Mobile unit attachment/update to cellular communication network Number:7,130,614 from the United States Patent and Trademark Office (PTO) owispatent A method for reducing IP level signaling and radio resource load during the attachment or update L3 of a mobile unit to a cellular wireless communication network is disclosed wherein access network elements and routing network elements are provided, an identification element is transmitted from the mobile unit to one of the access network elements. The identification element indicates a current attachment of the mobile unit to one of the routing network elements. The transmitted identification element is checked so as to determine whether the access network element is provided with a connection to the one routing network element.<H communication, attachment, Mobile, unit, att, 7130614.html, Patent, pto, 7130614

Title: Mobile unit attachment/update to cellular communication network

Abstract: A method for reducing IP level signaling and radio resource load during the attachment or update L3 of a mobile unit to a cellular wireless communication network is disclosed wherein access network elements and routing network elements are provided, an identification element is transmitted from the mobile unit to one of the access network elements. The identification element indicates a current attachment of the mobile unit to one of the routing network elements. The transmitted identification element is checked so as to determine whether the access network element is provided with a connection to the one routing network element.

Patent Number: 7,130,614 Issued on 10/31/2006 to Sreemanthula, et al.

Inventors: Sreemanthula; Srinivas (Flower Mound, TX), Purnadi; Rene (Coppell, TX)
Assignee: Nokia Corporation (Espoo, FI)

Appl. No.: 10/231,191

Filed: August 30, 2002

Current U.S. Class: 455/411 ; 370/338; 370/352; 370/355; 370/445; 370/473; 455/414.1; 455/414.4; 455/422.1; 455/426.1; 455/432.1; 455/445; 455/466

Current International Class: H04Q 7/20 (20060101); H04Q 7/32 (20060101)

Field of Search: 455/432.1,432.2,432.3,433,434,435.1,435.3,403,414.1,414.2,414.4,466,445,550.1,500,517,436,437,438,439,440,441,442,443,444,450,451,452.2,453,426.1,426.2 370/331,355,352,473,338,445

References Cited [Referenced By]

U.S. Patent Documents


6198927	March 2001	Wright et al.
6510323	January 2003	Stocker et al.
6535493	March 2003	Lee et al.
6826414	November 2004	Reynolds et al.
2002/0031107	March 2002	Li et al.

Foreign Patent Documents


1 011 241	Jun., 2000	EP
1 182 831	Feb., 2002	EP

Other References

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P. Mutaf, C. Castelluccia, IP Paging Threat Analysis, Internet Draft, Feb. 2002, p. 17. cited by other .
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Kempf, et al., Requirments and Functional Architecture for an IP Host Alerting Protocol, Informational, Aug. 2001, p. 16, The Internet Society (2001). cited by other .
Narten, et al., Neighbor Discovery for IP Verison 6 (IPv6), Standards Track, Dec. 1998, p. 93, The Internet Society (2001). cited by other .
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Primary Examiner: Ferguson; Keith
Attorney, Agent or Firm: Foley & Lardner, LLP

Claims

What is claimed is:

1. A method of attaching/updating a mobile unit to a cellular wireless communication network, said cellular wireless communication network comprising: a plurality of access network elements, each of which covering a respective cell area in said cellular wireless communication network, wherein said mobile unit is attached to one of said plurality of access network elements by means of a L2 type connection; and a plurality of routing network elements (AR1, AR2) for forwarding data transmitted via said plurality of access network elements to and from said mobile unit, each of said routing network elements being connected with at least one of said plurality of access network elements, wherein said mobile unit is attached to one of said plurality of routing network elements by means of a L3 type connection, said method comprising the steps of initializing an attachment/update procedure of said mobile unit to one of said plurality of access network elements by means of a L2 type update procedure; transmitting from said mobile unit to said one of said plurality of access network elements a L3 type identification element indicating the existing attachment of said mobile unit to said one of said plurality of routing network elements; and checking said transmitted L3 type identification element for determining whether said one of said plurality of access network elements is provided with the connection to said one of said plurality of routing network elements to which the mobile unit has an existing attachment; and wherein in case that said one of said plurality of access network elements is provided with a connection to said one of said plurality of routing network elements to which the mobile unit has an existing attachment, the method comprises the step of completing the attachment/update procedure between said mobile unit and said one of said plurality of access network elements by means of executing the L2 type procedure and without executing a L3 type update procedure for an attachment of said mobile unit and the routing network elements.

2. A method according to claim 1, further comprising a step of measuring and determining whether a network status for the connection of the mobile unit to said one of said plurality of routing network elements is sufficient or not.

3. A method according to claim 2, wherein said step of initializing said attachment/update procedure is performed when the network status for the connection of said mobile unit to said one of said plurality of routing network elements is not sufficient.

4. A method according to claim 1, wherein said step of initializing said attachment/update procedure is performed when said mobile unit moves from one cell area to another cell area covered by said one of said plurality of access network elements.

5. A method according to claim 1, wherein said step of checking said transmitted L3 type identification element comprises a step of comparing said transmitted L3 type identification elements with identification elements of the routing network elements to which said one of said plurality of access network elements is connected.

6. A method according to claim 5, wherein, when said comparing steps results that said transmitted L3 type identification element and said identification elements of the routing network elements to which said one of said plurality of access network elements is connected match, said step of completing the attachment/update procedure between said mobile unit and said one of said plurality of access network elements is executed while the attachment of said mobile unit to said one of said routing network elements is retained unaffected.

