Packet Acquisition Control for AGC Freeze and False Packet Detection
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Solution Overview
Problem
Existing wireless receiver systems face challenges in detecting low signal packets due to limited receiver sensitivity, false packet detection in MIMO configurations, and inefficiencies in AGC operations that result in time delays and incorrect packet identification.
Innovation Solution
A packet acquisition controller that freezes AGC processes for low-level signals, defers detection for high-level signals, detects false packets by timing, and selects the strongest stream for detection, using SNR_MODE to adjust correlation sample averaging and trigger thresholds for robust packet detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If AGC applies high gain to detect low level packets, then receiver sensitivity is improved, but false packet detection increases due to noise amplification
Solution Approach 1:
The system performs preliminary actions by freezing the AGC process upon detecting a packet and before completing AGC acquisition, and by performing preliminary noise floor measurements during intervals when no packet is detected. This allows the system to prepare detection thresholds in advance based on actual noise conditions, improving both sensitivity and reliability.
Solution Approach 2:
The system uses feedback by continuously monitoring the AGC output and comparing it against dynamically updated noise floor measurements. The packet detection threshold is adjusted based on feedback from the actual noise conditions measured during inter-packet intervals, allowing the system to adapt to changing environmental conditions and reduce false detections.
2Measurement precision
If AGC process is performed before packet detection, then signal level is optimized for ADC, but time delay is introduced that may cause packet loss
Solution Approach 1:
The system performs preliminary noise floor measurements and threshold calculations during inter-packet intervals before the actual packet arrives. This preliminary preparation allows packet detection to begin immediately upon packet arrival without waiting for complete AGC acquisition, reducing detection delay while maintaining signal optimization.
Solution Approach 2:
The system dynamically adjusts the detection threshold based on real-time noise floor measurements and AGC state. Rather than using a fixed threshold, the system adapts the threshold dynamically to match current conditions, allowing faster detection while maintaining accuracy even during the AGC transition period.
3Measurement precision
If AGC gain is increased for low signal packets, then detection capability is improved, but noise floor increases causing false detections
Solution Approach 1:
The system extracts and separately measures the noise floor component from the total signal during inter-packet intervals when no packet is present. By isolating and measuring only the noise portion, the system can establish accurate detection thresholds that account for the actual noise level without being contaminated by packet signals, thereby improving detection capability while filtering out noise-induced false detections.
Solution Approach 2:
The system introduces an intermediary noise floor measurement process that acts as a mediator between the AGC gain control and packet detection. By measuring and comparing against a separately obtained noise floor value, the system can distinguish between actual packet signals and amplified noise, reducing false detections while maintaining sensitivity to weak packets.
4Speed
If packet detection is performed continuously, then detection speed is improved, but false packets increase due to noise correlation
Solution Approach 1:
The system performs preliminary noise floor characterization during inter-packet intervals before packet detection begins. This preliminary measurement of noise conditions allows the detection algorithm to adjust its sensitivity and thresholds in advance, enabling faster detection of actual packets while filtering out noise-correlated false detections that would otherwise trigger continuous detection.
Solution Approach 2:
The system implements feedback by continuously updating the detection threshold based on measured noise floor levels. When noise conditions change, the threshold is adjusted accordingly, allowing the system to maintain high detection speed for actual packets while adapting to noise conditions to prevent false detections from noise correlations.
Data Source
AI summary
An packet detection controller accepts an input from an AGC controller which indicates the presence of an increased signal energy and also completion of an AGC process and generates an output to suspend the AGC process. The packet detection controller also receives a plurality of IQ receiver streams and forms a single stream for use by a packet detector, which is controllable by an SNR_MODE indicating whether the signal to noise ratio is above or below a particular threshold, and a PD_RESET signal indicating that no packet detection should occur. The controller also receives a PACKET_DET signal indicating that packet detection is completed. The packet detection controller examines the incoming receiver streams and suspends AGC process if a packet detect is generated, or suspends the packet detector if an AGC process is required.