RU2755529C1 - Method for establishing session of group packet voice communication over data transmission networks - Google Patents

Abstract

FIELD: data networks.

SUBSTANCE: invention relates to the field of services provided in data networks based on unidirectional selective call sessions, including direct talk (PTT), under the control of a PT server within the framework of a service based on SIP (Session Initiation Protocol). To achieve the effect, when establishing a group packet voice communication session over data transmission networks, the first user terminal sends a request to establish a group packet voice communication session to the multicast server via a signaling channel to initiate a connection between the server and the user terminal; the multicast server receives a request to establish a multicast session of packet voice communication from the first user terminal and creating a network route between the multicast server and user terminals, including at least transmitting a server connection request to the user terminals of the group, and transmission by the user terminal of voice packets to the multicast server, the created network route between the multicast server and the user terminals is maintained in an active state by sending repeated registration packets or keep-alive packets, the transmission of voice packets to the multicast server is also performed via signaling channels using the user datagram. Each voice packet is a request to establish a group packet voice session and contains information necessary to initiate a connection between the server and the user terminal.

EFFECT: reduction of the time to establish a multicast service due to the fact that a communication session begins without a preliminary exchange of signaling messages, and immediately upon receipt of the first voice packet.

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Description

The present invention relates to services provided in data networks based on unidirectional selective call sessions, including direct talk (PTT), under the control of a PT server, as part of a service based on SIP (Session Initiation Protocol). ).

In general, SIP is a signaling protocol that defines the procedure by which user terminals planning to communicate with each other determine and find their location, and establish or terminate (or change) communication sessions within the framework of a multimedia data service. each other. SIP-based services (ie, SIP services) use a challenge-response structure to control the establishment, modification, and termination of sessions within a media service. One session service based on the Session Initiation Protocol (SIP) may be a half-duplex (Push-To) service in which one user transmits multimedia data (e.g., voice or multimedia data packets) to one or more users, with whom a communication session has been established.

Group communication systems over data transmission channels have been around for several years. In 2016, the international consortium of manufacturers of mobile data transmission systems 3GPP defined protocols and standards that define the rules for PoC (Push-to-talk Over Cellular) systems in 3 / 4G networks. The protocol was named Mission Critical Push to Talk (MCPTT).

Existing PoC systems, both MCPTT and others, operate according to the following principle. The connection between the server and the users is established by the calling user terminal sending a request to establish a multicast session over the signaling channel. The request for establishing a multicast session contains information necessary to establish a connection: about the initiator of the connection, about the called terminal, about the codecs and voice ports used, etc. To do this, the calling user terminals, through the selected protocol and communication channel, send registration datagram packets to the server, including the data necessary to identify the user terminal. In case of authorization, the server saves data with information from where the registration request came from (the address of the calling terminal), and sends a packet confirming the registration of the terminal. Passing through various network elements, the packets form information about the network route between the server and the subscriber terminal. After the packet passes, the information about the generated route is stored on the server for a limited time to prevent the exhaustion of network resources, therefore, to save this route, repeated registration packets or so-called keepalive packets are sent at a given interval. As a result, the registration procedure and keepalive packets form and keep active a communication channel between a server and a terminal, also called a signaling channel, a control channel, or a connection setup channel. The signaling channel can transmit various information necessary for the interaction between the server and the terminals, including information necessary for the establishment, progress and termination of the connection. The voice packets themselves are transmitted over voice channels, the parameters of which are negotiated during the connection establishment process.

For example, a similar principle for establishing a multicast service is used in the technical solutions described in the following documents. RF patent for invention 2469501 "METHOD AND DEVICE FOR CONTROL OF PERMISSION FOR TRANSMISSION IN SERVICE" PUSH-TO "" (IPC H04W 4/10; H04L 29/06, publ. 10.12.2012), RF patent for invention 2477014 "METHOD OF GROUP Alerting IN THE SERVICE OF MESSAGE EXCHANGE BASED ON THE PROTOCOL OF INITIATION OF THE COMMUNICATION SESSION "SIP" (IPC H04W 4/08; H04W 80/10, publ. 27.02.2013), RF patent for invention 2447616 "METHOD AND DEVICE FOR THE SERVICE" PRESS AND SPEAK H04W 4/10; H04W 80/10 publ. 10.04.2012), Chinese patent for invention CN103024681 "Efficient push-to-talk method" IPC H04W4 / 10, publ. 2016-05-11), Korean patent for invention KR101225403 "Method and Terminal and system for A PoC Group Session Setup In PoC System" (IPC H04B7 / 24; H04L12 / 18; H04W4 / 08; H04W4 / 10; H04W84 / 08, publ. 2013-01-22) and others.

