White Space Receiving Station Frequency Allocation
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Solution Overview
Problem
The existing IEEE 802.22 wireless communication system using white spaces is inefficient due to its reliance on time division duplex (TDD) for duplex operation, leading to asymmetrical communication quality and potential unidirectional links, especially when downlink signals have low signal-to-interference ratios (SIR) and interfere with primary user systems.
Innovation Solution
A wireless communication system that includes a receiving station with interference suppression and communication quality estimation capabilities, allowing for dynamic frequency allocation based on communication quality information to optimize data transmission frequencies, even in low SIR environments, while maintaining the TDD system by using OFDMA for efficient resource utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If TDD is used for duplex operation in white space communication, then the system can operate with simple frequency allocation, but communication quality becomes asymmetrical and frequencies cannot be used efficiently when transmission powers differ
Solution Approach 1:
The patent segments frequency allocation into two distinct parts: control signal frequency and data signal frequency. This allows independent optimization of each frequency allocation based on communication quality requirements, resolving the contradiction between simple allocation and efficient usage.
Solution Approach 2:
The patent introduces asymmetrical frequency allocation where control signals and data signals use different frequencies. This asymmetry enables each frequency to be optimized for its specific purpose, improving overall system efficiency while maintaining manageable complexity.
2Device complexity
If the same frequency is allocated for both control and data transmission, then frequency allocation is simple, but communication quality deteriorates in low SIR environments due to interference
Solution Approach 1:
The patent separates control signal transmission and data signal transmission into different frequency resources. This segmentation allows control signals to use frequencies with better SIR conditions, improving reliability while keeping the allocation system manageable through structured separation.
Solution Approach 2:
The patent applies local quality by selecting specific frequencies based on their individual communication quality characteristics. Control signals are allocated to frequencies with acceptable SIR, while data signals can use frequencies optimized for their specific requirements, improving overall reliability.
3Ease of operation
If frequency allocation is based solely on transmittable frequency lists from database, then allocation is straightforward, but it cannot adapt to real-time communication quality variations
Solution Approach 1:
The patent uses preliminary action by pre-obtaining transmittable frequency lists from the database before actual communication. This provides a foundation for allocation while allowing subsequent adaptation based on real-time communication quality measurements.
Solution Approach 2:
The patent implements feedback by measuring actual communication quality (SIR) of allocated frequencies and using this information to make adaptive frequency allocation decisions. This feedback mechanism enables the system to adapt to real-time conditions while building upon the initial database information.
Data Source
AI summary
In a wireless communication system for performing wireless communication using a white space, a receiving station includes an interference suppression processing part which performs processing to reduce interference which is received by the signal transmitted from a transmitting station at a frequency of the white space, a receiving quality estimation part which estimates communication quality of the communication using the frequency of the white space based on the signal processed by the interference suppression processing part, and a receiving quality informing part which transmits to the transmitting station the communication quality information estimated by the receiving quality estimation part.