Adaptive Audio Buffering for Trunked Radio Zone Controllers
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Solution Overview
Problem
Trunked communication systems experience audio truncation due to long link delays when operating across multiple zones, leading to channel setup time issues and potential loss of audio information.
Innovation Solution
A method is implemented to measure the time necessary to set up call connections across multiple zones, determining the largest relative time delay and buffering audio information accordingly to prevent truncation, involving the use of timers and resource grants to synchronize communication across participating zone controllers and base sites.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If audio is transmitted immediately across multiple zones, then real-time communication is maintained, but audio truncation occurs due to long link delays
Solution Approach 1:
The system performs preliminary actions by measuring link delays between zones in advance before actual audio transmission. The controlling zone controller measures the time required for call setup across different zones and uses these pre-measured values to determine appropriate buffering durations, preventing audio truncation without requiring real-time adjustments during communication.
Solution Approach 2:
The system dynamically adapts buffering parameters based on measured link delays. Instead of using a fixed buffering time, the controlling zone controller calculates and applies variable buffer durations specific to each zone pair, allowing the system to optimize between real-time communication and audio integrity for different geographic configurations.
2Reliability
If buffering time is increased to prevent audio truncation, then audio information integrity is maintained, but channel setup time increases
Solution Approach 1:
The system performs preliminary measurements of link delays between zones before actual calls are established. By pre-measuring and storing these delay values, the system can quickly determine appropriate buffering times for each call without performing time-consuming measurements during call setup, thus maintaining both audio integrity and call establishment efficiency.
Solution Approach 2:
The system changes the buffering parameter dynamically based on measured link delay characteristics. The controlling zone controller adjusts the buffer duration to match the specific delay requirements of each zone configuration, using the formula: buffer time = measured link delay - minimum acceptable delay, thereby optimizing both audio integrity and setup efficiency.
Data Source
AI summary
A method and apparatus are provided for reducing truncation of time sensitive information such as audio in a trunked radio system having a plurality of zone controllers. The method includes the steps of receiving a call request from a calling radio or wireline console by a controlling zone controller of the plurality of zone controllers and measuring a time necessary to set up a call connection between the controlling zone controller and a plurality of called radios or wireline consoles where the call connections of the plurality of called radios or wireline consoles are each set up through a different participating zone controller of the plurality of zone controllers. The method also includes the steps of determining a largest relative measured time among the measured times and buffering audio information from the calling radio for a time period proportional to the determined largest relative time.