Vehicle telematics message transmission

Abstract

Load balancing method for vehicle telematics message transmission for sending telematics messages via a wireless data connection to an external vehicle telematics server, wherein the method comprises: Retaining a count of failed transmission attempts for individual telematics messages sent over the wireless data link to generate a count parameter; Generating a preliminary delay parameter by inputting the counter parameter into a nonlinear function or an exponential function; Generating a final repetition delay parameter between a lower delay threshold parameter and the preliminary delay parameter; Using the final retry delay parameter to determine a retry delay time for resending the failed message; and where the count of failed transmission attempts for a telematics message is periodically reset after a threshold has been exceeded.

Description

TECHNICAL AREA

[0001] The present disclosure relates to vehicle telematics message transmission. Aspects of the invention relate to a load distribution method for vehicle telematics messages, a load distribution control for a vehicle telematics unit, a telematics unit for a vehicle, a vehicle with a telematics unit, and a vehicle telematics system. BACKGROUND

[0002] Many modern vehicles are equipped with telematics units. These units can collect information from multiple vehicle systems, indicating the status and / or performance of these systems. Many telematics units are capable of sending telematics messages containing this information to an external vehicle telematics server. Messages received from the telematics server can be logged and analyzed to monitor the vehicle's condition and / or performance.

[0003] Telemetry data messages are generated during vehicle operation. Consequently, message activity increases significantly during peak traffic hours when more vehicles are in use. Vehicle telematics servers must therefore accommodate this peak demand for messages. One approach is to provide a vehicle telematics server with sufficient bandwidth to meet this peak demand. This minimizes message processing delays but increases costs. Furthermore, it is relatively inefficient, as most of the bandwidth remains unused outside of peak hours.

[0004] US 6078591 A concerns collision delay intervals that are modified at a network node to overcome a detected capture effect in a half-duplex network. A network interface with a Media Access Control (MAC) selectively modifies the collision delay interval based on the detected capture effect. In one implementation, a locked node resets its attempt counter to compete more aggressively for media access.

[0005] An alternative option is to provide a more limited bandwidth for the vehicle telematics server, allowing each telematics unit to implement a basic resend strategy to prevent service interruptions during peak demand. The currently known resend strategy is a constant delay strategy, where a failed message is resent after a fixed retry delay (e.g., 10 seconds). If delivery fails again, the message is resent after the specified retry delay has elapsed. This strategy enables the telematics server to handle all messages during peak demand despite insufficient bandwidth and is more cost-effective than adjusting the server bandwidth to the peak load.However, this load balancing strategy is limited in its ability to distribute message transmission requests that exceed the bandwidth. During extended periods when message transmission demand exceeds the bandwidth, a combination of messages is repeated multiple times, and new messages create an avalanche effect that leads to long delays in message processing.

[0006] The aim of the present invention is to eliminate disadvantages associated with the prior art. SUMMARY OF THE INVENTION

[0007] Aspects of the invention are defined in the attached claims.

[0008] Aspects and embodiments of the invention represent a load distribution method for vehicle telematics messages, a load distribution control for a vehicle telematics unit, a telematics unit for a vehicle, a vehicle with a telematics unit and a vehicle telematics system, as claimed in the attached claims.

[0009] According to one aspect of the invention, a load distribution method for messages is provided, wherein the method comprises: maintaining a count of failed transmission attempts for individual messages in order to generate a count parameter; randomly selecting a retry delay time from a range of possible retry delay times, which increases with the count parameter.

[0010] By selecting retry delay times from an increasing range, retry attempts for failed messages are distributed over a longer period than with the known constant delay strategy. This allows a telematics system to continue operating with a given bandwidth during higher peak demand than is possible with the known constant delay strategy.

[0011] In some embodiments, the above method can be applied to vehicle telematics messages.

[0012] According to a further aspect of the invention, a message load balancing method is provided, comprising: maintaining a count of failed transmission attempts for individual messages to generate a count parameter; generating a preliminary retry delay parameter by inputting the count parameter into an exponential function; generating a final retry delay parameter between a lower delay threshold parameter t and the preliminary retry delay parameter; and using the final retry delay parameter to determine a retry delay time for retransmitting the failed message. The count of failed transmission attempts for a message is periodically reset after a count threshold has been exceeded.

