A method and device for reporting MSD via RTCP

Abstract

The present invention discloses a method for reporting MSD through RTCP, comprising the following steps. Step S1: adding 6 subtypes to the RTCP packet of APP type. Step S2: after the eCall is established, the IVS sends an RTCP synchronization packet to the PSAP; after the PSAP receives the RTCP synchronization packet, it replies with an RTCP confirmation packet to the IVS; after the IVS receives the RTCP confirmation packet, it calculates the round-trip time RTT of the RTCP synchronization packet and the RTCP confirmation packet in the network transmission, and replies with an RTCP notification receipt packet carrying the RTT to the PSAP. Step S31: during the eCall call, the IVS sends an RTCP MSD data packet to the PSAP, which carries MSD data; if the PSAP successfully receives the RTCP MSD data packet, it replies with an RTCP notification receipt of the MSD data packet to the IVS; when the IVS still does not receive the RTCP notification receipt of the MSD data packet after the retransmission time, the IVS resends the RTCP MSD data packet to the PSAP, which carries the MSD data; the retransmission time is proportional to the RTT. The present invention sets the retransmission time in direct proportion to the round-trip time, thereby improving the efficiency of packet loss retransmission.

Description

Technical Field

[0001] The present invention relates to a method for transmitting data information by a vehicle-mounted system through RTCP (RTP Control Protocol, Real-time Transport Control Protocol). Background Art

[0002] With the development of wireless communication technology, more and more vehicles are equipped with wireless communication capabilities in emergency situations. For example, when a vehicle is involved in a traffic accident, the IVS (In-Vehicle System) can automatically call the PSAP (Public Safety Answering Point) through an emergency call (eCall), allowing the driver or passengers to contact the PSAP in a timely manner. The IVS can also send an MSD (Minimum Set of Data) to the PSAP. The MSD can include: vehicle identification number, vehicle location information, number of occupants, current timestamp, and other relevant information.

[0003] Reporting MSD quickly and accurately (i.e., IVS sends MSD information to PSAP) is crucial for vehicle rescue. Chinese invention patent application with application publication number CN102362476A, "Device and method for transmitting emergency call data via a wireless network," and Chinese invention patent application with application publication number CN104580218A, "Device and method for transmitting emergency call data via a wireless network," disclose methods for sending MSD using the RTCP protocol, which introduces the negotiation of MSD transmission methods (such as whether to use RTCP transmission), RTCP timeout retransmission, etc. It mentions using the predetermined time T2 as the timeout retransmission time, but does not explain how the T2 value is determined.

[0004] The Internet standard RFC 3550 defines multiple RTCP packet types: SR (type = 200), RR (type = 201), SDES (type = 202), BYE (type = 203), and APP (type = 204). The first four types are protocol types defined by RFC 3550, while the APP type can be defined by different applications. RFC 3550 allows applications to define their own subtypes, thereby defining new RTCP packets. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to propose a method for timely and reliably transmitting MSD (MSD over RTCP) through the RTCP protocol, which can accurately achieve timeout retransmission.

[0006] In order to solve the above technical problems, the present invention discloses a method for reporting MSD through RTCP, comprising the following steps. Step S1: Add 6 subtypes to the APP type real-time transport control protocol RTCP packet, namely: - RTCP synchronization packet, used for the vehicle system IVS to shake hands with the public safety answering point PSAP; a local time field is provided therein, used to record the current time point of the IVS when the IVS sends the RTCP synchronization packet. - RTCP confirmation packet, used for the PSAP to send a response to the IVS after receiving the RTCP synchronization packet; a remote time field and a delay time field are provided therein; the remote time field is used to record the content of the local time field in the RTCP synchronization packet received by the PSAP; the delay time field is used to record the time delayed between the PSAP receiving the RTCP synchronization packet and sending the RTCP confirmation packet. - RTCP notification receipt confirmation packet, used for the IVS to notify the PSAP of receipt after receiving the RTCP confirmation packet; a round-trip time field is provided therein, used to record the round-trip time of the RTCP synchronization packet and the RTCP confirmation packet transmitted over the network calculated by the IVS after receiving the RTCP confirmation packet. ——MSD request packet, used by PSAP to request IVS to send the minimum data set MSD. ——RTCP MSD data packet, used by IVS to send MSD data to PSAP; an MSD data field is provided therein to record the MSD data sent by IVS to PSAP. ——RTCP notification of receipt of MSD data packet, used by PSAP to notify IVS of receipt of MSD data after receiving it. Step S2: After the emergency call eCall is established, IVS sends an RTCP synchronization packet to PSAP; after receiving the RTCP synchronization packet, PSAP replies with an RTCP confirmation packet to IVS; after receiving the RTCP confirmation packet, IVS calculates the round-trip time RTT of the RTCP synchronization packet and the RTCP confirmation packet transmitted in the network, and replies with an RTCP notification of receipt confirmation packet carrying the RTT to PSAP. Step S31: During the eCall call, the IVS sends an RTCP MSD packet carrying MSD data to the PSAP. If the PSAP successfully receives the RTCP MSD packet, it replies with RTCP to the IVS to inform it of receiving the MSD packet. If the IVS still does not receive the RTCP notification of receiving the MSD packet after the retransmission time, the IVS resends the RTCP MSD packet carrying MSD data to the PSAP. The retransmission time is proportional to the RTT.

