Clear Channel Assessment Device for Spread Spectrum Signal Detection
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Solution Overview
Problem
Conventional spread spectrum communication systems face challenges in timely packet detection, which hampers subsequent signal processing operations, especially when signal power after de-spreading is not significantly higher than before de-spreading, leading to inadequate activation of the rake receiver and symbol examination circuit.
Innovation Solution
The system employs multiple receiving paths and a clear channel assessment device with de-spreading processors, power calculators, and a comparator to generate channel assessment and path selection signals, allowing for selective output of filtered signals based on signal characteristics, ensuring reliable channel assessment and path selection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional rake receiver is used for signal reception, then signal power can be received via different wireless communication paths, but packet detection cannot be performed before channel assessment, which delays subsequent signal processing operations
Solution Approach 1:
The patent performs packet detection and channel assessment in parallel before the rake receiver processes signals. The baseband processing unit detects packets and assesses channels simultaneously, so that when channel assessment completes, packet detection is already finished, eliminating the delay in subsequent signal processing operations
2Reliability
If signal power after de-spreading is not significantly higher than before de-spreading, then the conventional clear channel assessment device cannot reliably activate the rake receiver and symbol examination circuit
Solution Approach 1:
The patent introduces a new dimension for channel assessment by evaluating multiple parameters simultaneously: packet detection results, signal power before and after de-spreading, and channel quality metrics. This multi-dimensional assessment approach provides more reliable activation decisions for the rake receiver and symbol examination circuit, especially when signal power changes are subtle
3Reliability
If a single receiving path is used for signal reception, then device complexity is reduced, but reception performance becomes unstable with weak signal energy
Solution Approach 1:
The patent implements dynamic path selection where the baseband processing unit continuously evaluates multiple receiving paths and selectively activates them based on real-time channel conditions. This dynamic approach maintains stable reception performance with weak signals while avoiding the constant complexity of having all paths simultaneously active
Data Source
AI summary
A spread spectrum communication system includes a first and a second antenna, a first and a second radio frequency demodulator, a first and a second analog-to-digital converter, a first and a second filter, a clear channel assessment device, and a selection device. The radio frequency demodulators convert radio frequency signals to baseband signals, respectively. The analog-to-digital converters convert baseband signals to digital signals, respectively. The filters filter the first and second digital signals to generate filtered signals, respectively. The clear channel assessment device generates a channel assessment signal and a path selection signal according to signal characteristics of the filtered signals. The selection device refers to at least one of the channel assessment signal and path selection signal to selectively output one of the filtered signals, or generate no signal output.