[0013] In this method, the retry delay is randomly selected from a range that increases exponentially with the number of failed transmission attempts for each individual message. As a result, retry attempts for failed messages are spread out over a longer period than with the conventional constant delay strategy. This allows a telematics system to continue operating with a given bandwidth during higher peak demand than is possible with the conventional constant delay strategy. Furthermore, resetting the count parameter for high-importance or high-priority data enables relatively quick reprioritization of the corresponding message, as the retry delay is statistically much shorter.

[0014] In some embodiments, the above method can be applied to vehicle telematics messages.

[0015] In some embodiments, the method may involve determining the quality of service (QoS) category of a faulty message. The QoS category may be determined by looking up an identification code within the message. Determining the QoS category allows for variation in the priority given to message retransmission. This may, for example, result in messages in higher QoS categories being subject to earlier or more frequent retransmission attempts. In some embodiments, the method may involve retransmitting messages in the highest QoS category after a fixed retransmission delay and retransmitting messages in lower QoS categories after a retransmission delay determined by the final retransmission delay parameter.

[0016] The exponential function can be any suitable function where the growth rate of the output is directly proportional to the value of the output. In particular, the exponential function can be based on the natural exponential function.

[0017] In some embodiments, generating the preliminary repetition delay parameter may involve calculating the sum of the output of the exponential function and a preliminary threshold parameter. The preliminary threshold parameter may be a constant. Summing the exponential function and the preliminary threshold parameter ensures that the preliminary repetition delay parameter is greater than a minimum value.

[0018] Accordingly, the final delay parameter, and thus the retry delay time, will also exceed a minimum value. The preliminary threshold parameter can vary for messages in different quality-of-service (QoS) categories. This can, for example, allow for longer minimum retry delay times for messages with a lower QoS category.

[0019] In some embodiments, the counter parameter can be equal to the number of failed transmission attempts for a message. In other embodiments, the counter parameter can be equal to the modulus of the number of failed transmission attempts for a message with respect to a threshold. This sets an upper limit for the preliminary delay parameter and thus for the maximum retry delay time. The counter threshold can vary for messages in different quality-of-service categories. This would, for example, allow for shorter maximum retry delay times for messages in higher quality-of-service categories.

[0020] In some embodiments, the lower delay threshold can have a fixed value. In other embodiments, the lower delay threshold can vary for messages in different quality of service categories. This would, for example, allow for shorter minimum retry delays for messages in higher quality of service categories. In some embodiments, the lower delay threshold parameter can be zero.

[0021] In some embodiments, the final retry delay parameter can be generated by selecting a random number between a lower delay threshold parameter and the preliminary retry delay parameter. In some embodiments, the final retry delay parameter can be equal to the selected random number. In other embodiments, the final retry delay parameter can be equal to the sum of the selected random number and an offset parameter. Summing the selected random number and the offset parameter ensures that the final retry delay parameter is greater than a minimum value. Accordingly, the retry delay time also exceeds a minimum value. The offset parameter can vary for messages in different quality-of-service categories.This can, for example, allow for longer minimum retry delay times for messages in lower service quality categories.

[0022] In some embodiments, the numerical value of the final repetition delay parameter can directly correspond to the numerical value of the repetition delay time. In other embodiments, the numerical value of the final repetition delay parameter can be converted into the numerical value of the repetition delay time by using a suitable scaling factor.

[0023] According to yet another aspect of the invention, a load balancing control for message transmission is provided, the load balancing control comprising: means for counting, which is operable to maintain a count of failed transmission attempts for individual messages and thereby generate a count parameter; means for generating a final retry delay time by selecting a retry delay time from a range of possible retry delay times, which increases with the count parameter. The means for counting is operable to periodically reset the count of failed transmission attempts for a message after a count threshold has been exceeded.

[0024] By selecting retry delay times from an increasing range, retry attempts for failed messages are distributed over a longer period than with the known constant delay strategy. This allows a telematics system to continue operating with a given bandwidth during higher peak demand than is possible with the known constant delay strategy. Furthermore, resetting the counter parameter for high-importance or high-priority data enables relatively quick reprioritization of the corresponding message, as the delay in retrying the message is statistically much shorter.

[0025] In some embodiments, the above load distribution control can be a load distribution control for vehicle telematics messages.

[0026] According to a further aspect of the invention, a load balancing control is provided for a message unit, wherein the load balancing control comprises: means for counting, which is operable to maintain a count of failed transmission attempts for individual messages and thereby generate a count parameter; means for generating a preliminary retry delay parameter, which is operable to generate a preliminary retry delay parameter by inputting the count parameter into an exponential function; means for generating a final retry delay parameter, which is operable to generate a final retry delay parameter between a lower delay threshold parameter and the preliminary retry delay parameter;and a timing device that is operable to delay the retransmission of failed messages for a retry delay time determined by the final retry delay parameter. The counting device is operable to periodically reset the failed transmission count for a message after a count threshold has been exceeded.

