Cell Selection in Heterogeneous Networks via Measurement Restriction Patterns
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Solution Overview
Problem
In heterogeneous networks, user equipment (UE) in idle mode experiences varying Reference Signal Received Quality/Reference Signal Received Power (RSRQ/RSRP) at every subframe, affecting accurate cell selection or reselection due to inter-cell interference, which existing Enhanced Inter Cell Interference Coordination (eICIC) technologies struggle to address for UEs not connected to the network.
Innovation Solution
A cell selection method for UE that receives a measurement restriction pattern from the base station, allowing it to perform measurements only at specific subframes indicated by the pattern, and compares RSRQ/RSRP measurements between restricted and non-restricted subframes to determine cell selection or reselection, using Radio Resource Management (RRM) or Channel Quality Information (CQI) bitmaps to manage mobility and mitigate interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If measurement is performed at every subframe, then measurement coverage is complete, but measurement accuracy deteriorates due to inter-cell interference varying at every subframe
Solution Approach 1:
The patent segments the measurement process by dividing subframes into two categories: restricted subframes (where measurement is suspended) and non-restricted subframes (where measurement is performed). This segmentation is implemented through a measurement restriction pattern that the terminal receives from the base station, allowing measurements to be concentrated on subframes with lower interference, thereby improving measurement accuracy while avoiding harmful interference periods.
Solution Approach 2:
The terminal receives and stores the measurement restriction pattern in advance before performing measurements. This preliminary action allows the terminal to know which subframes will have lower interference beforehand, so it can plan its measurement activities accordingly, suspending measurements at restricted subframes and performing them only at non-restricted subframes.
2Reliability
If eICIC technology is applied to connected mode UEs, then interference mitigation is effective, but idle mode UEs remain unaffected by interference coordination
Solution Approach 1:
The patent extends the eICIC measurement restriction mechanism to serve dual purposes: it continues to help connected mode UEs while simultaneously enabling idle mode UEs to perform accurate measurements for cell reselection. The measurement restriction pattern and suspension mechanism are made universal, applicable to both connected and idle mode UEs, allowing the same technical approach to solve interference problems across different UE states.
3Measurement precision
If measurement restriction pattern is implemented, then measurement accuracy improves at non-restricted subframes, but device complexity increases due to pattern management
Solution Approach 1:
The terminal autonomously manages the measurement restriction pattern by storing it, identifying restricted versus non-restricted subframes, and automatically suspending or performing measurements based on the pattern without requiring continuous network control or complex coordination. This self-service approach simplifies the overall system complexity while maintaining measurement accuracy improvements.
Data Source
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AI summary
The present invention relates to a cell selection method of a terminal in a heterogeneous network, and cell selection method of a terminal in a heterogeneous network according to the present invention includes receiving a measurement restriction pattern from a base station; and selecting a cell based on the measurement restriction pattern. According to an embodiment of the present invention, it is possible to select a cell accurately and efficiently.