Uplink Synchronization Using Timing Advance Inheritance
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Solution Overview
Problem
In LTE systems, the existing uplink synchronization methods for user equipment (UE) are inefficient, leading to significant delays and wastage of network resources, particularly during carrier aggregation, hetero-frequency switchover, and synchronization loss scenarios, where the UE needs to repeatedly perform RACH access processes across multiple carriers.
Innovation Solution
The proposed method allows the UE to obtain timing advance (TA) for one frequency point and apply it to other frequency points, eliminating the need for repeated RACH access processes, thereby reducing network resource occupation and shortening delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE performs RACH access process on each uplink member carrier to obtain initialized uplink synchronization, then the uplink synchronization is achieved on each carrier, but the delay increases significantly and network resources are wasted
Solution Approach 1:
The patent segments the uplink synchronization process by identifying a primary uplink member carrier for RACH access and separating it from secondary carriers. The UE performs RACH access only on the primary carrier to obtain TA, while secondary carriers inherit synchronization through the base station's internal timing alignment mechanism, eliminating the need for repeated RACH processes on each carrier.
Solution Approach 2:
The base station performs universal timing alignment across all uplink member carriers using a single TA value obtained from the primary carrier. The base station's receiver is configured to align timing for multiple carriers simultaneously, making the synchronization mechanism universal rather than carrier-specific, thereby reducing overall access delay.
2Reliability
If the UE repeatedly sends RACH preamble n times to obtain n TAs, then the uplink synchronization is maintained, but the processing delay increases to at least 8n ms and network resources are occupied
Solution Approach 1:
The patent extracts the essential synchronization function from the repeated RACH process. Instead of requiring n separate RACH accesses for n carriers, the system extracts a single TA value from the primary carrier and reuses it for timing alignment on all secondary carriers through base station configuration, eliminating redundant access procedures.
Solution Approach 2:
The base station performs preliminary timing alignment configuration for secondary carriers based on the primary carrier's TA value before the UE needs to transmit on those carriers. This preliminary setup ensures that when the UE activates secondary carriers, synchronization is already established, avoiding last-minute RACH delays.
3Reliability
If the base station maintains multiple TAs for N uplink member carriers and sends them to the UE, then the uplink synchronization is maintained on all carriers, but network resources are wasted
Solution Approach 1:
The patent merges the timing alignment function across multiple carriers by using a single TA value from the primary carrier for all uplink member carriers. The base station combines the synchronization state of multiple carriers into one unified TA management approach, eliminating the need to maintain and transmit separate TA values for each carrier.
Solution Approach 2:
A single TA value obtained from the primary carrier serves multiple functions: it provides timing alignment for the primary carrier itself and simultaneously serves as the basis for timing alignment on all secondary carriers. This universal application of one TA value maximizes resource efficiency while maintaining synchronization across the entire carrier aggregation.
Data Source
AI summary
Embodiments of the present invention relates to an uplink synchronization method and apparatus, where the method includes: obtaining a timing advance of a second frequency point according to a timing advance of a first frequency point; and sending data at an uplink sending time corresponding to the timing advance of the second frequency point. According to embodiments of the present invention, the TA of the second frequency point can be obtained according to the TA of the first frequency point, and a RACH access process does not need to be performed at the second frequency point, which effectively reduces the network resources occupied by the RACH process, and shortens the produced delay, thereby improving the performance of the entire system.