[0007] Furthermore, the local time field, remote time field, and delayed time field record either absolute time or relative time; the length of the local time field, remote time field, and delayed time field are all 2 bytes; if the time to be recorded exceeds 2 bytes after being expressed in binary, only the lower 16 bits are recorded in the corresponding field.

[0008] Furthermore, in step S2, the method by which IVS calculates RTT is RTT = time_cur - time_last - time_delay; time_cur represents the current time; time_last represents the content of the remote time field in the RTCP confirmation packet, that is, the time when IVS last sent the RTCP synchronization packet; time_delay represents the content of the delay time field in the RTCP confirmation packet.

[0009] Furthermore, in step S3, if the IVS still does not receive the RTCP notification from PSAP of receiving the MSD data packet after the maximum number of retransmissions is reached, the IVS will try to retransmit the RTCP MSD data packet once at a fixed time until the IVS receives the RTCP notification from PSAP of receiving the MSD data packet; the fixed time is much longer than the retransmission time.

[0010] Furthermore, in step S31, if the IVS receives an MSD request packet from the PSAP, the IVS stops attempting to retransmit the RTCP MSD data packet at fixed intervals, immediately responds to the MSD request packet, and sends the RTCP MSD data packet to the PSAP.

[0011] Furthermore, in step S31, if the MSD data of the IVS is updated, the IVS stops trying to retransmit the RTCP MSD data packet at fixed intervals.

[0012] Alternatively, step S31 is replaced with step S32. Step S32: During the eCall call, the PSAP proactively sends an MSD request packet to the IVS, requesting MSD data. After receiving the MSD request packet, the IVS sends an RTCP MSD data packet containing the MSD data to the PSAP. If the PSAP successfully receives the RTCP MSD data packet, it replies with an RTCP message to the IVS to inform it of the receipt of the MSD data packet. If the PSAP still does not receive the RTCP MSD data packet after the retransmission time, the PSAP resends the MSD request packet to the IVS, requesting MSD data. The retransmission time is proportional to the RTT.

[0013] Furthermore, in step S32, if the PSAP still does not receive the RTCP MSD data packet sent by the IVS after the maximum number of retransmissions is reached, the PSAP will try to retransmit the MSD request packet once at a fixed time until the PSAP receives the RTCP MSD data packet sent by the IVS; the fixed time is much longer than the retransmission time.

[0014] The present invention also discloses a device for reporting MSD through RTCP, comprising a subtype adding unit, a synchronous handshake unit, and a data push unit. The subtype adding unit is used to add six subtypes to the APP type real-time transport control protocol RTCP packet, namely, an "RTCP synchronization packet" for the vehicle-mounted system IVS to shake hands with the public safety answering point PSAP, an "RTCP confirmation packet" for the PSAP to send a response to the IVS after receiving the RTCP synchronization packet, an "RTCP notification receipt confirmation packet" for the IVS to send to the PSAP after receiving the RTCP confirmation packet, an "MSD request packet" for the PSAP to request the IVS to send a minimum data set MSD, an "RTCP MSD data packet" for the IVS to send MSD data to the PSAP, and an "RTCP notification receipt MSD data packet" for the PSAP to send confirmation information to the IVS after receiving the MSD data. The RTCP synchronization packet is provided with a local time field for recording the current time point of the IVS when the IVS sends the RTCP synchronization packet. The RTCP confirmation packet is provided with a remote time field and a delay time field; the remote time field is used to record the content of the local time field in the RTCP synchronization packet received by the PSAP; the delay time field is used to record the time delayed between the PSAP receiving the RTCP synchronization packet and sending the RTCP confirmation packet. The RTCP notification receipt confirmation packet is provided with a round-trip time field, which is used to record the round-trip time of the RTCP synchronization packet and the RTCP confirmation packet transmitted in the network calculated by the IVS after receiving the RTCP confirmation packet. The RTCP MSD data packet is provided with an MSD data field, which is used to record the MSD data sent by the IVS to the PSAP. The synchronous handshake unit is used for the IVS to send an RTCP synchronization packet to the PSAP after the emergency call eCall is established; after the PSAP receives the RTCP synchronization packet, the RTCP confirmation packet is replied to the IVS; after the IVS receives the RTCP confirmation packet, the RTT of the RTCP synchronization packet and the RTCP confirmation packet transmitted in the network is calculated, and the RTCP notification receipt confirmation packet carrying the RTT is replied to the PSAP. The push data unit is used for the IVS to send an RTCP MSD data packet carrying MSD data to the PSAP during an eCall call; if the PSAP successfully receives the RTCP MSD data packet, it replies RTCP to the IVS to inform it of the receipt of the MSD data packet; when the IVS still does not receive the RTCP notification of the receipt of the MSD data packet after the retransmission time, the IVS resends the RTCP MSD data packet carrying MSD data to the PSAP; the retransmission time is proportional to the RTT.

