Vehicle telematics connection retry

A method of re-establishing a cellular connection between a vehicle telematics unit and a wireless carrier system includes detecting a loss of cellular connection between a vehicle telematics unit and a wireless carrier system; accessing a technology order table (TOT) that orders a plurality of radio access technologies (RATs) capable of use at the vehicle telematics unit according to desirability; attempting to re-establish the cellular connection by: determining the RAT used by the vehicle telematics unit when the loss of cellular connection was detected; searching the TOT to locate a less desirable RAT relative to the RAT used by the vehicle telematics unit when the loss of cellular connection was detected; attempting to connect with the wireless carrier system using the less desirable RAT and a group of PLMNs that is limited to home and home-equivalent PLMNs; and if that attempt fails, attempting to connect with the wireless carrier system by iterating through each of the RATs ordered in the TOT beginning with a next less desirable RAT and including in the iteration the RAT used by the vehicle telematics unit when the loss of cellular connection was detected, wherein step (c4) uses all non-forbidden PLMNs.

TECHNICAL FIELD

The disclosure relates to vehicle telematics units and more specifically how vehicle telematics units attempt to re-establish wireless communications with a wireless carrier system.

BACKGROUND

Wireless devices, such as cellular telephones, are commonly found in a variety of applications. In the past, cellular telephones have usually operated using only one of several cellular protocols, such as CDMA or GSM. However, more recent cellular telephone designs include cellular chipsets capable of communicating using two or more different cellular protocols so that a single device can operate on more than one cellular network. These cellular telephones are sometimes referred to as multimode phones.

Cellular or multimode telephone applications include handheld cellular telephones as well as vehicle telematics units. Yet, regardless of whether cellular telephones are used in handheld or vehicular environments, each cellular telephone application is often implemented using similar software/hardware, such as a common cellular chipset. Given that cellular/multimode telephones are used in handheld applications more frequently than vehicular applications, cellular/multimode telephone software/hardware is often optimized for handheld operation. However, this cellular/multimode telephone software/hardware can be used in a vehicle telematics unit, which may operate the software/hardware despite the handheld bias of the cellular telephone software/hardware. It can be helpful to design and implement applications for controlling the software/hardware that compensates for the handheld bias.

SUMMARY

According to an embodiment, there is provided a method of re-establishing a cellular connection between a vehicle telematics unit and a wireless carrier system. The method includes detecting a loss of cellular connection between a vehicle telematics unit and a wireless carrier system; accessing a technology order table (TOT) that orders a plurality of radio access technologies (RATs) capable of use at the vehicle telematics unit according to desirability; attempting to re-establish the cellular connection by: determining the RAT used by the vehicle telematics unit when the loss of cellular connection was detected; searching the TOT to locate a less desirable RAT relative to the RAT used by the vehicle telematics unit when the loss of cellular connection was detected; attempting to connect with the wireless carrier system using the less desirable RAT and a group of PLMNs that is limited to home and home-equivalent PLMNs; and if that attempt fails, attempting to connect with the wireless carrier system by iterating through each of the RATs ordered in the TOT beginning with a next less desirable RAT and including in the iteration the RAT used by the vehicle telematics unit when the loss of cellular connection was detected, wherein step (c4) uses all non-forbidden PLMNs.

According to another embodiment, there is provided a method of re-establishing a cellular connection between a vehicle telematics unit and a wireless carrier system. The method includes detecting a loss of cellular connection between a vehicle telematics unit and a wireless carrier system; defining a re-connection period, during which time the vehicle telematics unit will attempt reconnection to the wireless carrier system, by the length of time a vehicle battery can provide power to the vehicle telematics unit; accessing a technology order table (TOT) that orders a plurality of radio access technologies (RATs) capable of use at the vehicle telematics unit according to desirability; attempting to re-establish the cellular connection by: determining the RAT used by the vehicle telematics unit when the loss of cellular connection was detected; searching the TOT to locate a less desirable RAT relative to the RAT used by the vehicle telematics unit when the loss of cellular connection was detected; attempting to connect with the wireless carrier system using the less desirable RAT and a group of PLMNs that is limited to home and home-equivalent PLMNs; and attempting to connect with the wireless carrier system by iterating through each of the RATs ordered in the TOT beginning with a next less desirable RAT and including in the iteration the RAT used by the vehicle telematics unit when the loss of cellular connection was detected until the re-connection period ends.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

