KR20230111861A - Vehicle's device management system - Google Patents

Abstract

The present invention relates to a device management system for a vehicle with a short development period and economically applicable to OTA, to which OTA software and security are applied, receiving OTA firmware update data from a vehicle system, and performing a firmware update using at least a portion of the OTA firmware update data.

Description

Vehicle's device management system {Vehicle's device management system}

The present invention relates to a device management system of a vehicle, and more particularly, to a device management system of a vehicle capable of performing an update using OTA even if OTA and security software are not applied to all devices in the vehicle.

Over-The-Air (OTA) is a method of wirelessly distributing new software, firmware, settings and encryption key updates to devices such as mobile phones, set-top boxes and automobiles. In particular, in the case of a DMD (Digital Mirror Device) system applied to a recent vehicle, such an OTA is required to update image contents.

In the case of firmware update using general OTA, a method of transmitting OTA firmware update data to each device in a vehicle system and performing firmware update in each device was used. In this case, it was necessary to apply software and security software for applying OTA to each device, but it took a long development period and reduced economic feasibility to apply this to all devices.

Korean Registered Patent Publication No. 10-2336941 (“Apparatus and method for updating vehicle ECU with safety secured in OTA environment”, Publication date 2021.12.07)

The present invention has been made to solve the above problems, and an object of the vehicle device management system according to the present invention is to provide a vehicle device management system that can be economically applied OTA with a short development period.

A device management system for a vehicle according to the present invention to solve the above problems includes an upper controller that is applied with OTA software and security, receives OTA firmware update data from a vehicle system, and performs a firmware update using at least a portion of the OTA firmware update data, and a lower operating unit that receives at least another portion of the OTA firmware update data from the upper controller and performs a firmware update.

Further, the upper controller includes a first control unit that decrypts the OTA firmware update data, performs a firmware update using the firmware update data of the upper controller among the decoded data, and transmits the firmware update data of the lower operation unit to the lower operation unit, and a first memory unit in which the OTA firmware update data decoded by the first control unit is stored.

Further, the lower operation unit includes a second control unit receiving firmware update data of the lower operation unit from the upper controller and performing a firmware update, and a second memory unit storing existing firmware data and new firmware data.

Also, the second control unit uses the existing firmware data before the firmware update is completed, and uses the new firmware data after the firmware update is completed.

The at least one sub-operation unit is an image processor board, and further includes an LED driver controlled by the image processor board and an LED controlled by the LED driver, and when firmware update of the image processor board fails, the LED driver controls the LED to blink an emergency light, and the image processor board outputs information about a firmware update failure to a driver.

In addition, the host controller receives time information along with the OTA firmware update data from the vehicle system, and when the time is daytime, the host controller performs a firmware update.

In addition, the upper controller transmits firmware update data of the lower operating unit to the lower operating unit when the time is daytime.

In addition, the upper controller receives time information from the vehicle system, transmits the time information to a lower operating unit, and the lower operating unit performs a firmware update when the time is daytime.

The sub-operation unit may include at least one or more sub-operation units, or at least one or more functions of the sub-operation unit, and may further include an output means for outputting whether or not a type of the sub-operation unit or a function of the sub-operation unit has been updated.

The at least one lower operating unit is an image processor board, and further includes an LED driver controlled by the image processor board, an LED controlled by the LED driver, and a temperature sensor installed in the LED to sense a temperature of the LED, wherein the second control unit performs a firmware update when the temperature sensed by the temperature sensor is less than or equal to a reference value, and stops the firmware update when the temperature sensed by the temperature sensor exceeds the reference value.

In addition, the lower operation unit is an image processor board, the upper controller receives a lighting signal and sensor information together with the OTA firmware update data, and the first control unit transmits the lighting signal and the sensor information to the image processor board without separate decoding.

In addition, the upper controller is an LED Drive Module (LDM), and at least some of the lower operating units are devices used to drive a DMD system or a general headlamp.

In addition, at least a part of the lower operation unit is an image processor board, a DMD driver board, or an LDM different from the upper controller.

In addition, the firmware update data of the upper controller and the firmware update data of the lower operating unit are distinguished by a packet ID on a communication protocol.

