White Space Channel Access via Hash Function
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Solution Overview
Problem
Conventional Medium Access Control (MAC) schemes in wireless communication networks are deterministic, requiring precise coordination and control signal exchanges, leading to high overheads and fragility in real-world operations, especially in crowded unlicensed frequency bands and underutilized licensed spectrums.
Innovation Solution
The method involves identifying white spaces in licensed frequency bands not in use by primary users, using a hash function-based channel access factor to determine priority for channel selection and transmission, reducing the need for control signals and enabling efficient use of unlicensed devices in licensed bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional deterministic MAC schemes are used, then precise coordination among users is achieved, but communication overhead increases and reliability decreases
Solution Approach 1:
The patent enables each wireless node to independently determine its channel access rights by evaluating the channel access factor using locally available information (white space identification, node identifier, channel parameters). This self-service mechanism eliminates the need for complex control signal exchanges and coordination protocols, allowing nodes to autonomously make transmission decisions without central control or extensive signaling overhead
Solution Approach 2:
The patent introduces a hash function as an intermediary mechanism that deterministically maps node identifiers and channel parameters to channel access factors. This intermediary function provides a systematic and fair method for allocating channel access rights without requiring direct coordination between nodes, thereby simplifying the MAC protocol while maintaining reliability
2Productivity
If white space utilization is increased, then spectral efficiency improves, but interference with primary users may occur
Solution Approach 1:
The patent performs preliminary identification of white spaces before channel allocation and transmission. By pre-sensing the spectrum and identifying unused frequency bands, the system ensures that subsequent transmissions occur only in frequencies confirmed to be free from primary user activity, thereby preventing interference while maximizing spectral utilization
Solution Approach 2:
The patent applies different channel access factors to different nodes based on their specific characteristics (node identifier) and local white space conditions. This localized approach allows each node to adapt its transmission behavior to the specific spectral environment and its own identity, enabling efficient use of available white spaces while maintaining protection for primary users through individualized access control
Data Source
AI summary
A method includes identifying a white space at a first wireless node and selecting a channel in the identified white space. The white space includes at least one frequency or frequency band not in use (like a licensed frequency or frequency band). The method also includes identifying at the first wireless node a channel access factor for each of multiple wireless nodes including the first wireless node. The method further includes determining if the first wireless node has a specified channel access factor. In addition, the method includes transmitting data from the first wireless node on the channel when the first wireless node has the specified channel access factor. The channel access factors can be identified and the determination whether the first wireless node has the specified channel access factor can be performed without using control signals transmitted between the wireless nodes. The channel access factor could represent a hash function value.