METHODS AND APPARATUS FOR PERFORMING HANDOFF BASED ON THE MOBILITY OF A SUBSCRIBER STATION

• US 20150055627A1
• Filed: 10/06/2014
• Published: 02/26/2015
• Est. Priority Date: 03/21/2007
• Status: Active Grant

• Current Assignee: Cellular Transitions, LLC (Dominion Harbor Enterprises, LLC)
• Original Assignee: Quarterhill Inc. (f/k/a Wi-LAN Inc.)
• Inventors: Robbins, Barry R., Sutton, Todd R.
• Granted Patent: US 9,629,054 B2
• Time in Patent Office: Days
• US Class Current: 370/331
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 36/0094 Definition of hand-off measurement parameters
• CPC Class Codes: H04W 36/324 by mobility data, e.g. speed data
• CPC Class Codes: H04W 88/06 adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals

Abstract

In a wireless communication system, a mobility factor is used to influence handoff. If a subscriber station has been in a low mobility state for some period of time, the system may handoff operation from a first service type to a second service type. If the mobility factor indicates that the subscriber station is moving, the system may handoff operation from the second service type back to the first service type.

Claims

1. A base station configured to communicate with a subscriber station, the base station comprising:

a front end module configured to establish a service with the subscriber station in a licensed spectrum;

a mobility monitoring module configured to determine a first value of a mobility factor indicative of a relative motion of the subscriber station; and

the front end module further configured to transfer the service from the licensed spectrum to a non-licensed spectrum associated with the base station if the first value of the mobility factor indicates that the subscriber station has been in a low mobility state for at least a predetermined period of time.

2. The base station of claim 1, wherein the front end module is further configured to receive the first value of the mobility factor from the subscriber station.

3. The base station of claim 1, wherein at least one value of the mobility factor is based, at least in part, on correlating pilot signals of at least two distinct Orthogonal Frequency Division Multiplex (OFDM) symbols separated by a time offset.

4. The base station of claim 1, wherein at least one value of the mobility factor is based, at least in part, on a change in a frequency offset relative to a desired receive frequency over a time period by determining a product of symbol samples from an Orthogonal Frequency Division Multiplex (OFDM) symbol with corresponding samples from a cyclic prefix from the OFDM symbol.

5. The base station of claim 1, wherein at least one value of the mobility factor is based, at least in part, on a change in an average power of received Orthogonal Frequency Division Multiplex (OFDM) symbols.

6. The base station of claim 1, wherein at least one value of the mobility factor is a composite mobility factor based, at least in part, on a quantized combination of a plurality of distinct mobility factors.

7. The base station of claim 1, wherein at least one value of the mobility factor indicates one of a limited number of discrete mobility states.

8. The base station of claim 1, wherein at least one value of the mobility factor is based, at least in part, on a wireless signal received by the subscriber station.

9. The base station of claim 8, wherein the mobility monitoring module is further configured to determine an operating state based at least in part on information carried on the wireless signal, wherein the at least one value of the mobility factor is based, at least in part, on the operating state.

10. The base station of claim 1, wherein:

the mobility monitoring module is further configured to determine a second value of the mobility factor indicative of the relative motion of the subscriber station; and

the front end module is further configured to transfer the service from the non-licensed spectrum to the licensed spectrum associated with the base station if the second value of the mobility factor indicates that the subscriber station has been in a high mobility state for at least a second predetermined period of time.

11. A method performed by a subscriber station comprising:

establishing a service with a base station in a licensed spectrum;

determining a first value of a mobility factor indicative of a relative motion of the subscriber station communicating using the licensed spectrum;

determining an availability of the service from the base station via a non-licensed spectrum; and

initiating transfer of the service to the non-licensed spectrum associated with the base station if the first value of the mobility factor indicates that the subscriber station has been in a low mobility state for at least a predetermined period of time.

12. The method of claim 11, further comprising:

determining a second value of the mobility factor indicative of the relative motion of the subscriber station communicating using the non-licensed spectrum; and

initiating transfer of the service to the licensed spectrum associated with the base station if the second value of the mobility factor indicates that the subscriber station has been in a high mobility state for at least a second predetermined period of time.

13. A method performed by a subscriber station comprising:

establishing a service with a base station via a non-licensed spectrum;

determining a first value of a mobility factor indicative of a relative motion of the subscriber station communicating using the non-licensed spectrum;

determining an availability of the service from the base station via a licensed spectrum; and

initiating transfer of the service to the licensed spectrum associated with the base station if the first value of the mobility factor indicates that the subscriber station has been in a high mobility state for at least a predetermined period of time.

14. The method of claim 13 further comprising:

determining a second value of the mobility factor indicative of the relative motion of the subscriber station communicating using the licensed spectrum; and

initiating transfer of the service to the non-licensed spectrum associated with the base station if the second value of the mobility factor indicates that the subscriber station has been in a low mobility state for at least a second predetermined period of time.

15. The method of claim 13 further comprising:

transmitting a scan request message to the base station to determine the availability of the service via licensed spectrum.

16. A base station configured to communicate with a subscriber station, the base station comprising:

a front end module configured to establish a service with the subscriber station in a non-licensed spectrum;

a mobility monitoring module configured to determine a first value of a mobility factor indicative of a relative motion of the subscriber station; and

the front end module further configured to transfer the service from the non-licensed spectrum to a licensed spectrum associated with the base station if the first value of the mobility factor indicates that the subscriber station has been in a high mobility state for at least a predetermined period of time.

17. The base station of claim 16, wherein:

the mobility monitoring module is further configured to determine a second value of the mobility factor indicative of the relative motion of the subscriber station; and

the front end module is further configured to transfer the service from the licensed spectrum to the non-licensed spectrum associated with the base station if the second value of the mobility factor indicates that the subscriber station has been in a low mobility state for at least a second predetermined period of time.