for error control
• CPC Class Codes: H04L 1/08 by repeating transmission, e.g. Verdan system H04L1/1858 and H04L1/189 take precedence
• CPC Class Codes: H04L 1/1614 using bitmaps
• CPC Class Codes: H04L 1/1685 the supervisory signal being transmitted in response to a specific request, e.g. to a polling signal
• CPC Class Codes: H04L 1/18 Automatic repetition systems, e.g. Van Duuren systems
• CPC Class Codes: H04L 1/1803 Stop-and-wait protocols
• CPC Class Codes: H04L 1/1809 Selective-repeat protocols
• CPC Class Codes: H04L 1/1848 Time-out mechanisms
• CPC Class Codes: H04L 1/188 Time-out mechanisms
• CPC Class Codes: H04L 1/20 using signal quality detector
• CPC Class Codes: H04L 2001/0093 : Point-to-multipoint
• CPC Class Codes: H04L 9/40 : Network security protocols
• CPC Class Codes: H04W 48/10 : using broadcasted information
• CPC Class Codes: H04W 48/16 : Discovering, processing access restriction or access information
• CPC Class Codes: H04W 48/20 : Selecting an access point
• CPC Class Codes: H04W 52/0212 : managed by the network, e.g. network or access point is master and terminal is slave
• CPC Class Codes: H04W 52/0245 : according to signal strength
• CPC Class Codes: H04W 68/00 : User notification, e.g. alerting and paging, for incoming communication, change of service or the like
• CPC Class Codes: H04W 68/025 : Indirect paging
• CPC Class Codes: H04W 88/02 : Terminal devices
• CPC Class Codes: Y02D 30/70 : in wireless communication networks

Abstract

A method and system for locating control channels, particularly digital control channels, are described. By grouping the channels which are candidates for carrying supervisory messages in blocks indicative of their relative likelihood for being used as control channels, a mobile station can begin its search for a control channel with channels which are most likely to actually be control channels. Placing location information on other channels allows the mobile station to be redirected to a control channel when it reads one of these other channels. Similarly, by placing information describing the location of a control channel in a message associated with handoff, a mobile station avoids the necessity of having to relocate a new control channel associated with the base station to which the mobile has been handed off.

Claims

1. A method for locating a control channel among a plurality of traffic and control channels comprising the steps of:

broadcasting, on a plurality of traffic channels, location information which points toward said control channel;

reading, by a mobile station, one of said plurality of traffic channels to acquire said location information; and

locating, by said mobile station, said control channel using said location information.

2. The method of claim 1, wherein said plurality of traffic channels comprise digital traffic channels.

3. The method of claim 1, wherein said plurality of traffic channels comprise analog traffic channels.

20. The method of claim 1, wherein said step of broadcasting further comprises the step of:

providing, as said location information, a parameter which points to a subset of said plurality of traffic channels.

21. The method of claim 20, further comprising the step of:

ordering channels within said subset of said plurality of traffic channels.

22. The method of claim 21, wherein said step of reading further comprises the step of:

prioritizing a selection of said one of said plurality of traffic channels based upon said step of ordering.

23. The method of claim 1, wherein said step of broadcasting further comprises the step of:

providing a frequency on which said control channel can be found.

40. The method of claim 1, wherein said step of broadcasting further comprises the step of:

including, in each TDMA slot of said plurality of traffic channels, a digital control channel locator (DL) field as said location information.

4. A system for locating a control channel among a plurality of traffic and control channels comprising:

a base station which broadcasts said plurality of channels and includes location information on at least two traffic channels, said location information pointing toward said control channel; and

a mobile station which reads one of said at least two traffic channels to acquire said location information and which then locates said control channel using said location information.

5. The system of claim 4, wherein said at least two of said traffic channels comprise digital traffic channels.

6. The system of claim 4, wherein said at least two of said traffic channels comprise digital traffic channels.

24. The system of claim 4, wherein said base station broadcasts, as said location information, a parameter which points to a subset of said plurality of traffic and control channels.

25. The system of claim 24, wherein said base station orders channels within said subset of said plurality of traffic channels.

26. The system of claim 25, wherein said mobile station prioritizes reading of said subset of said plurality of traffic channels based upon an order created by said base station.

27. The system of claim 4, wherein said base station broadcasts, as said location information, a frequency on which said control channel can be found.

41. The system of claim 4, wherein said base station includes said location information in each TDMA slot of said at least two traffic channels.

7. A base station comprising:

means for transmitting data on a plurality of channels including a control channel and a plurality of traffic channels; and

means for including location information on said plurality of traffic channels, said location information pointing toward said control channel.

