Quantized PDU Buffering for IBOC Digital Radio Latency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In IBOC digital radio broadcasting systems, high PDU rates can lead to latency issues in data links, causing audio loss due to the inability to complete PDU transfers within the PDU interval.
Innovation Solution
The implementation of a quantized transport system that buffers a quantized number of PDUs at the audio client and importer, allowing for bulk transmission of PDUs in response to importer data requests, thereby reducing the importer data request rate and mitigating latency-induced audio loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the PDU rate is increased to improve audio transmission quality, then the audio fidelity is improved, but the data link latency causes PDUs to be lost because they cannot be transferred within the PDU interval
Solution Approach 1:
The system pre-calculates and pre-sends importer data requests to the audio client before the PDU interval elapses. By anticipating the need for PDUs and initiating requests in advance, the system compensates for data link latency, ensuring PDUs are received and transmitted on time without loss.
Solution Approach 2:
The system dynamically adjusts the importer data request rate based on the measured latency of the data link. When latency is high, the request rate is increased; when latency is low, the request rate is reduced. This dynamic adaptation allows the system to maintain reliable PDU transfer across varying network conditions while supporting high PDU rates for audio fidelity.
2Productivity
If the importer data request rate is increased to match the high PDU rate, then real-time audio transmission is achieved, but the data link latency prevents complete PDU transfer within the PDU interval
Solution Approach 1:
The importer sends data requests in advance of when PDUs are actually needed for transmission. This preliminary action accounts for the data link latency, ensuring that by the time the PDU interval arrives, the PDU has already been received and is ready for immediate transmission, achieving real-time audio transmission without timing conflicts.
Solution Approach 2:
The system rushes the PDU transfer process by sending importer data requests earlier than the nominal PDU interval would suggest. This skipping ahead in the timing sequence ensures that the PDU transfer completes well before the transmission deadline, compensating for latency and enabling real-time audio transmission even over high-latency data links.
3Productivity
If the data link latency is reduced to enable high PDU rates, then real-time PDU transfer is achieved, but the data link may not be controllable or available for optimization
Solution Approach 1:
The system changes the temporal parameters of data request transmission, specifically the timing and frequency of importer data requests. By adjusting these parameters based on measured latency, the system adapts to different data link conditions without requiring control over the physical link itself, enabling high PDU transfer rates across diverse, uncontrollable data links.
Solution Approach 2:
The system implements feedback by measuring the actual latency of the data link and using this information to adjust the importer data request rate. This closed-loop approach allows the system to adapt to varying latency conditions in real-time, maintaining optimal PDU transfer rates even when the data link characteristics cannot be directly controlled or modified.
Data Source
AI summary
A method comprising: at an importer of an IBOC digital radio broadcasting system: establishing a data link to an audio client configured to buffer audio from an audio source over a buffering duration, to produce buffered audio; receiving, from the audio client, an indication of the buffering duration; identifying a logical channel of an IBOC waveform assigned to the audio client and configured to transmit PDUs of the audio at a PDU rate; computing a quantized number of PDUs that is greater than one into which the buffered audio is to be divided at the audio client based on the buffering duration and the PDU rate; sending, to the audio client, an indication of the quantized number of the PDUs; and upon sending importer data requests to the audio client over the data link, receiving, from the audio client, client data responses each including the quantized number of the PDUs.