Cell Handover Method for SVLTE Terminal Interference Reduction
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Solution Overview
Problem
In SVLTE terminals supporting both CDMA2000 and LTE networks, mutual interference between radio frequency circuits leads to network disconnection, call drops, and reduced communication quality due to limited antenna isolation and intermodulation interference.
Innovation Solution
A cell handover method that acquires and prioritizes candidate cells based on signal interference strength, determining optimal frequency bands and transmit powers to minimize intermodulation interference, allowing the terminal to perform a handover to a target cell with minimal interference, thereby reducing signal interference and enhancing communication quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the physical distance between LTE antenna and CDMA antenna is increased to decrease coupling, then antenna isolation is improved, but device complexity and layout difficulty increase
Solution Approach 1:
The patent changes the frequency parameter of LTE signals dynamically during CDMA handover processes. By adjusting LTE transmit power and frequency selection based on handover status, the system reduces intermodulation interference without requiring increased physical distance between antennas, thus avoiding layout complexity while improving signal isolation.
Solution Approach 2:
The patent implements preliminary actions by notifying the network side of upcoming handover operations before they occur. This allows the network to pre-coordinate frequency and power adjustments, preventing interference proactively rather than reactively, thereby resolving the contradiction between maintaining signal quality and simplifying device layout.
2Object-affected harmful factors
If transmit power is backed off to reduce interference to CDMA received signal, then signal interference is reduced, but communication reliability deteriorates due to increased call drop probability
Solution Approach 1:
The patent implements dynamic transmit power adjustment for LTE signals based on real-time handover status. During CDMA handover periods, LTE power is temporarily reduced to minimize interference, while maintaining normal power levels during non-handover periods. This dynamic approach ensures communication reliability is maintained overall while reducing interference during critical handover moments.
Solution Approach 2:
The patent applies periodic power adjustment synchronized with the periodic nature of handover operations. By coordinating LTE transmit power changes with the periodic handover cycles of CDMA, the system reduces interference during specific critical periods without continuously reducing power, thereby maintaining call reliability while addressing interference issues.
3Object-affected harmful factors
If additional power backoff is performed autonomously at terminal, then signal interference is reduced, but call drop probability increases and user experience deteriorates
Solution Approach 1:
The patent establishes a feedback mechanism where the terminal reports handover status and interference conditions to the network side, which then coordinates appropriate power adjustments. This closed-loop feedback system ensures that power backoff is performed only when necessary and coordinated with network conditions, preventing autonomous over-adjustment that would cause call drops while still reducing interference effectively.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively prevents or reduces signal interference during cell handover, ensuring improved communication quality and user experience without increasing network overheads or hardware complexity.
Implementation Method 1
an intermodulation signal generated between a signal in the first transmit frequency band of the LTE network and a signal in the second transmit frequency band of the CDMA network interferes with the received signal of the CDMA network
Data Source
AI summary
A cell handover method and a terminal, where the method includes acquiring information about at least one candidate cell, performing priority sorting on the at least one candidate cell according to strength of interference to a received signal of a code division multiple access (CDMA) network of each candidate cell in the at least one candidate cell, sending a sorting result to a base station, receiving an indication message sent by the base station, where the indication message includes at least information about a target cell, performing a handover to the target cell according to the indication message, and hence interference to a received signal may be effectively prevented or reduced after a cell handover, communication quality and user experience are ensured, and additional network overheads and hardware design costs and complexity thereof are not increased.