7. A method according to claim 5, wherein, when said comparing steps results that said transmitted L3 type identification element and said identification elements of the routing network elements to which said one of said plurality of access network elements is connected match, said method comprises the steps of: measuring and determining whether a network status for the connection of the mobile unit to said one of said plurality of routing network elements is sufficient or not, and when said network status is sufficient; and said step of completing the attachment/update procedure between said mobile unit and said one of said plurality of access network elements is executed while the attachment of said mobile unit to said one of said routing network elements is retained unaffected.

8. A method according to claim 5, wherein, when said comparing steps results that said transmitted L3 type identification element and said identification elements of the routing network elements to which said one of said plurality of access network elements is connected match, said method comprises the steps of: measuring and determining whether a network status for the connection of the mobile unit to said one of said plurality of routing network elements is sufficient or not, and when said network status is not sufficient; establishing a radio bearer between said one of said plurality of access network elements and said mobile unit; providing said mobile unit with the L3 type identification element of another routing network element to which said one of said plurality of access network elements is connected; reconfiguring the attachment of said mobile unit to the new routing network element indicated by said provided L3 type identification element and performing a binding update procedure in said cellular wireless communication network; completing the attachment/update procedure between said mobile unit and said one of said plurality of access network elements and tearing down the radio bearer upon completion of the attachment/update procedure.

9. A method according to claim 1, wherein said L3 type identification element is transmitted from said mobile unit to said one of said plurality of access network elements by a location update procedure signaling.

10. A method according to claim 1, wherein said L3 type identification element is transmitted from said mobile unit to said one of said plurality of access network elements by a separate message when moving into the cell area of said one of said plurality of access network elements.

11. A method according to claim 1, wherein said step of initializing said attachment/update procedure is performed when a predetermined period of time is expired while said mobile unit remains in the same cell area.

12. A method according to claim 11, wherein said step of checking said transmitted L3 type identification element comprises the steps of: recognizing said transmitted L3 type identification element as an indication that said mobile unit is attached to one of said plurality of routing network elements to which said one of said plurality of access network elements is connected, wherein said step of completing the attachment/update procedure between said mobile unit and said one of said plurality of access network elements is executed while the attachment of said mobile unit to said one of said routing network elements is retained unaffected.

13. A method according to claim 11, wherein said step of checking said transmitted L3 type identification element comprises the steps of: recognizing said transmitted L3 type identification element as an indication that said mobile unit is attached to one of said plurality of routing network elements to which said one of said plurality of access network elements is connected; and measuring and determining whether a network status for the connection of the mobile unit to said one of said plurality of routing network elements is sufficient or not, and when said network status is sufficient, said step of completing the attachment/update procedure between said mobile unit and said one of said plurality of access network elements is executed while the attachment of said mobile unit to said one of said routing network elements is retained unaffected.

14. A method according to claim 11, wherein said step of checking said transmitted L3 type identification element comprises the steps of: recognizing said transmitted L3 type identification element as an indication that said mobile unit is attached to one of said plurality of routing network elements to which said one of said plurality of access network elements is connected; measuring and determining whether a network status for the connection of the mobile unit to said one of said plurality of routing network elements is sufficient or not, and when said network status is not sufficient; establishing a radio bearer between said one of said plurality of access network elements and said mobile unit; providing said mobile unit with the L3 type identification element of another routing network element to which said one of said plurality of access network elements is connected; reconfiguring the attachment of said mobile unit to the new routing network element indicated by said provided L3 type identification element and performing a binding update procedure in said cellular wireless communication network; completing the attachment/update procedure between said mobile unit and said one of said plurality of access network elements; and tearing down the radio bearer upon completion of the attachment/update procedure.

15. A method according to claim 11, wherein said transmitted L3 type identification element comprises a flag indicating that the attachment of said mobile unit to said one of said plurality of routing network elements is to be retained.

16. A system according to claim 11, wherein said system is usable for a one of L3 and IP attachment/updating.

17. A method according to claim 1, wherein said cellular wireless communication network is an IP based network, preferably an IPv6 based network, wherein said mobile unit is a mobile node, said access network elements are cellular access points, and said routing network elements are access routers.

18. A method according to claim 17 wherein said IP based network is an IPv6 based network.

19. A computer program product usable for data processing devices, comprising software code portions for performing the steps of claim 1 when said product is run on data processing devices in the wireless communication network.

20. A computer program product according to claim 19, wherein said computer program product comprises a medium readable by said data processing devices, on which said software code portions are stored.

21. A computer program product according to claim 19, wherein said computer program product is directly loadable into an internal memory of said data processing devices.

22. A computer program product according to claim 19, wherein said computer program product is executed by a data processing device of a mobile unit and a data processing device of an access network element.