According to the device management system of the vehicle according to the present invention as described above, OTA (Over-The-Air) software and security software are applied only to the upper controller, and OTA software and security software are not applied to the lower operating unit, so that the upper controller and the lower operating unit are economically effective in applying OTA software and security software to the upper controller and lower operating unit.

In addition, according to the present invention, the existing firmware software and the new firmware software are stored in the second memory unit of the lower operation unit, and the existing firmware software is used instead of the new firmware software until the firmware update of the lower operation unit is completed. When the update is completed, the new firmware software is used, so that the lower operation unit operates normally even if the firmware update fails.

In addition, according to the present invention, if the firmware update of the lower operating unit controlling the LED in the vehicle's DMD system or general headlamp fails, the LED operates to blink the emergency light, thereby preventing additional accidents.

In addition, according to the present invention, the firmware update of the lower operating unit controlling the LEDs in the DMD system or general headlamp of the vehicle is performed during the week when the DMD system or headlamp is not used, thereby preventing malfunction during use of the DMD system or headlamp. There is an effect that can be prevented.

In addition, according to the present invention, there is an effect that a firmware update can be performed only for a lower operating unit or function selected by a user through an output means.

In addition, according to the present invention, a temperature sensor is included in a lower operating unit that controls LEDs in a DMD system of a vehicle or a general headlamp, and firmware update is performed only when the temperature is below a certain reference value, thereby preventing firmware update from failing due to high temperature.

1 is a block diagram of a device management system for a vehicle according to the present invention;
2 is a detailed block diagram of an upper controller and a lower operating unit of a device management system for a vehicle according to a first embodiment of the present invention;
3 is a block diagram of an LDM and an image processor board of a vehicle device management system according to a first embodiment of the present invention;
4 is a structure of a communication protocol of a device management system of a vehicle according to a first embodiment of the present invention;
5 is a block diagram and operation schematic diagram of a vehicle device management system according to a second embodiment of the present invention;
6 is a block diagram of a vehicle device management system according to a fourth embodiment of the present invention;
7 is a block diagram of a vehicle device management system according to a fifth embodiment of the present invention;
8 is a block diagram of a vehicle device management system according to a sixth embodiment of the present invention;
9 is a block diagram of a vehicle device management system according to a seventh embodiment of the present invention;
10 is a block diagram of a vehicle device management system according to an eighth embodiment of the present invention.

Hereinafter, a preferred embodiment of a device management system for a vehicle according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a vehicle device management system according to the present invention.

As shown in FIG. 1 , the device management system of a vehicle according to the present invention may include an upper controller 100 and a lower operating unit, and the cloud server 10 and the vehicle system 20 may operate organically with the present invention.

The cloud server 10 serves to wirelessly transmit OTA firmware update data to various electronic devices such as the vehicle system 20 . The vehicle system 20 can be referred to as a top-level controller that manages devices inside the vehicle, and is wirelessly connected to the cloud server 10, receives OTA firmware update data from the cloud server 10, and transmits OTA firmware update data to various devices inside the vehicle.

The host controller 100 may be any one of various devices inside the vehicle. The vehicle device management system according to the present invention can be applied to a specific device group inside the vehicle, and the upper controller 100 can be any one of the specific device groups inside the vehicle. The upper controller 100 applies OTA software and security, and receives OTA firmware update data from the vehicle system 20 . Here, applying OTA software and security may mean that encoded OTA firmware update data can be decoded. Since the host controller 100 itself is one of a specific device group inside the vehicle, firmware can be updated using firmware update data corresponding to the host controller 100 among the decoded firmware update data, if necessary. In addition, the upper controller 100 may transmit firmware update data corresponding to a lower operating unit among decoded firmware update data.

Like the upper controller 100, the lower operating unit may be any one device among a group of specific devices inside the vehicle. In the present invention, there may be at least one lower operating unit, and referring to FIG. 1, it may be a first lower operating unit 200-1, a second lower operating unit 200-2, and an nth lower operating unit 200-n. Here, n is a natural number greater than or equal to 1.

The upper controller 100 and the first lower operating unit 200-1 to the nth lower operating unit 200-n may belong to the same device group among specific device groups inside the vehicle. However, the present invention does not limit the device group to which the upper controller 100 and the first lower operating unit 200-1 to the nth lower operating unit 200-n belong to the same device group, and at least one of the first lower operating unit 200-1 to the nth lower operating unit 200-n may belong to a different device group from the upper controller 100.

