Method for initiating handoff of a wireless access terminal based on the reverse activity bit

• US 8,107,438 B1
• Filed: 06/18/2008
• Issued: 01/31/2012
• Est. Priority Date: 06/18/2008
• Status: Active Grant

• Current Assignee: Sprint Spectrum LLC (Deutsche Telekom AG)
• Original Assignee: Sprint Spectrum LP (Deutsche Telekom AG)
• Inventors: Singh, Anil, Bhan, Ashish, Sigg, Jason, Singh, Jasinder P., Shah, Maulik K.
• Primary Examiner(s): Shah, Chirag
• Assistant Examiner(s): PERSAUD, AMARNAUTH G
• Application Number:
  US12/141,569
• Time in Patent Office: 1,322 Days
• Field of Search: None
• US Class Current: 370/332
• CPC Class Codes: H04W 36/30 by measured or perceived connection quality data
• CPC Class Codes: H04W 36/302 due to low signal strength
• CPC Class Codes: H04W 56/00 Synchronisation arrangements

Abstract

Methods are disclosed for initiating a handoff of a wireless access terminal based on a set of one or more factors including the determined value of the Reverse Activity Bit (RAB). The set of one or more factors may also further include (i) a determined round-trip delay for a bi-directional communications link between the first wireless access node and the wireless access terminal, wherein the bi-directional communications link comprises a forward link from the first wireless access node to the wireless access terminal and a reverse link from the wireless access terminal to the first wireless access node, and/or (ii) a determined forward-link signal-strength indicator for a forward link from the first wireless access node to the wireless access terminal.

Claims

1. A method comprising:

determining a value for a reverse activity bit (RAB) for a wireless network coverage area, wherein the wireless network coverage area corresponds to a first wireless access node;

determining a round-trip delay for a bi-directional communications link between the first wireless access node and a wireless access terminal, wherein the bi-directional communications link comprises a forward link from the first wireless access node to the wireless access terminal and a reverse link from the wireless access terminal to the first wireless access node; and

initiating a handoff of a wireless access terminal when (i) the determined value of the RAB is equal to one for a defined period of time, and (ii) the determined round-trip delay exceeds a minimum round-trip delay threshold value.

2. The method of claim 1 wherein the handoff is an inter-frequency hard handoff from a first frequency to a second frequency, wherein the first frequency and the second frequency are associated with the first wireless access node.

3. The method of claim 1 wherein the handoff is an inter-frequency hard handoff from a first frequency to a second frequency, wherein the first frequency is associated with the first wireless access node, and wherein the second frequency is associated with a second wireless access node.

4. The method of claim 1 wherein the handoff is a handoff from the first wireless access node to a second wireless access node.

5. The method of claim 1, wherein the determined value of the RAB is equal to zero when measured reverse noise rise (RNR) for the wireless network coverage area is less than a defined RNR threshold, and the determined value of the RAB is equal to one when measured RNR for the wireless network coverage area is equal to or greater than the defined RNR threshold.

6. The method of claim 1, further comprising:

determining a forward-link signal-strength indicator for a forward link from the first wireless access node to the wireless access terminal, and wherein initiating the handoff of the wireless access terminal further comprises;

initiating the handoff when (i) the determined value of the RAB is equal to one for a defined period of time, (ii) the determined forward-link signal-strength indicator is less than a first signal-strength threshold value, and (iii) the determined round-trip delay exceeds a minimum round-trip delay threshold value.

7. The method of claim 1, wherein the first wireless access node initiates the handoff.

8. The method of claim 1, wherein the wireless access terminal initiates the handoff.

9. A method comprising:

determining a round-trip delay for a bi-directional communications link between a first wireless access node and a wireless access terminal in a wireless network coverage area, wherein the bi-directional communications link comprises a forward link from the first wireless access node to the wireless access terminal and a reverse link from the wireless access terminal to the first wireless access node;

determining a forward-link signal-strength indicator for the forward link;

determining a value for a reverse activity bit (RAB) for the wireless network coverage area; and

initiating a handoff based on the determined value of the RAB and a set of one or more factors, the set including the determined round-trip delay and the determined forward-link signal-strength indicator for the forward link.

