Handover Command Using Low-Interference Resources
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Solution Overview
Problem
In wireless communication systems, user equipment (UE) experiences interference from neighboring cells, leading to difficulties in normal measurement and mobility, especially when handovers occur, due to inter-cell interference, which can result in deteriorated quality of service (QoS) and failed handovers.
Innovation Solution
A handover method using low-interference radio resources, specifically Almost Blank Subframes (ABS), is implemented to reduce interference during the handover process, where the UE receives a handover command message with information on low-interference radio resources, allowing it to perform handover and measurement through these resources, thereby minimizing interference from the source cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If UE performs measurement using normal radio resources in the presence of inter-cell interference, then measurement can be conducted continuously, but measurement precision deteriorates due to interference from neighboring cells
Solution Approach 1:
The patent segments the radio resources into normal resources and low-interference resources (such as almost blank subframes). By dividing the measurement process into parts conducted on different resource types, the system can achieve both continuous measurement capability and high precision measurements free from inter-cell interference.
Solution Approach 2:
The patent introduces low-interference radio resources as an intermediary medium for measurement purposes. These resources act as a mediator between the UE and the network, providing a clean measurement channel that is free from the harmful inter-cell interference present in normal radio resources.
2Reliability
If UE performs handover to improve service quality, then mobility is enhanced, but handover may fail or QoS deteriorates due to interference during the handover process
Solution Approach 1:
The patent applies preliminary action by configuring low-interference radio resources in advance before the handover event. The source cell and target cell prepare these special resources ahead of time, allowing the UE to perform critical measurement and handover signaling without interference during the actual handover execution, thereby ensuring handover reliability.
Solution Approach 2:
During the handover process, the patent uses low-interference radio resources as an intermediary communication channel. This mediator resource allows the UE to exchange handover-related messages with the network without the interference that would normally disrupt the handover, thus improving handover reliability and preventing QoS deterioration.
3Measurement precision
If source cell uses low-interference radio resources for measurement, then measurement precision is improved, but the source cell loses service coverage in those time slots
Solution Approach 1:
The patent segments the time domain into different slots: normal service time slots and low-interference resource time slots. By segmenting time rather than permanently sacrificing resources, the source cell can provide high-precision measurements during specific intervals while maintaining full service coverage during other intervals, thus balancing measurement precision with productivity.
Solution Approach 2:
The low-interference radio resources are configured periodically rather than continuously. The source cell alternates between providing normal service and providing low-interference measurement opportunities. This periodic action allows the system to maintain service coverage during most time while periodically offering high-precision measurement capabilities.
4Measurement precision
If UE performs restrictive measurement using low-interference radio resources, then measurement precision is improved, but device complexity increases due to additional configuration requirements
Solution Approach 1:
The patent makes the low-interference radio resources serve multiple functions: they are used for measurement purposes, for handover signaling, and for maintaining service continuity. By making these resources multi-functional, the system reduces the need for separate dedicated measurement channels, thereby reducing the overall configuration complexity despite the added measurement precision capabilities.
Data Source
AI summary
Provided is a method for a user equipment performing a handover in a wireless communication system. The method comprises a step of receiving from a source cell a handover command message, which indicates the handover to a target cell, and a step of performing the handover to the target cell, wherein the handover command message includes information on a low-interference wireless resource to be used by the user equipment inside the target cell. The low-interference wireless resource can be a wireless resource which is operated by the source cell in order to mitigate inter-cell interference, when the source cell is an interfering cell and the target cell is an interfered cell.