FEC Regulation System Using Location-Based Channel Statistics
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Solution Overview
Problem
Current asymmetric public safety communications networks face inefficiencies in real-time forward error correction (FEC) rate control, particularly in terrestrial DTV/LMRS systems, due to high network latency and the scarce nature of land mobile radio bands, leading to channel inefficiency and poor performance under mobile conditions with line-of-sight blockages.
Innovation Solution
A communications network with a forward error correction (FEC) regulation system that dynamically adjusts FEC strength based on mobile client location and channel statistics, using a map database and predictive algorithms to anticipate future paths and channel conditions, thereby reducing reliance on slow return channels and enhancing channel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous DTV channel measurements are reported using LMRS, then reception quality data feedback is provided, but valuable LMRS bandwidth is consumed and channel inefficiency occurs
Solution Approach 1:
The system performs preliminary actions by measuring DTV channel conditions during initial data transmission and storing this information in a database. When a mobile client requests data, the system queries the database for pre-measured channel statistics at the client's location, eliminating the need for continuous real-time measurements via LMRS while still providing accurate reception quality feedback.
Solution Approach 2:
The system creates a copy of channel condition information by measuring DTV channel statistics during initial transmission and storing them in a database. This copied information is then reused for multiple mobile clients without requiring continuous LMRS communication, thereby providing reception quality feedback while conserving LMRS bandwidth.
2Reliability
If FEC adjustments are made reactively based on signal blockage feedback, then channel conditions are adapted, but high network latency causes poor performance under mobile conditions
Solution Approach 1:
The system performs preliminary channel condition measurements during initial data transmission and stores the results in a database. When mobile clients request data, the system retrieves pre-measured channel statistics for their location, enabling proactive FEC adjustment before signal blockage occurs, thereby eliminating latency-induced performance degradation.
Solution Approach 2:
The system implements feedback by measuring DTV channel conditions during initial transmission and storing this information in a database. Mobile clients receive feedback information about expected channel quality at their location, allowing the system to proactively adjust FEC parameters before actual signal degradation occurs, eliminating reactive latency.
3Reliability
If strong FEC redundancy and interleave are applied proactively, then mobile signal quality is improved, but channel bandwidth is consumed
Solution Approach 1:
The system applies local quality by determining FEC strength based on the mobile client's specific location and stored channel statistics for that location. Clients in areas with poor channel conditions receive stronger FEC redundancy, while clients in areas with good channel conditions receive minimal FEC, thereby optimizing signal quality without unnecessarily consuming channel bandwidth.
Solution Approach 2:
The system changes the FEC parameter dynamically by selecting different FEC strengths based on stored channel statistics for each mobile client's location. The FEC strength is adjusted as a function of location and historical channel performance, allowing proactive optimization of signal quality while minimizing bandwidth consumption by applying strong FEC only where needed.
Data Source
AI summary
A communications system utilizes a forward error correction (FEC) regulation system in transmitting data to a mobile client. The FEC strength is regulated as a function of a mobile client location and channel statistics for the location. The communications system includes a server for providing the FEC, a channel statistics database for storing channel data for locations of the mobile client, and a map database. The FEC strength is based on mobile client position and channel performance statistics measured by the mobile client over a period of time and sent to the server or optionally on previously collected and stored channel statistics measurements for the mobile client position or predicted position. The collection of channel statistics is made with an automated system to create a channel statistics measurement database. The FEC strength is varied by modifying packet payload redundancy, packet time spreading, interleave characteristics and error coding rates.