23. A method according to claim 1, wherein said method is usable for one of L3 and IP attachment/updating.

24. A system for attaching/updating a mobile unit to a cellular wireless communication network, said cellular wireless communication network comprising: a plurality of access network elements, each of which covering a respective cell area in said cellular wireless communication network, wherein said mobile unit is attached to one of said plurality of access network elements by means of a L2 type connection; and a plurality of routing network elements for forwarding data transmitted via said plurality of access network elements to and from said mobile unit, each of said routing network elements being connected with at least one of said plurality of access network elements, wherein said mobile unit is attached to one of said plurality of routing network elements by means of an L3 type connection; said system comprising: means adapted to transmit, when an attachment/update procedure of said mobile unit to one of said plurality of access network elements is initialized by means of a L2 type update procedure, a L3 type identification element to said one of said plurality of access network elements, which L3 type identification element indicating the current attachment of said mobile unit to said one of said plurality of routing network elements; and means adapted to check said transmitted L3 type identification element so as to determine whether said one of said plurality of access network elements is provided with a connection to said one of said plurality of routing network elements to which the mobile unit has an existing attachment; and wherein in case that said one of said plurality of access network elements is provided with a connection to said one of said plurality of routing network elements to which the mobile unit has an existing attachment, the system is adapted to complete the attachment/update procedure between said mobile unit and said one of said plurality of access network elements by means of executing the L2 type procedure and without executing a L3 type update procedure for an attachment of said mobile unit and the routing network elements.

25. A system according to claim 24, further comprising means adapted to measure and determine whether a network status for the connection of the mobile unit to said one of said plurality of routing network elements is sufficient or not.

26. A system according to claim 25, wherein said attachment/update procedure is initialized when a network status for the connection of the mobile unit to said one of said plurality of routing network elements is determined to be not sufficient.

27. A system according to claim 24, wherein said attachment/update procedure is initialized when said mobile unit moves from one cell area to another cell area covered by said one of said plurality of access network elements.

28. A system according to claim 27, wherein said L3 type identification element is transmitted from said mobile unit to said one of said plurality of access network elements by a location update procedure signaling.

29. A system according to claim 27, wherein said L3 type identification element is transmitted from said mobile unit to said one of said plurality of access network elements by a separate message when moving into the cell area of said one of said plurality of access network elements.

30. A system according to claim 24, wherein said means adapted to check said transmitted L3 type identification element compares said transmitted L3 type identification element with identification elements of the routing network elements to which said one of said plurality of access network elements is connected.

31. A system according to claim 30, comprising means adapted to complete the attachment/update procedure between said mobile unit and said one of said plurality of access network elements and to retain the attachment of said mobile unit to said one of said routing network elements unaffected, when the comparison results that said transmitted L3 type identification element and said identification elements to which said one of said plurality of access network elements is connected match.

32. A system according to claim 30, comprising means adapted to measure and determine whether a network status for the connection of the mobile unit to said one of said plurality of routing network elements is sufficient or not; and means adapted to complete the attachment/update procedure between said mobile unit and said one of said plurality of access network elements and to retain the attachment of said mobile unit to said one of said routing network elements unaffected, when the comparison results that said transmitted L3 type identification element and said identification elements to which said one of said plurality of access network elements is connected match and the determination results that said network status for the connection of the mobile unit to said one of said plurality of routing network elements is sufficient.

33. A system according to claim 30, comprising, when said comparison results that said transmitted L3 type identification element and said identification elements of the routing network elements to which said one of said plurality of access network elements is connected match; means adapted to measure and determine whether a network status for the connection of the mobile unit to said one of said plurality of routing network elements is sufficient or not, and when the determination results that said network status for the connection of the mobile unit to said one of said plurality of routing network elements is not sufficient; means adapted to establish a radio bearer between said one of said plurality of access network elements and said mobile unit; means adapted to provide said mobile unit with the L3 type identification element of another routing network element to which said one of said plurality of access network elements is connected; means adapted to reconfigure the attachment of said mobile unit to the new routing network element indicated by said provided L3 type identification element and to perform a binding update procedure in said cellular wireless communication network; and means adapted to complete the attachment/update procedure between said mobile unit and said one of said plurality of access network elements and to tear down the radio bearer upon completion of the attachment/update procedure.

34. A system according to claim 24, wherein said attachment/update procedure is initialized when a predetermined period of time is expired while said mobile unit remains in the same cell area.

35. A system according to claim 34, wherein said means adapted to check said transmitted L3 type identification element is adapted to recognize said transmitted L3 type identification element as an indication that said mobile unit is attached to one of said plurality of routing network elements to which said one of said plurality of access network elements is connected, said system comprising: means adapted to complete the attachment/update procedure between said mobile unit and said one of said plurality of access network elements and to retain the attachment of said mobile unit to said one of said routing network elements unaffected.

36. A system according to claim 34, wherein said means adapted to check said transmitted L3 type identification element is adapted to recognize said transmitted L3 type identification element as an indication that said mobile unit is attached to one of said plurality of routing network elements to which said one of said plurality of access network elements is connected, said system comprising: means adapted to measure and determine whether a network status for the connection of the mobile unit to said one of said plurality of routing network elements is sufficient or not, and when the determination results that said network status for the connection of the mobile unit to said one of said plurality of routing network elements is sufficient; and means adapted to complete the attachment/update procedure between said mobile unit and said one of said plurality of access network elements and to retain the attachment of said mobile unit to said one of said routing network elements unaffected.