Each of the first lower operating unit 200-1 to the nth lower operating unit 200-n may receive firmware update data corresponding to the first lower operating unit 200-1 to the nth lower operating unit 200-n among the decoded firmware update data received from the upper controller 100, and perform a firmware update using the received data.

In the present invention, separate OTA software and security are not applied to each of the first lower operating unit 200-1 to the nth lower operating unit 200-n, and OTA software and security are applied only to the upper controller 100. Since the firmware update data decoded by the upper controller 100 is transmitted to the lower operating unit, the development and application period is relatively short, and the application period is relatively short, and the application period is relatively economical.

[First Embodiment]

Specific embodiments will be described with reference to the device management system for a vehicle according to the present invention described above.

2 is a detailed block diagram of an upper controller and a lower operating unit of a device management system for a vehicle according to a first embodiment of the present invention.

As shown in FIG. 2 , the vehicle device management system according to the first embodiment of the present invention can be applied to a DMD (Digital Mirror Device) system 30 . As some of the devices included in the DMD system 30, there may be an image processor board 400 and a DMD driver board 500. In the vehicle device management system according to the first embodiment of the present invention, the LDM (LED Drive Module) 300 may serve as an upper controller, and each of the image processor board 400 and DMD driver 500 included in the DMD system 30 may serve as a lower operating unit.

The LDM 300 serves to supply constant power to the head lamp LEDs included in the DMD system 30, the image processor board 400 serves to process video images required by the DMD system 30, and the DMD driver 500 serves to control the DMD.

The LDM 300 receives OTA firmware update data necessary for the DMD system 30 from the vehicle system 20, decrypts the entire data, and performs firmware update using the firmware update data corresponding to the LDM 300. In addition, the LDM 300 transmits firmware update data corresponding to the image processor board 400 and the DMD driver 500 among the decrypted OTA firmware update data to the image processor board 400 and the DMD driver 500, respectively. The image processor board 400 and the DMD driver 500 may perform a firmware update using the received firmware update data.

3 is a block diagram of an LDM and an image processor board of a vehicle device management system according to a first embodiment of the present invention.

Since each of the image processor board 400 and the DMD driver 500 is one of sub-operating units, description of the DMD driver 500 and the sub-operating units that may be included in the present invention is replaced by the image processor board 400.

As shown in FIG. 3 , the LDM 300 includes a first control unit 310 and a first memory unit 320, and the image processor board 400 includes a second control unit 410 and a second memory unit 420.

The first control unit 310 included in the LDM 300 may be implemented as a kind of Micro Control Unit (MCU). The first control unit 310 decrypts the OTA firmware update data received from the vehicle system 20 through communication with the vehicle system 20, and performs a firmware update of the LDM 300 using the firmware update data corresponding to the LDM 300 among the decoded data.

The first memory unit 320 stores the OTA firmware update data decrypted by the first control unit 310 . However, the decrypted OTA firmware update data includes firmware data for the LDM 300 and firmware data for the image processor board 400 . The first memory unit 320 stores these two separately. The first control unit 310 transmits firmware data for the image processor board 400 stored in the first memory unit 320 to the image processor board 400 .

Like the first control unit 310, the second control unit 410 may also be implemented as an MCU. The second control unit 410 receives firmware update data of the image processor board 400 from the LDM 300 and performs a firmware update of the image processor board 400 .

The second memory unit 420 stores existing firmware data and new firmware data received from the second control unit 410 .

Communication between the vehicle system 20 and the first controller 310 and communication between the first controller 310 and the second controller 410 may be a kind of local communication. In the device management system of the vehicle according to the first embodiment of the present invention, local communication may use the CAN protocol, which is frequently used as a communication standard between devices inside the vehicle.

4 is a structure of a communication protocol of an in-vehicle device management system according to a first embodiment of the present invention.

As shown in FIG. 4, the packet structure of the CAN protocol may include Start of Frame (SOF), identifier, Control, Data, CRC, ACK bits, and End of Frame (EOF) bits.

The SOF bit is a major bit indicating the start of a message and is used to synchronize nodes on the bus.

Identifier (ID) identifies the content of a message as an identifier and assigns priority to the message. Depending on the length of the ID in the CAN message, it can be divided into two modes: standard CAN and extended CAN. Standard CAN is an 11-bit identifier, and extended CAN is distinguished by a 29-bit identifier.