The system and method described below re-establishes cellular communications between a vehicle telematics unit and a wireless carrier system according to unique ordered combinations of radio access technologies (RATs) and public land mobile networks (PLMNs). The retry process can also control the cellular band(s) within which portions of the method are carried out. After detecting that cellular communications have failed or that the vehicle telematics unit is no longer “camped on” a base station of a wireless carrier system, the method can the change the RAT used by the vehicle telematics unit in a particular order that is found in a technology order table (TOT) and open the number of PLMNs to be searched to include home and home-equivalent networks. And if the vehicle telematics unit is still unable to establish cellular communications, the unit can then begin searching all non-forbidden PLMNs using different RATs in the TOT. While handheld wireless devices using cellular protocols attempt to re-establish cellular communication over a relatively short time frame (e.g., 30 seconds), vehicle telematics units can benefit from a lengthier and more detailed process for re-establishing cellular communications as is described in the present method. This lengthier process can be more than five minutes and possibly continue until the battery of the vehicle no longer is able to support it.

Furthermore, the determination of whether or not the vehicle telematics unit has successfully re-established cellular communications can be determined using a software application located apart from the instructions found in a cellular chipset of the vehicle telematics unit. This arrangement can provide more a sophisticated monitoring and direction of the status of cellular communications. For example, cellular chipsets can measure successful cellular communications as the ability to successfully transmit an SMS message. While, this may indicate that the SMS message has been sent successfully, the transmission of the SMS may be interrupted by a problem somewhere in the communication infrastructure used by the wireless carrier system. In that case, the cellular chipset concludes cellular communications are successful even though the SMS message may not arrive at its destination. In contrast, using a software application located apart from the cellular chipset can monitor not only successful transmissions from the vehicle telematics unit and cellular chipset but also for responses to the SMS message. When SMS messages are successfully sent, the software application can monitor when a response has been successfully received in response to the SMS message and determine that cellular communications have been re-established. Or the software application can determine that too much time has passed without receiving a response to the SMS message and determine that a failure has occurred. Thus, the software application located apart from the cellular chipset carries out more sophisticated communication monitoring than the instructions used at the cellular chipset itself.

With reference toFIG. 1, there is shown an operating environment that comprises a mobile vehicle communications system10and that can be used to implement the method disclosed herein. Communications system10generally includes a vehicle12, one or more wireless carrier systems14, a land communications network16, a computer18, and a call center20. It should be understood that the disclosed method can be used with any number of different systems and is not specifically limited to the operating environment shown here. Also, the architecture, construction, setup, and operation of the system10and its individual components are generally known in the art. Thus, the following paragraphs simply provide a brief overview of one such communications system10; however, other systems not shown here could employ the disclosed method as well.

Vehicle12is depicted in the illustrated embodiment as a passenger car, but it should be appreciated that any other vehicle including motorcycles, trucks, sports utility vehicles (SUVs), recreational vehicles (RVs), marine vessels, aircraft, etc., can also be used. Some of the vehicle electronics28is shown generally inFIG. 1and includes a telematics unit30, a microphone32, one or more pushbuttons or other control inputs34, an audio system36, a visual display38, and a GPS module40as well as a number of vehicle system modules (VSMs)42. Some of these devices can be connected directly to the telematics unit such as, for example, the microphone32and pushbutton(s)34, whereas others are indirectly connected using one or more network connections, such as a communications bus44or an entertainment bus46. Examples of suitable network connections include a controller area network (CAN), a media oriented system transfer (MOST), a local interconnection network (LIN), a local area network (LAN), and other appropriate connections such as Ethernet or others that conform with known ISO, SAE and IEEE standards and specifications, to name but a few.