[0015] Alternatively, the push data unit is replaced with a pull data unit. The pull data unit is used during an eCall call to enable the PSAP to proactively send an MSD request packet to the IVS to request MSD data. After receiving the MSD request packet, the IVS sends an RTCP MSD data packet carrying the MSD data to the PSAP. If the PSAP successfully receives the RTCP MSD data packet, it replies RTCP to the IVS to inform it of the receipt of the MSD data packet. If the PSAP still does not receive the RTCP MSD data packet after the retransmission time, the PSAP resends the MSD request packet to the IVS to request MSD data. The retransmission time is proportional to the RTT.

[0016] The technical effects achieved by the present invention are: (1) MSD data is sent by carrying it in RTCP packets. In addition to MSD data, there is not much control data in the RTCP packets, so sending and receiving are easy. (2) The sending and receiving of RTCP packets does not affect RTP (Real time Transport Protocol) packets and has no effect on voice transmission. (3) The reliability of RTCP packets in network transmission is improved. The sender can judge whether the MSD data has been received by the receiver through "RTCP notifies the receipt of MSD data packet". (4) The efficiency of packet loss retransmission is improved. The round-trip time of the RTCP packet in the network is calculated through the RTCP handshake (i.e., step S2), and the retransmission time is set in proportion to the round-trip time, so that timeout retransmission is performed efficiently. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a flowchart of embodiment 1 of the method for reporting MSD through RTCP disclosed in the present invention.

[0018] Figure 2 This is a schematic diagram of an exemplary data structure of the RTCP synchronization packet newly added in the present invention.

[0019] Figure 3 This is a schematic diagram of an exemplary data structure of the RTCP confirmation packet newly added in the present invention.

[0020] Figure 4 This is a schematic diagram of an exemplary data structure of the newly added RTCP notification of the receipt of an acknowledgment packet in the present invention.

[0021] Figure 5 This is a schematic diagram of an exemplary data structure of the newly added MSD request packet of the present invention.

[0022] Figure 6 This is a schematic diagram of an exemplary data structure of the newly added RTCP MSD data packet of the present invention.

[0023] Figure 7It is a schematic diagram of an exemplary data structure of the newly added RTCP in the present invention notifying the receipt of an MSD data packet.

[0024] Figure 8 It is a flowchart of embodiment 2 of the method for reporting MSD through RTCP disclosed in the present invention.

[0025] Figure 9 It is a structural diagram of embodiment 1 of the device for reporting MSD through RTCP disclosed in the present invention.

[0026] Figure 10 It is a structural diagram of embodiment 2 of the device for reporting MSD through RTCP disclosed in the present invention.

[0027] Explanation of the reference numerals in the figure: 1 is a subtype adding unit, 2 is a synchronous handshake unit, 31 is a push data unit, and 32 is a pull data unit. DETAILED DESCRIPTION

[0028] See also Figure 1 This is the first embodiment of the method for reporting MSD through RTCP disclosed in the present invention, which includes the following steps.

[0029] Step S1: Six subtypes are added to the APP type (type=204) RTCP packet, namely, the "RTCP sync packet" for the IVS to shake hands with the PSAP, the "RTCP confirm packet" for the PSAP to send a response to the IVS after receiving the RTCP sync packet, the "RTCP ack for confirm packet" for the IVS to send to the PSAP after receiving the RTCP confirm packet, the "MSD request packet" for the PSAP to request the IVS to send an MSD, the "RTCP MSDdata packet" for the IVS to send MSD data to the PSAP, and the "RTCP ack for MSDdata packet" for the PSAP to send confirmation information to the IVS after receiving the MSD data. As an example, the subtype field values ​​of these six subtypes of RTCP packets are 0, 1, 2, 3, 4, and 5, respectively. These six subtypes of RTCP packets (or RTCP data frames) are essentially extensions within the framework of the RFC3550 standard.

