4G Connected Mode PLMN Scan via DRX Interval Adjustment
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Solution Overview
Problem
In wireless communication networks, user devices struggle to perform home or higher priority PLMN scans when connected to a roaming network, especially in 4G systems, due to the discontinuous reception (DRX) mode that keeps them in a connected state, making it difficult to complete periodic scans efficiently.
Innovation Solution
A user device operating in a 4G communications system identifies its DRX wakeup interval and performs a preferred network scan if it exceeds a threshold, or requests a longer interval from the server if it does not, allowing scans to be conducted during DRX wakeup intervals while remaining in a connected state, or transitions to idle state if the request is not fulfilled.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a user device remains in connected state in 4G system to shorten connection times, then connection establishment speed is improved, but the ability to perform periodic PLMN scans deteriorates
Solution Approach 1:
The patent implements periodic PLMN scans during DRX wakeup intervals while maintaining connected state. The user device performs scans at predetermined intervals (e.g., every 6 minutes) by utilizing the periodic DRX mechanism, allowing it to switch between listening to serving cell and performing scans without fully transitioning to idle state.
Solution Approach 2:
The patent dynamically adjusts the DRX cycle length based on scan requirements. When a PLMN scan is needed, the system extends the DRX cycle to provide sufficient time for the scan procedure, then returns to normal DRX operation. This dynamic adjustment allows flexible accommodation of scan operations while maintaining connected state.
2Productivity
If a user device transitions to idle state to perform PLMN scan, then scan capability is improved, but connection time increases due to re-establishment overhead
Solution Approach 1:
The patent performs PLMN scans during periodic DRX wakeup intervals while maintaining connected state, rather than waiting for idle transitions. By proactively scanning during connected mode DRX cycles, the device eliminates the need for subsequent idle transitions and connection re-establishment procedures.
Solution Approach 2:
The patent makes the connected state serve dual purposes: maintaining active connection for data transmission and performing PLMN scans for network selection. The DRX mechanism enables the connected state to fulfill both functions simultaneously, eliminating the need for separate idle state transitions dedicated to scanning.
3Loss of time
If a user device performs frequent PLMN scans in connected state, then network selection timeliness is improved, but power consumption increases
Solution Approach 1:
The patent utilizes the existing periodic DRX mechanism to schedule PLMN scans, leveraging the natural sleep-wake cycles already in place for power saving. By aligning scan operations with DRX wakeup intervals, the device performs scans only when already awake and active, avoiding additional power consumption from frequent wakeups solely for scanning.
Solution Approach 2:
The patent adjusts the DRX cycle length parameter dynamically based on scan requirements. When scans are needed, the cycle is extended to accommodate scan duration; when scans are not needed, the cycle returns to normal shorter duration for power saving. This parameter adjustment optimizes the balance between scan timeliness and power consumption.
Data Source
AI summary
Methods and systems facilitating a preferred network scan in a 4G communications system are disclosed. A user device identifies a new search event when operating in connected state. The user device transitions to idle state, performs a preferred network scan, and returns to connected state.