Control means the length of data (DLC, Data Length Code).

CRC is a bit used for frame transmission errors and error detection.

The ACK bit is a bit indicating that a message without errors has been transmitted, and the CAN controller transmits an ACK (Acknowledgement) bit if the message is correctly received. The transmitting node checks whether there is an ACK bit on the bus and attempts retransmission if the ACK bit is not found.

The EOF bit indicates the end of the frame and means end.

The above-described first control unit 310 and the second control unit 410 refer to the identifier (ID) in the structure of the above-described CAN protocol, and among the firmware update data, which data is for the LDM 300 and image processor board 400. It can be confirmed. Also, existing firmware data and new firmware data may be stored together in the first memory unit 320 . Each of the first control unit 310 and the second control unit 410 may use existing firmware data stored in each of the first memory unit 320 and the second memory unit 420 before the firmware update is completed, and may use new firmware data after the firmware update is completed.

5 is a block diagram and operation schematic diagram of some components of a device management system for a vehicle according to a second embodiment of the present invention.

As shown in FIG. 5 , the vehicle device management system according to the second embodiment of the present invention may include an image processor board 400 , an LED driver 401 , and an LED 402 as lower operation units. The image processor board 400 controls the LED driver 401, and the LED driver 401 controls the LED 402. The second control unit 410 of the image processor board 400 may fail to update new firmware. In this case, a problem such as communication with the LED driver 401 becoming impossible may occur. In this case, the LED driver 401 controls the LED 402 to blink the hazard lights, and the second controller 410 of the image processor board 400 outputs firmware update failure information to the driver, thereby preventing additional accidents.

[Third Embodiment]

In the device management system of a vehicle according to the third embodiment of the present invention, the upper controller 100 receives time information along with OTA firmware update data from the vehicle system 20 . As described above, the vehicle device management system according to the third embodiment of the present invention can be applied to a DMD system or a headlamp system. In the case of a vehicle's DMD system or headlamp, it is used relatively infrequently during the daytime. Therefore, it is preferable to update the firmware of the devices included in the DMD system or general headlamp system during the daytime. To this end, the LDM (300), which is a higher level controller, receives time information when starting or receiving OTA firmware update data, and if it is determined that the determination time is week, the LDM (300) can perform a firmware update. In addition, when the first control unit 310 of the upper controller 100 determines that the judgment time is week, it transmits a firmware update to the image processor board 400 and the DMD driver board 500, which are lower operation units, so that the second control unit of the lower operation unit can also perform the firmware update.

In the above operation embodiment, when the LDM 300, which is an upper control unit, determines that the time of day is week, firmware update data is transmitted to the lower operation unit so that the firmware update is performed. In contrast, when receiving visual information from the vehicle system 20, the LDM 300 transmits the received visual information to the image processor board 400 and the DMD driver board 500, which are lower operation units. When the image processor board 400 and the second control unit 410 of each of the DMD driver board 500, which are lower operation units, determine that the time at the time of determination is daytime, the image processor board 400 and the DMD driver board 500. Each of the firmware can be updated.

In the device management system of a vehicle according to the third embodiment of the present invention, time information is received from the vehicle system 20, and it is determined whether the determination time is daytime through the time information. However, there may be cases in which OTA firmware update data is transmitted from the cloud server 10 to the vehicle system 20 while the vehicle is driving, not when the vehicle is started. In this case, the upper controller 100 and each of the lower operating units may perform a firmware update after confirming that the current DMD system and headlamps are not used through the illuminance sensor installed inside the vehicle. When the vehicle enters a specific place during the firmware update or the environment in which the DMD system and the headlamp are operated due to deteriorating weather conditions, the upper controller 100 and the lower operating unit each stop the firmware update, and use the DMD system and the headlamp through the illuminance sensor.

[Fourth Embodiment]

6 is a block diagram of a vehicle device management system according to a fourth embodiment of the present invention.