[0030] See also Figure 2, which is an exemplary data structure of the newly added RTCP synchronization packet of the present invention. The first line represents bytes (type), and the second line represents bits (bit). The value of the subtype field in the third line is, for example, 0, indicating that the RTCP packet is an RTCP synchronization packet. Some fields are defined in the RFC 3550 standard. The present invention is consistent with the RFC3550 standard and will not be described in detail. The present invention adds a local time field to the RTCP synchronization packet to record the current time point of the IVS when the IVS sends the RTCP synchronization packet. The local time field can record absolute time or relative time (such as the time from the device being turned on to the present). Preferably, the length of the local time field is 2 bytes, that is, 16 bits, and the value range is 0 to 65535, in milliseconds. The field length for recording the current time in common network protocols is usually 4 bytes, and a 2-byte local time field saves more space. Generally, the current time of IVS will exceed this value range after being expressed in binary. In this case, when constructing the RTCP synchronization packet, only the lower 16 bits (bits) of the binary form of the current time of IVS are recorded in the local time field.

[0031] See also Figure 3 , which is an exemplary data structure of the newly added RTCP confirmation packet of the present invention. The first row represents bytes, and the second row represents bits. The value of the subtype field in the third row is, for example, 1, indicating that the RTCP packet is an RTCP confirmation packet. Some fields are defined in the RFC 3550 standard. The present invention is consistent with the RFC 3550 standard and will not be described in detail. The present invention adds a remote time field and a delay time field to the RTCP confirmation packet. The remote time field is used to record the content of the local time field in the RTCP synchronization packet received by the PSAP. The delay time field is used to record the time delayed by the PSAP from receiving the RTCP synchronization packet to sending the RTCP confirmation packet. Preferably, the length of the remote time field is 2 bytes, and the length of the delay time field is 2 bytes, both in milliseconds. The field length for recording the current time in common network protocols is usually 4 bytes, and the 2-byte remote time field and delay time field save more space.

[0032] See also Figure 4, which is an exemplary data structure of the RTCP notification receipt confirmation packet newly added in the present invention. The first row represents bytes, and the second row represents bits. The value of the subtype field in the third row is 2, for example, indicating that the RTCP packet is an RTCP notification receipt confirmation packet. Some fields have been defined in the RFC 3550 standard. The present invention is consistent with the RFC 3550 standard and will not be described in detail. The present invention adds a round trip time (RTT) field to the RTCP notification receipt confirmation packet to record the round trip time of the RTCP synchronization packet and the RTCP confirmation packet calculated by the IVS after receiving the RTCP confirmation packet in the network. This round trip time is used for the subsequent timeout retransmission mechanism.

[0033] See also Figure 5 This is an exemplary data structure of the newly added MSD request packet of the present invention. The first row represents bytes, and the second row represents bits. The value of the subtype field in the third row is, for example, 3, indicating that the RTCP packet is an MSD request packet. All fields are defined in the RFC 3550 standard. The present invention is consistent with the RFC 3550 standard and will not be described in detail. The present invention does not add new fields to the MSD request packet.

[0034] See also Figure 6 , which is an exemplary data structure of the newly added RTCP MSD data packet of the present invention. The first row represents bytes, and the second row represents bits. The value of the subtype field in the third row is, for example, 4, indicating that the RTCP packet is an RTCP MSD data packet. Some fields are defined in the RFC 3550 standard. The present invention is consistent with the RFC 3550 standard and will not be described in detail. The present invention adds an MSD data field to the RTCP MSD data packet to record the MSD data sent by the IVS to the PSAP, for example, located at the end of the RTCP MSD data packet.

[0035] See also Figure 7 This is an exemplary data structure of the newly added RTCP notification of the receipt of the MSD data packet in the present invention. The first row represents bytes, and the second row represents bits. The value of the subtype field in the third row is, for example, 5, indicating that the RTCP packet is an RTCP notification of the receipt of the MSD data packet. All fields are defined in the RFC 3550 standard. The present invention is consistent with the RFC 3550 standard and will not be described in detail. The present invention does not add new fields to the RTCP notification of the receipt of the MSD data packet.

[0036] Step S2: After the eCall is established, the IVS sends an RTCP synchronization packet to the PSAP. Upon receiving the RTCP synchronization packet, the PSAP responds with an RTCP confirmation packet to the IVS. Upon receiving the RTCP confirmation packet, the IVS calculates the round-trip time (RTT) between the RTCP synchronization packet and the RTCP confirmation packet, and responds with an RTCP confirmation packet containing the RTT to the PSAP, indicating receipt of the confirmation packet. The RTT is used by the IVS or PSAP in subsequent timeout retransmission strategies.

