Mobile Device Uplink Synchronization Handling
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Solution Overview
Problem
In LTE wireless communication systems, when a time alignment timer expires, mobile devices are not synchronized with the base station on uplink timing, leading to signal collisions and communication disruptions, as existing methods fail to efficiently handle this synchronization loss.
Innovation Solution
A method and mobile device implementation that starts a time alignment timer upon receiving a time alignment message from the base station, and upon expiration, performs a random access procedure for uplink synchronization when specific events occur, such as receiving downlink grant information or having data to transmit, thereby ignoring irrelevant control messages and ensuring timely re-synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the mobile device continues to process control messages after time alignment timer expires, then the device may receive outdated or invalid scheduling commands, but processing these messages consumes unnecessary power and processing resources
Solution Approach 1:
The mobile device performs preliminary detection of the time alignment timer status before processing control messages. When the timer is expired or invalid, the device proactively determines not to process subsequent control messages, avoiding wasted power consumption on invalid commands while maintaining synchronization reliability through early detection and response.
2Reliability
If the mobile device performs random access procedure immediately when time alignment timer expires, then uplink synchronization is restored quickly, but this increases uplink transmission latency for regular data communication
Solution Approach 1:
Instead of performing a full random access procedure immediately when the time alignment timer expires, the mobile device applies partial action by selectively ignoring only the necessary control messages (such as uplink grants) during the unsynchronized period. This allows the device to maintain downlink reception and prepare for synchronization recovery without incurring the full latency penalty of immediate random access, thus balancing synchronization reliability with communication efficiency.
3Use of energy by moving object
If the mobile device ignores all control messages after time alignment timer expires, then power consumption is reduced and invalid commands are avoided, but the device may miss important downlink information and scheduling updates
Solution Approach 1:
The mobile device applies local quality by selectively processing different types of control messages based on their importance and the device's current state. Specifically, the device ignores uplink grant messages that would cause invalid transmissions but continues to monitor and process downlink data and other critical information. This differentiated approach reduces power consumption by avoiding processing of harmful messages while preserving important downlink information, thus resolving the contradiction between energy efficiency and information retention.
Data Source
AI summary
A method utilized in a mobile device includes: starting a time alignment timer when receiving a time alignment message transmitted by a base station, wherein the time alignment timer is used for determining whether the mobile device is synchronized with the base station on uplink timing, and the time alignment message is utilized to update timing advance for the mobile device; and ignoring at least a first control message sent from the base station after the time alignment timer expires.