37. A system according to claim 34, wherein said means adapted to check said transmitted L3 type identification element is adapted to recognize said transmitted L3 type identification element as an indication that said mobile unit is attached to one of said plurality of routing network elements to which said one of said plurality of access network elements is connected, said system further comprising: means adapted to measure and determine whether a network status for the connection of the mobile unit to said one of said plurality of routing network elements is sufficient or not, and when the determination results that said network status for the connection of the mobile unit to said one of said plurality of routing network elements is not sufficient; means adapted to establish a radio bearer between said one of said plurality of access network elements and said mobile unit; means adapted to provide said mobile unit with the L3 type identification element of another routing network element to which said one of said plurality of access network elements is connected; means adapted to reconfigure the attachment of said mobile unit to the new routing network element indicated by said provided L3 type identification element and to perform a binding update procedure in said cellular wireless communication network; and means adapted to complete the attachment/update procedure between said mobile unit and said one of said plurality of access network elements and to tear down the radio bearer upon completion of the attachment/update procedure.

38. A system according to claim 34, wherein said transmitted L3 type identification element comprises a flag indicating that the attachment of said mobile unit to said one of said plurality of routing network elements is to be retained.

39. A system according to claim 24, wherein said cellular wireless communication network is an IP based network, wherein said mobile unit is a mobile node, said access network elements are cellular access points, and said routing network elements are access routers.

40. A system according to claim 39, wherein the IP based network is an IPv6 based network.

41. An access network element according to claim 40, wherein said cellular wireless communication network is an IP based network, wherein said mobile unit is a mobile node, said access network element is a cellular access point, and said routing network elements are access routers.

42. An access network element acceding to claim 41 wherein the cellular wireless network is an IPv6 network.

43. A mobile unit attachable to a cellular wireless communication network, said cellular wireless communication network comprising: a plurality of access network elements, each of which covering a respective cell area in said cellular wireless communication network, wherein said mobile unit is attached to one of said plurality of access network elements by means of a L2 type connection; and a plurality of routing network elements for forwarding data transmitted via said plurality of access network elements to and from said mobile unit, each of said routing network elements being connected with at least one of said plurality of access network elements, wherein said mobile unit is attached to one of said plurality of routing network elements by means of a L3 type connection, said mobile unit comprising: means adapted to transmit, when an attachment/update procedure of said mobile unit to one of said plurality of access network elements is initialized by means of a L2 type update procedure, a L3 type identification element to said one of said plurality of access network elements, which L3 type identification element indicating the current attachment of said mobile unit to said one of said plurality of routing network elements to which the mobile unit has an existing attachment; and wherein in a case that said one of said plurality of access network elements is provided with a connection to said one of said plurality of routing network elements to which the mobile unit has an existing attachment, the attachment/update procedure between said mobile unit and said one of said plurality of access network elements is completed by means of executing the L2 type procedure and without executing a L3 type update procedure for an attachment of said mobile unit and the routing network elements.

44. A mobile unit according to claim 43, wherein said attachment/update procedure is initialized when said mobile unit moves from one cell area to another cell area covered by said one of said plurality of access network elements.

45. A mobile unit according to claim 43, wherein said attachment/update procedure is initialized when a determination is made that a network status for the connection of the mobile unit to said one of said plurality of routing network elements is not sufficient.

46. A mobile unit according to claim 43, said mobile unit being adapted to reconfigure the attachment of said mobile unit to a new routing network element to which said one of said plurality of access network elements is connected, indicated by a provided L3 type identification element, and to perform a binding update procedure in said cellular wireless communication network.

47. A mobile unit according to claim 43, wherein said L3 type identification element is transmitted from said mobile unit to said one of said plurality of access network elements by a location update procedure signaling.

48. A mobile unit according to claim 43, wherein said L3 type identification element is transmitted from said mobile unit to said one of said plurality of access network elements by a separate message when moving into the cell area of said one of said plurality of access network elements.

49. A mobile unit according to claim 43, wherein said attachment/update procedure is initialized when a predetermined period of time is expired while said mobile unit remains in the same cell area.

50. A mobile unit according to claim 49, wherein said transmitted L3 type identification element comprises a flag indicating that the attachment of said mobile unit to said one of said plurality of routing network elements is to be retained.

51. A mobile unit according to claim 43, wherein said cellular wireless communication network is an IP based network, wherein said mobile unit is a mobile node, said access network elements are cellular access points, and said routing network elements are access routers.

52. A mobile unit according to claim 51, wherein the IP based network is an IPv6 based network.

53. An access network element of a cellular wireless communication network to which a mobile unit is attachable, said cellular wireless communication network comprising: a plurality of access network elements, each of which covering a respective cell area in said cellular wireless communication network, wherein said mobile unit is attached to one of said plurality of access network elements by means of a L2 type connection; and a plurality of routing network elements for forwarding data transmitted via said plurality of access network elements to and from said mobile unit, each of said routing network elements being connected with at least one of said plurality of access network elements, wherein said mobile unit is attached to one of said plurality of routing network elements by means of a L3 type connection; said access network element comprising: means adapted to check, when an attachment/update procedure of said mobile unit to said network element is initialized by means of a L2 type update procedure, a L3 type identification element transmitted from said mobile unit to said access network element, which L3 type identification element indicating the current attachment of said mobile unit to said one of said plurality of routing network elements, wherein a determination is made whether said access network element is provided with a connection to said one of said plurality of routing network elements to which the mobile unit has an existing attachment; wherein in a case that said one of said plurality of access network elements is provided with a connection to said one of said plurality of routing network elements to which the mobile unit has an existing attachment, the access network element is adapted to complete the attachment/update procedure between said mobile unit and said one of said plurality of access network elements by means of executing the L2 type procedure and without executing a L3 type update procedure for an attachment of said mobile unit and the routing network elements.

