C-V2X Scheduler Subchannel Selection for Interference Mitigation
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Solution Overview
Problem
Cellular vehicle-to-everything (C-V2X) communication systems face interference from Unlicensed National Information Infrastructure (U-NII) devices, leading to out-of-band emissions that degrade Quality-of-Service (QoS) due to their spontaneous nature, especially near band edges, which existing scheduling methods struggle to handle effectively.
Innovation Solution
A scheduling approach that identifies and employs specific subchannels less susceptible to out-of-band interference, using a selective excluded resource mode to determine when to exclude or include subchannels based on data packet size and transmission availability, thereby reducing interference and ensuring robust communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If all subchannels are used for transmission, then transmission capacity is improved, but susceptibility to out-of-band interference increases
Solution Approach 1:
The patent segments the available subchannels into two distinct sets: a first set of subchannels that are excluded during selective excluded resource mode (to avoid out-of-band interference) and a second set of subchannels that can be used for transmission. This segmentation allows the system to selectively use only the less susceptible subchannels when interference is detected, thereby maintaining transmission capacity while reducing interference susceptibility.
Solution Approach 2:
The patent implements dynamic subchannel selection by configuring the scheduler to switch between different transmission modes based on traffic conditions. When traffic load is below a threshold, the system uses selective excluded resource mode avoiding the first set of subchannels. When traffic load exceeds the threshold, it switches to using all available subchannels. This dynamic adaptation resolves the contradiction by adjusting resource utilization based on real-time conditions.
2Reliability
If selective excluded resource mode is used, then resilience against interference is improved, but transmission availability decreases
Solution Approach 1:
The patent employs dynamic mode switching where the scheduler can transition between selective excluded resource mode and full resource usage mode based on traffic load conditions. When traffic demand is high (exceeding threshold), the system switches to using all subchannels including the first set, thereby improving transmission availability. When traffic is low, it maintains selective exclusion for enhanced reliability. This dynamic behavior ensures the system adapts to varying conditions.
Solution Approach 2:
The patent changes the operational parameters of the scheduler based on traffic conditions. By monitoring traffic load and comparing it against a configured threshold, the system adjusts which subchannels are available for transmission. This parameter change (from restricted to unrestricted subchannel access) allows the system to balance reliability and transmission availability based on real-time traffic demands.
3Productivity
If subchannels near band edges are used, then spectrum utilization is improved, but susceptibility to out-of-band emissions increases
Solution Approach 1:
The patent extracts and excludes specific subchannels located near the band edges (the first set of subchannels) from the available transmission resources during selective excluded resource mode. By taking these susceptible subchannels out of the transmission pool when interference is present, the system protects against out-of-band emissions while still utilizing the majority of the spectrum through the second set of subchannels, thereby maintaining good spectrum utilization.
Data Source
AI summary
A system includes an antenna and a controller. The controller is configured to detect a size of a data packet to be transmitted, and detect transmission availability among a set of primary subchannels. With a scheduler in a selective excluded resource mode, the controller identifies CSR for transmitting the data packet based on the primary subchannels in response to at least one of the size of the data packet being less than a packet size threshold and at least a portion of the primary subchannels being available to transmit the data packet; and identifies the CSR for transmitting the data packet based on the plurality of subchannels in response to at least one of the size of the data packet being greater than or equal to the packet size threshold and the primary subchannels not being available to transmit the data packet.