Base Station Base Methods and Apparatus For Supporting Break Before Making Handoffs In A Multi-Carrier System

• US 20080287130A1
• Filed: 05/19/2008
• Published: 11/20/2008
• Est. Priority Date: 12/05/2003
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Laroia, Rajiv, Li, Junyi, Lane, Frank A.
• Granted Patent: US 8,554,226 B2
• Time in Patent Office: Days
• US Class Current: 455/436
• CPC Class Codes: H04W 36/00692 using simultaneous multiple data streams, e.g. cooperative multipoint [CoMP], carrier aggregation [CA] or multiple input multiple output [MIMO] allocation of physical resources in CoMP or in CA H04L5/0035
• CPC Class Codes: H04W 36/06 Reselecting a communication resource in the serving access point
• CPC Class Codes: H04W 36/185 using make before break

Abstract

A mobile communications device initiates a handoff from its current base station (BS) sector network attachment point to a new BS sector. The mobile sends a handoff request over its current wireless link to the current BS sector, which forwards the request to the new BS sector, e.g., via a network link. The new BS sector processes the request assigning dedicated resources, e.g., an identifier and dedicated uplink segments. Information identifying the allocated resources is conveyed from the new BS sector via the current BS sector to the mobile. The mobile determines the time of the allocated dedicated segments based upon a received beacon signal from the new BS sector with known timing relationships to dedicated segments. The mobile breaks the original wireless link just prior to the time of the first assigned dedicated segment. The mobile communicates information on the assigned dedicated segments to perform registration operations, e.g., timing synchronization and power control, establishing a new wireless link.

Claims

1. A network attachment point for use in a multi-carrier communication system comprised of at least one wireless terminal in an active communication session with a serving network attachment point, where the active communication is in a first frequency band which is different from a second frequency band associated with the network attachment point for transmitting user data, comprising:

means for generating a broadcast signal message having a predetermined frequency into the first frequency band on a periodic basis; and

means, responsive to a request from a wireless terminal received from the corresponding serving network attachment point, for communicating dedicated system handoff information to the wireless terminal over the active communication session with the serving network attachment point without the wireless terminal establishing a communication session with the network attachment point.

2. The network attachment point of claim 1, further comprising means for detecting a request from the serving network attachment point to initiate a secure communication link over a network therewith.

3. The network attachment point of claim 2, further comprising means for assigning at least one of on-state identifier and hold-state identifier to wireless terminal, means for reserving resources for the wireless terminal, and means for transmitting information, including access state information in which the network attachment point has reserved dedicated tone set-up link communication segment for registration by the wireless terminal, this information being communicated to the wireless terminal via the secure communication link with the serving network attachment point.

4. The network attachment point of claim 3, further comprising, after termination by the wireless terminal of the active communication session with the serving network attachment point, means for detecting a wireless terminal registration attempt over the dedicated tone set-up link communication segment in a specified access slot.

5. The network attachment point of claim 4, further comprising means for registering the wireless terminal with the network, including means for transmitting at least one of timing synchronization and power control signaling to the wireless terminal.

6. The network attachment point of claim 5, further comprising means for detecting successful registration and means for releasing assigned identifiers and resources to establish an active communications session with the wireless terminal.

7. The network attachment point of claim 6, wherein the broadcast system message is a beacon signal having known timing offsets from uplink channel segments for use in a dedicated fashion by the wireless terminal during handoff initiation.

8. The network attachment point of claim 7, wherein the multi-carrier communication system is an OFDM system, the wireless terminal is a mobile node, and the network attachment point and the serving network attachment point are base stations.

9. The network attachment point of claim 8, wherein the network attachment point and the serving network attachment points are located in a same cell.

10. The network attachment point of claim 1, wherein the multi-carrier communication system is an OFDM system, the wireless terminal is a mobile node, and the network attachment point and the serving network attachment point are base stations.

11. The network attachment point of claim 10, wherein the network attachment point and the serving network attachment points are located in a same cell.

12. A network attachment point for use in a multi-carrier communication system comprised of at least one wireless terminal configured to generate requests to initiate handoff from the network attachment point to an adjacent network attachment point, where the adjacent network attachment point uses different frequency bands to establish communication sessions with the at least one wireless terminal than the frequency band used by the network attachment point, and where the adjacent network attachment point generates broadcast system messages in the frequency band of the network attachment point detectable by a wireless terminal when in an active communication session with the network attachment point to facilitate system handoff, the network attachment point comprising:

means for receiving a request from the wireless terminal to initiate handoff communications between the wireless terminal and the adjacent network attachment point; and

means for exchanging dedicated system handoff information between the adjacent network attachment point and the wireless terminal over the active communication session with the network attachment point without the wireless terminal establishing a communication session with the adjacent network attachment point.