54. An access network element according to claim 53, further comprising means adapted to measure and determine whether a network status for the connection of the mobile unit to said one of said plurality of routing network elements is sufficient or not.

55. An access network element according to claim 54, wherein said attachment/update procedure is initialized when the network status for the connection of the mobile unit to said one of said plurality of routing network elements is determined to be not sufficient.

56. An access network element according to claim 55, further comprising means adapted to complete the attachment/update procedure between said mobile unit and said one of said access network elements and to retain the attachment of said mobile unit to said one of said routing network elements unaffected, when the comparison results that said transmitted L3 type identification element and said identification elements to which said access network element is connected match.

57. An access network element according to claim 53, wherein said attachment/update procedure is initialized when said mobile unit moves from one cell area to another cell area covered by said access network element.

58. An access network element according to claim 53, wherein said means adapted to check said transmitted L3 type identification element compare said transmitted L3 type identification element with identification elements of the routing network elements to which said access network element is connected.

59. An access network element according to claim 58, further comprising: means adapted to measure and determine whether a network status for the connection of the mobile unit to said one of said plurality of routing network elements is sufficient or not; and means adapted to complete the attachment/update procedure between said mobile unit and said one of said plurality of access network elements and to retain the attachment of said mobile unit to said one of said routing network elements unaffected, when the comparison results that said transmitted L3 type identification element and said identification elements to which said one of said plurality of access network elements is connected match and the determination results that said network status for the connection of the mobile unit to said one of said plurality of routing network elements is sufficient.

60. An access network element according to 58, comprising, when said comparison results that said transmitted L3 type identification element and said registered identification element match, means adapted to measure and determine whether a network status for the connection of the mobile unit to said one of said plurality of routing network elements is sufficient or not, and when the determination results that said network status for the connection of the mobile unit to said one of said plurality of routing network elements is not sufficient; means adapted to establish a radio bearer between said access network element and said mobile unit; means adapted to provide said mobile unit with the L3 type identification element of another routing network element to which said access network element is connected; and means adapted to tear down the radio bearer upon completion of the attachment/update procedure.

61. An access network element according to claim 53, wherein said L3 type identification element is transmitted from said mobile unit to said access network element by a location update procedure signaling.

62. An access network element according to claim 53, wherein said L3 type identification element is transmitted from said mobile unit to said access network element by a separate message when moving into the cell area of said access network element.

63. An access network element according to claim 53, wherein said attachment/update procedure is initialized when a predetermined period of time is expired while said mobile unit remains in the same cell area.

64. An access network element according to claim 63, wherein said means adapted to check said transmitted L3 type identification element is adapted to recognize said transmitted L3 type identification element as an indication that said mobile unit is attached to one of said plurality of routing network elements to which said access network element is connected, said access network element comprising means adapted to complete the attachment/update procedure between said mobile unit and said access network element and to retain the attachment of said mobile unit to said one of said routing network elements unaffected.

65. An access network element according to claim 63, wherein said means adapted to check said transmitted L3 type identification element is adapted to recognize said transmitted L3 type identification element as an indication that said mobile unit is attached to one of said plurality of routing network elements to which said access network element is connected, said access network element further comprising: means adapted to measure and determine whether a network status for the connection of the mobile unit to said one of said plurality of routing network elements is sufficient or not, and when the determination results that said network status for the connection of the mobile unit to said one of said plurality of routing network elements is sufficient; and means adapted to complete the attachment/update procedure between said mobile unit and said access network element and to retain the attachment of said mobile unit to said one of said routing network elements unaffected.

66. An access network element according to claim 63, wherein said means adapted to check said transmitted L3 type identification element is adapted to recognize said transmitted L3 type identification element as an indication that said mobile unit is attached to one of said plurality of routing network elements to which said access network element is connected, said access network element comprising: means adapted to measure and determine whether a network status for the connection of the mobile unit to said one of said plurality of routing network elements is sufficient or not, and when the determination results that said network status for the connection of the mobile unit to said one of said plurality of routing network elements is not sufficient; means adapted to establish a radio bearer between said access network element and said mobile unit; means adapted to provide said mobile unit with the L3 type identification element of another routing network element to which said access network element is connected, and means adapted to tear down the radio bearer upon completion of the attachment/update procedure.

67. An access network element according to claim 63, wherein said transmitted L3 type identification element comprises a flag indicating that the attachment of said mobile unit to said one of said plurality of routing network elements is to be retained.

68. An access network element according to claim 53, wherein said access network element is used in one of a L3 and IP attachment/updating.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method and/or system and/or system units and/a computer program product which are usable for attaching a mobile unit to a cellular wireless communication network. In particular, the present invention relates to method and/or system and/or system units and/a computer program product, which minimize the L3 or IP signaling load during attachment or update procedures to the cellular wireless communication network.

