Distributed IP Voting for Land Mobile Radio Latency
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Solution Overview
Problem
Existing digital voting systems for Land Mobile Radio (LMR) systems require specialized equipment, synchronized data paths, and introduce significant latency due to buffering and serial polling of receivers, leading to high costs and inefficient signal selection.
Innovation Solution
A distributed Internet Protocol (IP) voting system that eliminates the need for specialized equipment and synchronized data paths, allowing asynchronous transmission of signal quality packets from receivers to the receive-and-transmit site, where the best signal is selected and re-transmitted within a predetermined acceptance window, reducing latency and system costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If specialized voting equipment is used to select the best signal, then signal selection reliability is improved, but system cost and device complexity increase
Solution Approach 1:
Each receiving site independently evaluates its own received signal quality and autonomously transmits voting information to the receive-and-transmit site without requiring complex centralized voting equipment. The system serves itself by distributing the voting function to individual sites rather than concentrating it in specialized equipment.
Solution Approach 2:
The centralized voting function is segmented and distributed to individual receiving sites. Each site performs local signal quality assessment and independently transmits its voting result, dividing the complex voting task into simpler independent operations performed by multiple sites.
2Measurement precision
If synchronized data paths are used for voting, then signal selection accuracy is improved, but latency increases
Solution Approach 1:
The voting system transitions from static synchronized timing to dynamic asynchronous operation. Receiving sites transmit voting information as soon as signal quality assessment is complete, without waiting for synchronization signals or fixed timing windows, allowing flexible transmission timing that reduces latency while maintaining assessment accuracy.
Solution Approach 2:
Signal quality assessment is performed in advance at each receiving site before transmission of voting information. The preliminary evaluation of signal-to-noise ratio and other quality metrics is completed locally, allowing sites to prepare their voting data ready for immediate transmission without waiting for centralized polling.
3Device complexity
If serial polling of receivers is performed, then equipment simplicity is improved, but productivity decreases
Solution Approach 1:
The traditional polling approach is inverted: instead of the centralized voter actively polling each receiver in sequence, each receiver actively transmits its voting information to the receive-and-transmit site. This reversal of the information flow direction eliminates the sequential polling bottleneck and enables parallel operation.
Solution Approach 2:
The voting information transmission occurs continuously as receiving sites complete their signal quality assessments, rather than in discrete sequential polling cycles. Multiple sites can transmit voting information simultaneously and continuously, maximizing the throughput and speed of the signal selection process.
Data Source
AI summary
A distributed Internet Protocol (IP) voting system and method for use in Land Mobile Radio (LMR) Systems having a central send-and-receive site and one or more receive-only sites. In the distributed voting system, receive-only sites are directly linked to the control point using a network and associated packet transmission protocol. This may be a high-speed asynchronous data link such as a standard IP network link. Each remote site receiving digital data, calculates a bit error for that data. This error calculation is incorporated into the data header information. The data header information and data are placed in an IP packet and transmitted as a User Data Protocol (UDP) message to the control point. The control point selects the lowest bit rate data message, or the first control message, and retransmits it using a standard radio air interface protocol, such as the APCO Project 25 air interface protocol.