[0027] The load balancing control described above can thus be operated to provide a randomly selected retry delay time from a range that increases exponentially with the number of failed transmission attempts for each individual message. As a result, retry attempts for failed messages are spread over a longer period than with the known constant delay strategy. This allows a telematics system to continue operating with a given bandwidth during higher peak demand than is possible with the known constant delay strategy. Furthermore, resetting the counter parameter for high-importance or high-priority data enables relatively quick reprioritization of the corresponding message, as the message retry delay is statistically significantly lower.

[0028] In some embodiments, the above load distribution control can be a load distribution control for vehicle telematics messages.

[0029] System as described above, wherein: the load balancing control includes an electronic processor with an electrical input for receiving details of failed message transmission attempts; and an electronic storage device that is electrically coupled to the electronic processor and contains instructions stored therein; wherein the load balancing control includes the processor configured to access the memory device and execute the instructions stored therein, so that it is operable to: maintain a count of failed transmit attempts for individual messages, thereby generating a count parameter; generate a preliminary retry delay parameter by inputting the count into an exponential function; generate a final retry delay parameter between a lower delay threshold parameter and the final retry delay parameter; and delay the retransmission of the failed messages for a retry delay time determined by the final retry delay parameter.The counting device can be operated to periodically reset the count of failed transmission attempts for a message after a count threshold has been exceeded.

[0030] In some embodiments, the load balancing control may include means for determining the quality of service (QoS) category of a failed message. The means for determining the QoS category of a failed message may be operable to determine the QoS category of the failed message by looking it up based on an identification code within the message. Determining the QoS category allows for variation in the priority given to message retransmission. This may, for example, result in messages of a higher QoS category being subject to earlier or more frequent retry attempts.In some embodiments, the timing mechanism can be operated depending on a determination by the means for determining the quality of service category of a failed message, such that a failed message is in the highest quality of service category, in order to resend the message after a fixed retransmission delay time, and depending on a determination by the means for determining the quality of service category of a failed message, such that a failed message is in a lower quality of service category, in order to resend the message after a retransmission delay time determined by the final retransmission delay parameter.

[0031] System as described above, wherein: The means for determining the quality of service category of a faulty message is an electronic processor with an electrical input for receiving details of an identification code within the message; and an electronic storage device that is electrically coupled to the electronic processor and contains instructions stored therein; The means for determining the quality of service category of a failed message includes the processor configured to access the storage device and execute the instructions stored therein, so that it is operable to: determine the quality of service category of the failed message by looking up an identification code within the message.

[0032] In some embodiments, the means for generating a preliminary repetition delay parameter can be operated to calculate the sum of the output of the exponential function and a preliminary threshold parameter. The preliminary threshold parameter can be a constant. Summing the exponential function and the preliminary threshold parameter ensures that the preliminary repetition delay parameter is greater than a minimum value. Accordingly, the final delay parameter, and thus the repetition delay time, will also exceed a minimum value. The means for generating a preliminary repetition delay parameter can be operated to vary the threshold parameter for messages in different quality-of-service categories. This can, for example, allow for longer minimum repetition delay times for messages in lower quality-of-service categories.

[0033] The counting mechanism can be operated to generate the count parameter by looking up the failed transmission count for a message. In some embodiments, the counting mechanism can be operated to periodically reset the failed transmission count for a message after a threshold has been exceeded. In other embodiments, the counting mechanism can be operated to generate the count parameter by calculating the modulus of the failed transmission count for a message with respect to a threshold. This establishes an upper limit for the preliminary delay parameter and, consequently, for the maximum retry delay time. The counting mechanism can be operated to vary the threshold for messages in different quality-of-service categories.This would, for example, allow for shorter maximum retransmission delay times for messages in higher service quality categories.

[0034] In some embodiments, the means for generating a final retry delay parameter can be operated to use a fixed value for the lower delay threshold parameter. In other embodiments, the means for generating a final retry delay parameter can be operated to vary the value of the lower delay threshold parameter for messages in different quality of service categories. This would, for example, allow for shorter minimum retry delay times for messages in higher quality of service categories.