According to one embodiment, telematics unit30utilizes cellular communication according to either GSM or CDMA standards and thus includes a standard cellular chipset50for voice communications like hands-free calling, a wireless modem for data transmission, an electronic processing device52, one or more digital memory devices54, and a dual antenna56. It should be appreciated that the modem can either be implemented through software that is stored in the telematics unit and is executed by processor52, or it can be a separate hardware component located internal or external to telematics unit30. The modem can operate using any number of different standards or protocols such as EVDO, CDMA, GPRS, EDGE, WCDMA, and LTE. These different standards can also be referred to as radio access technologies (RATs) Wireless networking between the vehicle and other networked devices can also be carried out using telematics unit30. For this purpose, telematics unit30can be configured to communicate wirelessly according to one or more wireless protocols, such as any of the IEEE 802.11 protocols, WiMAX, or Bluetooth. When used for packet-switched data communication such as TCP/IP, the telematics unit can be configured with a static IP address or can set up to automatically receive an assigned IP address from another device on the network such as a router or from a network address server.

Apart from the audio system36and GPS module40, the vehicle12can include other vehicle system modules (VSMs)42in the form of electronic hardware components that are located throughout the vehicle and typically receive input from one or more sensors and use the sensed input to perform diagnostic, monitoring, control, reporting and/or other functions. Each of the VSMs42is preferably connected by communications bus44to the other VSMs, as well as to the telematics unit30, and can be programmed to run vehicle system and subsystem diagnostic tests. As examples, one VSM42can be an engine control module (ECM) that controls various aspects of engine operation such as fuel ignition and ignition timing, another VSM42can be a powertrain control module that regulates operation of one or more components of the vehicle powertrain, and another VSM42can be a body control module that governs various electrical components located throughout the vehicle, like the vehicle's power door locks and headlights. According to one embodiment, the engine control module is equipped with on-board diagnostic (OBD) features that provide myriad real-time data, such as that received from various sensors including vehicle emissions sensors, and provide a standardized series of diagnostic trouble codes (DTCs) that allow a technician to rapidly identify and remedy malfunctions within the vehicle. As is appreciated by those skilled in the art, the above-mentioned VSMs are only examples of some of the modules that may be used in vehicle12, as numerous others are also possible.

Vehicle electronics28also includes a number of vehicle user interfaces that provide vehicle occupants with a means of providing and/or receiving information, including microphone32, pushbuttons(s)34, audio system36, and visual display38. As used herein, the term ‘vehicle user interface’ broadly includes any suitable form of electronic device, including both hardware and software components, which is located on the vehicle and enables a vehicle user to communicate with or through a component of the vehicle. Microphone32provides audio input to the telematics unit to enable the driver or other occupant to provide voice commands and carry out hands-free calling via the wireless carrier system14. For this purpose, it can be connected to an on-board automated voice processing unit utilizing human-machine interface (HMI) technology known in the art. The pushbutton(s)34allow manual user input into the telematics unit30to initiate wireless telephone calls and provide other data, response, or control input. Separate pushbuttons can be used for initiating emergency calls versus regular service assistance calls to the call center20. Audio system36provides audio output to a vehicle occupant and can be a dedicated, stand-alone system or part of the primary vehicle audio system. According to the particular embodiment shown here, audio system36is operatively coupled to both vehicle bus44and entertainment bus46and can provide AM, FM and satellite radio, CD, DVD and other multimedia functionality. This functionality can be provided in conjunction with or independent of the infotainment module described above. Visual display38is preferably a graphics display, such as a touch screen on the instrument panel or a heads-up display reflected off of the windshield, and can be used to provide a multitude of input and output functions. Various other vehicle user interfaces can also be utilized, as the interfaces ofFIG. 1are only an example of one particular implementation.

