Shared LNA Gain Scheduling for Concurrent WLAN and Bluetooth Reception
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Solution Overview
Problem
Collocated WLAN and Bluetooth receivers face challenges in setting the gain of a shared Low Noise Amplifier (LNA) to amplify weak RF signals without over-amplifying stronger signals, leading to potential corruption of receptions and reduced signal sensitivity, especially when one transceiver starts receiving data while the other is still active.
Innovation Solution
A system with a Primary Receiver (PR) and a Time Synchronized (TS) receiver, where the PR generates an LNA gain control signal based on timed signal strength predictions to create a shared amplified signal, allowing both receivers to concurrently receive packets, using a Multi-Chip Module (MCM) with separate Automatic Gain Control (AGC) for each receiver to adjust gains and manage signal strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the LNA gain is set to amplify the weakest RF signal, then signal sensitivity is improved, but stronger signals are over-amplified causing reception corruption
Solution Approach 1:
The LNA gain is made dynamic rather than fixed. The system continuously monitors RSSI from both WLAN and Bluetooth receivers and adjusts the LNA gain in real-time to match the current signal conditions. This dynamic adjustment allows the LNA to amplify weak signals when needed while preventing over-amplification of strong signals, resolving the contradiction between signal sensitivity and reception quality.
Solution Approach 2:
The system changes the gain parameter of the LNA based on detected signal conditions. By monitoring RSSI values from both receivers and comparing them against threshold values, the system selectively adjusts the LNA gain parameter to optimize performance for the active receiver, thereby maintaining both signal sensitivity and reception quality.
2Reliability
If the LNA gain is set to amplify strong signals, then reception of strong signals is improved, but weak signals are under-amplified causing loss of sensitivity
Solution Approach 1:
The LNA gain is dynamically adjusted based on the strength of the active signal. When a strong signal is detected, the gain is reduced to prevent over-amplification and distortion. When a weak signal is detected, the gain is increased to maintain sensitivity. This dynamic behavior ensures both strong and weak signals are received with optimal quality.
Solution Approach 2:
The system changes the LNA gain parameter in response to detected signal strength conditions. By implementing threshold-based control logic, the system adjusts the gain parameter to match the current operational requirements, ensuring reliable reception across varying signal conditions.
3Reliability
If a LNA with wider dynamic range is used to handle varying signal strengths, then reception quality for both weak and strong signals is improved, but power consumption increases
Solution Approach 1:
Instead of using a LNA with fixed wide dynamic range that consumes high power, the system dynamically changes the gain parameter of a standard LNA based on detected signal conditions. This approach achieves the same effective dynamic range adaptation while maintaining lower power consumption, as the LNA operates at optimized gain levels rather than maintaining maximum capability continuously.
Solution Approach 2:
The system uses the RSSI information already available from the WLAN and Bluetooth receivers to control the LNA gain. This self-service approach eliminates the need for additional high-power amplifiers or complex dynamic range management circuits, achieving adaptive reception quality using existing system resources.
4Measurement precision
If the LNA gain is changed during ongoing reception, then signal strength can be optimized for the new packet, but the current packet reception may be corrupted
Solution Approach 1:
The system performs preliminary detection of the active receiver and predicts which receiver will need the LNA gain adjustment before making the change. By using RSSI monitoring and timing information, the system anticipates the need for gain adjustment and prepares accordingly, minimizing the risk of corruption during packet reception.
Solution Approach 2:
The system continuously monitors RSSI feedback from both WLAN and Bluetooth receivers to determine when LNA gain adjustment is needed. This feedback mechanism allows the system to make informed decisions about gain changes, adjusting only when necessary and ensuring that changes occur at appropriate moments to avoid corrupting ongoing receptions.
Data Source
AI summary
An apparatus is disclosed comprising collocated primary receiver (PR) and a time synchronized receiver (TSR), with a Low Noise Amplifier (LNA) configured by a LNA gain control signal to create a shared amplified signal sent to the PR and the TSR for them to concurrently receive packets. The TSR is configured to generate a timed signal strength prediction signal based on the shared amplified signal and the LNA gain control signal. The primary receiver is configured to generate the LNA gain control signal based, at least in part, on the timed signal strength prediction signal. The PR may include a spread spectrum receiver, and the TSR may include a frequency hopping receiver.