Efficient handling of connections in a mobile communications network

• US 6,507,567 B1
• Filed: 04/09/1999
• Issued: 01/14/2003
• Est. Priority Date: 04/09/1999
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Willars, Per H. A.
• Primary Examiner(s): LE, THANH C
• Application Number:
  US09/288,862
• Time in Patent Office: 1,376 Days
• Field of Search: 455/337, 455/329, 455/342, 455/347, 455/350, 455/503, 455/504, 455/321, 455/422, 455/426, 455/507, 455/517, 455/436, 455/438, 375/355, 375/356
• US Class Current: 370/321
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 76/20 Manipulation of established connections
• CPC Class Codes: H04W 76/30 Connection release

Abstract

Efficient channel switching procedures are provided in a mobile communications system. A first channel is established to support a connection through a radio access network to a mobile station. Subsequently, if the first channel is no longer used to support that connection, a portion of that first channel is nevertheless maintained for a period of time. That way, if the first channel is again needed to support the connection to the mobile station, the maintained portion of the first channel is simply reactivated thereby reducing channel switching costs and delays associated with channel set-up and release operations. The portion of the first channel that is maintained may be associated with resources within the radio access network. Another portion of the first channel, corresponding for example to a radio channel resource supporting the connection between the radio access network and the mobile station, may be released after the first channel is no longer being used to support the connection in order to make that radio channel resource available for other mobile connections.

Claims

1. In a radio communications system including plural mobile stations and a radio network having plural base stations, a method comprising:

(a) initially establishing on a first type of channel a connection with a mobile station including establishing a first path link for the first channel from the radio network to a base station and a second path link for the first channel from the base station to a mobile station;

(b) switching the connection from the first channel to a second channel;

(c) thereafter, re-establishing the connection on the first channel by using at least a portion of the initially established first path link.

2. The method in claim 1, wherein the first and second channels are different types of channels.

3. The method in claim 1, wherein the first channel is a dedicated channel and the second channel is a common channel.

4. The method in claim 1, wherein the re-establishing step (c) further includes:

allocating a new second path link for the first channel to the connection.

5. The method in claim 1, wherein the second path link includes plural radio resources and the re-establishing step (c) further includes:

re-establishing the connection on the first channel by using at least one of the plural radio resources maintained from the initially established second path link and by allocating another new radio resource to the connection.

6. The method in claim 1, wherein the first path link includes plural portions, the re-establishing step (c) including using all of the plural portions initially established.

7. The method in claim 1, wherein for the re-establishing step (c), the initially established first path link is re-activated.

8. The method in claim 1, wherein the plural base stations are connected to a radio network controller, and wherein the first path link includes a first portion associated with a radio network control node, a second portion between the radio network control node and the one base station, and a third portion associated with the base station, and wherein the at least one portion corresponds to any one of the three portions.

9. The method in claim 8, wherein two of the three portions are used in the re-establishing step (c).

10. The method in claim 1, wherein the re-establishing step (c) including using only one portion radio resources allocated for the second path link.

11. The method in claim 1, further comprising:

maintaining at least a portion of the first path link for a predetermined period of time after the switching in step (b), and

detecting whether the predetermined period of time has expired;

if not, using at least the portion of the initially-established first link in the re-establishing step (c).

12. In a radio communications system including plural mobile stations and a radio network including plural base stations, a method where after establishing a first channel to support a connection through a radio access network to a mobile station, a portion of that first channel is maintained for a period of time after the first channel is no longer being used to support the connection, and subsequently, the maintained portion of the first channel is used to minimize a set-up cost associated with re-activating the first channel to again support the connection to the mobile station.

13. The method in claim 12, wherein the portion of the first channel is associated with resources within the radio access network and another portion of the first channel corresponds to a radio channel resource used to support the connection between the radio access network and the mobile station.

14. The method in claim 13, wherein the other portion of the first channel associated with one of plural radio channel resources is released after the first channel is no longer being used to support the connection in order to make available the one radio channel resource for other mobile communications.

15. The method in claim 12, further comprising:

establishing a value associated with the portion;

counting at the point when the first channel is no longer being used; and

releasing the maintained portion when the count reaches the value.

16. The method in claim 12, wherein the first channel is one of plural channels established between the mobile station and the radio access network employed in a handover operation.

17. The method in claim 16, wherein during the handover operation, the connection is handed over from a first radio access network cell where the first channel is established to a second radio access network cell where a second channel is established to support a connection through the radio access network to the mobile station.

18. The method in claim 12, wherein the first channel corresponds to a dedicated type of channel that is temporarily dedicated to the mobile station and the connection is switched to a second channel corresponding to a common type of channel that is not dedicated to a particular mobile station.

19. The method in claim 18, further comprising:

establishing a first value associated with the first sub-portion, a second value associated with the second sub-portion, and a third value associated with the third sub-portion;

counting at the point when the first channel is no longer being used; and

releasing the maintained first, second, or third portions when the count reaches to the first, second, or third values, respectively.

20. The method in claim 12, wherein the radio network includes a radio network control node connected to the plural base stations, and wherein the first channel includes several sub-portions including a first sub-portion associated with the radio network control node, a second sub-portion between the radio network control node and one of the base stations, and a third sub-portion associated with the one base station.