Common to the known analogs is the procedure for establishing a voice connection, which includes several mandatory stages: transmission of a request via a signaling channel to establish a logical connection (network route) between terminals, negotiation of a voice channel for the transmission of voice packets and subsequent transmission of voice packets over voice channels. At the same time, in order for the PTT server to send a voice packet to the subscriber's terminal, the terminal must first send the packet to the server via the signaling channel, via the port specified when establishing the connection. This multi-stage connection setup takes a significant amount of time with a large amount of redundant information. But for mission-critical applications such as PTT over IP, any excess latency is critical. At the same time, in PTT over IP systems and similar systems, there is no need to send a large amount of information to establish a connection.

Various methods of establishing a multicast service are known to reduce connection setup time. In particular, such solutions are described in the following documents: Chinese patent for invention CN103139718 "Push to talk over cellular (PoC) time delay optimizing processing method and device." (IPC H04W24 / 02; H04W4 / 10, publ. 2015-11-18), Chinese patent for invention CN101938707 "Method and device for optimizing push to talk time delay" (IPC H04W12 / 02; H04W4 / 10; H04W68 / 00, publ. 2013-08-07).

As the closest analogue, the decision on the RF patent for invention 2601187 was chosen. METHOD FOR QUICK INSTALLATION OF GROUP TRANSFER SERVICE A CORRESPONDING DEVICE AND SYSTEM (IPC H04W 4/10, publ. 27.10.2016). The known method includes sending by the first user terminal a request to establish a multicast session to the multicast server over a signaling channel to initiate a connection between the server and the user terminal, receiving by the multicast server a request to establish a multicast session from the first user terminal, and transmitting the request to connect the server to other user terminals. terminals of the group, while in order to reduce the time of establishing a voice connection, the PTT server can constantly hold an RRC (Radio Resource Control Connection) connection with the user terminal, which is in the multicast service mode, that is, without the user terminal transitioning from the RRC_IDLE state to the RRC_CONNECTED state. Thus, when a new voice packet arrives from it, its transmission can be directly performed, and there is no need to exchange signaling data to establish a connection, so the delay can be significantly reduced and a fast establishment of a multicast service is ensured.

The disadvantages of the known method for establishing a multicast service include, as before, the need to exchange signaling messages to establish a connection before transmitting voice packets, the likelihood of missing a communication session if at the time of the start of the connection there was no connection between any terminal and the server.

The claimed invention is aimed at eliminating the disadvantages of the known methods. The technical result consists in reducing the time of establishing a multicast service.

The claimed technical result is achieved in that in the method of establishing a session of group packet voice communication over data transmission networks, which includes the transmission by the first user terminal of a request to establish a session of group packet voice communication to the multicast server via a signaling channel to initiate a connection between the server and the user terminal, receiving by the multicast server a request to establish a multicast voice communication session from the first user terminal and create a network route between the multicast server and user terminals, including at least transmitting the server connection request to the user terminals of the group, and the user terminal transmitting voice packets to the server multicast, the created network route between the multicast server and user terminals is kept active by sending repeated registration packets or bursts In keeping up, the transmission of voice packets to the multicast server is also performed over signaling channels using the user datagram protocol, each voice packet being a request to establish a multicast voice communication session and containing information necessary to initiate a connection between the server and the user terminal.

The use of a network route, which is established at the stage of registration of the subscriber's terminal and is kept up to date all the time, the inclusion of a request to establish a group voice communication session in a voice packet and the transmission of these voice packets over signaling channels using the User Datagram Protocol (UDP) can significantly reduce the time establishing a voice connection for multicast. The inclusion of all the information necessary to establish a connection in the voice packet reduces the number of messages between the PTT server and the user terminal in the process of establishing a connection. In this case, the moment of receiving the first voice packet is already the beginning of the connection establishment. To release the channel, accept the absence of packets for some time as the moment of termination of the connection.

The claimed invention is further illustrated using the figures.

FIG. 1 is a signal flow diagram illustrating a method for using a PT service in accordance with the prior art.

FIG. 2 is a signal flow diagram illustrating a method for using the PT service in accordance with the claimed method.