[0035] In some embodiments, the means for generating a final repetition delay parameter can be operated to generate a final repetition delay time by randomly selecting a repetition delay time from a series of possible repetition delay times that increases with the count parameter. In some embodiments, the means for generating a final repetition delay parameter can be operated to compute the final repetition delay parameter equal to the selected random number. In other embodiments, the means for generating a final repetition delay parameter can be operated to compute the final repetition generating parameter by summing the selected random number and an offset parameter.Summing the selected random number and the offset parameter ensures that the final retry delay parameter is greater than a minimum value. Accordingly, the retry delay time also exceeds a minimum value. The method for generating a final retry delay parameter can be configured to vary the offset parameter for messages in different quality-of-service categories. This can, for example, allow for longer minimum retry delay times for messages in lower quality-of-service categories.

[0036] In some embodiments, the timing device can be operated such that the numerical value of the final repetition delay parameter directly corresponds to the numerical value of the repetition delay time. In other embodiments, the timing device can be operated such that the numerical value of the final repetition delay parameter can be converted into the numerical value of the repetition delay time by using a suitable scaling factor.

[0037] According to a further aspect of the invention, a vehicle telematics unit is provided which includes a load distribution control according to the preceding aspect of the invention.

[0038] The vehicle telematics unit can include means for receiving signals from one or more vehicle systems indicating the status of those systems. The vehicle telematics unit can also include means for generating messages, which can be operated based on the received signals to create telematics messages for transmission.

[0039] System as described above, wherein: The vehicle telematics unit comprises an electronic processor with an electrical input for receiving signals indicating the status of the vehicle systems; and an electronic storage device that is electrically coupled to the electronic processor and contains instructions stored therein; The means for message generation include the processor, which is configured to access the storage device and execute the instructions stored therein, so that it is operational to: receive the signals indicating the state of vehicle systems and generate telematics messages depending on this.

[0040] The vehicle telematics unit may include a communication unit that enables the sending of telematics messages to an external vehicle telematics server.

[0041] The vehicle telematics unit may include means for storing messages awaiting transmission from the communication unit. These message storage means may be capable of storing both new messages awaiting transmission from the communication unit and erroneous messages awaiting retransmission. The message storage means may be an electronic storage device.

[0042] According to a further aspect of the invention, a vehicle is provided which includes a vehicle telematics unit according to the preceding aspect of the invention.

[0043] The vehicle can include a motor vehicle. The vehicle can include a road vehicle. The vehicle can be a car.

[0044] According to a further aspect of the invention, a vehicle telematics system is provided, comprising: one or more vehicle telematics units according to the preceding aspect of the invention; and a vehicle telematics server that can be operated to receive telematics messages from the vehicle telematics unit.

[0045] Within the scope of this application, it is expressly provided that the various aspects, embodiments, examples, and alternatives set forth in the preceding paragraphs, in the claims, and / or in the following descriptions and figures, and in particular the individual features thereof, may be adopted independently or in any combination. That is to say, all embodiments and / or features of an embodiment may be combined in any way and / or combination, unless these features are incompatible. The applicant reserves the right to amend an originally filed claim or to file a new claim accordingly, including the right to amend an originally filed claim to be dependent on another claim and / or to include a feature of another claim, even if this was not originally asserted in this manner. BRIEF DESCRIPTION OF THE FIGURES

[0046] One or more embodiments of the invention will now be described by way of example only with reference to the accompanying figures, in which: Fig. 1 a schematic diagram of an embodiment of a vehicle telematics system according to an embodiment of the invention; Fig. 2 a schematic diagram of an embodiment of a vehicle telematics unit according to an embodiment of the invention; Fig. 3 a schematic diagram of an embodiment of a load distribution control for a vehicle telematics unit according to an embodiment of the invention; Fig. 4 shows a diagram illustrating how the maximum value of the count parameter can be limited; Fig. 5 is a flowchart that describes a load distribution procedure; Fig. 6 is a schematic flowchart illustrating the operation of the load distribution method for vehicle telematics messages according to an embodiment of the invention; Fig. 7 a schematic comparison of the repetition delay time generated by a load distribution method for vehicle telematics messages according to an embodiment of the invention and the prior art linear repetition strategy; and Fig. 8 is a schematic comparison of the average message processing time resulting from a repetition delay time generated by a load distribution method for vehicle telematics messages according to an embodiment of the invention and the linear repetition strategy of the prior art. DETAILED DESCRIPTION

[0047] Fig. Figure 1 schematically illustrates a vehicle telematics system 1 that can be operated to provide telematics monitoring services for a large number of vehicles V1-VN. In system 1, each vehicle V1-VN is equipped with a telematics unit 10. Each telematics unit 10 can generate telematics messages indicating the status of one or more vehicle systems (see Figure 1). Fig. 2) Telematics messages are sent to a vehicle telematics server 4 via a wireless data connection, such as a mobile network 3. Received messages can be monitored and analyzed by the service provider 5, as desired or required.

