Terminal and communication method

Abstract

A terminal according to the present invention determines the validity of a received packet on the basis of the sequence number of the packet, and processes valid packets and discards invalid packets. When the sequence number of a second packet received at the start of a call with a called terminal is lower than the sequence number of a first packet received while calling the called terminal, the terminal processes the second packet without discarding the same.

Description

Terminal and Communication Method

[0001] The present disclosure relates to a terminal and a communication method for controlling a call at the time of call establishment.

[0002] The 3rd Generation Partnership Project (3GPP: registered trademark) has standardized the 5th generation mobile communication system (also called 5G, New Radio (NR) or Next Generation (NG)), and is also promoting the standardization of the next generation called Beyond 5G, 5G Evolution or 6G.

[0003] In VoLTE (Voice over LTE) that provides a voice call service, an IP (Internet Protocol)-based voice communication technology is used instead of a circuit switch, and real-time communication is realized using SIP (Session Initiation Protocol) as a communication protocol.

[0004] In SIP, a user who starts voice communication sends an INVITE request from the originating terminal and calls the user of the terminating terminal via a proxy server. When the terminating terminal receives the INVITE request, it starts the user's call while sending a 180 Ringing response back to the originating terminal via the proxy server. When the originating terminal receives the 180 Ringing response, it subsequently plays the received call tone (RBT: Ringback Tone) to notify the user of the originating terminal that the other party is being called. After that, when the user of the terminating terminal responds, the terminating terminal sends a 200 OK to the originating terminal via the proxy server. As a result, the RBT stops, and the user of the originating terminal knows that the call has been answered. Then, when the originating terminal sends an ACK message, the call between the users is started (Non-Patent Document 1).

[0005] Furthermore, SIP uses RTP (Real Time Protocol) packets as packets containing data and voice data for calls. The sequence number (SN) of an RTP packet increments by one for each packet, which is used by the receiving end to detect packet discards or changes in the order of reception (Non-Patent Literature 2).

[0006] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M. and E. Schooler, “SIP: Session Initiation Protocol”, IETF RFC 3261, June 2002Schulzrinne, H., Casner, S., Frederick, R. and Jacobson, V., “RTP: A Transport Protocol for Real-Time Applications”, IETF RFC 3550, July 2003

[0007] However, currently, there is a problem where, after the calling device receives 200 OK, the other party's voice is not heard at the start of the call, resulting in silence.

[0008] In SIP, the originating and receiving terminals negotiate to determine a common codec to be used during a call. For example, in a case where the originating terminal is a 4G terminal and the receiving terminal is a 3G terminal, the codec for the call will be determined to be a codec available to both terminals (a codec supported by the 3G terminal), but the codec for the ringtone may be different. In such cases, the network side will switch codecs at the start of the call. This codec switch necessitates changing the sequence number assigned to the packets. As a result, the originating terminal may receive an RTP packet at the start of the call with a signal-to-noise ratio (SN) smaller than the RTP packets it had received during the call.

[0009] Additionally, as an added service, there is a service that provides the user of the originating terminal with a melody of their choice, such as a song of their preference, instead of the usual ringtone RBT. In such services, the codec used for the ringtone is a high-quality codec available to the originating terminal, so the codec used for the call and the codec used for the ringtone may be different. In such cases, as described above, a codec switch occurs on the network side when the call starts. As a result, the originating terminal may receive an RTP packet at the start of the call that has a smaller signal-to-noise ratio (SN) value than the RTP packets it received during the call.

[0010] According to IETF RFC3550, packets received from the same source are validated by checking whether their signal-to-noise ratio (SN) is within the expected range. Invalid packets may be discarded, or they may be stored and, if the delay is acceptable, delivered after validation is complete. Therefore, depending on the originating terminal, if the SN value of a packet received at the start of a call is smaller than the SN value of packets received during the call, the packet received at the start of the call may be discarded as an invalid packet. This packet discard results in no packets to decode, causing silence at the start of the call, as the other party's voice cannot be heard.

[0011] Therefore, the following disclosure is made in light of these circumstances and aims to provide a terminal and communication method that perform call control to avoid the phenomenon where the other party's voice is not heard and there is silence at the start of a call with the receiving terminal.

[0012] One aspect of the present disclosure is a terminal (100) comprising a packet processing unit (20) that determines the validity of a packet based on the sequence number of the received packet, processes valid packets, and discards invalid packets, and a control unit (30) that processes the second packet without discarding it if the sequence number of the second packet received at the start of a call with the receiving terminal is smaller than the sequence number of the first packet received during the call with the receiving terminal.

[0013] One aspect of the present disclosure is a communication method for a terminal (100) that includes the steps of determining the validity of a packet based on the sequence number of the received packet, processing valid packets and discarding invalid packets, and processing a second packet without discarding it if the sequence number of the second packet received at the start of a call with the receiving terminal is smaller than the sequence number of the first packet received during the call with the receiving terminal.

[0014] Figure 1 shows an example of the overall schematic configuration of the call control system according to this embodiment.

[0015] Figure 2 shows an example of the functional block configuration of a terminal.

[0016] Figure 3 is a sequence diagram showing an example of the overall operation of the call control system.

[0017] Figure 4 shows the structure of the RTP header.

[0018] Figure 5 is a sequence diagram showing call control at the originating terminal.

[0019] Figure 6 is a diagram (part 1) showing the control flow of the originating terminal according to this embodiment.

[0020] Figure 7 is a diagram (part 2) showing the control flow of the issuing terminal according to this embodiment.

[0021] Figure 8 is a sequence diagram showing call control in the originating terminal according to this embodiment.

[0022] Figure 9 shows an example of the hardware configuration of a terminal.

[0023] Figure 10 shows an example of the configuration of vehicle 2001.

[0024] The embodiments will be described below with reference to the drawings. Note that identical or similar reference numerals are used to denote the same functions and components, and their descriptions will be omitted as appropriate.

[0025] A call control system is a computer system that controls calls between an originating terminal and an incoming terminal. A call refers to the temporary occupancy of communication equipment for communication between an originating terminal and an incoming terminal. The originating terminal is the communication terminal that initially requests a call connection, and the incoming terminal is the communication terminal that responds to the call connection request. Once a call is established between these two communication terminals, the caller (user of the originating terminal) and the recipient (user of the incoming terminal) can communicate.

[0026] (1) Overall Configuration Example of Call Control System Figure 1 is a diagram showing an overall schematic configuration example of the call control system according to this embodiment. The call control system comprises a calling network 400 in which the calling terminal 100 is located, a receiving network 500 in which the receiving terminal 300 is located, and a core network 200 connecting the calling network 400 and the receiving network 500. In the call control system, a call (communication path) is established by the transmission of control signals between multiple devices and terminals, and voice data packets are transmitted through that call, enabling communication between users.

[0027] The originating terminal 100 and the receiving terminal 300 are communication terminals with calling capabilities. The originating terminal 100 and the receiving terminal 300 are, for example, wireless communication terminals, specifically mobile phones, smartphones, etc., but the type of terminal is not limited to these.

