PTT system, method for implementing PTT communication, PTT management server and terminal device thereof

A method for implementing a PTT communication by a PTT system, the method comprising:

• transmitting a call request to a PTT management server via a source terminal device;
• setting up a unicast connection between the PTT management server and the source terminal device and a multicast connection between the PTT management server and a destination terminal device according to the call request from the source terminal device using the PTT management server;
• transmitting an uplink media stream from the source terminal device to the PTT management server via the unicast connection;
• and
• transmitting the received uplink media stream from the PTT management server to the destination terminal device via the multicast connection.

A PTT management server comprising:

• a user group and presence management module configured to set a user group, to obtain and record presence information of a plurality of terminal devices, and to provide information of the user group and the presence information of the plurality of terminal devices;
• a call management module configured to set up an unicast connection according to a call request from a source terminal device of the plurality of terminal devices;
• a multicast management module configured to set up a multicast connection according to the information of the user group and the presence information of the terminal device;
• and
• a media stream forwarding module configured to receive an uplink media stream from the unicast connection, and to transmit the received uplink media stream to an online destination terminal device of the plurality of terminal devices via the multicast connection.

A terminal device[[,]] comprising:

• an access module configured to access to a connection network;
• a media stream processing module configured to obtain an uplink media stream, to transmit the uplink media stream to the PTT management server via the unicast connection, and to receive a downlink media stream via a multicast connection;
• a call control module configured to transmit a call request to a PTT management server, and to inform a media stream processing module to process the media stream after receiving a message on success of call request establishment;
• and
• a PTT initiation module configured to connect with the call control module.