As shown in FIG. 6 , in the device management system for a vehicle according to the fourth embodiment of the present invention, at least one or more sub-operation units or at least one or more functions of the sub-operation units are provided. If this is applied to the DMD system and explained, the function of the image processor board 400, which is a lower operating unit, may appear as a type of image output to the front of a vehicle in the DMD system. The OTA firmware update data transmitted from the cloud server 10 to the vehicle system 20 may include content for updating the type of image, but the user 40 may not want to update the type of image. This may be the same for specific functions of the DMD system as well as the type of image. Accordingly, the present embodiment may further include an output means 600 for outputting whether the lower operating unit is updated or not for each function of the lower operating unit. The user 40 selects an item to be updated from the type of the lower operation unit or the image (or function) of the lower operation unit output to the output unit 600, the output unit 600 transmits the user's selection information to the lower operation unit, and the second control unit 410 included in the lower operation unit performs a firmware update in response to the selection information. The output means 600 may be implemented as a display installed inside the vehicle, and may be implemented in a center fascia display or instrument panel inside the vehicle. In addition, the output unit 600 may include a touch function so that the user can select the type or function of the lower operation unit.

[Fifth Embodiment]

7 is a block diagram of a vehicle device management system according to a fourth embodiment of the present invention.

As shown in FIG. 7 , the vehicle device management system according to the fourth embodiment of the present invention may include an image processor board 400, an LED driver 401, an LED 402, and a temperature sensor 403.

Since the image processor board 400, the LED driver 401, and the LED 402 are devices previously described in the vehicle device management system according to the second embodiment of the present invention, their descriptions are omitted.

The second memory unit 420 included in the image processor board 400 is highly likely to malfunction in case of high temperature. Accordingly, in this embodiment, when the temperature sensed by the temperature sensor 403 is less than or equal to the reference value, the second controller 410 performs a firmware update of the image processor board 400, and when the temperature sensed by the temperature sensor 403 exceeds the reference value, the second controller 410 stops updating the firmware of the image processor board 400. This embodiment can prevent an update failure of a lower operating unit such as the image processor board 400 through this.

The vehicle device management system according to the above-described first to fifth embodiments of the present invention has been described by taking a DMD system or a general headlamp system as an example. However, the present invention can be applied to any group of devices inside a vehicle. In addition, in the present embodiments described above, the upper controller 100 and the lower operating unit are described as different types of devices, but when several devices of the same type are used in a specific device group, one of them serves as the upper controller 100, and at least one of the others may serve as a lower operating unit. Taking the DMD system as an example, there may be an upper LDM serving as the upper controller 100 and a lower LDM serving as the lower operating unit. In addition, there may be various devices controlled by the lower operation unit, such as the image processor board 400, the LED driver 401, and the LED 402. In addition, the upper controller 100 is not limited to any one of the devices included in a specific device group, and receives, decrypts, and transmits decrypted firmware update data to the lower operating units to control the lower operating units. It can be implemented as a kind of integrated controller. That is, when the device group is referred to as a DMD system, the upper controller 100 may be implemented in a form of controlling lower operation units such as LDM, image processor board, and DMD driver board without separately controlling LEDs.

The above embodiments will be described in more detail.

8 to 10 are block diagrams of vehicle device management systems according to sixth to eighth embodiments of the present invention, respectively.

As shown in FIG. 8 , in the sixth embodiment of the present invention, the first LDM 300-1 serves as an upper controller, and the second LDM 300-2 receives firmware update information from the first LDM 300-1 and performs a firmware update. That is, the 2nd LDM 300 - 2 may be connected in parallel with the DMD system 30 .

As shown in FIG. 9, in the seventh embodiment of the present invention, a separate integrated controller 101 serves as an upper controller, and the DMD system 30 and LDM 300 may serve as lower operating units. Of course, an embodiment applied to a vehicle to which a general headlamp system is applied without the DMD system 30 in the state shown in FIG. 9 is also possible.

As shown in FIG. 10, in the eighth embodiment of the present invention, a plurality of LDMs may be connected in parallel with the integrated controller 101. More specifically, the first LDM (300-1), the second LDM (300-2), ... , the n-th nLDM 300-n may be connected in parallel to the integrated controller 101 to receive firmware update data from the integrated controller 101 serving as a higher level controller.

As described in the above embodiments, in the device management system of a vehicle according to the present invention, any device configured to transmit/receive data with other devices among devices installed inside the vehicle may serve as an upper controller, and the other devices may serve as lower operating units that receive decrypted firmware update data from a device serving as an upper controller and update their own firmware. Here, the upper level controller may be a device newly added for the role of a higher level controller as well as an existing device installed inside the vehicle.