[0028] The type of audio codec supported by the originating terminal 100 may differ from the type of audio codec supported by the receiving terminal 300. A codec refers to a technology or circuit related to the encoding and decoding of data such as voice. For example, voice encoding schemes defined by 3GPP include the narrowband AMR-NB (Adaptive Multi-Rate NarrowBand), the wideband AMR-WB (Adaptive Multi-Rate WideBand), and the ultra-wideband EVS (Enhanced Voice Services). Higher quality calls can be provided by using a wider bandwidth codec.

[0029] VoLTE is a technology that provides voice communication as data communication (packet communication) using the LTE method, which speeds up data communication for 3G terminals. The voice codec for VoLTE is defined as AMR-NB, which is used in 3G circuit-switched voice services, as a mandatory codec. In addition, the use of higher quality AMR-WB and EVS is permitted as options. For this reason, terminals compliant with 3G (3G terminals) support AMR-NB as their voice codec, while terminals compliant with 4G and 5G (4G terminals, 5G terminals) can support AMR-WB and EVS in addition to AMR-NB.

[0030] Both the originating network 400 and the receiving network 500 are networks that include an access network to which the terminal directly connects. In this embodiment, if the originating network 400 is a 4G network, it is configured as LTE / EPC. The LTE / EPC includes a 4G base station eNodeB, MME (Mobility Management Entity), SGW (Serving Gateway), PGW (Packet Data Network Gateway), PCRF (Policy and Charging Rules Function), etc. If the originating network 400 is a 5G network, it is configured as an NSA (Non-Stand Alone) system and further includes a 5G base station gNodeB. The receiving network 500 is a 3G wireless network and is configured as UTRAN / CN. UTRAN / CN includes 3G base stations such as BTS (Base Transceiver Station), RNC (Radio Network Controller), MSC / VLR (Mobile Service Switching Center / Visitor Location Register), HLR (Home Location Register), SGSN (Serving GPRS Support Node), GGSN (Gateway GPRS Support Node), and GMSC (Gateway MSC).

[0031] Core Network 200 is the central network of the call control system, and is, for example, an IMS (IP Multimedia Subsystem) network. SIP is used as its communication protocol, enabling multimedia services that realize not only data communication but also real-time voice or video communication.

[0032] Specifically, the core network 200 consists of VGN201, originating CSN202, originating ASN203, incoming ASN204, incoming CSN205, SIN206, MGN207, MPN208, Storage209, and MRN210, which process calls.

[0033] VGN201 is a VoLTE Gateway Node (VGN), a gateway device for connecting VoLTE-enabled terminals to the IMS network.

[0034] SIN206 is a Signaling Interworking Node for 3G access, and is a gateway device for connecting 3G wireless access networks to the IMS network.

[0035] The SIN206 is responsible for connecting the 3G wireless access network to the IMS and operates as a virtual SIP-enabled terminal in place of 3G terminals that do not have SIP communication capabilities. In other words, when the SIN206 receives a CC (Call Control) protocol signal for outgoing calls, it converts it to a SIP signal and sends it out, and when it receives a call, it converts from SIP to CC.

[0036] Furthermore, SIN206 assigns a sequence number to packets. In the call connection sequence, if a switch occurs from the ringtone codec to the call codec, the sequence number assigned to the packets needs to be changed in accordance with the codec switch. As a result, the sequence number assigned to the packets at the start of the call may differ from the sequence number assigned to the packets during the call. In other words, the value of the sequence number becomes smaller.

[0037] The originating CSN202 and the receiving CSN205 are Call Session function nodes (CSNs) that control the session, which is a series of communications in the call control sequence. Control signals and data signals (e.g., voice data) are transmitted and received between the originating CSN202 and the receiving CSN205, thereby interconnecting the originating terminal 100 and the receiving terminal 300.

[0038] The originating ASN203 and receiving ASN204 are Application Server Nodes (ASNs) that control various voice services.

[0039] MGN207 is a Media Gateway Node (MGN) that controls connectivity with other networks.

[0040] MPN208 is a Media Processing Node (MPN) that provides an audio media service to the user of the sending terminal 100, delivering melodies such as songs selected by the user of the receiving terminal 300. It analyzes the SDP information of the sending terminal 100 and performs conversion to a high-quality codec and melody transmission.

[0041] Storage 209 is a storage device that stores high-quality audio sources of melodies, such as songs, for audio media services.

[0042] The MRM 210 is a Media Resource Node (MRM) that performs guidance transmission control and performs RBT transmission, among other things.

[0043] (2) Example of the function block configuration of the sending terminal Figure 2 is a diagram showing an example of the function block configuration of the sending terminal.

[0044] As shown in FIG. 2, the originating terminal 100 includes a communication unit 10, a packet processing unit 20, and a control unit 30. Note that in FIG. 2, only the main functional blocks related to the description of the embodiment are shown, and it should be noted that the originating terminal 100 also has other functional blocks (for example, a power supply unit, etc.). Further, FIG. 2 shows the functional block configuration of the originating terminal 100. For the hardware configuration, refer to FIG. 9.

[0045] The communication unit 10 exchanges signals for call control messages by SIP and establishes a voice call. The communication unit 10 of the originating terminal 100 uses an access method compliant with the 4G or 5G network 400.

[0046] The packet processing unit 20 processes the packets transmitted and received by the communication unit 10. For example, it checks the sequence number in the header of the RTP packet to determine the validity of the packet, processes the valid packets, and discards the invalid packets. Specifically, it checks the sequence number of the received packet to detect discarding or reordering, determines whether the sequence number is within the expected range, processes the valid packets, and discards the invalid packets. Also, according to the control of the control unit 30, even if a packet with a smaller sequence number is received later, the packet is processed without being discarded.

[0047] The control unit 30 controls the communication unit 10 and the packet processing unit 20. When the sequence number of the second packet received at the start of the call with the terminating terminal is smaller than the sequence number of the first packet received during the call of the terminating terminal, the control unit 30 processes the second packet without discarding it. That is, when the sequence number of the RTP packet received at the start of the call is smaller than the sequence number of the RTP packet received during the call, the control unit 30 processes the RTP packet at the start of the call without discarding it. Here, during the call, it refers to the period after receiving the call (SIP_180 Ringing) and before receiving the connection response (SIP_200OK). Also, at the start of the call, it refers to the period after receiving the connection response (SIP_200OK).

[0048] Specifically, even if the sequence number of the RTP packet of the voice data received at the start of a call is smaller than the sequence number of the RTP packet of the call tone / melody data received during the call, the control unit 30 controls the packet processing unit 20 to process the RTP packet of the voice data at the start of the call as a valid packet. Or, even if the sequence number of the RTP packet of the voice data received at the start of a call is smaller than the sequence number of the RTP packet of the call tone / melody data received during the call, the control unit 30 temporarily stores the RTP packet of the voice data at the start of the call as an invalid packet, but if the delay can be tolerated and the verification is achieved as a result, it controls to deliver the stored packet.