[0048] Now to Fig. 2: The telematics unit 10 comprises means 11 in the form of an electronic processor for receiving signals from one or more vehicle systems 9, indicating the status of the systems 9. Depending on the received signals, a message generation means 12 can be operated to generate telematics messages that are sent to the vehicle telematics server 4. The message generation means can be in the form of an electronic processor, which may be separate from the processor or a part thereof that includes the means 11 for receiving signals from one or more vehicle systems. The messages are sent to the vehicle telematics server 4 by a communication unit 13, the communication unit being adapted to transmit messages via a suitable data connection.Optionally, the vehicle telematics unit 10 can also include means 14, such as an electronic storage device, for storing messages waiting to be sent by the communication unit 13 and failed messages waiting to be resent by the communication unit 13. To provide for the event that attempts to send messages fail, the vehicle telematics unit 10 is equipped with a load distribution control 20.

[0049] The load balancing controller 20 can be operated to control the timing of attempts to retransmit messages. In particular, the load balancing controller 20 can be operated to determine a variable retry delay time for each failed message, which is randomly selected from a range that, in one embodiment of the invention, increases exponentially with the number of failed transmission attempts for each individual message. This distributes retry attempts for failed messages over a longer period than with the known constant delay strategy, thus enabling the continued operation of a telematics system with a specific bandwidth.

[0050] In relation to Fig. 3 comprises the load balancing control 20 means for counting 21, means for generating a preliminary repetition delay parameter 22, means for generating a final repetition delay parameter 23, and means for timing 24. Each of the means for counting 21, means for generating a preliminary repetition delay parameter 22, means for generating a final repetition delay parameter 23, and means for timing 24 can be executed by a single electronic processor. Alternatively, each of them can be embodied by a single electronic processor.

[0051] The counting device 21 is operable to maintain a count of failed transmission attempts for individual telematics messages. This count is used to generate a count parameter. The count parameter, in turn, is used to vary the retry delay for attempting to resend the failed message. The counting device 21 is operable to generate the count parameter by calculating the modulo of the failed transmission attempt count for a message with respect to a count threshold. This limits the maximum value of the count parameter. In alternative embodiments, the count parameter can be equal to the failed transmission attempt count for a message. In both cases, the maximum value of the count parameter can be limited by periodically resetting the count after exceeding the threshold.

[0052] The method for generating a preliminary repetition delay parameter 22 can be used to generate a preliminary repetition delay parameter for determining the repetition delay time. The preliminary repetition delay parameter is generated by inputting the counter parameter into an exponential function. Thus, the value of the preliminary repetition delay parameter increases exponentially with an increase in the counter parameter.

[0053] Optionally, the method for generating a preliminary repetition delay parameter 22 can also be used to sum the output of the exponential function and a preliminary threshold parameter for generating the preliminary repetition delay parameter. The advantage of such summation is that the preliminary repetition delay parameter does not fall below a desired minimum value.

[0054] The means for generating a final repetition delay parameter 23 is operable to generate a final repetition delay that is used to determine the repetition delay time. The final repetition delay parameter is generated by selecting a random number between a lower threshold delay parameter and the preliminary repetition delay parameter. The final repetition delay parameter can be equal to the selected random number or equal to the sum of the selected random number and an offset parameter.

[0055] The timing device 24 can be operated to control the delay of retransmitting failed messages depending on the generated final retry delay parameter. In one embodiment, the timing device 24 can be operated to determine a retry delay time that corresponds to the numerical value of the generated final retry delay parameter. Optionally, a different scaling factor can be used to generate the retry delay time from the numerical value of the generated final delay parameter.

[0056] Optionally, the load distribution control can be configured as described in Fig. Figure 3 also includes a means for determining the quality of service category of a faulty message 25. Determining the quality of service category of the faulty message can be achieved by looking up an identification code within the faulty message. The means for determining the quality of service category of a faulty message 25 can be embodied by a dedicated electronic processor or in an electronic processor configured to include one or more of the means for counting 21 to a preliminary retry delay parameter 22, means for generating a final retry delay parameter 23, and means for timing 24.