21. The method in claim 20, wherein the portion in claim 12 corresponds to one or more of the three sub-portions.

22. In a radio communications system including plural mobile stations and a radio network having plural cells coupled to a radio network controller, each cell associated with a base station, a handover method comprising:

initially establishing on a first channel in a first cell a connection with a mobile station, the first channel having plural links;

establishing on a second channel in a second cell the connection with the mobile station;

releasing the first channel so that it no longer supports the first connection with the mobile station;

maintaining one or a portion of one of the plural links of the first channel; and

activating the maintained link of the dropped channel or portion thereof when the connection is re-established in the first cell with the mobile station.

23. The method in claim 22, wherein the first cell corresponds to a first base station and the second cell corresponds to a second base station, and wherein the handover is a hard handover.

24. The method in claim 22, wherein the first cell corresponds to a first base station and the second cell corresponds to a second base station, and wherein the handover is a soft handover.

25. The method in claim 22, wherein the first cell corresponds to a first base station sector and the second cell corresponds to a second base station sector, and wherein the handover is a softer handover.

26. The method in claim 22, wherein another of the plural links corresponds to plural radio channel resources used to support the connection between the radio access network and the mobile station, the releasing step including releasing one of the radio channel resources in order to make available the one radio channel resource for other mobile communications.

27. The method in claim 26, further comprising:

establishing a value associated with the one link;

counting at the point when the first channel is dropped; and

releasing the maintained link when the count reaches the value.

28. In a radio communications system including plural mobile stations and a radio network having plural base stations, a radio network control node comprising:

a channel type switch for selecting one of a first type of channel and a second type of channel to support a connection with a mobile station;

a controller initially establishing on the first channel the connection with a mobile station where the first channel includes first and second channel links, and thereafter, controlling the channel type switch to switch the connection from the first channel to the second type of channel,

wherein the controller controls the channel type switch to switch the connection from the second channel to the first channel and re-establishes the connection on the first channel by using a portion of the initially-established first or second channel link.

29. The radio network control node in claim 28, wherein the radio network control node is a base station.

30. The radio network control node in claim 28, wherein the radio network control node is coupled to plural base stations, the controller establishing a first path link for the first channel from the radio network to a base station and a second path link for the first channel from the base station to the mobile station.

31. The radio network control node in claim 30, wherein the first path link includes a first resource within the RNC between the channel switch and a transport processing interface, a second transmission resource between the transport processing interfaces of the RNC and a base station, and a third resource within the base station between the base station transport processing interface and a radio transceiver, and wherein the at least one portion corresponds to any one of the first, second, or third resources.

32. The radio network control node in claim 28, further comprising:

a first counter for the first link detecting whether a first predetermined period of time has expired;

a second counter for the second link detecting whether a second predetermined period of time has expired; and

a third counter for the third link detecting whether a third predetermined period of time has expired,

wherein when the first, second, or third counter detects expiration of the first, second, or third time period, respectively, the controller releases the maintained first, second, or third links respectively.

33. The radio network control node in claim 28, wherein the second path link includes plural radio resources and the controller allocates a new one of the plural radio resources and uses another one of the plural radio resources initially established for the first channel link when the first channel is re-established to support the connection.

34. The radio network control node in claim 28, wherein the controller maintains at least a portion of the first path link for a predetermined period of time after switching the connection to the second channel, the radio network control node further comprising:

a counter corresponding to the first path link detecting whether a predetermined period of time has expired, and

wherein the counter has detects expiration of the time period, the controller releases the maintained first link.

35. In a radio communications system including plural mobile stations and a radio network having plural cells coupled to a radio network controller, each cell associated with a base station, apparatus, comprising:

means for initially reserving a first channel in a first cell to support a connection with a mobile station;

means for establishing on a second channel in a second cell the connection with the mobile station;

means for releasing the first channel so that it no longer supports the first connection with the mobile station;

means for maintaining a portion of the first channel; and

means for activating the maintained portion of the first channel when the connection is re-established in the first cell with the mobile station.

36. The apparatus in claim 35, wherein the first cell corresponds to a first base station and the second cell corresponds to a second base station, and wherein the handover is a soft handover.

37. The apparatus in claim 35, wherein the first cell corresponds to a first base station sector and the second cell corresponds to a second base station sector, and wherein the handover is a softer handover.

38. The apparatus in claim 35, wherein the means for maintaining maintains one or more channel links associated with the radio network and the first cell while a channel link or portion thereof from the first cell to the mobile station is released to be available for use in other connections.

39. In a radio communications system including plural mobile stations and a radio network having plural cells coupled to a radio network controller, each cell associated with a base station, a method comprising:

initially reserving a first channel to support a connection with a mobile station, the first channel having plural resources supporting the connection between a base station and a mobile station;

establishing on a second channel the connection with the mobile station;

releasing one of plural resources for the first channel so that it no longer supports the connection with the mobile station;

maintaining another of the plural resources for the first channel; and

activating the maintained resource of the first channel when the first channel is re-established to again support the connection with the mobile station.

40. The method in claim 39, wherein the one radio resource includes a transmission power resource and the other radio resource includes a spreading code.