Termination Burst for Early Voice Call Release in TDMA
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Solution Overview
Problem
In TDMA communication systems, terminating a voice call within a multi-burst superframe is inefficient as it requires maintaining the slot channel active until the end of the superframe, causing delays and preventing other units from using the channel, especially during call interruptions.
Innovation Solution
A termination burst is generated upon detecting a dekey event and can be transmitted in any burst within the superframe after all buffered voice information has been sent, including a data synchronization pattern, a slot type field indicating the end of a call, and encoded information frames, allowing for early call termination without occupying the slot channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the termination burst is transmitted only after the last burst in the superframe, then the call termination is reliable and synchronized with the superframe structure, but the slot channel remains occupied until the end of the superframe causing delays and preventing other units from using the channel
Solution Approach 1:
The patent segments the superframe structure by introducing a special termination burst that can be transmitted independently at any burst position within the superframe, rather than requiring transmission only at the end. This segmentation allows the call termination function to be separated from the superframe boundary constraints, enabling early channel release while maintaining reliability through the structured burst format.
Solution Approach 2:
The termination burst is transmitted as soon as the dekey event is detected and all buffered voice information has been sent, which is a preliminary action that occurs well before the end of the superframe. This preliminary transmission of the termination burst releases the channel early, preventing the delay that would otherwise occur until the superframe concludes.
2Productivity
If the termination burst is transmitted early in the superframe, then the slot channel can be released immediately for other units to use, but the risk of mistaken termination increases without proper synchronization patterns
Solution Approach 1:
The patent uses distinct synchronization patterns as visual identifiers - the termination burst contains a data synchronization pattern that is a symbol complement to the voice frame synchronization pattern. This 'color change' in the synchronization pattern allows receiving units to easily distinguish termination bursts from regular voice bursts, enabling reliable early termination detection without mistaken termination.
Solution Approach 2:
The synchronization pattern acts as an intermediary element that mediates between the early transmission need and the reliability requirement. By embedding the distinctive data synchronization pattern in the termination burst, the system creates a reliable signaling mechanism that allows early channel release while preventing mistaken termination through pattern recognition.
3Reliability
If call interruptions are handled by buffering audio until the current call ends, then the interrupting audio can be sent over the air, but delays up to the duration of the superframe are introduced
Solution Approach 1:
The termination burst is transmitted preliminarily as soon as the dekey event occurs and buffered voice is complete, rather than waiting for the superframe to end. This preliminary action releases the channel immediately, allowing interrupting calls to be established without buffering delays, while still maintaining reliable termination detection through the structured burst format.
Data Source
AI summary
A system and method for effectively and reliably terminating a voice call in any burst within a multi-burst superframe. A transmitting unit generates a termination burst upon detecting a dekey event. The termination burst includes a data synchronization pattern, a slot type field indicating an end of a call, and an information field surrounding the data synchronization pattern and the slot type field. The information field is encoded from a predetermined voice encoder frame unique to the termination burst. Once all buffered voice information is transmitted, the termination burst is transmitted prior to the end of the multi-burst superframe. A base station or other receiving unit monitors the incoming signal. Upon detecting the data synchronization pattern, the receiving unit decodes the slot type field and the information field. The receiving unit determines whether the decoded slot type field is indicative of the end of a call, and whether a specific portion of the decoded information field matches the predetermined voice encoder frame. If both are true, the receiving unit terminates the call.