Expedited handoff

• US 8,064,401 B2
• Filed: 07/14/2006
• Issued: 11/22/2011
• Est. Priority Date: 07/14/2006
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Laroia, Rajiv, Li, Junyi, Anigstein, Pablo, Srinivasan, Murari
• Primary Examiner(s): Corsaro; Nick
• Assistant Examiner(s): PATEL, MAHENDRA R
• Application Number:
  US11/486,712
• Publication Number:
  US 20080013489A1
• Time in Patent Office: 1,957 Days
• Field of Search: 455/436, 455/439, 455/562, 455/448, 455/450, 455/561, 455/452, 455/447, 370/331, 370/395, 370/342, 370/328, 370/332, 370/330, 342/357
• US Class Current: 370/331
• CPC Class Codes: H04W 36/06 Reselecting a communication resource in the serving access point

Abstract

Systems and methodologies are described that facilitate handing off from a first sector to a second sector. An established link to the first sector may be employed to communicate with the second sector. A handoff request from a wireless terminal to the second sector and an associated handoff response from the second sector to the wireless terminal may both traverse the first sector.

Claims

1. A method of handing off from a first sector to a second sector, comprising:

detecting a signal emanating from the second sector;

deriving a connection identifier associated with the second sector based upon the detected signal;

sending a handoff request that is received by the second sector, wherein the handoff request is sent via a first link with the first sector, wherein the handoff request comprises the derived connection identifier, and wherein the derived connection identifier identifies the second sector to the first sector;

receiving a handoff response from the second sector through the first link and the first sector, wherein the handoff response includes identified information, wherein the identified information includes an index of an allocated access slot, wherein the allocated access slot is a portion of an access channel that is reserved for handoff, and wherein the handoff response indicates whether access request, access grant, and access exchange operations should be performed; and

establishing a second link with the second sector utilizing the identified information.

2. The method of claim 1, wherein the identified information further comprises at least one of timing related information, a session ON ID, an active ID, a destination MAC state and a time period during which an assigned ID is valid.

3. The method of claim 1, further comprising:

sending an access signal in the access slot to the second sector;

receiving an access grant message from the second sector, the access grant message including at least a timing correction command;

adjusting a transmitter symbol timing as a function of the timing correction command; and

sending signals to the second sector using the transmitter symbol timing.

4. The method of claim 3, wherein the access slot is a dedicated access resource and cannot be used by a disparate access terminal.

5. The method of claim 3, further comprising:

transmitting an uplink access exchange to the second sector;

receiving a downlink access exchange from the second sector, wherein at least one of the uplink access exchange and the downlink access exchange conveys an identifier; and

using the identifier in the second link.

6. The method of claim 1, wherein the identified information includes an identifier, the method further comprising using the identifier in the second link.

7. The method of claim 1, further comprising breaking the first link with the first sector prior to establishing the second link with the second sector.

8. The method of claim 1, further comprising:

selecting a random access slot;

sending an access signal in the random access slot to the second sector;

receiving an access grant message from the second sector, the access grant message including at least a timing correction command;

adjusting a transmitter symbol timing as a function of the timing correction command;

sending an uplink access exchange to the second sector using the transmitter symbol timing, wherein the uplink access exchange conveys at least part of the identified information; and

receiving a downlink access exchange from the second sector.

9. The method of claim 8, wherein the identified information includes a time period during which an assigned ID is valid, the random access slot being associated with a time prior to an end of the time period during which the assigned ID is valid.

10. The method of claim 1, further comprising:

recording a transmitter symbol timing associated with the first link; and

using the transmitter symbol timing in the second link.

11. A wireless communications apparatus, comprising:

a memory that retains instructions for handing off from a first sector to a second sector; and

a processor that detects a signal associated with a second sector, derives a connection identifier associated with the second sector based upon the detected signal, transmits a handoff request that is received by the second sector, wherein the handoff request is sent via a first link with the first sector, wherein the handoff request comprises the derived connection identifier, wherein the derived connection identifier identifies the second sector to the first sector, wherein the processor also receives a handoff response from the second sector via the first link and the first sector, and creates a second link with the second sector based upon identified information included in the handoff response, wherein the identified information includes an index of an allocated access slot, wherein the allocated access slot is a portion of an access channel that is reserved for handoff, and wherein the handoff response indicates whether access request, access grant, and access exchange operations should be performed.

12. The wireless communications apparatus of claim 11, wherein the identified information further comprises at least one of timing related information, a session ON ID, an active ID, a destination MAC state and a time period during which an assigned ID is valid.