[0057] Fig. Figure 4 shows a diagram illustrating how the maximum value of the counter parameter can be limited by periodically resetting the counter after exceeding the threshold, for situations where different thresholds are used for messages in different quality-of-service categories. In other words, depending on the determination of the quality-of-service categories, it is possible to vary the priority of retransmitting individual messages. In this exemplary embodiment, the counter 21 can be operated, depending on the means of determining the quality-of-service category of a failed message 25, to vary the threshold at which the counter of failed transmission attempts for a message is reset.

[0058] If one considers Fig. 4. The solid lines represent a threshold of 3 for a message of the best quality of service category, so that after 3 failed attempts to send the message, the count parameter is reset. This effectively reduces the delay time for sending the message on the fourth attempt and thus gives this message a higher priority. This lower count threshold represents best quality of service and can be used for critical messages. Fig. 4 is the longest waiting time allowed before the count threshold for resetting critical messages is exceeded. 8 time units, but this is only an illustration, and the exact time must be evaluated based on each application.

[0059] The dashed lines represent a threshold of 5 for a medium quality of service (QoS) message, meaning that after 5 failed attempts to send the message, the counter parameter is reset. This effectively reduces the delay for sending the message on the sixth attempt compared to not resetting it, and gives that message a higher priority at that point, allowing it to move up the priority hierarchy. This medium counter threshold represents a medium QoS and can be used for live or real-time data. Fig. 4 is the longest waiting time allowed before the count threshold for resetting medium priority messages is exceeded. 32 time units, but this is only an illustration, and the exact time must be evaluated based on each application.

[0060] The dotted and dashed lines represent a threshold of 8 for a lowest quality of service (LQS) message, meaning that after 8 failed attempts to send the message, the counter parameter is reset. This effectively reduces the delay for sending the message on the fourth attempt compared to not resetting it, thus giving this message a higher priority. This lowest threshold represents the lowest LQS and can be used for message logging. Fig. 4 is the longest waiting time allowed before the log message reset count threshold is exceeded (256 time units), but this is only an illustration, and the exact time must be evaluated based on each application.

[0061] Fig. Figure 4 shows an exponential curve, but this is only an illustration, as the actual delay parameter between message repetitions varies between the gradually increasing time windows.

[0062] In one variation, the counting mechanism can be operated to reset the count threshold for messages in all but the lowest service quality category.

[0063] Fig. Figure 5 is a flowchart describing a load distribution procedure 500.

[0064] The procedure includes: In step S510: Retain a count of failed send attempts for individual messages to generate a count parameter.

[0065] In step S520: Generating a preliminary repetition delay parameter by inputting the count parameter into a nonlinear function.

[0066] At step S530: Generating a final retry delay parameter between a lower delay threshold parameter and the preliminary retry delay parameter.

[0067] At step S540: Use the final retry delay parameter to determine a retry delay time to resend the failed message.

[0068] Step S550: Periodic reset of the count parameter after exceeding a threshold value.

[0069] In another example, the method for generating a preliminary retry delay parameter 22 can be operated as a function of the method for determining the quality of service category of a failed message 25 in order to vary the preliminary threshold parameter summed together with the exponential function of the count. In yet another example, the method for generating a final retry delay parameter 23 can be operated as a function of the method for determining the quality of service category of a failed message 25 in order to vary the parameter of the lower delay threshold.

[0070] Now, let us consider Fig. Figure 6 shows a schematic representation of the load distribution procedure implemented by the load distribution controller 20. As described above, load distribution is achieved by calculating an appropriate repetition delay time.

[0071] At S1, the quality of service (QoS) category of the message is determined. If S1 determines that the message is in a low QoS category, the counting method (S2) is used to determine the failed transmission count for the message. Subsequently, the counting method (S3) is used to generate the count parameter by calculating the modulo of the count relative to a threshold. The count threshold is fixed for a given QoS category but can vary depending on the QoS category.

[0072] In S4, the means for generating the preliminary delay parameter - 22 can be operated to input the counter value parameter into an exponential function. In some embodiments, the output of the exponential function can be used directly as the preliminary delay parameter.

[0073] In the embodiment of Fig. Step 6, which is the means for generating the preliminary delay parameter 22, can additionally be operated to generate a preliminary threshold parameter at S5. The value of the preliminary threshold parameter is fixed for a specific service quality category, but can vary depending on the service quality category. Subsequently, at S6, the preliminary threshold parameter is summed with the output of the exponential function to generate the preliminary delay parameter.

