Wireless Device Cell Reselection Based on UE Preference
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Solution Overview
Problem
In wireless communication systems, particularly in NR standalone operation on unlicensed bands, initial access and random access procedures are hindered by LBT failures, which can lead to service delays due to the unpredictable availability of unlicensed spectrum, necessitating a method to deprioritize unlicensed frequencies based on user equipment (UE) preferences for efficient cell reselection.
Innovation Solution
A method where a wireless device attempts to access a cell on an unlicensed frequency, starts a timer, and upon expiration, if it is a licensed preferred device, deprioritizes the unlicensed frequency, and if unlicensed preferred, deprioritizes the cell, allowing for cell reselection based on UE preferences to minimize service delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If LBT is applied on unlicensed bands for initial access and random access procedures, then spectrum availability and flexibility are improved, but access reliability and service latency deteriorate due to unpredictable channel availability
Solution Approach 1:
The patent implements dynamic cell reselection by allowing UEs to switch between unlicensed and licensed frequencies based on real-time LBT success conditions. The network configures multiple serving cells with different frequency types, and UEs dynamically reselect cells when LBT failures occur, adapting to changing channel conditions rather than statically remaining on unlicensed bands.
Solution Approach 2:
The patent changes the operational parameters of the wireless system by introducing a mechanism where UEs monitor LBT success rates and trigger cell reselection based on predefined thresholds. This parameter-based approach allows the system to transition from always using unlicensed bands to conditionally using licensed bands when LBT failure rates exceed acceptable levels.
2Productivity
If UEs continuously retry LBT on unlicensed bands, then access attempts are maintained, but service delay increases due to repeated access failures
Solution Approach 1:
The patent implements preliminary action by pre-configuring multiple serving cells (both unlicensed and licensed) before access attempts begin. When LBT failures occur, UEs can immediately reselect to pre-configured licensed cells without waiting for new configuration, thereby reducing service delay while maintaining access persistence through advance preparation of alternative cells.
3Ease of manufacture
If unlicensed frequencies are prioritized for free services, then cost efficiency is improved, but access stability deteriorates in high LBT failure rate scenarios
Solution Approach 1:
The patent introduces licensed frequencies as an intermediary solution between unlicensed band cost-efficiency and access stability requirements. The system allows UEs to primarily use unlicensed bands for cost efficiency while providing licensed bands as a stable fallback option when LBT failures occur, thereby mediating between the two conflicting requirements through conditional cell reselection.
Data Source
AI summary
A method and apparatus for deprioritizing access on an unlicensed band based on user equipment (UE) preference in a wireless communication system is provided. A wireless device attempts to access a cell on an unlicensed frequency and starts a timer. When the timer expires, if the wireless device is a licensed preferred wireless device, the wireless device deprioritizes the unlicensed frequency. If the wireless device is an unlicensed preferred wireless device, the wireless device deprioritizes only the cell. The wireless device performs a cell reselection according to the de-prioritization.