The present invention is not limited to the above embodiments, and the scope of application is diverse, and various modifications and implementations are possible without departing from the gist of the present invention claimed in the claims.

10 : Cloud server
20: vehicle system
30: DMD system
40: user
100: upper controller
101: integrated controller
200-1 ~ 200-n: 1st lower operating unit ~ nth lower operating unit
300: LDM
300-1 to 300-n: 1st LDM to 300-n LDM
310: first control unit
320: first memory unit
400: image processor board
401: LED driver
402: LEDs
403: temperature sensor
410: second control unit
420: second memory unit
500: DMD driver board
600: output means

Claims (14)

an upper controller to which OTA software and security are applied and to receive OTA firmware update data from a vehicle system; and
A lower operating unit receiving at least another part of the OTA firmware update data from the upper controller;
The upper controller updates the firmware of the upper controller using at least a part of the received OTA firmware update data;
The lower operating unit updates the firmware of the lower operating unit using at least another part of the received OTA firmware update data.
A device management system for a vehicle, characterized in that:
According to claim 1,
The upper controller,
a first control unit that decrypts the OTA firmware update data, updates the firmware of the upper controller using the firmware update data of the upper controller among the decoded data, and transmits the firmware update data of the lower operating unit to the lower operating unit; and
a first memory unit storing the OTA firmware update data decoded by the first control unit;
Device management system of the vehicle comprising a.
According to claim 2,
The sub-operation unit,
a second control unit receiving firmware update data of the lower operation unit from the upper controller and updating firmware of the lower operation unit; and
a second memory unit storing old firmware data and new firmware data;
Device management system of the vehicle comprising a.
According to claim 3,
The second control unit,
The device management system of a vehicle using the existing firmware data before completion of the firmware update and using the new firmware data after completion of the firmware update.
According to claim 3,
at least one of the lower operating units is an image processor board;
an LED driver controlled by the image processor board; and
LED controlled by the LED driver;
Including more,
If the firmware update of the image processor board fails,
The LED driver controls the LED to blink the emergency light,
The image processor board outputs firmware update failure information to a driver.
According to claim 1,
The upper controller,
The device management system of a vehicle that receives time information together with the OTA firmware update data from the vehicle system when the vehicle is started, and updates the firmware of the upper controller when the time is daytime.
According to claim 6,
The upper controller,
and transmitting firmware update data of the lower operating unit to the lower operating unit when the time is daytime.
According to claim 1,
The upper controller,
receiving time information from the vehicle system and transmitting the time information to a lower operation unit;
The sub-operation unit,
A device management system of a vehicle that updates the firmware of the sub-operation unit when the time is daytime.
According to claim 1,
At least one sub-operation unit, or at least one function of the sub-operation unit,
an output means for outputting the type of the lower operating unit or whether or not the function of the lower operating unit is updated;
Including more,
The output means,
Sending selection information about the type of the lower operation unit selected by the user or the function of the lower operation unit to the corresponding lower operation unit;
The lower operating unit receiving the selection information updates firmware of the lower operating unit in response to the selection information.
According to claim 3,
at least one of the lower operating units is an image processor board;
an LED driver controlled by the image processor board;
LED controlled by the LED driver; and
a temperature sensor installed on the LED to sense the temperature of the LED;
Including more,
The second control unit,
If the temperature sensed by the temperature sensor is less than a reference value, the firmware of the image processor board is updated, and if the temperature sensed by the temperature sensor exceeds the reference value, the firmware update of the image processor is stopped.
According to claim 2,
The sub-operation unit is an image processor board,
The host controller receives a lighting signal and sensor information together with the OTA firmware update data,
The first control unit transmits the lighting signal and the sensor information to the image processor board without separate decoding.
According to claim 1,
The upper controller is an LDM (LED Drive Module),
At least some of the lower operating units are devices used to drive a DMD system or a general headlamp.
According to claim 12,
At least some of the lower operating units,
An image processor board, a DMD driver board, or a device management system of a vehicle that is an LDM different from the upper controller.
According to claim 1,
The device management system of a vehicle in which the firmware update data of the upper controller and the firmware update data of the lower operating unit are distinguished by a packet ID on a communication protocol.