Cognitive Radio Full-Duplex Spectrum Sensing
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Solution Overview
Problem
Current cognitive radio systems using the Listen-Before-Talk scheme face inefficiencies due to interruptions in secondary user (SU) transmissions for spectrum sensing, leading to reduced throughput and potential interference with primary user (PU) communications, as well as limitations in transmission rates due to half-duplex operations.
Innovation Solution
The implementation of self-interference suppression (SIS) techniques enables simultaneous transmission-and-sensing or transmission-and-reception modes in cognitive radios, allowing SUs to operate in full-duplex mode while adapting between different operational modes based on PU state and SU traffic, thereby enhancing throughput and reducing collision probabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the Listen-Before-Talk scheme is used for spectrum sensing, then primary user detection is performed, but secondary user throughput is reduced due to periodic transmission interruptions
Solution Approach 1:
The patent implements continuous spectrum sensing during data transmission by utilizing the received signal for both communication and sensing purposes. The SU receiver continuously monitors the channel for PU activity while maintaining data reception, eliminating the need to interrupt transmission for periodic sensing. This continuous operation maintains both high throughput and reliable detection.
Solution Approach 2:
The received signal at the SU is used for multiple purposes simultaneously: decoding data from the SU transmitter and detecting PU activity on the channel. This multi-functional use of the receiving chain allows the system to maintain transmission while performing spectrum sensing, resolving the contradiction between throughput and detection reliability.
2Reliability
If periodic spectrum sensing is performed to detect primary user activity, then collision avoidance is achieved, but transmission efficiency is reduced due to interruptions
Solution Approach 1:
The system performs continuous collision avoidance monitoring during data transmission by analyzing the received signal continuously. Instead of periodic sensing that interrupts transmission, the SU continuously checks for PU activity while maintaining data flow, ensuring collision avoidance without efficiency loss.
Solution Approach 2:
The SU's received signal serves dual purposes: maintaining the communication link and providing collision detection capability. The system uses its own receiving infrastructure to perform sensing functions, eliminating the need for separate sensing operations that would reduce transmission efficiency.
3Device complexity
If half-duplex operation is used for spectrum sensing, then simple implementation is achieved, but transmission rates are limited
Solution Approach 1:
The system implements full-duplex operation where the SU simultaneously transmits data and performs spectrum sensing using the same frequency channel. The receiving chain processes both the transmitted signal for data decoding and the channel signal for PU detection, doubling the effective utilization of the communication resources and increasing transmission rates.
Solution Approach 2:
The patent transitions from periodic sensing to continuous sensing during transmission. The SU continuously monitors the channel throughout the transmission period rather than interrupting periodically, maintaining simple implementation while achieving higher effective transmission rates through uninterrupted data flow.
Data Source
AI summary
Systems and methods for adaptive method exploits self-interference suppression (SIS) and full-duplex (FD) capabilities in cognitive radio and dynamic spectrum access (DSA) systems to enable simultaneous transmission-and-sensing (TS) or transmission-and-reception (TR) over the same frequency channel in a single operation. The adaptive methods enable secondary users or units (SUs) to switch between different modes of operation, taking into account the primary units (PUs) state, the SUs' traffic, and standards' rules. These adaptive methods significantly enhance the SU throughput and reduce the probability of colliding with PU transmissions.