Cognitive Radio Power Control via Spectrum Sensing Distance
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Solution Overview
Problem
Cognitive radio systems face challenges in minimizing interference with licensed users due to difficulties in locating primary receivers and unreliable SNR measurements, leading to inefficient power control and potential interference.
Innovation Solution
The system controls the transmit power of cognitive radios based on spectrum sensing side information, determining the distance to primary transmitters to guarantee quality of service for licensed users by dynamically regulating power to avoid interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If cognitive radios use SNR measurements to control transmit power, then power control can be implemented, but the measurements are unreliable and cannot accurately locate primary receivers
Solution Approach 1:
The patent introduces spectrum sensing side information as an intermediary that indirectly provides location information about primary receivers. Instead of relying on unreliable direct SNR measurements from cognitive radios, the system uses sensing data from the primary network to determine whether primary receivers are present and to control cognitive radio transmit power accordingly, resolving the contradiction between measurement capability and location accuracy
Solution Approach 2:
The patent replaces the mechanical measurement approach (cognitive radios directly measuring SNR to infer location) with an information-based approach (using spectrum sensing side information from the primary network). This substitution eliminates the fundamental limitation of unreliable measurements while maintaining the ability to control transmit power based on primary receiver presence
2Productivity
If cognitive radios transmit at high power to improve spectrum utilization, then spectrum efficiency increases, but interference with licensed users occurs
Solution Approach 1:
The patent implements a feedback mechanism where spectrum sensing side information from the primary network continuously informs cognitive radio transmit power decisions. The system monitors primary receiver presence through sensing data and dynamically adjusts cognitive radio power levels in response, enabling high spectrum utilization when primary users are absent while preventing interference when they are present
Solution Approach 2:
The patent makes cognitive radio transmit power dynamic rather than static. Power levels are continuously adjusted based on real-time spectrum sensing side information about primary receiver presence, allowing the system to maximize spectrum utilization during opportunities while ensuring protection of licensed users when needed
3Object-affected harmful factors
If cognitive radios are restricted to low power transmission to protect licensed users, then interference is minimized, but spectrum utilization efficiency decreases
Solution Approach 1:
The patent applies partial action by allowing cognitive radios to transmit at high power only partially - specifically when spectrum sensing side information indicates that primary receivers are not present. When primary users are detected, power is reduced to protective levels. This selective application of high power transmission resolves the contradiction by achieving high utilization efficiency during safe periods while maintaining protection during critical periods
Data Source
AI summary
For cognitive radio systems, the transmit power of a cognitive radio device is controlled so that the cognitive, unlicensed radio device does not interfere with the use of a shared spectrum by a primary, licensed device. Controlling the transmit power includes determining a distance, or a function of the distance, between a primary transmitter of the primary device and the cognitive radio device based on sensing information from a spectrum sensing process. The maximum transmit power of the cognitive radio device is then dynamically controlled based on the distance, or the function of the distance, while considering a worst case scenario of an underlying cognitive radio model, to guarantee a quality of service requirement of the primary device.