13. The network attachment point of claim 12, wherein the means for exchanging dedicated system handoff information includes means for receiving from the adjacent network attachment point and means for passing to the wireless terminal over a currently active communication link between the wireless terminal and the network attachment point, information identifying registration operations to be performed by the wireless terminal after terminating the currently active communication link.

14. The network attachment point of claim 13, wherein the broadcast system message is a beacon signal.

15. The network attachment point of claim 12, wherein the broadcast system message is a beacon signal.

16. The network attachment point of claim 15, wherein the beacon signal includes at least one of a cell identifier and a sector identifier, the means for receiving a request including the at least one of a cell identifier and a sector identifier.

17. The network attachment point of claim 16, wherein the dedicated system handoff information is dedicated airlink resource assignment information associated with the adjacent network attachment point for use by the wireless terminal when performing a system handoff, the information being received in the form of a packet from the adjacent network attachment point to the wireless terminal over a currently active communication link between the wireless terminal and the network attachment point.

18. The network attachment point of claim 17, wherein the dedicated airlink resource assignment information comprises information for the wireless terminal to communicate with the adjacent network attachment point over a dedicated resource assigned to the wireless terminal, this resource including a set of tones in an uplink communications segment, the wireless terminal being adapted to identify the set of tones from information received from the adjacent network attachment point via the uplink communications segment and from the information regarding the structure of the communications segment derived from the beacon signal.

19. The network attachment point of claim 18, wherein the multi-carrier communication system is an OFDM system, the wireless terminal is a mobile node, and the network attachment point and the adjacent network attachment point are base stations.

20. The network attachment point of claim 12, wherein the multi-carrier communication system is an OFDM system, the wireless terminal is a mobile node, and the network attachment point and the adjacent network attachment point are base stations.

21. The network attachment point of claim 20, further comprising means for terminating a currently active communication link between the wireless terminal in response to a request to do so by the wireless terminal which then establishes a new communication link with the adjacent network attachment point, the new communication link being established only after the currently active communication link is terminated and on the basis of system handoff information received from the adjacent network attachment point via the network attachment point.

22. The network attachment point of claim 12, wherein the first and adjacent network attachment points are located in a same cell.

23. The network attachment point of claim 12, wherein the means for exchanging dedicated system handoff information includes:

means for receiving from the wireless terminal a handoff request to the adjacent network attachment point via a currently active communication link with the first network attachment point and communicating the request directly to the adjacent network attachment point over a separate communication link; and

means for receiving from the adjacent network attachment point, and communicating back to the wireless terminal via the currently active communication link, assigned dedicated allocated resources including at least one of an identifier and dedicated uplink segments.

24. The network attachment point of claim 23, wherein the broadcast system message is a beacon signal, the wireless terminal determining a timing associated with the assigned dedicated allocated resources based on the beacon signal and predefined timing relationships thereof to the dedicated uplink segments.

25. The network attachment point of claim 24, further comprising means for terminating the currently active communication link prior to a first assigned dedicated allocated resource occurrence to the wireless terminal by the adjacent network attachment point.

26. The network attachment point of claim 25, wherein the request from the wireless terminal for a handoff request wireless terminal is based on the wireless terminal detecting a weak signal strength condition with respect to the currently active communications link with the network attachment point.

27. A method of operating a network attachment point for use in a multi-carrier communication system comprised of at least one wireless terminal in an active communication session with a serving network attachment point, where the active communication is in a first frequency band which is different from a second frequency band associated with the network attachment point for transmitting user data, comprising:

generating a broadcast signal message having a predetermined frequency into the first frequency band on a periodic basis; and

transmitting, responsive to a request from a wireless terminal received from the corresponding serving network attachment point, dedicated system handoff information to the wireless terminal over the active communication session with the serving network attachment point without the wireless terminal establishing a communication session with the network attachment point.

28. The method of claim 27, further comprising detecting a request from the serving network attachment point to initiate a secure communication link over a network therewith.

29. The method of claim 28, further comprising assigning at least one of on-state identifier and hold-state identifier to wireless terminal, reserving resources for the wireless terminal, and transmitting information, including access state information in which the network attachment point has reserved dedicated tone set-up link communication segment for registration by the wireless terminal, this information being communicated to the wireless terminal via the secure communication link with the serving network attachment point.

30. The method of claim 29, further comprising, after termination by the wireless terminal of the active communication session with the serving network attachment point, detecting a wireless terminal registration attempt over the dedicated tone set-up link communication segment in a specified access slot.

31. The method of claim 30, further comprising registering the wireless terminal with the network, including transmitting at least one of timing synchronization and power control signaling to the wireless terminal.