[0037] The RTT calculation method is as follows: The IVS obtains the current time, recorded as time_cur. The IVS obtains the contents of the remote time field in the RTCP acknowledgment packet, which is the time when the IVS last sent an RTCP synchronization packet, recorded as time_last. The IVS obtains the contents of the delay time field in the RTCP acknowledgment packet, recorded as time_delay. The RTT calculation formula is RTT = time_cur - time_last - time_delay.

[0038] Step S31: During the eCall call, the IVS sends an RTCP MSD data packet to the PSAP, which carries the MSD data. If the PSAP successfully receives the RTCP MSD data packet, it replies with RTCP to the IVS to inform that the MSD data packet has been received. If the PSAP does not receive the RTCP MSD data packet, for example, the RTCP MSD data packet is lost in the network, no RTCP notification is sent to the IVS to inform that the MSD data packet has been received. When the IVS still does not receive the RTCP notification that the MSD data packet has been received after the retransmission time (timeout), the IVS resends (i.e., retransmits) the RTCP MSD data packet to the PSAP, which carries the MSD data. The retransmission time is generally set to 2 times the RTT, or proportional to it. If the PSAP successfully receives the retransmitted RTCP MSD data packet, it replies with RTCP to the IVS to inform that the MSD data packet has been received. There is no limit on the number of retransmissions. Generally, it is preferred to retransmit up to 3 times, and a total of up to 4 times including the first transmission.

[0039] If the maximum number of retransmissions is reached and IVS still does not receive the RTCP notification from PSAP that the MSD data packet has been received, it is considered that the transmission has failed, which indicates that the network condition is very poor at this time. Subsequently, IVS will try to retransmit the RTCP MSD data packet every 5 seconds. Sending an RTCP MSD data packet every 5 seconds will not occupy too much RTP bandwidth. After the network is restored, the MSD data can also be sent out in time until it is successfully sent (that is, IVS receives the RTCP notification from PSAP that the MSD data packet has been received). However, if there are two situations below, the above retransmission attempt every 5 seconds will be terminated: (1) IVS receives the MSD request packet from PSAP. For example, PSAP sends the MSD request packet just after the network is restored. At this time, IVS stops the previous retransmission attempt every 5 seconds, immediately responds to the MSD request packet, and sends the RTCP MSD data packet to PSAP. (2) The MSD data may be updated after a period of time, such as changes in vehicle information (vehicle position movement, vehicle angle change (rollover), vehicle temperature change (fire), etc.). If the MSD data of the IVS is updated, the previous retransmission attempt every 5 seconds will be stopped, and the new MSD data will be sent to the PSAP subsequently.

[0040] See also Figure 8 This is the second embodiment of the method for reporting MSD via RTCP disclosed in the present invention. In the second embodiment, only step S31 in the first embodiment is replaced by step S32.

[0041] Step S32: During the eCall call, the PSAP proactively sends an MSD request packet to the IVS, requesting to obtain MSD data. After receiving the MSD request packet, the IVS sends an RTCP MSD data packet to the PSAP, which carries the MSD data. If the PSAP successfully receives the RTCP MSD data packet, it replies RTCP to the IVS to inform it of the receipt of the MSD data packet. If the PSAP does not receive the RTCP MSD data packet, for example, if the MSD request packet is lost in the network, it does not send RTCP to the IVS to inform it of the receipt of the MSD data packet. When the PSAP still does not receive the RTCP MSD data packet after the retransmission time, the PSAP resends (i.e., retransmits) the MSD request packet to the IVS, requesting to obtain the MSD data. The retransmission time is generally selected to be twice the RTT, or proportional. After receiving the retransmitted MSD request packet, the IVS sends an RTCP MSD data packet to the PSAP, which carries the MSD data. If the PSAP successfully receives the RTCP MSD data packet, it replies RTCP to the IVS to inform it of the receipt of the MSD data packet. There is no limit on the number of retransmissions. Generally, it is preferred to retransmit up to 3 times, and together with the first transmission, a total of up to 4 times.

[0042] If the PSAP still does not receive the RTCP MSD packet from the IVS after the maximum number of retransmissions has been reached, it considers the request to have failed, indicating that the network conditions are very poor. The PSAP will then attempt to retransmit the MSD request packet every 5 seconds until it receives the RTCP MSD packet from the IVS.

