Cell Reselection Using Intra Frequency Reselection Timer
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Solution Overview
Problem
In wireless communication systems, especially in environments with coexisting cells of varying sizes, conventional cell reselection methods are ineffective due to the constraints imposed by Closed Subscriber Group (CSG) cells, leading to interference and reduced utilization of micro cells like CSG cells.
Innovation Solution
A method and apparatus that utilize an Intra Frequency Reselection (IFR) timer and indicator to manage cell reselection, allowing the user equipment (UE) to search for neighboring cells on the same frequency of a barred CSG cell initially and then switch to different frequencies after the timer expires, ensuring efficient cell reselection and minimizing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional cell reselection is performed in environments with coexisting cells of various sizes, then cell reselection is executed, but it becomes ineffective due to constraints from CSG cells causing interference and reduced micro cell utilization
Solution Approach 1:
The patent applies preliminary action by introducing an IFR timer that operates in advance to manage the cell reselection process. When a barred cell is detected, the timer is started and controls the search behavior for a predetermined period, preventing premature or ineffective reselection attempts and ensuring systematic exploration of available cells before finalizing a selection.
Solution Approach 2:
The patent implements dynamics by making the cell reselection process adaptive and flexible. The IFR timer dynamically adjusts the reselection behavior based on the network environment, allowing the UE to switch between different search strategies (intra-frequency vs inter-frequency) depending on the timer state and detected barred cells, thereby optimizing reselection effectiveness in varying conditions.
2Adaptability or versatility
If UE searches for neighboring cells in the frequency of a barred cell, then more cell options are available, but interference increases and micro cell utilization decreases
Solution Approach 1:
The patent uses the IFR timer as an intermediary mechanism that mediates between the UE's desire to search all available cells and the network's requirement to minimize interference. The timer acts as a controller that temporarily enables broad search capability while preventing sustained interference by limiting the search duration and triggering frequency changes after a predetermined period.
Solution Approach 2:
The patent applies parameter changes by dynamically modifying the cell search parameters based on the IFR timer state. When the timer is active, the UE is allowed to search within the barred cell's frequency range; when the timer expires, the search parameters are changed to exclude that frequency, thereby controlling interference levels while maintaining search flexibility during the timer period.
3Reliability
If CSG cells are used to provide limited access to specific subscribers, then quality of service improves, but cell reselection becomes ineffective for non-members
Solution Approach 1:
The patent applies preliminary action by having the UE preliminarily identify and mark CSG cells as barred before the reselection process. This preliminary classification allows the UE to handle CSG cells differently during reselection, using the IFR timer to manage the search process in a way that respects CSG restrictions while still providing fair access opportunities for non-member UEs in appropriate scenarios.
Data Source
AI summary
A method and apparatus of selecting a cell in a wireless communication system is provided. A user equipment receives an Intra Frequency Reselection indicator (IFRI) from a barred cell. The user equipment starts an Intra Frequency Reselection (IFR) timer when the IFRI indicates not to allow reselection of a neighboring cell in a frequency of the barred cell, and searches neighboring cells in the frequency of the barred cell while the IFR timer is running.