10. The method of claim 9 wherein the handoff is an inter-frequency hard handoff from a first frequency to a second frequency, wherein the first frequency and the second frequency are associated with the first wireless access node.

11. The method of claim 9 wherein the handoff is an inter-frequency hard handoff from a first frequency to a second frequency, wherein the first frequency is associated with the first wireless access node, and wherein the second frequency is associated with a second wireless access node.

12. The method of claim 9 wherein the handoff is a handoff from the first wireless access node to a second wireless access node.

13. The method of claim 9, wherein the determined value of the RAB is equal to zero when measured reverse noise rise (RNR) for the wireless network coverage area is less than a defined RNR threshold, and the determined value of the RAB is equal to one when measured RNR for the wireless network coverage area is equal to or greater than the defined RNR threshold.

14. The method of claim 9, further comprising:

initiating the handoff when (i) the determined value of the RAB is equal to one for a defined period of time and (ii) (a) the determined round-trip delay exceeds a minimum round-trip delay threshold value and/or (b) the determined forward-link signal-strength indicator is less than a first signal-strength threshold value.

15. The method of claim 9, further comprising:

initiating the handoff when (i) the determined round-trip delay exceeds a minimum round-trip delay threshold, (ii) the determined signal-strength indicator is less than a first signal-strength threshold value, and (iii) the determined value of the RAB is equal to one for a defined period of time.

16. The method of claim 9, further comprising:

initiating the handoff when (i) the determined round-trip delay exceeds a maximum round-trip delay threshold value, (ii) the determined forward-link signal-strength indicator is less than a second signal-strength threshold value, and (iii) the determined value of the RAB is equal to one.

17. The method of claim 9, further comprising:

initiating the handoff when (i) the determined round-trip delay exceeds a maximum round-trip delay threshold value, or (ii) the determined signal-strength indicator is less than a second signal-strength threshold value, or (iii) the determined value of the RAB is equal to one for a defined period of time.

18. A method comprising:

initiating a handoff of a wireless access terminal based on (i) a determined round-trip delay for a bi-directional communications link between a first wireless access node and the wireless access terminal in a wireless network coverage area, wherein the bi-directional communications link comprises a forward link from the first wireless access node to the wireless access terminal and a reverse link from the wireless access terminal to the first wireless access node, (ii) a determined forward-link signal-strength indicator for the forward link, and (iii) a determined value for a reverse activity bit (RAB) for the wireless network coverage area.

19. The method of claim 18 wherein the handoff is an inter-frequency hard handoff from a first frequency to a second frequency, wherein the first frequency and the second frequency are associated with the first wireless access node.

20. The method of claim 18 wherein the handoff is an inter-frequency hard handoff from a first frequency to a second frequency, wherein the first frequency is associated with the first wireless access node, and wherein the second frequency is associated with a second wireless access node.

21. The method of claim 18 wherein the handoff is a handoff from the first wireless access node to a second wireless access node.

22. The method of claim 18, wherein the determined value of the RAB is equal to zero when measured reverse noise rise (RNR) for the wireless network coverage area is less than a defined RNR threshold, and the determined value of the RAB is equal to one when measured RNR for the wireless network coverage area is equal to or greater than the defined RNR threshold.

23. The method of claim 18, further comprising:

initiating the handoff when (i) the determined value of the RAB is equal to one and (ii) (a) the determined round-trip delay exceeds a minimum round-trip delay threshold value and/or (b) the determined signal-strength indicator is less than a first signal-strength threshold value.

24. The method of claim 18, wherein initiating the handoff is performed by one of either the wireless access terminal or the first wireless access node.