[0049] As a result, even if the sequence number of the packet received at the start of a call is smaller than the sequence number of the packet received during the call, the packet at the start of the call is not discarded, and as a result of the packet being decoded, it is possible to avoid the situation where the voice of the other party cannot be heard and there is silence at the start of the call.

[0050] (3) Operation of the Call Control System Next, the operation of the call control system will be described with respect to the call connection sequence using SIP.

[0051] (3.1) Premise (3.1.1) Call Connection Sequence FIG. 3 is a sequence diagram showing an example of the overall operation of the call control system. The overall operation will be described while also referring to FIG. 1.

[0052] In step S301, in response to a voice call operation by the user of the originating terminal 100, a call request (SIP_INVITE) is transmitted from the originating terminal 100. The call request (SIP_INVITE) is set with ability information (SDP: Session Description Protocol) regarding the session, such as the identifiers of the originating and terminating users and the codec of the originating terminal 100. The call request (SIP_INVITE) from the originating terminal 100 is transferred to the VGN201, originating CSN202, originating ASN203, terminating ASN204, terminating CSN205, and is received by the SIN206.

[0053] In step S302, when SIN206 receives an outgoing request (SIP_INVITE), it sends an outgoing request (CC_Set up) to the receiving terminal 300.

[0054] In step S303, SIN206 sends a provisional response (SIP_183 Session Progress). The provisional response (SIP_183 Session Progress) contains session capability information (SDP), such as SIN206's address and codec. SIN206's codec is set to be the same as the codec of the 3G terminal, which is the receiving terminal 300. The provisional response (SIP_183 Session Progress) from SIN206 is forwarded to VGN201 and received by the sending terminal 100.

[0055] In step S304, when the receiving terminal 300 receives a call request (CC_Setup) from SIN206, it replies to SIN206 with a call request confirmation (CC_Call Confirmed).

[0056] In step S305, when the originating terminal 100 receives a provisional response (SIP_183 Session Progress), it compares its own capabilities with those of the incoming terminal (=SIN206) and determines the codec for the call.

[0057] In step S306, the originating terminal 100 notifies the incoming terminal (=SIN206) of the determined call codec using PRACK, and receives a SIP_200 OK response from SIN206.

[0058] In step S307, the receiving terminal 300 sends a call (CC_Alerting).

[0059] In step S308, when SIN206 receives a call (CC_Alerting) from the incoming terminal 300, it sends a call (SIP_180 Ringing). The call (SIP_180 Ringing) from the incoming terminal 300 is forwarded to the incoming CSN205, incoming ASN204, outgoing CSN202, outgoing ASN203, and VGN201, and is received by the outgoing terminal 100.

[0060] In step S309, the incoming ASN204, upon receiving the call (SIP_180 Ringing), recognizes the RBT connection and requests a sound source connection from the MRN210 via the incoming CSN202 and the MGN207 shown in Figure 1, thereby transmitting the RBT from the MRN210 to the originating terminal 100. The MRN210 encodes the RBT sound source using a predetermined ringtone codec.

[0061] Furthermore, in step S309, if the incoming ASN204 determines that the user of the incoming terminal 300 has subscribed to an additional service that provides a melody instead of the normal ringtone RBT, it requests the MPN208 shown in Figure 1 to send a melody, and the MPN208 sends the melody to the originating terminal 100. If the MPN208 determines from the SDP information of the melody transmission request signal that the originating terminal is requesting high-quality communication, it uses a high-quality codec as the ringtone codec to encode the sound source acquired from Storage209, so that the originating terminal 100 plays a high-quality melody. If the originating terminal 100 does not support a high-quality codec, it uses a codec that matches the originating terminal as the ringtone codec.

[0062] In step S310, when the user of the receiving terminal 300 responds (goes off-hook), a connection response (CC_Connect) is sent.

[0063] In step S311, when SIN206 receives a connection response (CC_Connect) from the receiving terminal 300, it sends a connection response (SIP_200 OK). This connection response (SIP_200 OK) is forwarded to the receiving ASN204 via the receiving CSN. When the receiving ASN204 receives the connection response (SIP_200 OK), it recognizes the RBT release and sends an RBT release request to the sound source MPN208 via the receiving CSN205, causing MPN208 to stop sending the RBT to the sending terminal 100.

[0064] In step S312, the connection response (SIP_200 OK) received by the incoming CSN205 is forwarded to the outgoing CSN202, outgoing ASN203, and VGN201, and received by the outgoing terminal 100.

[0065] In step S313, the originating terminal 100 receives a connection response (SIIP_200 OK), establishing a session between the originating terminal 100 and the receiving terminal 200, enabling a call with the user of the receiving terminal 300. The previously determined call codec is used for this call. If the ringtone codec and the call codec are different, the codecs are switched. Along with the codec switch, the sequence number assigned to the packets is changed before and after the switch.

[0066] (3.1.2) Packet configuration diagram 4 is a diagram showing the configuration of the RTP header.

[0067] RTP is a communication protocol for transmitting continuous data streams, such as voice and video, in real time. The RTP payload stores and transmits ringtone / melody data and call audio data.

[0068] In Figure 4, V is the RTP version number, P is the padding indication, X indicates the presence or absence of an extended header, CC is the CSRC count, M is the marker, PT is the payload type, sequence number is the sequence number (SN), timestamp is the transmission time of the first byte, and SSRC is the Synchronization Source (SSRC) identifier.

[0069] A sequence number (SN) is a number used to manage the order of data packets in a session or media stream, and is used when dividing media streams such as audio and video into packets for transmission. The sender assigns a unique SN to each packet, and the receiver uses the SN to verify and reconstruct the correct order of the packets.

[0070] The Synchronized Source Identifier (SSRC) is an identifier used to identify the source of an RTP packet, ensuring audio and video synchronization in a communication session.

[0071] (3.1.3) RTP Packet Verification IETF RFC 3550 requires that RTP packets be verified using the SSRC identifier and SN as follows:

[0072] "If the SSRC identifier in a packet has been received before, the packet is likely valid, and further verification can be performed by checking whether the sequence number is within the expected range. If the SSRC identifier is not previously seen, data packets with that identifier may be considered invalid until a small number of packets with consecutive sequence numbers arrive. These invalid packets may be discarded, or they may be stored and delivered after verification is achieved, provided that the resulting delay is acceptable."

[0073] (3.2) As explained in Figure 3 of the problem, in the call control sequence, the codec for the call and the codec for the ringtone are determined based on different criteria.

[0074] In other words, the codec used for calls is determined by which codecs are available on both the calling and receiving terminals. 3G terminals support AMR-NB, while 4G and 5G terminals can support AMR-WB and EVS in addition to AMR-NB.

[0075] On the other hand, the codec for the ringtone uses a predetermined codec for sending the sound source RBT. However, if the incoming terminal 300 uses the melody transmission service, the sending terminal 100 uses a high-quality codec that is available to it (for example, AMR-WB).

[0076] If the codec used for ringing and the codec used for the call are different, a codec switch will occur. This codec switch necessitates a change in the sequence number assigned to the packets. As a result, the sequence number assigned to the packet at the start of the call may differ from the sequence number assigned to the packets during the call (i.e., the sequence number value may be smaller).

