Smart Uplink Repeater Gain Control for Mixed Signal Levels
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Solution Overview
Problem
Over-the-air repeaters in wireless communication systems face limitations in uplink performance due to high dynamic range differences between weak and strong signals, especially in GSM frequency hopping mode, leading to power amplifier overload and reduced coverage for weak signals.
Innovation Solution
A digital repeater system with time division multiplexed (TDM) communication signals, synchronized digital filters, delay buffers, power measurement units, and gain setting units for each RF channel, allowing independent gain adjustments based on automatic limit control (ALC) or automatic gain control (AGC) to prevent power amplifier overload while maintaining optimal signal strength for weak signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If high gain is used to amplify weak signals, then coverage range is improved, but power amplifier overload occurs due to strong signals
Solution Approach 1:
The patent segments the RF signal processing into multiple independent digital filter banks, each handling specific frequency channels. This allows independent gain control for each channel, enabling the system to apply high gain to weak signals on certain channels while limiting gain on channels with strong signals, thus preventing power amplifier overload while maintaining coverage range.
Solution Approach 2:
The patent implements dynamic gain control through automatic gain control (AGC) circuits that continuously monitor signal levels and adjust gain settings in real-time. This dynamic adjustment allows the system to adapt to varying signal conditions, applying appropriate gain levels to prevent overload while ensuring weak signals receive sufficient amplification for coverage.
2Adaptability or versatility
If separate RF chains and power amplifiers are used for each RF channel, then independent gain control is achieved, but device complexity and cost increase
Solution Approach 1:
The patent merges multiple RF channels into a single shared power amplifier output while maintaining independent digital signal processing paths. By combining the power amplification function for multiple channels into one amplifier and using digital filtering to separate channels, the system achieves independent gain control without requiring separate power amplifiers for each channel, thus reducing device complexity and cost.
Solution Approach 2:
The patent replaces physical RF chain separation with digital signal processing. Instead of using separate physical RF paths and amplifiers for each channel, the system uses digital filter banks to separate and process channels independently in the digital domain, then combines them for power amplification. This substitution of mechanical/physical separation with digital processing reduces hardware complexity while maintaining independent gain control capability.
3Object-affected harmful factors
If digital filtering is used to isolate individual RF channels, then interfering signals are eliminated, but gain coupling limitations remain due to shared MCPA
Solution Approach 1:
The patent segments the signal processing into independent digital filter banks, each with its own AGC circuit for independent gain control. This segmentation occurs in the digital domain after ADC conversion, allowing each filtered channel to have autonomous gain adjustment capability even though they share a common power amplifier, thus eliminating the gain coupling limitation while maintaining interference rejection.
4Reliability
If dynamic gain control is applied to prevent PA overload, then strong signals are protected, but weak signals simultaneously receive reduced gain
Solution Approach 1:
The patent segments gain control to the individual channel level through separate digital filter banks, each with independent AGC circuits. This allows the system to apply dynamic gain control selectively to channels with strong signals to prevent PA overload, while simultaneously maintaining high gain settings on channels with weak signals to ensure their coverage, thus resolving the trade-off between overload protection and weak signal coverage.
Data Source
AI summary
An over the air repeater for enhancing wireless communication is provided. The repeater employs a system and method by which strong signals can be prevented from exceeding the repeater's uplink output limits while still providing full operational gain to any concurrently amplified weak signals, while adapting to time slot variations and optionally to frequency hopping variations. Power measurements are performed on each channel with resultant gain changes being performed on delayed versions of those same signals. Digital delay buffers are used to provide adequate processing time to make an accurate determination of the uplink signal levels of each RF carrier. The repeater alternatively monitors the downlink path from the donor base station to determine the frequencies to be processed on the uplink communication.