2. Description of the Prior Art

Recently, development of communication networks has made considerable progress. Among such communication networks, there is an increasing number of communication networks supporting mobility of the users having subscribed to the networks. A user is represented by a terminal unit or terminal node he uses for communication with a communication partner unit or node. Note that in general a communication partner node is of the same or a similar type than a terminal node, while "partner node" has only been chosen to illustrate that this is the destination or called node in communication. A terminal node/communication partner node may for example be a mobile phone, mobile laptop computer, a personal digital assistant (PDA) or the like. Nevertheless, a called communication partner node may also be a fixed terminal such as a personal computer PC or the like.

Currently, 3.sup.rd generation communication networks, e.g. the Universal Mobile Telecommunication System (UMTS), are under development in 3.sup.rd Generation Partnership Project (3GPP). In general, UMTS networks includes a core network, Universal Terrestrial Radio Access (UTRA) network (UTRAN), and user equipment (i.e. user terminal units). The UTRAN provides interfaces to the core network and radio interfaces to the user equipment. As commonly known, protocols used for these interfaces are arranged into so-called layers. For example, the radio (L2) interface protocol architecture comprises a data link layer comprising e.g. medium access control (MAC) and radio link control (RLC) sublayers, and radio resource control (RRC). Furthermore, also a network layer is provided. The architecture, design as well as the used protocols of the UMTS are commonly known to those skilled in the art and will thus not be described in further detail herein.

With the increasing spreading and acceptance of the Internet, a harmonization of communication networks arises in that communication networks, in particular wireless communication networks, tend to be compatible with the Internet. Thus there is a tendency to adopt the Internet Protocol IP also in communication networks other than the Internet. IP is a packet based protocol type which allows transmitting data via the network in so-called packets comprising a header (including routing information) and a payload. In the case of mobility supporting communication networks, IP is adopted in a mobility supporting version still compatible with IP "as such". For example, Mobile IPv4, Mobile IPv6 or Cellular IP protocol version exist.

Mobile IP specifications and definitions of common terms in this technical field can be found under http://www.ietf.org, retrieved from the Internet on Aug. 8, 2002.

There is developed a variety of wireless communication networks which support IP based communication, i.e. packet-switched networks supporting mobility of the users, such as GPRS, UMTS, Mobile IP (MIP) or the like.

In wireless cellular networks, user terminal units are able to perform communications with each other (for example within the same wireless cellular communication network) or with corresponding terminals of other networks (for example wired LANs, WLANs, fixed or mobile cellular communication networks and the like) via corresponding communication protocols. The general architecture of a wireless cellular network, for example IPv6 based, is commonly known and thus described only shortly. The key elements of a cellular access network are the user terminal units or nodes and cellular access points (CAP) with which the user terminal communicates over a wireless communication interface, e.g. radio based. A cellular access point (also referred to as base station) covers a specific area, which is referred to hereinafter as a cell. The size of a cell may vary in dependence of the environment, network operator specifications, number of associated subscribers and the like. The CAP is adapted to control communications of the user terminals within this cell, for example, by allocating frequency channels, establishing connections for the user terminals, forwarding data and the like. A user terminal is normally associated with one access point, which is referred to hereinafter as the serving CAP. A cellular access point can be associated to one or more access routers AR which routes the transmitted data via the cellular access points to and from the terminal node. Via a distribution network to which the cellular access points may be connected via the access router, communication connections between different cellular access networks or external networks (e.g. fixed networks, mobile telecommunications networks such as GSM, UMTS, WLAN and the like) can be established for a user terminal. Normally, for the communication control, the user terminal may be attached to the corresponding serving CAP via a L2 protocol and to the access router via a L3 or IP protocol.

For forwarding correctly data to and from the (mobile) user terminal, it is necessary that the network knows where the user terminal is located in the network. For this purpose, the user terminal is provided with addresses received by the respective network elements, such as the associated access point, the attached access router and the like. The addresses are registered, for example, in the home agent (HA) of the user terminal's home site. When the mobile user terminal is moved to another cell (i.e. another access point coverage area) it receives a new temporarily address which is called the Care-of-Address (CoA). When the user terminal knows the new CoA, it performs a so-called binding update procedure, e.g. a Mobile IPv6 binding update, with a corresponding network registering element, for example, with its HA. By means of this the CoA is mapped to the "permanent" address of the user terminal so as to ensure the reachability of the user terminal in the network.

A further development in the field of IP based communication networks is known as Hierarchical Mobile IP (HMIP). In this solution, a further network element is provided which is called Mobile Anchor Point (MAP). This MAP is used as a mobility agent for supporting mobility management of the user terminal in the network, e.g. in case of handovers.

In IP based communication networks, in particular in an IPv6 based network, a procedure known as Neighbor Discovery is performed. Neighbor Discovery is a commonly known concept and is described in further detail, for example, in the Internet Engineering Task Force (IETF) Requests For Comments (RFC) 1970 and 2461. In short, nodes (hosts and routers) use Neighbor Discovery to determine the link-layer addresses for neighbors known to reside on attached links and to quickly purge cached values that become invalid. Hosts also use Neighbor Discovery to find neighboring routers that are willing to forward packets on their behalf. Finally, nodes use the protocol to actively keep track of which neighbors are reachable and which are not, and to detect changed link-layer addresses. When a router or the path to a router fails, a host actively searches for functioning alternates.

According to the IPv6 Neighbor Discovery, the AR sends periodic Router Advertisements via the access points to user terminals, which are also designated as mobile nodes MN. That means, routers advertise their presence together with various link and Internet parameters periodically (or in response to a Router Solicitation message). The Router Advertisements comprise prefixes that are used, e.g., for on-link determination and/or address configuration.