[0043] Comparing the two embodiments, we can see that in the first embodiment, the IVS pushes MSD data to the PSAP, which includes the process of retransmitting RTCP MSD packets in specific scenarios. In the second embodiment, the PSAP pulls MSD data from the IVS, which includes the process of retransmitting MSD request packets in specific scenarios.

[0044] See also Figure 9 This is the first embodiment of the device for reporting MSD through RTCP disclosed in the present invention, which includes an adding subtype unit 1, a synchronous handshake unit 2, and a pushing data unit 31. Figure 9 The device shown is Figure 1 The method shown corresponds to .

[0045] The adding subtype unit 1 is used to add 6 subtypes in the APP type RTCP packet, namely, the "RTCP synchronization packet" for IVS to shake hands with PSAP, the "RTCP confirmation packet" for PSAP to send a response to IVS after receiving the RTCP synchronization packet, the "RTCP notification receipt confirmation packet" for IVS to send to PSAP after receiving the RTCP confirmation packet, the "MSD request packet" for PSAP to request IVS to send MSD, the "RTCP MSD data packet" for IVS to send MSD data to PSAP, and the "RTCP notification receipt MSD data packet" for PSAP to send confirmation information to IVS after receiving the MSD data.

[0046] The RTCP synchronization packet is provided with a local time field for recording the current time point of the IVS when the IVS sends the RTCP synchronization packet.

[0047] The RTCP acknowledgment packet is provided with a remote time field and a delay time field. The remote time field is used to record the content of the local time field in the RTCP synchronization packet received by the PSAP. The delay time field is used to record the time delayed between the PSAP receiving the RTCP synchronization packet and sending the RTCP acknowledgment packet.

[0048] The RTCP notification confirmation packet is provided with a round trip time field for recording the round trip time of the RTCP synchronization packet and the RTCP confirmation packet transmitted over the network calculated by the IVS after receiving the RTCP confirmation packet.

[0049] The RTCP MSD data packet is provided with an MSD data field for recording the MSD data sent by the IVS to the PSAP.

[0050] The synchronization handshake unit 2 is used to send an RTCP synchronization packet to the PSAP after the eCall is established. After receiving the RTCP synchronization packet, the PSAP replies with an RTCP confirmation packet to the IVS. After receiving the RTCP confirmation packet, the IVS calculates the round-trip time (RTT) between the RTCP synchronization packet and the RTCP confirmation packet in the network transmission, and replies with an RTCP confirmation packet carrying the RTT to the PSAP to inform it of the receipt of the confirmation packet.

[0051] The push data unit 31 is used for the IVS to send an RTCP MSD data packet carrying MSD data to the PSAP during an eCall call. If the PSAP successfully receives the RTCP MSD data packet, it replies to the IVS with an RTCP notification that the MSD data packet has been received. When the IVS still has not received an RTCP notification that the MSD data packet has been received after the retransmission time, the IVS resends the RTCP MSD data packet carrying MSD data to the PSAP. The retransmission time is proportional to the RTT. Furthermore, if the IVS still has not received an RTCP notification that the MSD data packet has been received after the maximum number of retransmissions is reached, it attempts to retransmit the RTCP MSD data packet once at a fixed interval. The fixed time is much greater than (greater than or equal to 10 times or more) the retransmission time.

[0052] See also Figure 10 This is the second embodiment of the device for reporting MSD via RTCP disclosed in the present invention. In the second embodiment, the push data unit 31 in the first embodiment is replaced by a pull data unit 32. Figure 10 The device shown is Figure 8 The method shown corresponds to .

[0053] The data pulling unit 32 is used for the PSAP to actively send an MSD request packet to the IVS during an eCall call to request MSD data. After receiving the MSD request packet, the IVS sends an RTCP MSD data packet to the PSAP, which carries the MSD data. If the PSAP successfully receives the RTCP MSD data packet, it replies RTCP to the IVS to inform it of the receipt of the MSD data packet. When the PSAP still does not receive the RTCP MSD data packet after the retransmission time, the PSAP resends the MSD request packet to the IVS to request MSD data. The retransmission time is proportional to the RTT. Furthermore, if the PSAP still does not receive the RTCP MSD data packet after the maximum number of retransmissions is reached, the PSAP attempts to retransmit the MSD request packet once at a fixed interval until the PSAP receives the RTCP MSD data packet. The fixed time is much longer than the retransmission time.