8. The base station of claim 7, wherein the plurality of traffic channels comprise digital traffic channels.

9. The base station of claim 7, wherein of the plurality of traffic channels comprise analog traffic channels.

28. The base station of claim 7, wherein said location information includes a parameter which points to a subset of said plurality of channels.

29. The base station of claim 28, wherein said base station further comprises:

means for ordering channels within said subset.

30. The base station of claim 7, wherein said location information includes a frequency on which said at least one of said control channels can be found.

42. The base station of claim 7, wherein said means for including location information includes said location information in each TDMA slot of said at least two traffic channels.

10. A method for transmitting from a base station on traffic channels and a digital control channel comprising the steps of:

providing location information pointing to said digital control channel on at least two of said traffic channels; and

transmitting data, including said location information on said traffic channels, and on said digital control channel over an air interface.

11. The method of claim 10, wherein said at least two of said traffic channels comprise digital traffic channels.

12. The method of claim 10, wherein said at least two of said traffic channels comprise analog traffic channels.

31. The method of claim 10, wherein said location information includes a parameter which points to a subset of said traffic channels.

32. The method of claim 31, further comprising the step of:

ordering channels within said subset.

33. The method of claim 10, wherein said location information includes a frequency on which said digital control channel can be found.

43. The method of claim 10, wherein said step of providing further comprises the step of:

including said location information in each TDMA slot of said at least two of said traffic channels.

13. A mobile station comprising:

means for reading location information pointing to a digital control channel from any one of a plurality of traffic channels which are broadcast over an air interface; and

means for tuning to said digital control channel using said location information.

14. The mobile station of claim 13, wherein said plurality of traffic channels comprise digital traffic channels.

15. The mobile station of claim 13, wherein said plurality of traffic channels comprise analog traffic channels.

16. The mobile station of claim 13, wherein said pluarality of traffic channels comprise analog control channels.

34. The mobile station of claim 13, wherein said location information includes a parameter which points to a subset of said plurality of traffic channels.

35. The mobile station of claim 34, wherein said mobile station further comprises:

means for prioritizing a search for said digital control channel based upon a predetermined order of channels within said subset.

36. The mobile station of claim 13, wherein said location information includes a frequency on which said digital control channel can be found.

44. The mobile station of claim 13, wherein said means for reading is also for reading said location information from any TDMA slot of any one of said plurality of traffic channels.

17. A method for monitoring a digital control channel among a plurality of traffic channels using a mobile station comprising the steps of:

reading any one of said plurality of traffic channels;

acquiring location information pointing to said digital control channel from said any one of said plurality of traffic channels; and

monitoring said digital control channel using said location information.

18. The method of claim 17, wherein said any one of said plurality of traffic channels comprises a digital traffic channel.

19. The method of claim 17, wherein said any one of said plurality of traffic channels comprises an analog traffic channel.

37. The method of claim 17, wherein said location information includes a parameter which points to a subset of said plurality of traffic channels.

38. The method of claim 37, further comprising the step of:

prioritizing a search for said digital control channel based upon a predetermined order of channels within said subset.

39. The method of claim 17, wherein said location information includes a frequency on which said digital control channel can be found.

45. The method of claim 17, wherein said step of acquiring further comprises the step of:

acquiring said location information from any TDMA slot of said any one of said plurality of traffic channels.

46. A method for locating a digital control channel associated with a base station among a plurality of channels comprising the steps of:

broadcasting, on an analog control channel from said base station, location information which points toward said digital control channel;

reading, by a mobile station, said analog control channel; and

locating, by said mobile station, said digital control channel using said location information.

47. A base station comprising:

means for broadcasting data over an analog control channel and a digital control channel; and

means for including location information on said analog control channel pointing toward said digital control channel.

48. A mobile station comprising:

means for reading an analog control channel to obtain location information pointing to a digital control channel; and

means for tuning to said digital control channel using said location information.

49. A method for locating a digital control channel in a radiocommunication system having a plurality of analog and digital communication channels comprising the steps of:

grouping said plurality of channels into a plurality of blocks;

ranking each of said blocks based upon a relative likelihood of finding said digital control channel therein;

reading a channel within a highest ranked one of said blocks;

determining if said channel is a digital channel;

continuing, if said channel is not a digital channel, to read and determine channels in said highest ranked one of said blocks until a digital channel is located; and

identifying, once a digital channel has been located, said digital channel as one of a digital traffic channel and a digital control channel.

50. The method of claim 49, further comprising the steps of:

acquiring, from a read digital traffic channel, location information pointing toward a digital control channel; and

locating said digital control channel using said information.

51. The method of claim 50, wherein said location information comprises a field which identifies a subset of said plurality of analog and digital communication channels within which a digital control channel resides.