Hierarchical Spectrum Access with Reserving Signals
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Solution Overview
Problem
Wireless communication networks face interference and congestion due to increased demand for mobile broadband access, as multiple users share limited spectrum resources, leading to degraded performance on both downlink and uplink transmissions.
Innovation Solution
Implementing a method for wireless communication that involves receiving indications of available shared spectrum resources, performing clear channel assessments (CCA), and transmitting data over these resources, with a hierarchical access model that prioritizes second-tier transmitters and allows third-tier transmitters to access shared channels only when clear, ensuring efficient use and minimizing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple users share limited spectrum resources, then network capacity and coverage are improved, but interference and congestion increase leading to degraded performance
Solution Approach 1:
The patent segments the shared spectrum access into multiple tiers (first tier, second tier, third tier) with different access priorities and rights. First tier transmitters have priority access, second tier transmitters access when first tier is absent, and third tier transmitters access when both first and second tiers are absent. This segmentation resolves the contradiction by organizing users into hierarchical groups, allowing network capacity to increase through multiple users while controlling interference through structured access patterns that prevent simultaneous transmissions from all tiers.
2Productivity
If more users access the wireless network, then network utilization is improved, but congestion and interference degrade transmission performance
Solution Approach 1:
The patent implements preliminary action through clear channel assessment (CCA) procedures that transmitters perform before accessing shared spectrum resources. Second tier transmitters perform CCA to detect the presence of first tier transmitters, and third tier transmitters perform CCA to detect both first and second tier transmitters. This preliminary detection action allows the system to accommodate more users by enabling them to sense the channel state before transmitting, thereby improving spectrum utilization while preventing congestion through coordinated access that avoids simultaneous transmissions.
3Adaptability or versatility
If shared spectrum resources are allocated to multiple tiers, then access flexibility is improved, but access control complexity increases
Solution Approach 1:
The patent applies local quality by assigning different access characteristics to different tiers of transmitters. First tier transmitters have unrestricted access to shared channels, second tier transmitters have access conditional on first tier absence (determined through CCA), and third tier transmitters have access conditional on both first and second tier absence. This differentiated local quality approach improves access flexibility by allowing multiple tiers to utilize the spectrum while managing access control complexity through a structured hierarchy where each tier has clearly defined, simple access rules based on its position in the hierarchy.
Data Source
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AI summary
Shared spectrum access is disclosed in which multiple tiers of users are allowed to access a set of shared spectrum resources. Second tier users, which receive priority access from the first spectrum tier, transmit reserving signals over the available shared channels during clear channel assessment (CCA) periods associated with the shared channels. Third tier users, which access the shared spectrum at a lower priority than the second tier users, attempt to synchronize timing with second tier users when second tier user presence is detected. Third tier users will be blocked from transmission on the shared channels when the third tier users detect the reserving signals. Second tier users, thus, transmit on the shared channels with a lower likelihood of interference from third tier users, and third tier users will be able to transmit on any of the shared channels when the third tier user detects a clear CCA.