Cognitive Sensor Medium Access Control via Broadcast Preamble Sampling
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Solution Overview
Problem
Traditional cognitive wireless sensor networks face issues with control channel saturation, resource wastage, and increased transmission time delays due to the dormancy-awakening mechanism, especially when accessing authorized frequency bands.
Innovation Solution
A medium access control method based on broadcast preamble sampling, where cognitive sensors perform spectrum sensing, carrier listening, data queue detection, preamble code transmission, and dormancy cycles to establish communication links without a common control channel, ensuring reliable and low-overhead data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a common control channel is adopted for interaction among cognitive sensors, then control information can be exchanged, but the channel becomes saturated and wastes spectrum resources
Solution Approach 1:
The patent extracts the control information exchange function from a dedicated common control channel and integrates it into the data transmission channels. Cognitive sensors can exchange control information (such as spectrum sensing results and channel availability) alongside data traffic on the same physical medium, eliminating the need for a separate control channel and thus freeing up spectrum resources.
Solution Approach 2:
The patent makes the data transmission channel multi-functional by enabling it to carry both data traffic and control information simultaneously. This universal channel approach allows the same spectrum resources to serve dual purposes, improving resource utilization efficiency while maintaining reliable control information exchange among cognitive sensors.
2Use of energy by moving object
If cognitive sensors adopt a dormancy-awakening mechanism to save energy, then energy consumption is reduced, but data packet transmission time delay increases
Solution Approach 1:
The patent implements preliminary action by having cognitive sensors perform spectrum sensing and channel assessment during dormancy periods, and maintain lightweight listening capabilities that can quickly transition to full operation. This preliminary preparation reduces the awakening time and allows sensors to resume data transmission faster, thereby reducing overall transmission delay while maintaining energy savings.
Solution Approach 2:
The patent introduces dynamic dormancy-awakening intervals that adapt to network conditions and traffic patterns. When traffic load is high or channel conditions are favorable, sensors wake up more frequently to reduce delay. When traffic is low or energy constraints are tight, sensors extend dormancy periods. This dynamic adjustment optimizes the trade-off between energy consumption and transmission delay based on real-time conditions.
3Measurement precision
If spectrum sensing is performed continuously to detect primary users, then detection accuracy is improved, but energy consumption increases
Solution Approach 1:
The patent implements periodic spectrum sensing where cognitive sensors perform detection at regular intervals rather than continuously. The sensing period is optimized to balance detection accuracy with energy consumption - sensors wake up at predetermined intervals to perform spectrum sensing, then return to dormancy. This periodic approach maintains adequate detection capability while dramatically reducing energy usage compared to continuous monitoring.
Solution Approach 2:
The patent maintains continuity of useful action by implementing a cooperative sensing mechanism where multiple cognitive sensors share spectrum sensing results and channel state information. Individual sensors can enter deeper dormancy states while the network collectively maintains continuous spectrum monitoring through information sharing. This ensures detection accuracy is preserved at the network level while individual energy consumption is minimized.
Data Source
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AI summary
The present invention relates to cognitive wireless sensor network technologies, and in particular to a medium access control method for a cognitive sensor network based on broadcast preamble sampling. A cognitive node in the cognitive sensor network adopts a periodical dormancy-awakening mechanism. Firstly, a state of a primary user is judged by using a spectrum sensing technology. If the primary user is not active, a data sending node establishes a communication link by using a broadcast preamble code. Each neighbor node simultaneously considers information of hops from a gateway according to an awakening order, and independently determines to serve as a relay node for forwarding data. Furthermore, a transmission conflict between the cognitive node and the primary user may be caused due to return or missed alarm of the primary user. The present invention adopts a retransmission mechanism based on confirmation to ensure transmission reliability of data packets. The present invention is independent of a common control channel, and can realize reliable access of the cognitive sensor network for an authorized frequency band at low overhead.