Primary connection strategy for vehicle originated cellular communication to a call center
View Patent ↗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. The system and method can be carried out in connection with various cellular system technologies, but is especially suited for use with GSM systems.
1. A connection method for use by a vehicle telematics unit to establish a wireless telephone connection between the telematics unit and a call center, comprising the steps of:
(a) verifying that the vehicle telematics unit is in communication with an attached base station;
(b) attempting to originate a connection with the call center using the attached base station; and
(c) if the origination attempt fails, then the method further comprises the steps of:
(c1) identifying a neighboring base station using a base station list received from the attached base station;
(c2) attempting to attach to the identified base station and, if successful, attempting to originate the connection with the call center over the identified base station; and
(c3) iteratively repeating steps (c1) and (c2) until either a successful origination occurs or steps (c1) and (c2) have been carried out for each neighboring base station on the base station list.
2. A connection method as defined in claim 1 , wherein step (b) further comprises attempting to originate the connection as a voice channel data connection.
3. A connection method as defined in claim 2 , wherein, if the origination attempt in step (c) fails, then the method further comprises attempting to originate the connection with the call center using an alternative connection strategy.
4. A connection method as defined in claim 2 , wherein the alternative connection strategy includes the step of establishing a packet switched data connection.
5. A connection method as defined in claim 1 , wherein step (a) further comprises the steps of:
determining that the telematics unit is not currently attached to a base station; and
executing an idle mode process involving cell reselection and attaching to a base station following cell reselection.
6. A connection method as defined in claim 1 , wherein the method is carried out using a GSM cellular system and wherein steps (c1) and (c2) further comprise receiving and decoding base station information via a broadcast control channel (BCCH) and attempting to originate the connection using the decoded information.
7. A connection method as defined in claim 6 , wherein step (c1) further comprises obtaining a BCCH Allocation (BA) list and identifying the neighboring base station from the BA list.
8. A connection method as defined in claim 6 , wherein step (c1) further comprises obtaining connection information for the neighboring base station from the BA list.
9. A connection method as defined in claim 1 , further comprising the steps of:
receiving a PLMN change event interrupt;
carrying out a PLMN reselection process based on the interrupt; and
attaching to a base station following PLMN reselection.
10. A connection method as defined in claim 9 , wherein the step of carrying out a PLMN reselection process further comprises the step of executing an idle mode process involving PLMN reselection.