The signal flow diagram of FIG. 1 illustrates the implementation of a PTT service in accordance with the prior art. In general, the calling terminal A sends a connection request to the PTT server on the signaling channel (control channel). The PTT server creates a network route, for which it determines in accordance with its settings that the group members, in addition to subscriber A, are subscribers B and C, and forwards the connection request also via the signaling channel to terminals B and C using IP addresses and ports obtained during registration these terminals. Terminals B and C, having received a request to establish a connection, send a confirmation of the connection to the PTT server, and the PTT server, in turn, sends a confirmation of the connection to terminal A. After that, the RTP (Real-time Transport Protocol) exchange is established. ), through which the transmission of voice packets occurs. Establishing and terminating a connection is not included in the list of RTP capabilities; such actions are performed by the signaling protocol, in particular, the SIP protocol. Upon completion of the transmission of voice packets, terminal A transmits to the PTT server, again via the signaling channel, a connection termination message, the PTT server transmits a connection termination message to terminals B and C, receives from them a confirmation of connection completion and sends confirmation of connection completion to terminal A, and also deletes the data about the created network route. Thus, in addition to the direct transmission of voice packets, many signaling messages are exchanged, often redundant, which significantly increases the time required for the transmission of multicast voice messages.

Next, referring to FIG. 2 illustrates the implementation of the claimed method for establishing a multicast service.

Before the establishment of a multicast session, the terminals are registered on the UDP server via the signaling channel (control channel) and a network route is created between the server and the terminals. Further, the created network route is maintained in an active state, for which each terminal of the group periodically sends registration or keep-alive packets to the server. Packets are sent to a specific IP address and IP port of the server. (for example, the IP address is 192.168.1.2, the IP port is 5080). Registration packages contain a subscriber identifier (ID) - a number assigned to a subscriber in the group communication system, and an encrypted password. The server checks the password, remembers the subscriber's IP address and port and sends a confirmation of the terminal registration in response to the subscriber's IP address and port. The interval for periodically sending packets is selected so that the data transmission system maintains up-to-date information about the routing of packets between the server and the terminal, even if the terminal is located in the local network and does not have a public IP address. In particular, the interval for sending registration packets or keep-alive is selected in the range from 13 to 60 seconds, the interval is determined by the typical time of keeping the route by the network equipment.

To initiate a group packet voice session in group 1, the first user terminal A (ID = 100) sends voice packets to the UDP server at the same address via the user datagram protocol from the same address and port from which it sent registration requests, as registration packages (192.168.1.2:5080), i.e. uses a signaling channel.

Voice packs contain:

• Subscriber ID A = 100;

• recipient identifier (it can be group or subscriber identifier), in this case group identifier GroupID = 1;

• session identifier SessID - a unique number in a certain time interval;

• information about the used voice codec and other information necessary for processing voice packets and recovering speech at the receiving terminal.

When the UDP server receives the first voice packet from a specific IP address and IP port, the same as when receiving a registration request, it establishes the fact of receiving a request to establish a group packet voice session and decides to start a new group session on the initiative of terminal A. in group 1, determines in accordance with its settings that members of group 1 are, in addition to subscriber A (ID = 100), also subscribers B (ID = 101) and C (ID = 102) and sends voice packets along the created network route , by IP addresses and ports obtained during registration of terminals B (ID = 101) and C (ID = 102). Terminals B and C receive and play voice packets.

In this case, even if some of the voice packets are not delivered to the server, the session will be started when the first of them is received, since each voice packet is a request to establish a group packet voice session and contains information necessary for initiating a connection between the server and the user terminal. In this case, the claimed technical result is achieved, which consists in reducing the time of establishing the multicast service. The session begins without a preliminary exchange of signaling messages, but immediately upon receipt of the first voice packet. If any terminal at the time of the beginning of the session or at any other moment during the session was not in touch, then the subscriber will not hear only part of the voice information that disappeared at the time of the absence of communication. As soon as the data transmission channel is restored, the voice reception at the terminal will be restored as well.

The claimed invention can be used in data networks to provide half-duplex communication services, in which one user transmits voice data packets to one or more users with whom a communication session is established, known as direct talk (PTT) services, under the control of a PT server within services based on SIP (Session Initiation Protocol).

Claims (2)

1. A method of establishing a session of group packet voice communication over data transmission networks, including the transmission by the first user terminal of a request to establish a session of group packet voice communication to the multicast server via a signaling channel to initiate a connection between the server and the user terminal, and the receipt by the multicast server of the request to establish a session multicast packet voice communication from the first user terminal and creating a network route between the multicast server and user terminals, including at least transmitting a server connection request to the user terminals of the group, and transmitting voice packets by the user terminal to the multicast server, characterized in that the created network route between the multicast server and user terminals is maintained in an active state, the transmission of voice packets to the multicast server is also performed via signaling channels communication through the protocol of user datagrams, wherein each voice packet is a request to establish a group packet voice session and contains the information necessary to initiate a connection between the server and the user terminal. 2. The method for establishing a multicast packet voice session over data networks according to claim 1, characterized in that the created network route between the multicast server and user terminals is maintained in an active state by sending repeated registration packets or keep-alive packets.

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