Uplink Time Alignment Using Dual TA Timers in Multi-TRP
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Solution Overview
Problem
In multi-TRP operations, existing mechanisms for maintaining uplink time alignment result in premature termination of uplink transmissions when a TA timer expires, leading to reduced uplink coverage and network throughput.
Innovation Solution
The method involves maintaining uplink time alignment based on one or two TA timers associated with a serving cell, allowing continued UL transmission when at least one TRP is aligned, enhancing coverage and network performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the existing TA timer mechanism is used in multi-TRP operations, then the uplink time alignment is maintained per TAG, but the uplink transmission is prematurely terminated when one TA timer expires even if another TRP is still aligned
Solution Approach 1:
The patent segments the uplink time alignment maintenance by introducing separate TA timers for each TRP (first TA timer for first TRP, second TA timer for second TRP) instead of using a single TA timer per TAG. This allows independent tracking of time alignment status for each TRP, enabling continued uplink transmission through one TRP even when the other TRP's alignment expires.
2Ease of operation
If the existing mechanism stops all uplink transmissions when one TA timer expires, then the time alignment control is simplified, but the uplink coverage and network throughput are reduced
Solution Approach 1:
The patent implements dynamic uplink transmission control by evaluating the status of multiple TA timers independently. Instead of a static all-or-nothing approach, the system dynamically determines which TRPs can continue uplink transmission based on their individual TA timer statuses, thereby expanding uplink coverage while maintaining appropriate time alignment control.
3Device complexity
If the existing mechanism releases uplink configurations when one TA timer expires, then the time alignment management is simplified, but the network throughput is reduced
Solution Approach 1:
The patent segments the uplink configuration management by associating different uplink configurations with different TRPs and their respective TA timers. When one TA timer expires, only the uplink configuration associated with that specific TRP is released, while configurations for other TRPs with valid TA timers are preserved, thereby maintaining network throughput.
Data Source
AI summary
An apparatus, configured in a terminal equipment, includes: processor circuitry configured to: maintain uplink time alignment of a serving cell based on one or two timing advance (TA) timers, one TA timer in the one or two TA timers being associated with a timing advance group (TAG), and the serving cell being associated with two TA timers; and start or restart a TA timer in the two TA timers when the signal is received, the TA timer corresponding to a TAG which corresponds to the TAG ID of the one or more TAGS; and a receiver configured to receive a signal including a timing advance command (TAC) of the serving cell and TAG ID of one or more TAGS, the signal being a random access response (RAR) message or a message B (MSGB).