[0054] Compared with the prior art, the present invention discloses a method for transmitting MSD data through the RTCP protocol and RTCP packets, comprising calculating the round-trip time of the RTCP packet in the network, setting the timeout retransmission time to be twice the round-trip time, a timeout retransmission instance of the IVS sending the RTCP MSD data packet to the PSAP, and a timeout retransmission instance of the PSAP sending the MSD request packet to the IVS, which can timely and accurately achieve timeout retransmission. During retransmission, retransmission is first performed at a smaller time interval (i.e., the retransmission time), and after reaching the maximum number of retransmissions, retransmission is changed to a larger time interval (i.e., a fixed time), which neither interferes with normal RTP voice communication nor can timely and successful retransmission be achieved after the network returns to normal.

[0055] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for reporting MSD via RTCP, characterized in that: The method includes the following steps: Step S1: Add 6 subtypes to the APP type Real-time Transport Control Protocol RTCP packet, namely: -- RTCP synchronization packet, used by the vehicle system IVS to shake hands with the public safety answering point PSAP; a local time field is set in it to record the current time point of the IVS when the IVS sends the RTCP synchronization packet; -- RTCP confirmation packet, used by PSAP to send a response to IVS after receiving the RTCP synchronization packet; it contains a remote time field and a delay time field; the remote time field is used to record the content of the local time field in the RTCP synchronization packet received by PSAP; the delay time field is used to record the delay between PSAP receiving the RTCP synchronization packet and sending the RTCP confirmation packet; --RTCP notification of receipt of confirmation packet, used by IVS to inform PSAP of receipt after receiving RTCP confirmation packet; a round-trip time field is set to record the round-trip time of RTCP synchronization packet and RTCP confirmation packet transmitted in the network calculated by IVS after receiving RTCP confirmation packet; ——MSD request packet, used by PSAP to request IVS to send minimum data set MSD; --RTCP MSD data packet, used by IVS to send MSD data to PSAP; it contains an MSD data field to record the MSD data sent by IVS to PSAP; ——RTCP notifies the receipt of MSD data packet, which is used by PSAP to inform IVS of the receipt after receiving MSD data; Step S2: After the emergency call eCall is established, the IVS sends an RTCP synchronization packet to the PSAP; After receiving the RTCP synchronization packet, the PSAP replies with an RTCP confirmation packet to the IVS; After receiving the RTCP confirmation packet, the IVS calculates the round-trip time RTT of the RTCP synchronization packet and the RTCP confirmation packet in the network transmission, and replies to the PSAP with RTCP carrying RTT to inform the PSAP of the receipt of the confirmation packet; RTT = time_cur - time_last - time_delay; time_cur represents the current time; time_last represents the content of the remote time field in the RTCP confirmation packet, that is, the time when the IVS last sent the RTCP synchronization packet; time_delay represents the content of the delay time field in the RTCP confirmation packet; RTT is used for the subsequent timeout retransmission strategy of the IVS or PSAP; Step S31: During an eCall call, the IVS sends an RTCP MSD packet carrying MSD data to the PSAP. If the PSAP successfully receives the RTCP MSD packet, it replies to the IVS with an RTCP notification that the MSD packet has been received. If the IVS still does not receive an RTCP notification that the MSD packet has been received after the retransmission time, the IVS resends an RTCP MSD packet carrying MSD data to the PSAP. The retransmission time is proportional to the RTT. If the IVS still does not receive an RTCP notification that the MSD packet has been received from the PSAP after the maximum number of retransmissions, the IVS attempts to retransmit the RTCP MSD packet at a fixed interval until the IVS receives an RTCP notification that the MSD packet has been received from the PSAP. The fixed time is much longer than the retransmission time. If the MSD data of the IVS is updated, the IVS stops retransmission attempts at fixed intervals and sends the new MSD data to the PSAP instead; Alternatively, step S31 is replaced by step S32; Step S32: During the eCall call, the PSAP proactively sends an MSD request packet to the IVS, requesting to obtain MSD data; after receiving the MSD request packet, the IVS sends an RTCP MSD data packet carrying the MSD data to the PSAP; if the PSAP successfully receives the RTCP MSD data packet, it replies RTCP to the IVS to inform it of the receipt of the MSD data packet; when the PSAP still does not receive the RTCP MSD data packet after the retransmission time, the PSAP resends the MSD request packet to the IVS, requesting to obtain the MSD data; the retransmission time is proportional to the RTT; if the PSAP still does not receive the RTCP MSD data packet sent by the IVS after the maximum number of retransmissions is reached, the PSAP will try to retransmit the MSD request packet at a fixed time until the PSAP receives the RTCP MSD data packet sent by the IVS; the fixed time is much longer than the retransmission time.

2. The method for reporting MSD via RTCP according to claim 1, wherein: The local time field, remote time field, and delayed time field record either absolute time or relative time; the length of the local time field, remote time field, and delayed time field are all 2 bytes; if the time to be recorded exceeds 2 bytes after being expressed in binary, only the lower 16 bits are recorded in the corresponding field.