The MN listens to the Router Advertisements. In the case that a new prefix is advertised, the MN determines that the network layer attachment has changed (i.e. the attachment to the AR) and computes a new CoA based on the new AR prefix (from the new AR) and then performs MIPv6 binding procedures.

However, IPv6 Neighbor Discovery, as well as MIPv6 procedures in general, affects spectrum efficiency of wireless communication networks. Particularly, for all messages concerning the network attachment (i.e. L3 messages) a radio bearer has to be established between the MN and the network. This requires the establishment of expensive traffic channels.

In FIGS. 5 and 6 a part of a cellular wireless communication network is shown for illustrating different Neighbor Discovery situations. In general, when the MN is for example L2 dormant (i.e. a state in which the MN restricts its ability to receive normal IP traffic by reducing monitoring of radio channels, which allows the MN to save power and reduces signaling load on the network), it "wakes up" after specific periods of time to perform periodic routine functions, for example to monitor paging channel (PCH) and for periodic L2 updates depending on the CELL_PCH or the URA_PCH (URA: UTRAN Registration Area) dormancy levels. However, every time it performs an L2 update, for radio efficiency reasons, the AP must also send (or allow from AR) the L3 network information to provide the current network attachment information, like the Router Advertisement. If the information is different from current network attachment in the MN, the MN obtains a new CoA and performs MIPv6 Binding Updates to all the mobility agents like HA and/or MAP (if HMIP is used).

Referring to FIG. 5, we assume a case where MN (i.e. MN1) has a network attachment (CoA) previously from an AR (in FIG. 5, AR1). That means, that the original Cellular Access Point CAP1 has provided the MN1 with the Router Advertisement of AR1, and the MN has a CoA from AR1 and performs a corresponding binding update for mapping this CoA at its HA. Thereafter, e.g. after a specific period of time, the MN1 may go L2 dormant. The MN1 can become L2 dormant in either cell level (CELL_PCH) or RRA (Radio Resource Allocation) level (URA_PCH). When the MN1 moves from one cellular Access Point CAP1 to another CAP2, as shown in FIG. 5, if it is in the CELL_PCH dormant state, it will perform cell updates. At the same time, the new CAP2 must allow the MN1 to receive a Router Advertisement to check its latest network attachment. In the case that the new CAP2 belongs to a different AR (not shown) a different network prefix is sent and an attachment procedure is performed. However, in the other case, in which the new CAP2 belongs to the same network coverage as the previous CAP1 to which the MN1 was associated before (as shown in FIG. 5), there is also established a Radio Bearer to provide the MN1 with the Router Advertisement (i.e. the prefix of AR1). The same situation applies to URA_PCH state, only that the MN wakes up only when it changes the cells at the RRA level, while the rest of the procedure remains the same.

In a more complex network scenario, such as shown in FIG. 6, where there may be many-to-many relation between different CAP (CAP1, CAP2) and AR (AR1, AR2, AR3), the situation becomes also more complex. Again, MN1 is provided with the Router Advertisement of AR1 by the CAP1, has performed the binding update, and may be gone to L2 dormant state. When the MN1 moves from its original CAP1 area to a new CAP2 area, the CAP2 could theoretically selectively provide one (or more) optimum Router Advertisements to the MN1. However, due to efficiency reasons, the CAP2 is not adapted to provide Router Advertisements from every AR it is connected to. Thus, the new CAP2 selects one of the connected AR (e.g. AR3) of which the Router Advertisement is sent to the MN1, which in turn performs the described attachment procedure.

This existing scheme is in particular problematic with regard to radio resources. As described above, for the provision of the network attachment information (L3), a Radio Bearer has to be established. In the case of FIG. 5, it is actually unnecessary for the MN to receive the Router Advertisements of the AR1. The problem is not just to send the Router Advertisement, but also to send it over the default Radio Bearer, which must be established if the MN1 was L2 dormant. In the case of FIG. 6, even though the CAP2 also belongs to the same AR that the MN was originally connected to (i.e. AR1), the CAP2 must provide a new Router Advertisement from any of AR1, AR2 or AR3 after establishing a new default Radio Bearer. The problem amplifies when the MN receives the new Router Advertisement, for example, of AR3. Then MN1 has to reconfigure a new CoA and perform all the MIPv6 binding procedures, while there was actually no need for this. Thus, this mechanism is a drain on the MN power and also very inefficient on radio resources.

One approach to reduce the signaling load in IP based communication networks is the so-called IP Dormancy/Paging, which is described, for example in IETF RFC 3154 and RFC 3132. However, this approach is still vague and will increase the network complexity of the network due to the involved paging network architecture.

SUMMARY OF THE INVENTION

Thus, it is an object of the present invention to provide an improved method and/or system and/or system units and or a computer program product for attaching a mobile unit to a wireless communication network.

Furthermore, it is an object of the present invention to provide a method and/or system and/or system units and/or a computer program product, which save network unit resources and/or network radio resources.

Moreover, it is an object of the present invention to provide a method and/or system and/or system units and or a computer program product, which are usable for minimizing signaling load during an attachment/update procedure to the wireless communication network.