The vehicle12as well as the vehicle electronics28are powered by a vehicle battery58. The vehicle battery58can take a variety of forms, such as those of a lead-acid design or lithium-ion design. In the past, vehicle battery58has been rated to provide approximately 12 volts (V) but in the future automotive manufacturers anticipate increasing the voltage output of the vehicle battery58to 40-50 V.

Wireless carrier system14is preferably a cellular telephone system that includes a plurality of cell towers70(only one shown), one or more mobile switching centers (MSCs)72, as well as any other networking components required to connect wireless carrier system14with land network16. Each cell tower70includes sending and receiving antennas and a base station, with the base stations from different cell towers being connected to the MSC72either directly or via intermediary equipment such as a base station controller. Cellular system14can implement any suitable communications technology, including for example, analog technologies such as AMPS, or the newer digital technologies such as CDMA (e.g., CDMA2000 or 3G) or any one of GSM, GPRS, WCDMA, HSPA+, and LTE. These technologies can also be referred to as radio access technologies (RATs). As will be appreciated by those skilled in the art, various cell tower/base station/MSC arrangements are possible and could be used with wireless system14. For instance, the base station and cell tower could be co-located at the same site or they could be remotely located from one another, each base station could be responsible for a single cell tower or a single base station could service various cell towers, and various base stations could be coupled to a single MSC, to name but a few of the possible arrangements.

Computer18can be one of a number of computers accessible via a private or public network such as the Internet. Each such computer18can be used for one or more purposes, such as a web server accessible by the vehicle via telematics unit30and wireless carrier14. Other such accessible computers18can be, for example: a service center computer where diagnostic information and other vehicle data can be uploaded from the vehicle via the telematics unit30; a client computer used by the vehicle owner or other subscriber for such purposes as accessing or receiving vehicle data or to setting up or configuring subscriber preferences or controlling vehicle functions; or a third party repository to or from which vehicle data or other information is provided, whether by communicating with the vehicle12or call center20, or both. A computer18can also be used for providing Internet connectivity such as DNS services or as a network address server that uses DHCP or other suitable protocol to assign an IP address to the vehicle12.

Call center20is designed to provide the vehicle electronics28with a number of different system back-end functions and, according to the exemplary embodiment shown here, generally includes one or more switches80, servers82, databases84, live advisors86, as well as an automated voice response system (VRS)88, all of which are known in the art. These various call center components are preferably coupled to one another via a wired or wireless local area network90. Switch80, which can be a private branch exchange (PBX) switch, routes incoming signals so that voice transmissions are usually sent to either the live adviser86by regular phone or to the automated voice response system88using VoIP. The live advisor phone can also use VoIP as indicated by the broken line inFIG. 1. VoIP and other data communication through the switch80is implemented via a modem (not shown) connected between the switch80and network90. Data transmissions are passed via the modem to server82and/or database84. Database84can store account information such as subscriber authentication information, vehicle identifiers, profile records, behavioral patterns, and other pertinent subscriber information. Data transmissions may also be conducted by wireless systems, such as 802.11x, GPRS, and the like. Although the illustrated embodiment has been described as it would be used in conjunction with a manned call center20using live advisor86, it will be appreciated that the call center can instead utilize VRS88as an automated advisor or, a combination of VRS88and the live advisor86can be used.

