Wireless Channel Switching for Unlicensed Spectrum Congestion
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Solution Overview
Problem
In NR-U systems, consecutive Listen Before Talk (LBT) failures lead to radio link failures and high latency due to system congestion, as NR-U UEs experience challenges in switching channels efficiently, especially when RACH and PUCCH-SR signaling need to be transmitted over unlicensed spectrum, resulting in prolonged data transfer delays.
Innovation Solution
A method for UE to detect channel congestion and initiate a channel switch to a less busy channel by measuring and selecting alternative channels based on preconfigured criteria, involving BWP or carrier switches, and performing handover procedures as necessary to ensure continuous network access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If NR-U UE transmits RACH and PUCCH-SR signaling over unlicensed spectrum, then network access is enabled, but consecutive LBT failures occur due to channel congestion
Solution Approach 1:
The patent implements dynamic channel selection by configuring multiple downlink and uplink channels with different priorities. The UE dynamically switches between channels based on LBT success/failure conditions, transitioning from a primary channel to alternative channels when congestion is detected. This dynamic adaptation resolves the contradiction by maintaining network access reliability through multiple pathways while reducing latency through automated channel switching.
Solution Approach 2:
The patent changes the operational parameters by configuring alternative channels with different priorities and characteristics. When LBT failures occur on the current channel, the system changes parameters by switching to a pre-configured alternative channel with potentially different frequency, bandwidth, or priority levels, thereby maintaining access reliability while avoiding the latency of exhaustive retransmission attempts.
2Loss of time
If the UE switches channels to avoid congestion, then latency is reduced, but channel switching complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring multiple alternative channels and their priorities before the UE needs to switch. The network provides the UE with a set of configured channels and switching criteria in advance. When congestion is detected, the UE can immediately switch to a pre-identified alternative channel without performing complex real-time analysis, thus reducing latency while keeping the switching mechanism relatively simple.
Solution Approach 2:
The patent implements feedback mechanisms where the UE monitors LBT success/failure on the current channel and automatically triggers channel switching based on predefined thresholds. This feedback-driven approach reduces the need for complex decision-making logic, as the switching is triggered by clear performance metrics rather than complex algorithms, thereby reducing device complexity while maintaining low latency.
3Adaptability or versatility
If multiple channels are configured for the UE, then channel switching capability is improved, but signaling overhead increases
Solution Approach 1:
The patent applies partial action by configuring a limited set of alternative channels (e.g., 1-3 alternative channels) rather than allowing the UE to access all available channels. This partial configuration provides sufficient adaptability for channel switching while significantly reducing the signaling overhead required to manage and coordinate numerous channel configurations between the network and UE.
Data Source
AI summary
Embodiments of the disclosure provide methods, apparatus and machine-readable media relating to wireless channel switching. A method performed by a wireless device for utilizing a portion of wireless spectrum shared between multiple radio-access technologies is provided, in which the portion of wireless spectrum comprises a plurality of channels at respective transmission frequencies. The method comprises detecting an event which is indicative of congestion at a first channel of the plurality of channels, wherein the first channel is assigned to the wireless device for accessing a cellular network. The method further comprises, responsive to detection of the event, initiating a procedure to switch to a second channel of the plurality of channels for accessing the cellular network.