Carrier Aggregation Timing Advance Group Configuration
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Solution Overview
Problem
In LTE systems with carrier aggregation, the lack of clear definitions for indicating the carrier on which a preamble has been transmitted and the absence of rules for determining the downlink signal to carry timing advance information lead to challenges in synchronizing uplink transmission timings across different eNB locations, causing interference and decoding failures.
Innovation Solution
A method is introduced to transmit a Random Access Response message that includes Timing Advance Group (TAG) information, allowing for accurate uplink timing adjustments by specifying the TAG to which the Timing Advance Command (TAC) is applied, thereby defining the downlink timing reference signal and configuring downlink reference cells for carrier groups with multiple uplink transmission timings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If carrier aggregation is used to expand bandwidth by aggregating multiple carriers, then system capacity and bandwidth are improved, but uplink timing synchronization deteriorates when eNB apparatuses are located at different places
Solution Approach 1:
The patent segments the uplink timing management by introducing Timing Advance Groups (TAGs) that associate different carriers with different timing advance values. This allows each carrier group to have independent timing synchronization, resolving the timing conflict caused by carrier aggregation across distributed eNB locations.
Solution Approach 2:
The patent applies local quality by allowing different timing advance configurations for different carrier groups based on their specific eNB locations. Each TAG can have its own downlink timing reference signal, enabling localized timing optimization for each carrier group while maintaining overall system bandwidth expansion.
2Measurement precision
If multiple uplink timings are used for different eNB locations, then timing accuracy for each location is improved, but system complexity increases due to need for multiple reference signals and timing rules
Solution Approach 1:
The patent creates a universal TAG structure that can be applied across multiple carriers and eNB configurations. The TAG mechanism provides a multi-functional framework that handles both single-carrier and multi-carrier scenarios, as well as distributed and centralized eNB deployments, through a unified timing management approach.
Solution Approach 2:
Instead of managing multiple timing references separately for each carrier, the patent inverts the approach by grouping carriers under common timing references (TAGs). This inversion simplifies management by allowing multiple carriers to share timing resources while still supporting location-specific timing accuracy when needed.
3Device complexity
If downlink timing reference signal configuration is not clearly defined, then system simplicity is maintained, but uplink timing adjustment reliability deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-configuring TAG structures and downlink timing reference signal associations before random access procedures begin. This pre-configuration ensures that when timing adjustments are needed, the appropriate reference signals and TAG mappings are already established, improving reliability without adding operational complexity.
Data Source
AI summary
A method of configuring downlink timings and transmitting a random access response message is provided for a random access procedure in a Long Term Evolution (LTE) system supporting carrier aggregation. The method for adjusting timing of a terminal in a wireless communication system supporting carrier aggregation of at least one carrier includes transmitting a Random Access Preamble to a base station, and receiving a Random Access Response with a Timing Advance Command (TAC) for commanding uplink timing adjustment from the base station, wherein the Random Access Response comprises information indicating a Timing Advance Group (TAG) to which the TAC is applied.