Turning now toFIG. 2, there is shown a method200of re-establishing a cellular connection between the vehicle telematics unit30and the wireless carrier system14. The method200begins at step210by detecting a loss of a cellular connection between the vehicle telematics unit30and the wireless carrier system14. When the vehicle telematics unit30attaches to a cell tower70of the wireless carrier system14, the unit30can be considered to have established a cellular connection or “camped on” the cell tower70. Similarly, when the vehicle telematics unit30loses the connection such that the unit30is no longer camped on the cell tower70, the unit30can be determined to have lost a cellular connection. The vehicle telematics unit30can attempt to re-establish the lost cellular connection by changing one or more cellular variables. These cellular variables include the radio access technology (RAT) used to establish the cellular connection and the PLMN through which the cellular connection is made. Each cellular connection can be determined to have a particular RAT and/or a particular PLMN. In one example, the initially established cellular connection can be a packet-data connection between the vehicle telematics unit30and the wireless carrier system14that has been established using a primary access point name (APN). APNs can identify the back office facility (e.g., computer18) or call center20that the vehicle telematics unit30is contacting as well as various settings used to govern communications between the unit30and the computer18/call center20. In some cases, two different APNs can be used to identify one recipient, such as the computer18/call center20. The two different APNs can be referred to as a primary APN and a secondary APN. When the initial cellular connection via the primary APN fails, the vehicle telematics unit30can use the secondary APN to re-establish cellular communications. The vehicle telematics unit30can detect that it is no longer camped on or registered with the cell tower70it once was. This can be detected when the vehicle telematics unit30periodically attempts to maintain its registration with the cell tower70or when the unit30attempts to establish a cellular telephone connection with the wireless carrier system14. After determining that the cellular connection is lost (or similarly registration is lost), the vehicle telematics unit30can begin re-establishing the connection. The method200proceeds to step220.

At step220, a technology order table (TOT) is accessed. Once the vehicle telematics unit30detects the loss of cellular connection, it can begin identifying cellular variables to change before attempting to re-establish cellular communication. The TOT orders a plurality of RATs capable of use at the vehicle telematics unit30. For instance, the TOT can be stored as data in a memory device54located at the vehicle12. The processor52of the vehicle telematics unit30can access and read the data from the TOT that identifies each RAT. Examples of RATs that can be used by the vehicle telematics unit30and included in the TOT include GSM, GPRS, WCDMA, HSPA+, and LTE, to name a few. The ordering of the TOT can be based on how desirable each RAT is relative to the other RATs. In one example, LTE can be the most desirable RAT, so it can be ranked the highest in the TOT. A less desirable RAT can be WCDMA, and a next less desirable RAT can be GSM. That is, LTE, WCDMA, and GSM can be ranked first, second, and third, respectively, with regard to how desirable the RAT is, from most desirable to least desirable. While this example of the TOT is described using LTE, WCDMA, and GSM, it should be appreciated that other combinations of RATs capable of being used by the vehicle telematics unit30may also be used. In one implementation, the TOT can use a circular queue that orders the RATs with respect to their desirability and the iterates through the queue or list such that the TOT outputs a particular order of RATs without disruption of this order. In other words, the circular queue would not be able to jump from the most desirable RAT to the third most desirable RAT by skipping the second most desirable RAT. It should be appreciated that the selection of RATs in the TOT occurs manually away from the internal decision making of the cellular chipset. The method200proceeds to step220.

At step230, the vehicle telematics unit30attempts to re-establish the cellular connection. First, the method200determines the RAT used by the vehicle telematics unit30when the loss of cellular connection was detected. For instance, the vehicle telematics unit30can determine the RAT as well as the PLMN used when cellular communication was lost. In one example, the vehicle telematics unit30could have been using LTE. In that case, the vehicle telematics unit30could recognize on its own that it is (or was) communicating using LTE. And as part of communicating with the cell tower70, the vehicle telematics unit30can receive a network code indicating the identity of the particular PLMN used. The vehicle telematics unit30can store this code as a most-recently used PLMN and access it when needed.

