Terminal Time Alignment Timer Control in LTE Random Access
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Solution Overview
Problem
In LTE systems, the existing non-contention based random access procedure can lead to unnecessary uplink synchronization breaks and signal interference due to the potential shared use of random access preambles among multiple terminals, causing resource wastage and communication delays.
Innovation Solution
A method where a terminal selectively applies an uplink synchronization command based on whether the random access preamble was selected by the network or itself, restarting or starting a timer only if the preamble is determined to be selected by the network, thereby preventing unnecessary resource usage and interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the terminal applies the time alignment command received during non-contention based random access procedure, then uplink synchronization is maintained, but unnecessary uplink transmissions occur when preambles are shared among multiple terminals causing signal interference and resource wastage
Solution Approach 1:
The patent changes the parameter of timer operation based on the type of random access procedure. When non-contention based random access is detected, the terminal determines whether to start or restart the time alignment timer based on specific conditions (whether the random access procedure was initiated by a PDCCH order and whether the time alignment timer was already running). This conditional parameter change prevents unnecessary timer operations that would lead to unnecessary uplink transmissions and signal interference.
2Loss of time
If the terminal restarts or starts the time alignment timer upon receiving time alignment command, then uplink timing is maintained, but resource wastage occurs due to unnecessary timer operations in contention based random access
Solution Approach 1:
The patent modifies the timer operation parameters based on the random access procedure type. In contention based random access, the terminal does not start or restart the time alignment timer upon receiving a time alignment command, thereby avoiding resource wastage. In non-contention based random access, the terminal conditionally starts or restarts the timer based on whether the procedure was initiated by PDCCH order and the current timer state, optimizing resource usage while maintaining necessary timing alignment.
3Reliability
If the terminal applies time alignment command in all random access scenarios, then synchronization is ensured, but communication delays occur due to unnecessary uplink transmission restrictions
Solution Approach 1:
The patent changes the operational parameters of the time alignment timer based on the random access procedure type and specific conditions. By conditionally starting or restarting the timer only when necessary (in non-contention based random access under specific conditions), the patent avoids unnecessary uplink transmission restrictions that would cause communication delays, while still ensuring synchronization when required.
Data Source
AI summary
Disclosed is the radio (wireless) communication system providing a radio communication service and the terminal, and more particularly, a method of handling time alignment command during a random access procedure in an Evolved Universal Mobile Telecommunications System (E-UMTS) evolved from the Universal Mobile Telecommunications System (UMTS) or a Long Term Evolution (LTE) system is provided.