Dynamic Frame Structure for Cognitive Radio Interference Reduction
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Solution Overview
Problem
Existing cognitive radio systems face increased collision probability between secondary and primary users due to the periodic and uniform structure of sensing and transmission slots, which fails to account for the rising likelihood of primary user channel reoccupation over time.
Innovation Solution
A frame structure is introduced where the length of data transmission slots is dynamically reduced based on collected channel status information and traffic models, with each subsequent frame being progressively shorter, and spectrum sensing is re-executed to adapt to potential primary user traffic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If uniform periodic sensing and transmission slots are used, then the system structure is simple and easy to implement, but the collision probability between secondary user transmission and primary user channel reoccupation increases over time
Solution Approach 1:
The patent applies dynamics by transitioning from a static uniform frame structure to a dynamic adaptive frame structure. The transmission slot length is adjusted based on elapsed time and primary user traffic models, making the system adaptable to changing conditions. Specifically, the frame structure changes its parameters (transmission slot length) over time to optimize performance and reduce collisions.
Solution Approach 2:
The patent implements parameter changes by modifying the transmission slot length parameter based on the primary user's traffic characteristics and elapsed time. The system calculates optimal transmission slot lengths dynamically, changing this key parameter to balance throughput and collision probability. This involves computing different frame structures with varying transmission slot lengths according to traffic models.
2Productivity
If longer transmission slots are used, then the throughput of secondary users is improved, but the interference to primary users increases when primary user traffic arrives
Solution Approach 1:
The patent uses parameter changes to adjust transmission slot length dynamically. By calculating optimal slot lengths based on primary user traffic models and elapsed time, the system adapts the transmission duration parameter to maximize throughput while minimizing interference. This involves continuously adjusting the transmission slot length parameter according to changing channel conditions and traffic patterns.
Solution Approach 2:
The system applies dynamics by making the transmission slot length adaptive rather than fixed. The frame structure dynamically adjusts its transmission duration based on real-time conditions and predicted primary user behavior. This dynamic adjustment allows the system to optimize throughput when the channel is clear while reducing transmission time to minimize interference when primary user traffic is likely to arrive.
3Productivity
If the secondary user transmits data for a long period, then the data transmission efficiency is improved, but the collision probability with primary user channel reoccupation increases
Solution Approach 1:
The patent applies dynamics by making the transmission slot length adaptive based on elapsed time and primary user traffic models. Instead of using fixed long transmission slots, the system dynamically adjusts the slot length to balance transmission efficiency and collision probability. The frame structure evolves over time, with transmission slots becoming shorter as the probability of primary user return increases.
Solution Approach 2:
The system implements parameter changes by adjusting the transmission slot length parameter according to the primary user's traffic characteristics and the elapsed time since channel acquisition. This dynamic parameter adjustment optimizes the trade-off between maintaining long transmission slots for efficiency and shortening them to reduce collision probability with primary user reoccupation.
Data Source
AI summary
Disclosed are an apparatus and method for determining a frame structure for reducing interference between users using the same frequency band in a communication system using a cognitive radio, the method including, collecting channel status information related to a primary user with a priority to occupancy of a predetermined frequency band, executing spectrum sensing for the frequency band to check whether the primary user's traffic exists, deciding a length of a data frame to be transmitted in consideration of interference to the primary user based upon the collected channel status information if a channel in which the primary user's traffic is not present is sensed through the spectrum sensing, constructing a data frame based upon the decided frame length to transmit via the sensed channel, and re-executing the spectrum sensing for the channel, if data to be additionally transmitted exists, and rechecking whether the primary user's traffic is present.