[0077] Figure 5 is a sequence diagram showing call control at the originating terminal.

[0078] In Figure 5(A), during the ringing of the incoming terminal 300 (from the reception of the ringing (SIP_180 Ringing) until the reception of the connection response (SIP_200 OK)), packets of ringtone / melody data (i.e., RTP packets with SSRC: AAAA, SN: 1000 and RTP packets with SSRC: AAAA, SN: 1001) are received sequentially. Then, at the start of the call when the incoming terminal 300 responds (receives the connection response (SIP_200 OK)) and the call begins, packets of voice data (i.e., RTP packets with SSRC: AAAA, SN: 1002 and RTP packets with SSRC: AAAA, SN: 1003) are received consecutively.

[0079] The originating terminal 100 verifies the validity of the received packets using the RTP data header. In the example shown in Figure 5(A), the series of packets received from the start of the call to the start of the call are processed as valid packets because the SSRC is identical at AAAA and the SN values ​​are consecutive. As a result, the user of the originating terminal 100 can hear the other party's voice without interruption at the start of the call.

[0080] Figure 5(B) is a sequence diagram (part 2) showing call control at the originating terminal.

[0081] In Figure 5(B), unlike in Figure 5(A), the SN values ​​of the voice data packets received at the start of a call after receiving the connection response (SIP_200OK) (i.e., RTP packets with SSRC: AAAA, SN: 500 and RTP packets with SSRC: AAAA, SN: 501) are smaller than the SN values ​​of the ringtone / melody data packets received during the call (i.e., RTP packets with SSRC: AAAA, SN: 1000 and RTP packets with SSRC: AAAA, SN: 1001).

[0082] In such cases, depending on the originating terminal 100, the signal-to-noise ratio (SN) value of the RTP packet at the start of the call may be smaller than the SN value of the RTP packets received during the call, causing the packet to be discarded as invalid. This resulted in a problem where the other party's voice could not be heard at the start of the call, resulting in silence.

[0083] (3.3) Example of operation The following disclosure makes it possible to avoid silence at the start of a call.

[0084] (3.3.1) Operation Example 1 Figure 6 is a diagram (part 1) showing the control flow of call control at the originating terminal in this embodiment. It will be explained with reference to Figure 2.

[0085] In step S600, the communication unit 10 receives an RTP packet, and the control unit 30 verifies the validity of the RTP data header.

[0086] In step S601, the control unit 30 determines whether the SSRC identifier in the RTP data header has been received previously.

[0087] In step S602, if the SSRC identifier has not been received previously, the data packet with that identifier may be the first packet, and therefore, it is treated as an invalid packet until a small number of packets with consecutive sequence numbers arrive.

[0088] In step S603, if the SSRC identifier has been received previously, the control unit 30 determines whether the SN value of the RTP packet at the start of the call is greater than the SN value of the RTP packet received during the call.

[0089] In step S604, if the SN value of the RTP packet at the start of the call is greater than the SN value of the RTP packets received during the call, the packet processing unit 20 processes it as a valid packet.

[0090] In step S605, the control unit 30 determines whether the SN value of the RTP packet at the start of the call is smaller than the SN value of the RTP packets received during the call. If the SN value of the RTP packet at the start of the call is smaller than the SN value of the RTP packets received during the call, in step S604, it is treated as a valid packet and processed by the packet processing unit 20. This prevents the packet from being discarded as an invalid packet, thus avoiding silence at the start of a call due to the other party's voice not being heard.

[0091] In step S606, if the SN value of the RTP packet at the start of the call is the same as the SN value of the RTP packet received during the call, the packet processing unit 20 either discards it as an invalid packet or stores such a packet and delivers it after verification is completed, provided that the resulting delay is acceptable.

[0092] (3.3.2) Operation Example 2 Figure 7 is a diagram (part 2) showing the control flow of call control at the originating terminal in this embodiment.

[0093] In Figure 7, unlike in Figure 6, the control unit 30, if the SN value of the RTP packet at the start of a call is smaller than the SN value of the RTP packet received during the call, stores it as an invalid packet in step S607. However, if the resulting delay is acceptable, it controls the packet processing unit 20 to deliver the packet after verification is complete. In other words, while in Figure 6 the packet is processed as a valid packet, in Figure 7, even such packets are stored initially and then delivered if the delay is acceptable and verification is complete. As a result, the delivered packets are processed in the same way as valid packets, thus avoiding silence at the start of a call due to the other party's voice not being heard.

[0094] Figure 8 is a sequence diagram showing call control in the originating terminal according to this embodiment.

[0095] In Figure 8, similar to Figure 5(B), the SN values ​​of the voice data packets received at the start of a call after receiving the connection response (SIP_200OK) (i.e., RTP packets with SSRC: AAAA, SN: 500 and RTP packets with SSRC: AAAA, SN: 501) are smaller than the SN values ​​of the ringtone / melody data packets received during the call (i.e., RTP packets with SSRC: AAAA, SN: 1000 and RTP packets with SSRC: AAAA, SN: 1001).

[0096] However, in the case of Operation Example 1, in step S605 shown in Figure 6, the SN value of the RTP packet at the start of the call is smaller than the SN value of the RTP packet received during the call. As a result, it is processed as a valid packet in step S604, and the other party's voice is not heard at the start of the call, resulting in silence (audibility).

[0097] Furthermore, in the case of operation example 2, in step S605 shown in Figure 7, the SN value of the RTP packet at the start of the call is smaller than the SN value of the RTP packets received during the call. Therefore, in step S607, such packets are not discarded but are temporarily stored, and after the delay is acceptable and verification is achieved, they are delivered. As a result, the delivered packets are processed in the same way as valid packets, so there is no silence at the start of the call due to the other party's voice not being heard (audible).

[0098] (4) Effects and Actions According to the embodiments described above, the following effects and actions can be obtained.

[0099] The originating terminal determines the validity of a packet based on its sequence number, processes valid packets, and discards invalid packets. The originating terminal processes the second packet received at the start of a call with the receiving terminal even if its sequence number is smaller than the sequence number of the first packet received during the call with the receiving terminal.

[0100] As a result, even if a codec switch occurs during the call control sequence, causing the sequence number assigned to the packet to change and become smaller, packets received at the start of the call will not be discarded. This prevents the situation where the other party's voice is not heard at the start of the call, resulting in silence.

[0101] Furthermore, the originating terminal will process the second packet as a valid packet even if the sequence number of the second packet received at the start of a call with the receiving terminal is smaller than the sequence number of the first packet received during the call with the receiving terminal.

[0102] As a result, even if a codec switch occurs during the call control sequence, causing the sequence number assigned to the packet to change and become smaller, the packet received at the start of the call will still be processed as a valid packet. This prevents the situation where the other party's voice is not heard at the start of the call, resulting in silence.

[0103] (5) Other Embodiments The contents of the present invention have been described above in accordance with the embodiments, but it will be obvious to those skilled in the art that the present invention is not limited to these descriptions and that various modifications and improvements are possible.

