Shared-Band Spectrum Notching for Incumbent Protection
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Solution Overview
Problem
In shared communication bands like the CBRS band, devices with Priority Access Licenses (PAL) must protect higher-tier incumbents, leading to disruptive channel clearances and increased interference or outage when incumbents like Navy shipborne radars are detected, as existing methods fail to selectively mitigate interference.
Innovation Solution
Implementing spectrum notching techniques such as Physical Resource Block (PRB) blanking and preamble puncturing to allow shared band devices (SBDs) to selectively avoid interference with incumbents by disabling specific frequency portions, using a Spectrum Access Controller (SAC) to manage channel allocations and notching capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If shared band devices operate in the CBRS band without spectrum notching, then spectrum utilization is maximized, but interference with incumbent users occurs
Solution Approach 1:
The patent segments the frequency spectrum into protected portions (notches) and usable portions. The spectrum access controller divides the CBRS band into specific frequency ranges, identifying which segments are occupied by incumbents and which are available for SBD operation. This segmentation allows SBDs to operate in non-occupied segments while avoiding interference in protected segments.
Solution Approach 2:
The patent applies local quality by implementing spectrum notching at specific frequency locations rather than uniformly across the entire band. Each incumbent user receives protection only in the specific frequency ranges they occupy, while other frequency ranges remain fully available for SBD operation. This localized approach maintains high spectrum utilization while providing targeted protection.
2Reliability
If channel clearances are implemented when incumbents are detected, then incumbent protection is ensured, but network disruptions and outages increase
Solution Approach 1:
Instead of clearing entire channels when incumbents are detected, the patent segments the channel into protected and non-protected frequency portions. SBDs continue operating in non-protected portions while incumbents are protected in their specific frequency ranges. This segmentation eliminates the need for disruptive full-channel clearances while maintaining incumbent protection.
Solution Approach 2:
The patent applies partial action by implementing protection only for the specific frequency ranges occupied by incumbents rather than applying blanket channel clearances. This partial approach provides sufficient protection for incumbents while minimizing impact on SBD operations in other frequency portions, thereby maintaining network continuity.
3Object-affected harmful factors
If spectrum notching is implemented to protect incumbents, then interference avoidance is achieved, but spectrum access complexity increases
Solution Approach 1:
The patent introduces a spectrum access controller as an intermediary between incumbents and SBDs. The SAC receives incumbent location and spectrum usage information, processes this data to determine notched frequency ranges, and generates spectrum access information for SBDs. This intermediary automates the complex notching process, reducing the burden on individual devices while ensuring proper incumbent protection.
Solution Approach 2:
The system implements feedback mechanisms where the spectrum access controller continuously monitors incumbent activity and adjusts spectrum access information for SBDs accordingly. When incumbents are detected or their usage patterns change, the SAC updates the notching configuration and notifies affected SBDs, ensuring dynamic adaptation while maintaining relatively simple device implementations.
Data Source
AI summary
Methods to protect incumbent communications in a shared band (e.g., shared by incumbents and shared band devices), are provided. In one example, a method includes receiving information, by a spectrum access controller (SAC) associated with a shared band, indicating usage of a sub-portion of a channel in the shared band. The method includes receiving, by the SAC, information associated with one or more shared band devices (SBDs) with spectrum notching capability (SNC) to reduce interference in the sub portion of the channel being used by the incumbent. The method includes determining, by the SAC, spectrum access information (SAI) for the one or more SBDs based at least in part on the SNC of the one or more SBDs. The method includes transmitting, from the SAC, SAI to the one or more SBDs, and SBDs accessing the channel according to the SAI.