Transmit-Power-Based AGC for Small Duplex Separation Bands
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Solution Overview
Problem
In frequency division duplex (FDD) bands with small duplex separation, out-of-band leakage of the transmit signal causes desensitization of the receiver, leading to reduced downlink performance due to saturation or clipping of active RF components.
Innovation Solution
The user equipment (UE) dynamically modifies the analog gain applied to the received signal based on the transmit power, using mechanisms such as adjusting the gain in response to expected transmit power thresholds and incorporating hysteresis to prevent rapid gain state toggling, and estimating receive signal strength with consideration for transmit leakage components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the analog gain is increased to improve signal-to-noise ratio, then the receiver sensitivity is improved, but the RF components become saturated or clipped due to transmit signal leakage
Solution Approach 1:
The patent implements dynamic automatic gain control that continuously adjusts the analog gain based on real-time transmit power levels. The gain is modified in response to expected transmit power thresholds, allowing the system to adapt to varying transmit conditions and prevent saturation while maintaining optimal receiver sensitivity.
Solution Approach 2:
The system incorporates feedback mechanisms where the receiver monitors transmit signal leakage and adjusts the analog gain accordingly. The gain adjustment is based on feedback from transmit power measurements and expected interference levels, creating a closed-loop control system that prevents RF component saturation.
2Object-affected harmful factors
If the analog gain is decreased to prevent saturation, then the harmful effects of transmit leakage are reduced, but the signal-to-noise ratio deteriorates
Solution Approach 1:
The system dynamically adjusts the analog gain based on current transmit power conditions rather than using a fixed reduced gain. This allows the gain to be high when transmit power is low (maintaining good SNR) and automatically reduce when transmit power increases (preventing saturation).
Solution Approach 2:
The patent changes the analog gain parameter in response to transmit power parameter changes. By monitoring transmit power levels and adjusting the gain parameter accordingly, the system optimizes the balance between preventing saturation and maintaining signal-to-noise ratio.
3Speed
If the gain is rapidly adjusted to respond to changing transmit power, then the receiver adapts quickly to prevent saturation, but rapid gain state toggling occurs causing instability
Solution Approach 1:
The system incorporates hysteresis as a cushioning mechanism that prevents rapid gain state toggling. By introducing hysteresis thresholds, the system requires a certain amount of change in transmit power conditions before triggering a gain state transition, thereby preventing instability from rapid adjustments while still responding quickly to genuine changes.
Solution Approach 2:
The patent uses expected transmit power thresholds to trigger gain adjustments in advance. By anticipating transmit power changes and adjusting gain before saturation occurs, the system responds proactively while the hysteresis mechanism prevents over-reacting to minor fluctuations.
Data Source
AI summary
Aspects relate to mechanisms for dynamically modifying the gain applied to a received signal based on the transmit power of a transmit signal. The transmit signal may be transmitted in a first frequency band and the received signal may be received in a second frequency band, where the frequency separation between the first frequency band and the second frequency band is less than a threshold.