[0104] For example, although the above embodiment was explained using the example of VoLTE, other examples may be used as long as SIP is used. For example, it can also be applied to VoNR (Voice over NR), which provides voice call services using only 5G NR and 5GC without relying on 4G.

[0105] Furthermore, while AMR-NB, AMR-WB, and EVS were given as examples of audio codecs, other audio coding schemes are also acceptable.

[0106] Furthermore, in the above description, configure, activate, update, indicate, enable, specify, and select may be interpreted interchangeably. Similarly, link, associate, correspond, and map may be interpreted interchangeably, as may allocate, assign, monitor, and map.

[0107] Furthermore, "specific," "dedicated," "UE specific," and "UE individual" may be interpreted interchangeably. Similarly, "common," "shared," "group-common," "UE common," and "UE shared" may be interpreted interchangeably.

[0108] The block diagram (Figure 2) used in the description of the above-mentioned embodiments shows functional units. These functional blocks (components) are realized by any combination of at least one of hardware and software. Furthermore, the method of realizing each functional block is not particularly limited. That is, each functional block may be realized using one device that is physically or logically coupled, or it may be realized using two or more physically or logically separated devices that are directly or indirectly connected (for example, using wired or wireless connections). A functional block may also be realized by combining the above one device or the above multiple devices with software.

[0109] Functions include, but are not limited to, judgment, decision, judgment, calculation, calculation, processing, derivation, investigation, exploration, confirmation, reception, transmission, output, access, resolution, selection, selection, establishment, comparison, assumption, expectation, assumption, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocating (mapping), and assigning. For example, a functional block (configuration part) that enables transmission is called a transmitting unit or transmitter. In any case, as mentioned above, the method of implementation is not particularly limited.

[0110] Furthermore, the terminal 100 (the device) described above may function as a computer that processes the wireless communication method of this disclosure. Figure 9 shows an example of the hardware configuration of the device. As shown in Figure 9, the device may be configured as a computer device including a processor 1001, memory 1002, storage 1003, communication device 1004, input device 1005, output device 1006, and bus 1007.

[0111] In the following explanation, the term "device" can be replaced with "circuit," "device," "unit," etc. The hardware configuration of the device may include one or more of the devices shown in the diagram, or it may be configured to omit some of the devices.

[0112] Each functional block of the device (Figure 2) is implemented by any hardware element of the computer device, or a combination of such hardware elements.

[0113] Furthermore, each function in the device is realized by loading predetermined software (programs) onto hardware such as the processor 1001 and memory 1002, which allows the processor 1001 to perform calculations, control communication by the communication device 1004, and control at least one of the reading and writing of data in the memory 1002 and storage 1003.

[0114] The processor 1001 controls the entire computer, for example, by running an operating system. The processor 1001 may consist of a central processing unit (CPU) that includes interfaces with peripheral devices, control units, arithmetic units, registers, and so on.

[0115] Furthermore, the processor 1001 reads programs (program code), software modules, data, etc., from at least one of the storage 1003 and the communication device 1004 into the memory 1002 and executes various processes accordingly. The program used is one that causes the computer to execute at least a part of the operations described in the above embodiment. Moreover, the above-mentioned various processes may be executed by one processor 1001, or by two or more processors 1001 simultaneously or sequentially. The processor 1001 may be implemented by one or more chips. The program may also be transmitted from a network via a telecommunications line.

[0116] Memory 1002 is a computer-readable recording medium and may consist of at least one of the following: Read Only Memory (ROM), Erasable Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), Random Access Memory (RAM), etc. Memory 1002 may also be called a register, cache, main memory, etc. Memory 1002 can store a program (program code), software module, etc., that can execute a method according to one embodiment of this disclosure.

[0117] Storage 1003 is a computer-readable recording medium and may consist of at least one of the following: an optical disc such as a Compact Disc ROM (CD-ROM), a hard disk drive, a flexible disk, a magneto-optical disk (e.g., Compact Disc, Digital Multipurpose Disc, Blu-ray® Disc), a smart card, flash memory (e.g., a card, stick, key drive), a floppy® disk, a magnetic strip, etc. Storage 1003 may also be called an auxiliary storage device. The recording medium described above may also be, for example, a database, server, or other suitable medium including at least one of memory 1002 and storage 1003.

[0118] The communication device 1004 is hardware (transceiver / receiver device) for communicating between computers via at least one of a wired network and a wireless network, and is also referred to as a network device, network controller, network card, communication module, etc.

[0119] The communication device 1004 may be configured to include, for example, a high-frequency switch, a duplexer, a filter, a frequency synthesizer, etc., in order to implement at least one of frequency division duplex (FDD) and time division duplex (TDD).

[0120] The input device 1005 is an input device that accepts input from an external source (e.g., a keyboard, mouse, microphone, switch, button, sensor, etc.). The output device 1006 is an output device that outputs to an external source (e.g., a display, speaker, LED lamp, etc.). The input device 1005 and the output device 1006 may be configured as an integrated unit (e.g., a touch panel).

[0121] Furthermore, each device, such as the processor 1001 and the memory 1002, is connected by a bus 1007 for communicating information. The bus 1007 may be configured using a single bus, or different buses may be configured for each device.

[0122] Furthermore, the device may include hardware such as a microprocessor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a field-programmable gate array (FPGA), and some or all of the functional blocks may be implemented by such hardware. For example, processor 1001 may be implemented using at least one of these hardware components.

[0123] Furthermore, notification of information is not limited to the embodiments described herein and may be carried out by other means. For example, notification of information may be carried out by physical layer signaling (e.g., Downlink Control Information (DCI), Uplink Control Information (UCI)), upper layer signaling (e.g., RRC signaling, Medium Access Control (MAC) signaling, broadcast information (Master Information Block (MIB), System Information Block (SIB))), other signals, or combinations thereof. RRC signaling may also be called RRC messages, and may be, for example, RRC Connection Setup messages, RRC Connection Reconfiguration messages, etc.

[0124] Each aspect / embodiment described herein may be applied to at least one of the following: Long Term Evolution (LTE), LTE-Advanced (LTE-A), SUPER 3G, IMT-Advanced, 4th generation mobile communication system (4G), 5th generation mobile communication system (5G), 6th generation mobile communication system (6G), xth generation mobile communication system (xG) (where x is, for example, an integer or decimal), Future Radio Access (FRA), New Radio (NR), W-CDMA®, GSM®, CDMA2000, Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi®), IEEE 802.16 (WiMAX®), IEEE 802.20, Ultra-WideBand (UWB), Bluetooth®, and other appropriate systems, as well as next-generation systems extended based thereon. Furthermore, multiple systems may be applied in combination (for example, a combination of at least one of LTE and LTE-A with 5G).

[0125] The processing procedures, sequences, flowcharts, etc., of each aspect / embodiment described in this disclosure may be reordered, provided they do not contradict each other. For example, the methods described in this disclosure present various step elements using exemplary order and are not limited to the specific order presented.