[0074] In S7, the means for generating a final repetition delay parameter 23 can be operated to select a random number between a lower delay threshold parameter and the preliminary delay parameter. In the example of Fig. 6. The lower delay threshold parameter can have a fixed value of 1, but in other embodiments, other values ​​of the lower delay threshold parameter are possible. In particular, in such embodiments, the value of the preliminary threshold parameter can vary between the service quality categories.

[0075] In S8, the means to generate a final repetition delay parameter 23 can be used to generate an offset parameter. The value of the offset parameter can vary between the quality of service categories. In S9, the means to generate a final repetition delay parameter 23 can then be used to sum the selected random number and the offset parameter to generate the final repetition delay parameter.

[0076] In S10, the time control mechanism 24 can be used to generate a retransmission delay for sending the message again. The retransmission delay can be generated by directly converting the value of the final retransmission delay parameter into a retransmission delay value in seconds. Alternatively, a suitable scaling factor can be used to convert the value of the final retransmission delay parameter into a retransmission delay value in seconds.

[0077] If S1 determines that the message falls into a high-quality-of-service category, S2-S7 can be omitted. Accordingly, the final delay parameter is generated directly from the specified offset parameter. This allows these highest-priority messages to be resent using a linear retransmission strategy, while simultaneously enabling lower-priority messages to be sent using a variable retransmission strategy described herein.

[0078] To now Fig. Returning to point 7, this is a diagram illustrating the difference between the retry delay times produced by the prior art linear retry strategy (and optionally applied to high-quality-of-service messages included herein) and the delay times produced by the variable retry strategy. The figure represents the number of failed message transmission attempts on the horizontal axis and the retry delay time on the vertical axis. Using the prior art linear retry strategy, all retry requests have a fixed delay time, illustrated by line 101. With the variable retry strategy, each retry attempt would have a retry delay time within the shaded area 102.In particular, the retry delay time would be randomly selected from the vertical extent of the hatched area 102, which corresponds to the number of failed retry attempts.

[0079] Fig.Figure 8 shows a diagram illustrating the difference in average message processing time between messages retransmitted using the retransmission delay periods generated by the prior art linear retransmission strategy (optionally applied to the high-quality-of-service messages included herein) and messages retransmitted using the retransmission delay periods generated by the variable retransmission strategy. The figure represents the time of day on the horizontal axis (from 00:00 to 23:59) and the average message processing delay on the vertical axis. New message requests are represented by row 201. As can be seen, new message requests have two peak times in the morning and evening, corresponding to maximum vehicle activity.As a result of the increased message activity, the average processing time per message increases because many messages fail to send due to server bandwidth limitations. Above a threshold illustrated by line 202, the number of attempts to resend messages becomes a significant proportion of the total message load. Using a linear retry strategy for resending all failed messages, as shown in line 203, this leads to a very rapid increase in the average processing time for each message.If, instead, a variable retry strategy is used for retransmitting all failed messages, as shown in line 204, this results in the average processing time for each message increasing much less rapidly and leading to a much lower maximum average processing time.