32. The method of claim 31, further comprising detecting successful registration and releasing assigned identifiers and resources to establish an active communications session with the wireless terminal.

33. The method of claim 32, wherein the broadcast system message is a beacon signal having known timing offsets from uplink channel segments for use in a dedicated fashion by the wireless terminal during handoff initiation.

34. The method of claim 33, wherein the multi-carrier communication system is an OFDM system, the wireless terminal is a mobile node, and the network attachment point and the serving network attachment point are base stations.

35. The method of claim 34, wherein the network attachment point and the serving network attachment points are located in a same cell.

36. The method of claim 27, wherein the multi-carrier communication system is an OFDM system, the wireless terminal is a mobile node, and the network attachment point and the serving network attachment point are base stations.

37. The method of claim 36, wherein the network attachment point and the serving network attachment points are located in a same cell.

38. A method of operating a network attachment point for use in a multi-carrier communication system comprised of at least one wireless terminal configured to generate requests to initiate handoff from the network attachment point to an adjacent network attachment point, where the adjacent network attachment point uses different frequency bands to establish communication sessions with the at least one wireless terminal than the frequency band used by the network attachment point, and where the adjacent network attachment point generates broadcast system messages in the frequency band of the network attachment point detectable by a wireless terminal when in an active communication session with the network attachment point to facilitate system handoff, the method comprising:

in response to a request from the wireless terminal to initiate handoff communications between the wireless terminal and the adjacent network attachment point,

exchanging dedicated system handoff information between the adjacent network attachment point and the wireless terminal over the active communication session with the network attachment point without the wireless terminal establishing a communication session with the adjacent network attachment point.

39. The method of claim 38, wherein the exchanging dedicated system handoff information includes receiving from the adjacent network attachment point and passing to the wireless terminal over a currently active communication link between the wireless terminal and the network attachment point, information identifying registration operations to be performed by the wireless terminal after terminating the currently active communication link.

40. The method of claim 39, wherein the broadcast system message is a beacon signal.

41. The method of claim 38, wherein the broadcast system message is a beacon signal.

42. The method of claim 41, wherein the beacon signal includes at least one of a cell identifier and a sector identifier, the receiving a request including the at least one of a cell identifier and a sector identifier.

43. The method of claim 42, wherein the dedicated system handoff information is dedicated airlink resource assignment information associated with the adjacent network attachment point for use by the wireless terminal when performing a system handoff, the information being received in the form of a packet from the adjacent network attachment point to the wireless terminal over a currently active communication link between the wireless terminal and the network attachment point.

44. The method of claim 43, wherein the dedicated airlink resource assignment information comprises information for the wireless terminal to communicate with the adjacent network attachment point over a dedicated resource assigned to the wireless terminal, this resource including a set of tones in an uplink communications segment, the wireless terminal being adapted to identify the set of tones from information received from the adjacent network attachment point via the uplink communications segment and from the information regarding the structure of the communications segment derived from the beacon signal.

45. The method of claim 44, wherein the multi-carrier communication system is an OFDM system, the wireless terminal is a mobile node, and the network attachment point and the adjacent network attachment point are base stations.

46. The method of claim 38, wherein the multi-carrier communication system is an OFDM system, the wireless terminal is a mobile node, and the network attachment point and the adjacent network attachment point are base stations.

47. The method of claim 46, further comprising terminating a currently active communication link between the wireless terminal in response to a request to do so by the wireless terminal which then establishes a new communication link with the adjacent network attachment point, the new communication link being established only after the currently active communication link is terminated and on the basis of system handoff information received from the adjacent network attachment point via the network attachment point.

48. The method of claim 38, wherein the first and adjacent network attachment points are located in a same cell.

49. The method of claim 38, wherein the exchanging dedicated system handoff information includes:

receiving from the wireless terminal a handoff request to the adjacent network attachment point via a currently active communication link with the first network attachment point and communicating the request directly to the adjacent network attachment point over a separate communication link; and

receiving from the adjacent network attachment point, and communicating back to the wireless terminal via the currently active communication link, assigned dedicated allocated resources including at least one of an identifier and dedicated uplink segments.

50. The method of claim 49, wherein the broadcast system message is a beacon signal, the wireless terminal determining a timing associated with the assigned dedicated allocated resources based on the beacon signal and predefined timing relationships thereof to the dedicated uplink segments.

51. The method of claim 50, further comprising terminating the currently active communication link prior to a first assigned dedicated allocated resource occurrence to the wireless terminal by the adjacent network attachment point.

52. The method of claim 51, wherein the request from the wireless terminal for a handoff is based on the wireless terminal detecting a weak signal strength condition with respect to the currently active communications link with the network attachment point.