[0126] The specific operations described in this disclosure as being performed by a base station may, in some cases, be performed by its upper node. In a network consisting of one or more network nodes having a base station, it is clear that various operations performed for communication with a terminal can be performed by the base station and at least one other network node (for example, an MME or S-GW, but not limited to these). Although the above example illustrates the case where there is one other network node besides the base station, it may also be a combination of multiple other network nodes (for example, an MME and an S-GW).

[0127] Information and signals (such as data) can be output from a higher layer (or lower layer) to a lower layer (or higher layer). Input and output may occur via multiple network nodes.

[0128] Input and output information may be stored in a specific location (e.g., memory) or managed using a management table. Input and output information may be overwritten, updated, or appended to. Output information may be deleted. Input information may be sent to other devices.

[0129] The determination may be made by a value represented by one bit (0 or 1), by a boolean value (true or false), or by a numerical comparison (for example, a comparison with a predetermined value).

[0130] Each aspect / embodiment described in this disclosure may be used individually, in combination, or switched between as needed during implementation. Furthermore, notification of specific information (e.g., notification that "X is") is not limited to explicit notification, but may also be implicit (e.g., by not providing such notification).

[0131] Software should be broadly interpreted to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, execution threads, procedures, functions, and so on, whether they are called software, firmware, middleware, microcode, hardware description languages, or by any other name.

[0132] Furthermore, software, instructions, information, etc., may be transmitted and received via a transmission medium. For example, if software is transmitted from a website, server, or other remote source using at least one of wired technologies (such as coaxial cable, fiber optic cable, twisted pair, or Digital Subscriber Line (DSL)) and wireless technologies (such as infrared or microwave), then at least one of these wired and wireless technologies is included in the definition of a transmission medium.

[0133] The information, signals, etc. described in this disclosure may be represented using any of the various different technologies. For example, the data, instructions, commands, information, signals, bits, symbols, chips, etc. that may be referred to throughout the above description may be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, optical fields or photons, or any combination thereof.

[0134] In addition, terms used in this disclosure and terms necessary for understanding this disclosure may be replaced with terms having the same or similar meanings. For example, at least one of the channel and symbol may be a signal (signaling). Also, a signal may be a message. Furthermore, a component carrier (CC) may be called a carrier frequency, cell, frequency carrier, etc.

[0135] The terms “system” and “network” as used in this disclosure are interchangeable.

[0136] Furthermore, the information, parameters, etc., described in this disclosure may be expressed using absolute values, relative values ​​from a given value, or other corresponding information. For example, wireless resources may be indicated by an index.

[0137] The names used for the parameters described above are not restrictive in any way. Furthermore, the formulas and other expressions using these parameters may differ from those expressly disclosed in this disclosure. Since various channels (e.g., PUCCH, PDCCH, etc.) and information elements can be identified by any suitable name, the various names assigned to these various channels and information elements are not restrictive in any way.

[0138] In this disclosure, terms such as "Base Station (BS)," "wireless base station," "fixed station," "NodeB," "eNodeB (eNB)," "gNodeB (gNB)," "access point," "transmission point," "reception point," "transmission / reception point," "cell," "sector," "cell group," "carrier," and "component carrier" may be used interchangeably. Base stations may also be referred to by terms such as macrocell, small cell, femtocell, and picocell.

[0139] A base station can house one or more (e.g., three) cells (also called sectors). If a base station houses multiple cells, the entire coverage area of ​​the base station can be divided into multiple smaller areas, each of which can also be provided with communication services by a base station subsystem (e.g., a small indoor base station (Remote Radio Head: RRH)).

[0140] The terms "cell" or "sector" refer to a portion or all of the coverage area of ​​at least one of the base stations and base station subsystems that provide communication services in this coverage.

[0141] In this disclosure, the transmission of information by a base station to a terminal may be interpreted as the base station instructing the terminal to perform control or operation based on the information.

[0142] In this disclosure, terms such as "Mobile Station (MS)," "user terminal," "User Equipment (UE)," and "terminal" may be used interchangeably.

[0143] A mobile station may also be referred to by those skilled in the art as a subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, client, or some other appropriate term.

[0144] At least one of the base station and the mobile station may be called a transmitting device, a receiving device, a communication device, etc. At least one of the base station and the mobile station may also be a device mounted on a mobile body, the mobile body itself, etc. The mobile body may be a vehicle (e.g., a car, an airplane, etc.), an unmanned mobile body (e.g., a drone, an autonomous vehicle, etc.), or a robot (manned or unmanned). At least one of the base station and the mobile station may also be a device that does not necessarily move during communication operation. For example, at least one of the base station and the mobile station may be an Internet of Things (IoT) device such as a sensor.

[0145] Furthermore, the term "base station" in this disclosure may be interpreted as "mobile station" (user terminal, hereinafter the same). For example, the various aspects / embodiments of this disclosure may be applied to a configuration in which communication between a base station and a mobile station is replaced with communication between multiple mobile stations (which may be called, for example, Device-to-Device (D2D), Vehicle-to-Everything (V2X), etc.). In this case, the mobile station may have the functions that a base station has. Also, terms such as "uplink" and "downlink" may be interpreted as terms corresponding to terminal-to-terminal communication (for example, "side"). For example, uplink channel, downlink channel, etc. may be interpreted as side channel (or side link).

[0146] Similarly, the term "mobile station" in this disclosure may be interpreted as "base station." In this case, the base station may be configured to have the functions that a mobile station has.

[0147] A wireless frame may consist of one or more frames in the time domain. Each of these one or more frames in the time domain may be called a subframe. A subframe may further consist of one or more slots in the time domain. A subframe may have a fixed time length (e.g., 1 ms) that is independent of numerology.

[0148] Numerology may be communication parameters applied to at least one of the transmission and reception of a signal or channel. Numerology may include, for example, at least one of the following: subcarrier spacing (SCS), bandwidth, symbol length, cyclic prefix length, transmission time interval (TTI), number of symbols per TTI, radio frame configuration, specific filtering processes performed by the transceiver in the frequency domain, and specific windowing processes performed by the transceiver in the time domain.

[0149] A slot may consist of one or more symbols in the time domain (such as Orthogonal Frequency Division Multiplexing (OFDM) symbols or Single Carrier Frequency Division Multiple Access (SC-FDMA) symbols). A slot may also be a time unit based on neurology.

[0150] A slot may include multiple mini-slots. Each mini-slot may consist of one or more symbols in the time domain. Mini-slots may also be called sub-slots. Mini-slots may consist of fewer symbols than a slot. A PDSCH (or PUSCH) transmitted in a time unit larger than a mini-slot may be called PDSCH (or PUSCH) mapping type A. A PDSCH (or PUSCH) transmitted using a mini-slot may be called PDSCH (or PUSCH) mapping type B.

[0151] Wireless frames, subframes, slots, minislots, and symbols all represent units of time when transmitting a signal. Different names may be used for each of these terms.