These objects are achieved, for example, by a method of attaching/updating a mobile unit to a cellular wireless communication network, said cellular wireless communication network comprising a plurality of access network elements, each of which covering a respective cell area in said cellular wireless communication network, wherein said mobile unit is attached to one of said plurality of access network elements, and a plurality of routing network elements for forwarding data transmitted via said plurality of access network elements to and from said mobile unit, each of said routing network elements being connected with at least one of said plurality of access network elements, wherein said mobile unit is attached to one of said plurality of routing network elements, said method comprising the steps of initializing an attachment/update procedure of said mobile unit to one of said plurality of access network elements, transmitting from said mobile unit to said one of said plurality of access network elements an identification element indicating the current attachment of said mobile unit to said one of said plurality of routing network elements, and checking said transmitted identification element so as to determine whether said one of said plurality of access network elements is provided with a connection to said one of said plurality of routing network elements.

According to a further refinement of the method, the method may comprise a step of measuring and determining whether a network status for the connection of the mobile unit to said one of said plurality of routing network elements is sufficient or not.

According to still further refinements of the method the step of initializing said attachment/update procedure may be performed when said mobile unit moves from one cell area to another cell area covered by said one of said plurality of access network elements, and/or the step of initializing said attachment/update procedure may be performed when the network status for the connection of said mobile unit to said one of said plurality of routing network elements is not sufficient.

In still further refinements of the method, the step of checking said transmitted identification element may comprise a step of comparing said transmitted identification element with identification elements of the routing network elements to which said one of said plurality of access network elements is connected;--when said comparing steps results that said transmitted identification element and said identification elements of the routing network elements to which said one of said plurality of access network elements is connected match, said method further may comprise the step of completing the attachment/update procedure between said mobile unit and said one of said plurality of access network elements while the attachment of said mobile unit to said one of said routing network elements is retained unaffected; when said comparing steps results that said transmitted identification element and said identification elements of the routing network elements to which said one of said plurality of access network elements is connected match, said method may further comprise the steps of measuring and determining whether a network status for the connection of the mobile unit to said one of said plurality of routing network elements is sufficient or not, and when said network status is sufficient, completing the attachment/update procedure between said mobile unit and said one of said plurality of access network elements (CAP2) while the attachment of said mobile unit to said one of said routing network elements is retained unaffected; when said comparing steps results that said transmitted identification element and said identification elements of the routing network elements to which said one of said plurality of access network elements is connected match, said method further comprises the steps of measuring and determining whether a network status for the connection of the mobile unit to said one of said plurality of routing network elements is sufficient or not, and when said network status is not sufficient, establishing a radio bearer between said one of said plurality of access network elements and said mobile unit, providing said mobile unit with the identification element of another routing network element to which said one of said plurality of access network elements is connected, reconfiguring the attachment of said mobile unit to the new routing network element indicated by said provided identification element and performing a binding update procedure in said cellular wireless communication network, completing the attachment/update procedure between said mobile unit and said one of said plurality of access network elements, and tearing down the radio bearer upon completion of the attachment/update procedure; the identification element may be transmitted from said mobile unit to said one of said plurality of access network elements by a location update procedure signaling; the identification element may be transmitted from said mobile unit to said one of said plurality of access network elements by a separate message when moving into the cell area of said one of said plurality of access network elements;

Alternatively, as a further refinement of the method, the step of initializing said attachment/update procedure may be performed when a predetermined period of time is expired while said mobile unit remains in the same cell area; and if this is the case; the step of checking said transmitted identification element may comprise the steps of recognizing said transmitted identification element as an indication that said mobile unit is attached to one of said plurality of routing network elements to which said one of said plurality of access network elements is connected, measuring and determining whether a network status for the connection of the mobile unit to said one of said plurality of routing network elements is sufficient or not, and when said network status is not sufficient, establishing a radio bearer between said one of said plurality of access network elements and said mobile unit, providing said mobile unit with the identification element of another routing network element to which said one of said plurality of access network elements is connected, reconfiguring the attachment of said mobile unit to the new routing network element indicated by said provided identification element and performing a binding update procedure in said cellular wireless communication network, completing the attachment/update procedure between said mobile unit and said one of said plurality of access network elements and tearing down the radio bearer upon completion of the attachment/update procedure; the step of checking said transmitted identification element may comprise the steps of recognizing said transmitted identification element as an indication that said mobile unit is attached to one of said plurality of routing network elements to which said one of said plurality of access network elements is connected, measuring and determining whether a network status for the connection of the mobile unit to said one of said plurality of routing network elements is sufficient or not, and when said network status is sufficient, completing the attachment/update procedure between said mobile unit and said one of said plurality of access network elements while the attachment of said mobile unit to said one of said routing network elements is retained unaffected; the step of checking said transmitted identification element may comprise the steps of recognizing said transmitted identification element as an indication that said mobile unit is attached to one of said plurality of routing network elements to which said one of said plurality of access network elements is connected, measuring and determining whether a network status for the connection of the mobile unit to said one of said plurality of routing network elements is sufficient or not, and when said network status is not sufficient, establishing a radio bearer between said one of said plurality of access network elements and said mobile unit, providing said mobile unit with the identification element of another routing network element to which said one of said plurality of access network elements is connected, reconfiguring (S140) the attachment of said mobile unit to the new routing network element indicated by said provided identification element