Claims

[1] Load balancing method for vehicle telematics message transmission for sending telematics messages via a wireless data link to an external vehicle telematics server, the method comprising: Retaining a count of failed transmission attempts for individual telematics messages sent over the wireless data link to generate a count parameter; Generating a preliminary delay parameter by inputting the counter parameter into a nonlinear function or an exponential function; Generating a final repetition delay parameter between a lower delay threshold parameter and the preliminary delay parameter; Using the final retry delay parameter to determine a retry delay time for resending the failed message; and where the count of failed transmission attempts for a telematics message is periodically reset after a threshold has been exceeded. [2] Load distribution method according to claim 1, wherein the method includes determining the service quality category of a failed telematics message. [3] Load distribution method according to any preceding claim, wherein generating the preliminary repetition delay parameter includes calculating the sum of the output of the nonlinear function and a preliminary threshold parameter. [4] Load distribution method according to claim 3 when dependent on claim 2, wherein the preliminary threshold parameter for telematics messages is varied in different service quality categories. [5] Load distribution method according to any preceding claim, wherein the count parameter is equal to the count of failed transmission attempts for a telematics message. [6] Load distribution method according to any one of claims 1 to 4, wherein the count parameter is equal to the module of the count of failed transmission attempts for a telematics message with respect to a threshold. [7] Load balancing method according to any preceding claim, if it depends directly or indirectly on claim 2, wherein the telematics message threshold is varied in different service quality categories; and / or the telematics message threshold is periodically reset in all but one lowest service quality category. [8] Load distribution method according to any one of claims 2 to 7, wherein the parameter of the lower delay threshold for telematics messages varies in different service quality categories. [9] Load distribution method according to any preceding claim, wherein the method includes generating a final repetition delay parameter by selecting a random number between a lower delay threshold parameter and the preliminary delay parameter. [10] Load distribution method according to claim 9, wherein the final repetition delay parameter is equal to the sum of the selected random number and an offset parameter, wherein the offset parameter varies for telematics messages in different quality of service categories if it depends directly or indirectly on claim 2. [11] Vehicle telematics message transmission method for sending telematics messages indicating the status of one or more vehicle systems to a vehicle server; wherein the method comprises: Receiving signals from one or more vehicle systems that indicate the status of the systems; Generating telematics messages via a wireless data connection from the vehicle telematics server; and Implementing a load balancing method according to any of the preceding claims to control the timing of attempts to resend failed messages. [12] Load balancing control for a vehicle telematics messaging unit for sending telematics messages via a wireless data link to an external vehicle telematics server, wherein the load balancing control comprises: Means of counting that is operable to maintain a count of failed transmission attempts for individual telematics messages sent via the wireless data link and thereby generate a count parameter; Means for generating a preliminary repetition delay parameter, which is operable to generate a preliminary repetition delay parameter by inputting the count parameter into a nonlinear function or an exponential function; Means for generating a final repetition delay parameter, which is operable to generate a final repetition delay parameter between a lower delay threshold parameter and the preliminary delay parameter; Means of timing control that is operable to delay the retransmission of the failed messages for a retry delay time determined by the final retry delay parameter; wherein the counting device is operable to periodically reset the count of failed transmission attempts for a telematics message after a threshold has been exceeded. [13] Load balancing control according to claim 12, wherein the load balancing control comprises means for determining the quality of service category of a failed message, which is operable to determine the quality of service category of the failed message by looking up an identifier code within the telematics messages. [14] Load distribution control according to claim 12 or claim 13, wherein the means for generating a preliminary repetition delay parameter is operable to calculate the sum of the output of the nonlinear function and a preliminary threshold parameter. [15] Load distribution control according to claim 14 when dependent on claim 13, wherein the means for generating a preliminary repetition delay parameter is operable to vary the threshold parameter for telematics messages in different quality of service categories. [16] Load distribution control according to one of claims 13 to 15, wherein the counting means is operable to generate the count value parameter by looking up the value of the count of failed transmission attempts for a telematics message. [17] Load distribution control according to one of claims 12 to 15, wherein the counting means is operable to generate the count value parameter by calculating the module of the count value of the failed transmission attempts for a telematics message with respect to a threshold value. [18] Load balancing control according to any one of claims 12 to 17, if it is directly or indirectly dependent on claim 13, wherein the counting means is operable to vary the threshold for counting telematics messages in different quality of service categories and / or the counting means is operable to reset the threshold for counting messages in all but one lowest quality of service category. [19] Load distribution control according to any one of claims 13 to 18, wherein the means for generating a final repetition delay parameter is operable to vary the value of the lower delay threshold parameter for telematics messages in different quality of service categories. [20] Load distribution control according to any one of claims 12 to 19, wherein the means for generating a final repetition delay parameter is operable to generate a final repetition delay parameter by selecting a random number between a lower delay threshold parameter and the preliminary repetition delay parameter. [21] Load distribution control according to claim 20, wherein the means for generating a final repetition delay parameter is operable to calculate the final repetition generation parameter by summing the selected random number and an offset parameter. [22] Load balancing control according to claim 21 when it is directly or indirectly dependent on claim 13, wherein the means for generating a final repetition delay parameter is operable to vary the offset parameter for messages in different quality of service categories. [23] Load distribution control according to one of claims 12 to 22, wherein the means for controlling is operable such that the numerical value of the final repetition delay parameter is directly equal to the numerical value of the repetition delay time. [24] Vehicle telematics unit capable of generating telematics messages indicating the status of one or more vehicle systems; wherein the vehicle telematics unit comprises: an electronic processor for receiving signals from one or more vehicle systems indicating the status of the systems; message generation means for generating telematics messages depending on the received signals; a communication unit designed to send telematics messages to a vehicle telematics server via a wireless data connection; and a load balancing control according to one of claims 12 to 23, which is operable to control the timing of attempts to resend failed messages. [25] Vehicle comprising at least one load distribution control according to any one of claims 12 to 23.

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