[0152] For example, one subframe may be called a transmission time interval (TTI), multiple consecutive subframes may be called a TTI, or one slot or one minislot may be called a TTI. In other words, at least one of a subframe and a TTI may be a subframe in existing LTE (1ms), a period shorter than 1ms (e.g., 1-13 symbols), or a period longer than 1ms. Note that the unit representing the TTI may be called a slot, minislot, etc., instead of a subframe.

[0153] Here, TTI refers to, for example, the smallest unit of time for scheduling in wireless communication. For example, in an LTE system, the base station schedules each user terminal to allocate wireless resources (such as the frequency bandwidth and transmission power available to each user terminal) in TTI units. However, the definition of TTI is not limited to this.

[0154] TTI may be a transmission time unit for channel-encoded data packets (transport blocks), code blocks, code words, etc., or it may be a processing unit for scheduling, link adaptation, etc. Note that when a TTI is given, the actual time interval (e.g., number of symbols) in which the transport block, code block, code word, etc. are mapped may be shorter than the given TTI.

[0155] Furthermore, if one slot or one mini-slot is referred to as TTI, then one or more TTIs (i.e., one or more slots or one or more mini-slots) may constitute the minimum time unit of scheduling. In addition, the number of slots (number of mini-slots) that constitute the minimum time unit of scheduling may be controlled.

[0156] A TTI with a time length of 1ms may also be called a normal TTI, long TTI, normal subframe, long subframe, slot, etc. A TTI shorter than a normal TTI may also be called a shortened TTI, short TTI, partial or fractional TTI, shortened subframe, short subframe, mini slot, sub slot, slot, etc.

[0157] Furthermore, long TTIs (e.g., normal TTIs, subframes, etc.) may be interpreted as TTIs with a time length exceeding 1 ms, and short TTIs (e.g., shortened TTIs, etc.) may be interpreted as TTIs with a TTI length less than that of a long TTI but 1 ms or more.

[0158] A resource block (RB) is a resource allocation unit in the time domain and frequency domain, and in the frequency domain, it may contain one or more consecutive subcarriers. The number of subcarriers in an RB may be the same regardless of the neurology, for example, 12. The number of subcarriers in an RB may be determined based on the neurology.

[0159] Furthermore, the time domain of RB may contain one or more symbols and may be the length of one slot, one minislot, one subframe, or one TTI. One TTI, one subframe, etc., may each consist of one or more resource blocks.

[0160] One or more RBs may also be called a Physical RB (PRB), Sub-Carrier Group (SCG), Resource Element Group (REG), PRB pair, RB pair, etc.

[0161] Furthermore, a resource block may consist of one or more resource elements (REs). For example, one RE may be a radio resource area comprising one subcarrier and one symbol.

[0162] A Bandwidth Part (BWP), also known as a partial bandwidth, may represent a subset of consecutive common resource blocks (RBs) for a given neurology in a given carrier. Here, the common RBs may be identified by an index of the RBs relative to the carrier's common reference point. PRBs may be defined and numbered within a given BWP.

[0163] A BWP may include BWPs for UL (UL BWP) and BWPs for DL ​​(DL BWP). One or more BWPs may be set within a single carrier for a UE.

[0164] At least one of the configured BWPs may be active, and the UE does not need to assume that it will send or receive a given signal / channel outside of the active BWP. In this disclosure, terms such as "cell" and "carrier" may be read as "BWP".

[0165] The structures described above, such as wireless frames, subframes, slots, minislots, and symbols, are merely illustrative. For example, the number of subframes included in a wireless frame, the number of slots per subframe or wireless frame, the number of minislots included in a slot, the number of symbols and RBs included in a slot or minislot, the number of subcarriers included in an RB, and the number of symbols, symbol length, and cyclic prefix (CP) length within a TTI can be varied in various ways.

[0166] The terms “connected,” “coupled,” and any variations thereof mean any direct or indirect connection or coupling between two or more elements, and may include the presence of one or more intermediate elements between two elements that are “connected” or “coupled” with each other. The coupling or connection between elements may be physical, logical, or a combination thereof. For example, “connection” may be reinterpreted as “access.” As used in this disclosure, two elements may be considered to be “connected” or “coupled” with each other using at least one of one or more wires, cables, and printed electrical connections, and, in some non-limiting and non-exclusive examples, electromagnetic energy having wavelengths in the radio frequency domain, microwave domain, and optical (both visible and invisible) domain.

[0167] The reference signal can also be abbreviated as Reference Signal (RS), and may be called a pilot depending on the applicable standard.

[0168] In this disclosure, the phrase "based on" does not mean "based solely on" unless otherwise specified. In other words, the phrase "based on" means both "based solely on" and "based at least on."

[0169] In the configuration of each of the above devices, "means" may be replaced with "part," "circuit," "device," etc.

[0170] Any reference to elements using designations such as “First,” “Second,” etc., as used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient way to distinguish between two or more elements. Accordingly, references to the First and Second elements do not imply that only two elements may be employed therein, or that the First element must precede the Second element in any way.

[0171] Where the terms “include,” “including,” and variations thereof are used in this disclosure, these terms are intended to be inclusive, as is the term “comprising.” Furthermore, the term “or” as used in this disclosure is not intended to be exclusive OR.

[0172] In this disclosure, if articles are added through translation, such as a, an, and the in English, this disclosure may include the fact that the noun following these articles is plural.

[0173] The terms “determining” and “determining” as used in this disclosure may encompass a wide variety of actions. “Determining” and “determining” may include, for example, judging, calculating, computing, processing, deriving, investigating, looking up, searching, or inquiring (e.g., searching in a table, database, or other data structure), or ascertaining. “Determining” and “determining” may also include receiving (e.g., receiving information), transmitting (e.g., sending information), inputting, outputting, or accessing (e.g., accessing data in memory). Furthermore, "judgment" and "decision" can include considering something as having "judgmented" or "decided" after resolving, selecting, choosing, establishing, comparing, etc. In other words, "judgment" and "decision" can include considering something as having "judgmented" or "decided" about some action. Also, "judgment (decision)" can be reinterpreted as "assuming," "expecting," or "considering."

[0174] In this disclosure, the term "A and B are different" may mean "A and B are different from each other." The term may also mean "A and B are each different from C." Terms such as "separate" and "combine" may be interpreted similarly to "different."

[0175] Figure 10 shows an example of the configuration of vehicle 2001. As shown in Figure 10, vehicle 2001 includes a drive unit 2002, a steering unit 2003, an accelerator pedal 2004, a brake pedal 2005, a shift lever 2006, left and right front wheels 2007, left and right rear wheels 2008, an axle 2009, an electronic control unit 2010, various sensors 2021 to 2029, an information service unit 2012, and a communication module 2013.

[0176] The drive unit 2002 is composed of, for example, an engine, a motor, or a hybrid of an engine and a motor.

[0177] The steering unit 2003 includes at least a steering wheel (also called a handle) and is configured to steer at least one of the front wheels and the rear wheels based on the operation of the steering wheel, which is operated by the user.