3. The method for reporting MSD via RTCP according to claim 1, wherein: In step S31, if the IVS receives the MSD request packet from the PSAP, the IVS stops trying to retransmit the RTCP MSD data packet at fixed intervals, and immediately responds to the MSD request packet by sending the RTCP MSD data packet to the PSAP.

4. A device for reporting MSD via RTCP, characterized in that: Including adding subtype unit, synchronous handshake unit, and push data unit; The added subtype unit is used to add 6 subtypes in the real-time transport control protocol RTCP packet of the APP type, namely, an "RTCP synchronization packet" for the in-vehicle system IVS to shake hands with the public safety answering point PSAP, an "RTCP confirmation packet" for the PSAP to send a response to the IVS after receiving the RTCP synchronization packet, an "RTCP notification receipt confirmation packet" for the IVS to send to the PSAP after receiving the RTCP confirmation packet, an "MSD request packet" for the PSAP to request the IVS to send a minimum data set MSD, an "RTCP MSD data packet" for the IVS to send MSD data to the PSAP, and an "RTCP notification receipt MSD data packet" for the PSAP to send confirmation information to the IVS after receiving the MSD data; The RTCP synchronization packet is provided with a local time field, which is used to record the current time point of the IVS when the IVS sends the RTCP synchronization packet; The RTCP acknowledgment packet is provided with a remote time field and a delay time field; the remote time field is used to record the content of the local time field in the RTCP synchronization packet received by the PSAP; the delay time field is used to record the time delayed between the PSAP receiving the RTCP synchronization packet and sending the RTCP acknowledgment packet; The RTCP notification confirmation packet is provided with a round trip time field, which is used to record the round trip time of the RTCP synchronization packet and the RTCP confirmation packet calculated by the IVS after receiving the RTCP confirmation packet. The RTCP MSD data packet is provided with an MSD data field for recording the MSD data sent by the IVS to the PSAP; The synchronous handshake unit is used for the IVS to send an RTCP synchronization packet to the PSAP after the emergency call eCall is established; After receiving the RTCP synchronization packet, the PSAP replies with an RTCP confirmation packet to the IVS; After receiving the RTCP confirmation packet, the IVS calculates the round-trip time RTT of the RTCP synchronization packet and the RTCP confirmation packet in the network transmission, and replies to the PSAP with RTCP carrying RTT to inform the PSAP of the receipt of the confirmation packet; RTT = time_cur - time_last - time_delay; time_cur represents the current time; time_last represents the content of the remote time field in the RTCP confirmation packet, that is, the time when the IVS last sent the RTCP synchronization packet; time_delay represents the content of the delay time field in the RTCP confirmation packet; RTT is used for the subsequent timeout retransmission strategy of the IVS or PSAP; The push data unit is used for the IVS to send an RTCP MSD data packet carrying MSD data to the PSAP during an eCall call; if the PSAP successfully receives the RTCP MSD data packet, it replies to the IVS with an RTCP notification of receipt of the MSD data packet; when the IVS still does not receive the RTCP notification of receipt of the MSD data packet after the retransmission time, the IVS resends the RTCP MSD data packet carrying MSD data to the PSAP; the retransmission time is proportional to the RTT; if the IVS still does not receive the RTCP notification of receipt of the MSD data packet from the PSAP after the maximum number of retransmissions is reached, the IVS will attempt to retransmit the RTCP MSD data packet at a fixed time until the IVS receives the RTCP notification of receipt of the MSD data packet from the PSAP; the fixed time is much longer than the retransmission time; If the MSD data of the IVS is updated, the IVS stops retransmission attempts at fixed intervals and sends the new MSD data to the PSAP instead; Alternatively, replace the push data unit with the pull data unit; The data pulling unit is used for the PSAP to actively send an MSD request packet to the IVS during the eCall call to request the acquisition of MSD data; After receiving the MSD request packet, IVS sends an RTCP MSD data packet carrying MSD data to PSAP; if PSAP successfully receives the RTCP MSD data packet, it replies RTCP to IVS to inform it of the receipt of the MSD data packet; when PSAP still does not receive the RTCP MSD data packet after the retransmission time, PSAP resends the MSD request packet to IVS to request MSD data; the retransmission time is proportional to the RTT; if the PSAP still does not receive the RTCP MSD data packet sent by IVS after the maximum number of retransmissions is reached, PSAP will try to retransmit the MSD request packet at a fixed time until PSAP receives the RTCP MSD data packet sent by IVS; the fixed time is much longer than the retransmission time.

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