VEHICLE TELEMATICS UNIT BACKGROUND SCAN FOR NETWORK SELECTION IN A CELLULAR COMMUNICATION SYSTEM

• US 20110039556A1
• Filed: 08/14/2009
• Published: 02/17/2011
• Est. Priority Date: 08/14/2009
• Status: Abandoned Application

• Current Assignee: General Motors LLC (General Motors Company)
• Original Assignee: General Motors Company
• Inventors: Madhavan, Sethu K., Yi, Ki Hak
• Application Number:
  US12/541,726
• Publication Number:
  US 20110039556A1
• Time in Patent Office: Days
• US Class Current: 455/434
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 48/18 Selecting a network or a communication service
• CPC Class Codes: H04W 60/04 using triggered events
• CPC Class Codes: H04W 76/18 Management of setup rejection or failure

Abstract

A system and method for making vehicle originated calls to a telematics service provider or other call center. The method includes identifying a call type associated with a desired wireless communication of speech or data to the call center, and then carrying out one of a number of different call connection processes depending on the call type. For voice channel cellular connections, an in-band modem cellular connection is preferably established in most instances using a connection retry strategy that includes primary, secondary, and possibly tertiary connection attempts. Cell selection can be carried out using an acquisition task, background scan and inter-country PLMN reselection process that are used to select among available PLMNs and base stations. The system and method can be carried out in connection with various cellular system technologies, but is especially suited for use with GSM systems.

Claims

1. A background scanning method for use by a vehicle telematics unit for network selection in a wireless communication system, comprising the steps of:

(a) determining if the telematics unit has an attached base station and, if not, then attaching to a base station in an available cellular network on which the telematics unit is registered;

(b) starting a timer;

(c) upon expiration of the timer, determining if the registered cellular network is a home cellular network to which the telematics unit is assigned;

(d) maintaining the registration of the telematics unit with the attached base station if the registered cellular network is determined to be the home cellular network;

(e) if the registered cellular network is determined not to be the home cellular network, then determining if there is a more preferred cellular network than the registered cellular network and, if so, carrying out a cellular network reselection process.

2. A background scanning method as defined in claim 1, wherein step (a) further comprises carrying out the network reselection process if the telematics unit does not have an attached base station.

3. A background scanning method as defined in claim 2, wherein carrying out the network reselection process in step (a) further comprises identifying a cellular network that is more preferred than a current cellular network on which the telematics unit is registered.

4. A background scanning method as defined in claim 3, wherein carrying out the network reselection process in step (a) further comprises receiving a BCCH Allocation (BA) list from the more preferred cellular network and scanning the BA list during a standby mode of the telematics unit for an available base station in the more preferred cellular network.

5. A background scanning method as defined in claim 3, wherein the identifying step further comprises using a one or more preferred network lists.

6. A background scanning method as defined in claim 5, wherein the step of using one or more preferred network lists further comprises using at least a user controlled selector list and an operator controlled selector list.

7. A background scanning method as defined in claim 6, wherein the step of using one or more preferred network lists further comprises using a list of cellular networks to which the vehicle telematics unit has previously connected.

8. A background scanning method as defined in claim 7, wherein the step of using a list of cellular networks further comprises maintaining the list as a list of registered PLMNs for which the telematics unit has previously successfully completed an IMSI attach procedure.

9. A background scanning method as defined in claim 1, wherein the step of attaching to a base station in an available cellular network on which the telematics unit is registered further comprises attaching to a base station in a cellular network on which the telematics unit is already registered.

10. A background scanning method as defined in claim 1, wherein the step of attaching to a base station in an available cellular network on which the telematics unit is registered further comprises the steps of changing registration of the telematics unit from a current cellular network to a new cellular network and attaching to a base station in the new cellular network.

11. A background scanning method as defined in claim 10, wherein the step of changing registration further comprises determining that the new cellular network is more preferred than the current cellular network.

12. A background scanning method as defined in claim 11, wherein the step of determining that the new cellular network is more preferred than the current cellular network further comprises determining that the new cellular network is more preferred than the current cellular network using one or more preferred network lists.

13. A background scanning method as defined in claim 1, wherein step (b) further comprises starting a timer having a timeout period greater than one minute.

14. A background scanning method as defined in claim 1, wherein the step of determining if there is a more preferred cellular network further comprises identifying the more preferred cellular network using one or more preferred network lists.

15. A background scanning method as defined in claim 14, wherein the step of using one or more preferred network lists further comprises using at least a user controlled selector list and an operator controlled selector list.

16. A background scanning method as defined in claim 14, wherein the step of using one or more preferred network lists further comprises using a list of cellular networks to which the vehicle telematics unit has previously connected.

17. A background scanning method as defined in claim 16, wherein the step of using a list of cellular networks further comprises maintaining the list as a list of registered PLMNs for which the telematics unit has previously successfully completed an IMSI attach procedure.

18. A background scanning method as defined in claim 1, wherein carrying out the network reselection process in step (e) further comprises receiving a BCCH Allocation (BA) list from the more preferred cellular network and scanning the BA list during a standby mode of the telematics unit for an available base station in the more preferred cellular network.

19. A background scanning method for use by a vehicle telematics unit for network selection in a wireless communication system, comprising the steps of:

(a) determining if the telematics unit has an attached base station and, if not, then attaching to a base station in an available cellular network on which the telematics unit is registered;

(b) starting a timer;

(c) following expiration of the timer, determining if there is a more preferred cellular network than the registered cellular network and, if so, carrying out a cellular network reselection process, wherein the reselection process includes the steps of;

(c1) obtaining a BA list containing BCCHs for various base stations within at least one more preferred cellular network;

(c2) scanning the BCCHs and attaching to a base station for which a decodable BCCH is found.

20. A background scanning method as defined in claim 19, wherein the step of determining if there is a more preferred cellular network further comprises the step of determining if there is at least one available cellular network identified in a preferred network list as having a higher priority than the registered cellular network.