[0178] The electronic control unit 2010 consists of a microprocessor 2031, memory (ROM, RAM) 2032, and communication ports (IO ports) 2033. Signals from various sensors 2021 to 2027 installed in the vehicle are input to the electronic control unit 2010. The electronic control unit 2010 may also be called an ECU (Electronic Control Unit).

[0179] Signals from various sensors 2021 to 2028 include current signals from the current sensor 2021 that senses motor current, front and rear wheel rotation speed signals obtained by the rotation speed sensor 2022, front and rear wheel air pressure signals obtained by the air pressure sensor 2023, vehicle speed signals obtained by the vehicle speed sensor 2024, acceleration signals obtained by the acceleration sensor 2025, accelerator pedal depression signals obtained by the accelerator pedal sensor 2029, brake pedal depression signals obtained by the brake pedal sensor 2026, shift lever operation signals obtained by the shift lever sensor 2027, and detection signals obtained by the object detection sensor 2028 for detecting obstacles, vehicles, pedestrians, etc.

[0180] The Information Services Unit 2012 consists of various devices for providing (outputting) various types of information such as driving information, traffic information, and entertainment information, including car navigation systems, audio systems, speakers, televisions, and radios, and one or more ECUs that control these devices. The Information Services Unit 2012 uses information acquired from external devices via communication modules 2013, etc., to provide various multimedia information and multimedia services to the occupants of the vehicle 2001.

[0181] Information Services Unit 2012 may include input devices that accept input from external sources (e.g., keyboards, mice, microphones, switches, buttons, sensors, touch panels, etc.) and output devices that perform output to external sources (e.g., displays, speakers, LED lamps, touch panels, etc.).

[0182] The driver assistance system unit 2030 consists of various devices that provide functions to prevent accidents or reduce the driver's workload, such as millimeter-wave radar, LiDAR (Light Detection and Ranging), cameras, positioning locators (e.g., GNSS), map information (e.g., high-definition (HD) maps, autonomous vehicle (AV) maps), gyro systems (e.g., IMU (Inertial Measurement Unit), INS (Inertial Navigation System)), AI (Artificial Intelligence) chips, and AI processors, as well as one or more ECUs that control these devices. The driver assistance system unit 2030 also sends and receives various information via the communication module 2013 to realize driver assistance functions or autonomous driving functions.

[0183] The communication module 2013 can communicate with the microprocessor 2031 and components of the vehicle 1 via its communication port. For example, the communication module 2013 sends and receives data via the communication port 2033 between the drive unit 2002, steering unit 2003, accelerator pedal 2004, brake pedal 2005, shift lever 2006, left and right front wheels 2007, left and right rear wheels 2008, axle 2009, the microprocessor 2031 and memory (ROM, RAM) 2032 in the electronic control unit 2010, and sensors 2021 to 2028 provided in the vehicle 2001.

[0184] The communication module 2013 is a communication device that can be controlled by the microprocessor 2031 of the electronic control unit 2010 and can communicate with external devices. For example, it can send and receive various types of information to and from external devices via wireless communication. The communication module 2013 may be located either inside or outside the electronic control unit 2010. The external device may be, for example, a base station or a mobile station.

[0185] The communication module 2013 may transmit at least one of the following to an external device via wireless communication: signals from the various sensors 2021 to 2028 input to the electronic control unit 2010, information obtained based on said signals, and information based on input from an external source (user) obtained via the information service unit 2012. The electronic control unit 2010, the various sensors 2021 to 2028, the information service unit 2012, etc., may also be called input units that accept input. For example, the PUSCH transmitted by the communication module 2013 may include information based on the above input.

[0186] The communication module 2013 receives various information (traffic information, signal information, vehicle-to-vehicle information, etc.) transmitted from external devices and displays it on the information service unit 2012 installed in the vehicle. The information service unit 2012 may also be called an output unit, which outputs information (for example, it outputs information to devices such as displays and speakers based on the PDSCH (or data / information decoded from the PDSCH) received by the communication module 2013).

[0187] Furthermore, the communication module 2013 stores various information received from external devices in memory 2032, which is available to the microprocessor 2031. Based on the information stored in memory 2032, the microprocessor 2031 may control the drive unit 2002, steering unit 2003, accelerator pedal 2004, brake pedal 2005, shift lever 2006, left and right front wheels 2007, left and right rear wheels 2008, axle 2009, sensors 2021 to 2028, etc., which are provided in the vehicle 2001.

[0188] Although the present disclosure has been described in detail above, it will be clear to those skilled in the art that the present disclosure is not limited to the embodiments described herein. The present disclosure may be implemented in modified and altered forms without departing from the intent and scope of the present disclosure as defined by the claims. Accordingly, the descriptions in the present disclosure are for illustrative purposes only and are not intended to be restrictive in any way.

[0189] 10 Communication Unit 20 Packet Processing Unit 30 Control Unit 100 Outgoing Terminal 200 Core Network 201 VGN 202 Outgoing CSN 203 Outgoing ASN 204 Incoming ASN 205 Incoming Call CSN 206 SIN 207 MGN 208 MPN 209 Storage 210 MRN 300 Incoming Terminal 400 Outgoing Network 500 Incoming Network 1001 Processor 1002 Memory 1003 Storage 1004 Communication Device 1005 Input Device 1006 Output Device 1007 Bus 2001 Vehicle 2002 Drive Unit 2003 Steering Unit 2004 Accelerator Pedal 2005 Brake Pedal 2006 Shift Lever 2007 Left and Right Front Wheels 2008 Left and Right Rear Wheels 2009 Axle 2010 Electronic Control Unit 2012 Information Service Unit 2013 Communication Module 2021 Current Sensor 2022 Rotation Speed ​​Sensor 2023 Pneumatic Sensor 2024 Vehicle Speed ​​Sensor 2025 Acceleration Sensor 2026 Brake Pedal Sensor 2027 Shift Lever Sensor 2028 Object Detection Sensor 2029 Accelerator Pedal Sensor 2030 Driving Assistance System Unit 2031 Microprocessor 2032 Memory (ROM, RAM) 2033 Communication Port (IO Port)

Claims

1. A terminal comprising a packet processing unit that determines the validity of a packet based on the sequence number of the received packet, processes valid packets, and discards invalid packets, and a control unit that processes the second packet without discarding it if the sequence number of the second packet received at the start of a call with the receiving terminal is smaller than the sequence number of the first packet received during the call with the receiving terminal.

2. The terminal according to claim 1, wherein the control unit, when the identification information indicating the source of the first packet and the second packet is the same, causes the packet processing unit to process the second packet having a sequence number smaller than the sequence number of the first packet as a valid packet.

3. The terminal according to claim 1, wherein the control unit causes the packet processing unit to process the second packet as a valid packet.

4. The terminal according to claim 1, wherein the first packet is a packet containing a ringtone, and the second packet is a packet containing a call voice.

5. A terminal communication method comprising the steps of: determining the validity of a packet based on the sequence number of the received packet, processing valid packets and discarding invalid packets; and, if the sequence number of a second packet received at the start of a call with the receiving terminal is smaller than the sequence number of a first packet received during the call with the receiving terminal, processing the second packet without discarding it.

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