PAL Channel Reallocation Using Circular Frequency Shifting
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Solution Overview
Problem
Existing CBRS systems lack guidance on reliably selecting an available secondary channel when a PAL user's primary channel is vacated due to incumbent user interference, leading to potential transmission disruptions and inefficiencies.
Innovation Solution
A method involving circular frequency shifting is employed to relocate PAL users to new channels by determining available PAL channels that are not licensed in the region, authorized for transmission, and not utilized by incumbent users, ensuring seamless channel reassignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a PAL user is assigned a static primary PAL channel, then the channel assignment is simple and stable, but the channel may become unavailable when an incumbent user needs to use it, causing interference issues
Solution Approach 1:
The patent implements dynamic channel assignment where the SAS can reallocate PAL channels from PAL users to incumbent users when needed. The system transitions from static channel assignment to dynamic allocation based on incumbent user activity, allowing channels to be temporarily taken from PAL users when incumbents require spectrum access.
Solution Approach 2:
The system changes the operational parameters of channel assignment by introducing circular shifting of channel indices. When a PAL channel is taken by an incumbent, the SAS applies a circular shift to reallocate channels, transforming the channel assignment parameters dynamically rather than maintaining fixed assignments.
2Reliability
If a PAL user is moved to a secondary channel when their primary channel is taken, then interference protection is maintained, but the process of selecting an available secondary channel is complex and inefficient
Solution Approach 1:
The patent pre-calculates and stores a circular shift mapping table that defines how channels are reallocated under various incumbent scenarios. This preliminary preparation allows the SAS to quickly apply pre-determined shift patterns rather than performing complex real-time analysis when channel reallocation is needed.
Solution Approach 2:
The system uses circular shift parameters to efficiently determine new channel assignments. Instead of searching for available channels, the SAS applies a mathematical circular shift operation to the original channel index, transforming it into a new channel index that is guaranteed to be available based on pre-computed mappings.
3Reliability
If the SAS performs complex real-time analysis to select available secondary channels, then channel availability is ensured, but the processing time and computational resources increase
Solution Approach 1:
The SAS performs channel availability analysis and circular shift mapping computations in advance, storing the results in lookup tables. When reallocation is triggered by incumbent activity, the system simply retrieves and applies pre-computed mappings rather than performing complex real-time analysis, dramatically reducing processing time.
Solution Approach 2:
The system prepares contingency channel allocation plans in advance by computing circular shift mappings for various incumbent scenarios. This beforehand cushioning ensures that when incumbents actually activate, the SAS has pre-prepared allocation schemes ready to deploy immediately without computational delay.
4Productivity
If multiple PAL users share the same primary channel, then spectrum utilization is efficient, but when the channel is taken by an incumbent, all users must be reallocated causing system complexity
Solution Approach 1:
The patent merges the reallocation process for multiple users by applying a single circular shift operation to all users sharing the same primary channel. Instead of individually managing reallocation for each user, the system combines their assignments and applies a unified shift transformation, simplifying the management of multi-user reallocation.
Data Source
AI summary
Techniques are provided for more reliably selecting an available secondary channel for a PAL user when the PAL user must relinquish its primary channel to an incumbent user for use in a geographic region. An indication is received that the incumbent user is utilizing or will utilize at least one PAL channel. It is determined whether the at least one PAL channel is utilized by at least one PAL user. Upon determining that the at least one PAL channel is utilized by at least one PAL user, then each PAL channel, used by the PAL user and for which the indication has been received, is shifted higher or lower in frequency to an available PAL channel.