13. The wireless communications apparatus of claim 11, wherein the processor further transmits an access signal in the allocated access slot to the second sector, receives an access grant message from the second sector including at least a timing correction command, alters a transmitter symbol timing base at least in part upon the timing correction command, and transmits signals to the second sector using the transmitter symbol timing.

14. A wireless communications apparatus for mitigating delay associated with handing off from a first sector to a second sector, comprising:

means for detecting a signal emanating from the second sector;

means for deriving a connection identifier associated with the second sector based upon the detected signal;

means for transmitting a handoff request that is received by the second sector, wherein the handoff request is sent via a first link with the first sector, wherein the handoff request comprises the derived connection identifier, and wherein the derived connection identifier identifies the second sector to the first sector;

means for receiving a handoff response from the second sector through the first link and the first sector, wherein the handoff response includes identified information, wherein the identified information includes an index of an allocated access slot, wherein the allocated access slot is a portion of an access channel that is reserved for handoff, and wherein the handoff response indicates whether access request, access grant, and access exchange operations should be performed; and

means for establishing a second link with the second sector.

15. The wireless communications apparatus of claim 14, further comprising:

means for establishing the second link with the second sector with a contention-free access.

16. The wireless communications apparatus of claim 14, wherein the identified information further comprises at least one of timing related information, a session ON ID, an active ID, a destination MAC state and a time period during which an assigned ID is valid.

17. The wireless communications apparatus of claim 14, further comprising:

means for transmitting an access signal in the allocated access slot to the second sector;

means for obtaining an access grant message from the second sector, the access grant message includes at least a timing correction command;

means for adjusting a transmitter symbol timing as a function of the timing correction command; and

means for transmitting signals to the second sector using the transmitter symbol timing.

18. A non-transitory machine-readable medium having stored thereon machine-executable instructions for:

receiving a beacon associated with a second sector;

deriving a connection identifier associated with the second sector based upon the received beacon;

transmitting a handoff request that is received by the second sector, wherein the handoff request is routed through a first link with a first sector, wherein the handoff request comprises the derived connection identifier, and wherein the derived connection identifier identifies the second sector to the first sector;

obtaining a handoff response from the second sector routed through the first link and the first sector, wherein the handoff response includes identified information, wherein the identified information includes an index of an allocated access slot, wherein the allocated access slot is a portion of an access channel that is reserved for handoff, and wherein the handoff response indicates whether access request, access grant, and access exchange operations should be performed; and

creating a second link with the second sector by utilizing the identified information.

19. The machine-readable medium of claim 18, wherein the identified information further comprises at least one of timing related information, a session ON ID, an active ID, a destination MAC state and a time period during which an assigned ID is valid.

20. The machine-readable medium of claim 19, wherein the allocated access slot is a dedicated access resource and disparate wireless terminals are inhibited from utilizing the allocated access slot.

21. A processor that executes the following instructions:

detecting a signal related to a second sector;

deriving a connection identifier associated with the second sector based upon the detected signal;

sending an expedited handoff request that is received by the second sector, wherein the handoff request is sent via a first link with a first sector, wherein the handoff request comprises the derived connection identifier, and wherein the derived connection identifier identifies the second sector to the first sector;

receiving a handoff response that includes identified information from the second sector via the first link and the first sector, wherein the identified information includes an index of an allocated access slot, wherein the allocated access slot is a portion of an access channel that is reserved for handoff, and wherein the handoff response indicates whether access request, access grant, and access exchange operations should be performed; and

establishing a second link with the second sector utilizing the identified information.

22. The processor of claim 21 that further executes the following instructions:

transmitting an access request in the access slot to the second sector;

receiving an access grant from the second sector, the access grant including at least a timing correction command;

modifying a transmitter symbol timing based at least in part upon the timing correction command; and

sending signals to the second sector using the transmitter symbol timing.

23. The processor of claim 21, wherein the identified information further comprises at least one of timing related information, a session ON ID, an active ID, a destination MAC state and a time period during which an assigned ID is valid.

24. A method that facilitates allocating resources to a wireless terminal to mitigate handoff delay, comprising:

receiving, by a second sector, a handoff request from a wireless terminal via a first sector, wherein the handoff request comprises a connection identifier that identifies the second sector to the first sector;

allocating resources to the wireless terminal;

transmitting a handoff response that includes identified information related to the allocated resources, wherein the identified information includes an index of an allocated access slot, wherein the allocated access slot is a portion of an access channel that is reserved for handoff, and wherein the handoff response indicates whether access request, access grant, and access exchange operations should be performed; and

establishing a link with the wireless terminal by employing the allocated resources.

