DTMF Signaling Error Correction and Acknowledgment
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Solution Overview
Problem
DTMF signaling between mobile devices and servers is unreliable and inefficient, particularly when the data channel is unavailable, leading to challenges in reliable data transmission and user experience degradation due to potential tone loss or corruption.
Innovation Solution
Implementing error correction algorithms and redundant coding for DTMF tone sequences, along with acknowledging and re-sending critical messages, to ensure message integrity and reliability, and using negative acknowledgments for unidentifiable messages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If DTMF signaling is used for communication between mobile devices and servers, then the system can operate when the data channel is unavailable, but the reliability and efficiency of signal transmission deteriorates due to tone loss or corruption
Solution Approach 1:
The system performs preliminary actions by sending DTMF tones in advance before actual data transmission is needed. The server and mobile device exchange DTMF sequences proactively to establish communication state, ensuring that signaling can begin immediately when data channel becomes available or when voice channel is the only option.
Solution Approach 2:
The system applies beforehand cushioning by implementing error correction codes and redundancy in DTMF sequences. Multiple DTFM tones are sent for the same signal, and error detection/correction mechanisms are pre-configured to handle potential tone loss or corruption during transmission through the voice channel.
2Reliability
If error correction algorithms and redundant coding are implemented for DTMF tone sequences, then message integrity is improved, but the number of DTMF tones exchanged and transmission time increases
Solution Approach 1:
The system applies partial or excessive action by selectively applying error correction and redundancy only to critical DTMF sequences rather than all sequences. Important signaling messages receive full error protection with multiple redundant tones, while less critical messages use simpler encoding, balancing reliability needs against transmission time constraints.
Data Source
AI summary
In a method of processing an incoming sequence of one or more DTMF tones at a mobile device, the sequence is decoded to thereby identify any encoded message. Where the decoding does not identify a message, at least applying an error correction algorithm to the sequence to identify a message. Where the algorithm fails to correct the sequence, the sequence is compared to messages currently expected by the mobile device. If a message is not identified, a negative acknowledgement message may be sent. At a server, upon receipt of a negative acknowledgement message, it is determined if a message was sent to the mobile device in a previous pre-determined time window. If so, the message is re-sent. The server repeatedly sends certain messages to a mobile device until an acknowledgement message indicating receipt of the message by the mobile device is received.