At step240, the TOT is searched to locate a less desirable RAT relative to the RAT used by the vehicle telematics unit30when the loss of cellular connection was detected and an attempt is made to connect with the wireless carrier system14using the less desirable RAT and a group of PLMNs that is limited to home and home-equivalent PLMNs. The method200can locate a less desirable RAT because may know that service has already been lost using the more-desirable RAT. Thus, the less desirable RAT may increase chances of connection. After the vehicle telematics unit30has determined that the cellular connection has been lost, both the RAT used for re-establishing communication and the scope of the PLMNs used change. Using the example above in which the vehicle telematics unit30had been communicating using LTE, the telematics unit30then identifies a different RAT to use when re-establishing communications and opens the possible PLMN selection to not only the last PLMN used but to any PLMN that is considered a home network or a home-equivalent network. Here, a home network is a wireless carrier system14that provides a cellular subscription to the vehicle telematics unit30such that an identifier of the unit30is found in a home location register (HLR). Home-equivalent networks can be wireless carrier systems14other than the home network that have reciprocal agreements in place to service the vehicle telematics unit30when roaming. In this example, if the vehicle telematics unit30had been operating using LTE and camped on a cell tower operated by a home network, the unit30can then access the TOT, locate LTE and its corresponding place in the order of desirability, and then select the less desirable RAT—WCDMA. In addition to changing the RAT from LTE to WCDMA, the vehicle telematics unit30can begin searching for cellular connections that are either provided by the home network or home equivalent networks.

It should be appreciated that step240can be modified to incorporate a cellular band search contour in addition to or instead of controlling the PLMN variables. Again referring to the example above in which the vehicle telematics unit30loses a cellular connection using LTE and begins using WCDMA after searching the TOT, the unit30can also be programmed to control the cellular band(s) searched during the method200. For instance, the vehicle telematics unit30can begin using WCDMA and limit the attempts to one cellular band (or frequency band), such as 850 MHz. Alternatively, the vehicle telematics unit30can begin using WCDMA and limit the search to multiple cellular bands, such as 850 MHz and 1700 MHz. In yet another implementation, the vehicle telematics unit30can also use the secondary APN to re-establish the cellular connection.

If step240is successful, the method200ends. Otherwise, an attempt is made at step250to connect with the wireless carrier system14by iterating through each of the RATs ordered in the TOT beginning with a next less desirable RAT and including in the iteration the RAT used by the vehicle telematics unit30when the loss of cellular connection was detected. The iteration can also begin using all non-forbidden PLMNs. Continuing the example from above, after the vehicle telematics unit30determines that attempts to re-establish the cellular connection have failed using the less desirable RAT, the unit30can access the TOT and locate the next less desirable RAT. In this example, if the less desirable RAT is WCDMA, the next less desirable RAT can be GSM. Then, the vehicle telematics unit30can use GSM to make attempts to re-establish cellular communications and also widen the scope of the PLMNs searched to include all non-forbidden PLMNs and not just the home or home-equivalent networks. Forbidden networks can be identified by searching a list of network identifiers stored at the vehicle12. The list can be established by the wireless carrier system14and identify other carriers the system14does not want the unit30using. For each RAT or RAT/PLMN combination attempted, the vehicle telematics unit30can apply a timer to limit the amount of time allotted to establish a cellular connection. In one example, the timer can be set to no more than thirty seconds. A second, global timer can also be used to govern an amount of time the vehicle telematics unit30is allowed to make attempts for each RAT.

The method200can continue to use the TOT to control the subsequent order in which the identities of RATs are selected. In one example, the TOT can be a circular queue of RATs and the vehicle telematics unit30can continue attempting cellular connections over all non-forbidden PLMNs according to this queue. In the example provided in which the TOT includes LTE, WCDMA, and GSM, respectively, the method200can next attempt cellular connections using LTE as the selected RAT until a timer indicates that the next RAT in the TOT should be selected. At this point, the method200selects the most desirable RAT for the first time during the method200. Since the TOT does not include any more less desirable RATs, the method200can begin at the beginning of the list with the most desirable RAT. It should also be appreciated that the method200can be limited by the amount of time the vehicle battery58can provide power to the vehicle telematics unit30. Unlike the approximately 30 second long retry strategies used by handheld wireless devices, the vehicle telematics unit30can continue to re-establish cellular communications using the method200until the vehicle battery58can no longer provide enough power for the unit30to function. The method200then ends.