25. The method of claim 24, wherein the identified information further comprises at least one of timing related information, a session ON ID, an active ID, a destination MAC state and a time period during which an assigned ID is valid.

26. The method of claim 24, wherein establishing the link with the wireless terminal further comprises:

receiving an access request message in the allocated access slot from the wireless terminal;

transmitting an access grant message to the wireless terminal that includes at least a timing correction command; and

receiving signals from the wireless terminal adjusted based upon the timing correction command.

27. The method of claim 26, wherein the allocated access slot is dedicated to the wireless terminal.

28. The method of claim 26, further comprising:

receiving an uplink access exchange from the wireless terminal; and

transmitting a downlink access exchange to the wireless terminal, wherein at least one of the uplink access exchange and the downlink access exchange includes an identifier.

29. The method of claim 24, further comprising synchronizing the wireless terminal while establishing the link.

30. The method of claim 24, further comprising:

receiving an access signal in a random access slot;

transmitting an access grant message to the wireless terminal, the access grant message includes at least a timing correction command;

receiving an uplink access exchange from the wireless terminal, the uplink access exchange being synchronized based upon the timing correction command and includes at least part of the identified information; and

transmitting a downlink access exchange to the wireless terminal.

31. The method of claim 30, wherein the random access slot is earlier than the allocated access slot.

32. A wireless communications apparatus comprising a first sector, comprising:

a memory that retains an identifier related to a wireless terminal; and

a processor that receives a handoff request from the wireless terminal, wherein the handoff request comprises a connection identifier that identifies a second sector to the first sector, wherein the processor incorporates the identifier related to the wireless terminal in the handoff request, routes the handoff request to the second sector, receives a handoff response from the second sector, and forwards the handoff response to the wireless terminal, and wherein the handoff response indicates whether access request, access grant, and access exchange operations should be performed.

33. The wireless communications apparatus of claim 32, wherein the processor routes the handoff request based at least in part upon the connection identifier.

34. A wireless communications apparatus for allocating resources to a wireless terminal for utilization in connection with a handoff, comprising:

means for obtaining, by a second sector, a handoff request from a wireless terminal through a first sector, wherein the handoff request comprises a connection identifier that identifies the second sector to the first sector;

means for allocating resources to the wireless terminal;

means for sending identified information associated with the allocated resources in a handoff response to the wireless terminal via the first sector, wherein the identified information includes an index of an allocated access slot, wherein the allocated access slot is a portion of an access channel that is reserved for handoff, and wherein the handoff response indicates whether access request, access grant, and access exchange operations should be performed; and

means for establishing a link with the wireless terminal utilizing the allocated resources.

35. The wireless communications apparatus of claim 34, further comprising:

means for receiving an access signal in the allocated access slot from the wireless terminal;

means for transmitting an access grant message to the wireless terminal, the access grant message including at least a timing correction command; and

means for receiving signals from the wireless terminal, the signals being modified based upon the timing correction command.

36. The wireless communications apparatus of claim 34, wherein the identified information further comprises at least one of timing related information, a session ON ID, an active ID, a destination MAC state and a time period during which an assigned ID is valid.

37. A non-transitory machine-readable medium having stored thereon machine-executable instructions for:

receiving, by a second sector, a handoff request in response to a beacon from a wireless terminal via a first sector, wherein the handoff request comprises a connection identifier that identifies the second sector to the first sector;

allocating resources to the wireless terminal;

transmitting identified information associated with the resources in a handoff response to the wireless terminal through the disparate sector, wherein the identified information includes an index of an allocated access slot, wherein the allocated access slot is a portion of an access channel that is reserved for handoff, and wherein the handoff response indicates whether access request, access grant, and access exchange operations should be performed; and

creating a link with the wireless terminal employing the resources.

38. The machine-readable medium of claim 37, wherein the identified information further comprises at least one of timing related information, a session ON ID, an active ID, a destination MAC state and a time period during which an assigned ID is valid.

39. The machine-readable medium of claim 38, wherein the allocated access slot is dedicated to the wireless terminal.

40. A processor for a first sector that executes the following instructions:

receiving a handoff request for a second sector from a wireless terminal, wherein the handoff request comprises a connection identifier that identifies the second sector to the first sector;

incorporating an identifier related to the wireless terminal in the handoff request;

routing the handoff request to the second sector;

receiving a handoff response for the wireless terminal from the second sector; and

transmitting the handoff response to the wireless terminal, wherein the handoff response indicates whether access request, access grant, and access exchange operations should be performed.

41. The processor of claim 40 that further executes the following:

routing the handoff request to the second sector based upon the connection identifier.

42. The processor of claim 40 that further executes the following:

determining the identifier related to the wireless terminal.