Terminal Emergency Private Call Setup in Off-Network MCPTT
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Solution Overview
Problem
In public safety networks, especially during emergency situations, existing communication systems face challenges in managing call setups and floor control without a central server, particularly in off-network scenarios where direct communication between terminals is necessary for Mission Critical Push To Talk (MCPTT) services.
Innovation Solution
A terminal-based method for generating a private call setup request message with specific information elements (IEs) and setting proximity-based services (ProSe) per-packet priority, enabling emergency private calls by transmitting the message to another terminal and managing timers for retransmission, allowing for direct communication without a central controller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct communication between terminals is implemented in off-network scenarios, then communication reliability in emergency situations is improved, but device complexity increases due to the need for terminal-based call setup and floor control mechanisms
Solution Approach 1:
The terminal performs self-service by autonomously generating call setup request messages, managing floor control, and handling retransmission timers without requiring a central server. The terminal itself becomes the controller for call setup and floor management functions that would traditionally be server-based, thereby enabling off-network operation while maintaining communication reliability.
2Adaptability or versatility
If terminal-based call setup and floor control is implemented without a central server, then adaptability to off-network scenarios is improved, but loss of information increases due to the need for manual message generation and timer management
Solution Approach 1:
The terminal performs preliminary actions by pre-defining the structure of call setup request messages with necessary information elements (call identifier, caller ID, callee ID, call type) and pre-configuring retransmission timers before actual communication occurs. This preliminary preparation ensures that all necessary information is properly formatted and transmitted, reducing the risk of information loss during off-network operation.
Solution Approach 2:
The terminal implements feedback mechanisms through retransmission timers that monitor whether call setup requests and floor control messages are successfully received by the other terminal. If no acknowledgment is received within the timer period, the terminal automatically retransmits the message, ensuring information integrity and preventing loss of critical communication data.
Data Source
AI summary
Provided is a method performed by a terminal of performing communication, the method including generating a private call setup request message including a call identifier information element (IE), a caller IE, a callee IE, and a call type IE set to an emergency private call, based on receiving a user indication to upgrade a call to emergency call, wherein the terminal is in an in-progress private call state; setting a proximity-based services (ProSe) per-packet priority corresponding to the emergency private call; transmitting, to another terminal, the private call setup request message; starting a timer relating to private call request retransmission based on the emergency call setup request message; and entering an in-progress emergency private call state from the in-progress private call state.