Frequency Translating Bi-Directional Amplifier Control Channel Modification
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Solution Overview
Problem
Double translation using two bi-directional amplifiers (BDAs) in trunked networks incurs additional costs and signal propagation delays, limiting the distance of radio coverage in open-area applications, especially when network protocols are incompatible with frequency translation.
Innovation Solution
A single-frequency-translating bi-directional amplifier (BDA) with a field programmable gate array (FPGA) and local controller, which analyzes and modifies control channel messages to change the operating frequency of digital mobile radio communication devices, allowing them to use frequencies repeatable by the BDA, thereby extending radio coverage without the need for double translation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If double translation using two BDAs is used in trunked networks, then network protocol compatibility is achieved, but additional costs and signal propagation delays increase, limiting radio coverage distance
Solution Approach 1:
The patent extracts the frequency translation function from a dual-BDA configuration and consolidates it into a single BDA. The single BDA performs both frequency translations (donor to coverage frequency and vice versa) in one device, eliminating the need for a second BDA and thereby reducing signal propagation delays while maintaining network protocol compatibility through intelligent control channel message modification.
Solution Approach 2:
The patent merges the functions of two separate BDAs into a single BDA device. This consolidation combines the frequency translation capabilities and control channel processing functions into one unit, reducing system complexity, minimizing signal propagation delays, and lowering deployment costs while achieving the same network protocol compatibility that previously required double translation.
2Ease of operation
If non-frequency-translating BDA is deployed, then antenna isolation requirements are stringent, but gain is limited to 15 dB less than RF isolation level to avoid feedback
Solution Approach 1:
The patent changes the frequency parameter between input and output signals. By translating the donor frequency to a different coverage frequency and vice versa, the system eliminates the feedback problem that constrains gain in non-frequency-translating BDAs. This frequency parameter change allows the BDA to operate with high gain (not limited by antenna isolation) while maintaining ease of antenna placement and higher output power capability.
3Power
If frequency-translating BDA is used, then gain and power output are improved, but control channel message compatibility with network must be maintained
Solution Approach 1:
The patent introduces an intermediary processing function that intercepts, modifies, and retransmits control channel messages. This intermediary layer translates network control channel messages into coverage area-compatible messages and vice versa, enabling the frequency-translating BDA to maintain high power output while ensuring network protocol compatibility through intelligent message manipulation.
4Ease of manufacture
If single-frequency-translating BDA is used instead of double translation, then installation and servicing costs are reduced, but control channel message analysis and modification capability is required
Solution Approach 1:
The patent replaces traditional hardware-based control channel processing with an FPGA-based software-defined approach. This substitution allows the single BDA to perform complex control channel message analysis and modification through reconfigurable logic, reducing the need for additional physical BDAs and lowering installation and servicing costs while maintaining the necessary control channel compatibility capabilities.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution reduces installation and servicing costs, minimizes signal propagation delays, and enables effective radio coverage extension in trunked networks by allowing high gain and high power operation with improved antenna placement flexibility, while maintaining network operability and reducing simulcast interference.
Implementation Method 1
a BDA will receive a signal from a donor base station transmitter, boost the signal level, and retransmit the signal
Implementation Method 2
a frequency-translating BDA will convert the boosted output signal to a frequency that is different to the input frequency. Typically in either frequency-translating or non-frequency-translating modes, the downlink frequencies will be different to the uplink frequencies
Data Source
AI summary
A frequency translating bi-directional amplifier (10) for extending radio coverage for digital mobile radio communication devices (200) on a trunked network using a digital modulation scheme, comprising: a field programmable gate array (FPGA) with local controller (CPU) and firmware (22) configured to analyse control channel messages of a downlink control channel and modify the control channel messages of the downlink control channel that contain traffic channel information; and an antenna (12) to transmit the modified control channel messages to the digital mobile radio communication devices (200) in order to change an operating frequency of the digital mobile radio communication devices (200) to use a predetermined set of frequencies that are repeatable by the bi-directional amplifier (10); wherein the operating frequency between the digital mobile radio communication devices (200) and the bi-directional amplifier (10) is different to an operating frequency between a donor base station (300) and the bi-directional amplifier (10).