53. A computer program product for use in a base station to be employed in a multi-carrier communication system comprised of at least one mobile device in an active communication session with a serving base station, where the active communication is in a first frequency band which is different from a second frequency band associated with the base station for transmitting user data, the computer program product including a computer-readable medium having instructions to,

generate a beacon signal having a predetermined frequency into the first frequency band on a periodic basis;

and

transmit, responsive to a request from a wireless terminal received from the corresponding serving base station, dedicated system handoff information to the mobile device over the active communication session with the serving base station without the mobile device establishing a communication session with the base station.

54. The computer program product of claim 53, further comprising an instruction to request from the serving base station to initiate a secure communication link over a network.

55. The computer program product of claim 54, further comprising instructions to assign at least one of on-state identifier and hold-state identifier to the mobile device, reserve resources for the mobile device, and transmit information, including access state information in which the base station has reserved dedicated tone set-up link communication segment for registration by the mobile device, this information being communicated to the mobile device via the secure communication link with the serving base station.

56. The computer program product of claim 55, further comprising, after termination by the mobile device of the active communication session with the serving base station, an instruction to detect a mobile device registration attempt over the dedicated tone set-up link communication segment in a specified access slot.

57. The computer program product of claim 53, further comprising an instruction to register the mobile device with the network, including an instruction to transmit at least one of timing synchronization and power control signaling to the mobile device.

58. The computer program product of claim 57, further comprising instructions to detect successful registration and release assigned identifiers and resources to establish an active communications session with the mobile device.

59. The computer program product of claim 58, wherein the beacon signal has known timing offsets from uplink channel segments for use in a dedicated fashion by the mobile device during handoff initiation.

60. A computer program product for use in a base station to be employed in a multi-carrier communication system comprised of at least one mobile device configured to generate requests to initiate handoff from the base station to an adjacent base station, where the adjacent base station uses different frequency bands to establish communication sessions with the at least one mobile device than the frequency band used by the base station, and where the adjacent base station generates a beacon signal in the frequency band of the base station detectable by a mobile device when in an active communication session with the base station to facilitate system handoff, the computer program product including a computer-readable medium having instructions to,

in response to a request from the mobile device to initiate handoff communications between the mobile device and the adjacent base station, exchange dedicated system handoff information between the adjacent base station and the mobile device over the active communication session with the base station without the mobile device establishing a communication session with the adjacent base station.

61. The computer program product of claim 60, wherein the instruction to exchange dedicated system handoff information includes instructions to receive from the adjacent base station and pass to the mobile device over a currently active communication link between the mobile device and the network base station, information identifying registration operations to be performed by the mobile device after terminating the currently active communication link.

62. The computer program product of claim 61, wherein the beacon signal includes at least one of a cell identifier and a sector identifier, the request to initiate handoff including the at least one of a cell identifier and a sector identifier.

63. The computer program product of claim 62, wherein the dedicated system handoff information is dedicated airlink resource assignment information associated with the adjacent base station for use by the mobile device when performing a system handoff, the information being received in the form of a packet from the adjacent base station to the mobile device over a currently active communication link between the mobile device and the base station.

64. The computer program product of claim 63, wherein the dedicated airlink resource assignment information comprises information for the mobile device to communicate with the adjacent base station over a dedicated resource assigned to the mobile device, this resource including a set of tones in an uplink communications segment, the mobile device being adapted to identify the set of tones from information received from the adjacent base station via the uplink communications segment and from the information regarding the structure of the communications segment derived from the beacon signal.

65. The computer program product of claim 64, further comprising instructions to terminate a currently active communication link between the mobile device in response to a request to do so by the mobile device which then establishes a new communication link with the adjacent base station, the new communication link being established only after the currently active communication link is terminated and on the basis of system handoff information received from the adjacent base station via the base station.

66. The computer program product of claim 65, wherein the base station and adjacent base station are located in a same cell.

67. The computer program product of claim 60, wherein the instruction to exchange dedicated system handoff information includes instructions to:

receive from the mobile device a handoff request to the adjacent base station via a currently active communication link with the base station and communicating the request directly to the adjacent base station over a separate communication link; and

receive from the adjacent base station, and communicating back to the mobile device via the currently active communication link, assigned dedicated allocated resources including at least one of an identifier and dedicated uplink segments.

68. The computer program product int of claim 67, wherein the mobile device determines a timing associated with the assigned dedicated allocated resources based on the beacon signal and predefined timing relationships thereof to the dedicated uplink segments, the computer program product further comprising instructions to terminate the currently active communication link prior to a first assigned dedicated allocated resource occurrence to the mobile device by the adjacent base station.