Push-to-Talk
Land Mobile Radio (LMR), known as Push-to-Talk (PTT), is a professional wireless communication tool in public safety, fire, police, military, emergency medical service, factory, maintenance, private sector, etc. LMR provides two-way communication between one-talker and multiple listeners. LMR is used mainly on VHF and UHF narrow bands. Project 25 (P25) and Terrestrial Trunked Radio (TETRA) are two big names of LMR standards. P25 and TETRA communication is mainly voice/audio with tiny digital data, like location, and human body bionics (heartbeat, temperature, etc.).
However, the demands for multimedia communication have been increasing in the professional communication area. Video communications are desirable to improve the protection of the lives of officers and members. It is essential to aggregate real-time voice, video, and data in a command center.
LTE the Multimedia Technology
Third Generation Partnership Project (3GPP) published LTE standards. LTE is the most popular multimedia communication technology in the private sector. Some PTT systems perform on LTE technology, known as Over-the-top PTT (OTT-PTT). OTT-PTT runs like other applications in smartphones and server computers. OTT-PTT carries voice, video, and data. Since the OTT-PTT system runs on LTE, also, Wi-Fi (wireless media), the OTT-PTT system provides wireless media inter-communication.
On the other hand, there is no interoperability among other OTT-PTT systems due to their proprietary protocol. Also, OTT-PTT cannot guarantee real-time communication. PTT system must have a tight connection with the LTE core (communication control part) to provide real-time communication service.
Mission Critical Push-to-Talk Standard
Mission Critical Push-to-Talk (MCPTT) is a suite of standards published by 3GPP. 3GPP standardized new interfaces among modules of the LTE core, new functionalities, and Key Performance Indicators (KPI) in Release 13 and 14. The PTT system, which complies with the MCPTT standards, offers real-time communication and inter-operability and communication quality with KPI. The PKIs are defined in 3GPP TP 22.179”.
Release 13 (March 2016)
・Mission Critical Push to Talk (MCPTT) completed.Release 14 (September 2017)
・Mission Critical Push to Talk Improvements completed
・Mission Critical Data completed
・Mission Critical Video completed
MCPTT KPI (Quoted from “3GPP TP 22.179”)
Outlook from PTT
The table below shows a comparison between MCPTT and P25 PTT functionalities. MCPTT includes not only essential functions of P25 but also additional functions that P25 does not have.
|
# |
Features |
P25 |
MCPTT |
|
1 |
Private call 1:1 |
Yes |
Yes |
|
2 |
Broadcast call |
Yes |
Yes |
|
3 |
Group call |
Yes |
Yes |
|
4 |
Emergency call |
Yes |
Yes |
|
5 |
Ambient Listening |
Yes |
Yes |
|
6 |
Encryption |
Yes |
Yes |
|
7 |
Text messaging 1:1 |
No (or limited) |
Yes |
|
8 |
Text messaging group |
No |
Yes |
|
9 |
Location |
Limited |
Yes |
|
10 |
Dynamic talk grouping |
No |
Yes |
The officers and control centers eagerly request connectivity and broadband communication. They have a reason to protect front-line warriors and workers and to operate effectively. We expect that private LTE systems deploy MCPTT. MCPTT is necessary for public safety.
For further information, please check out our other blogs and use cases. If you have any questions, please do not hesitate to contact us.
