Uplink Timing Synchronization in Mobile Communication Systems
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Solution Overview
Problem
The existing OFDM-based mobile communication systems face inefficiencies in maintaining uplink timing synchronization, leading to interference and resource wastage due to periodic transmission of preamble codes and timing difference information, which affects orthogonality and decoding success rates.
Innovation Solution
A method and apparatus for maintaining uplink timing synchronization by storing initial reference timings, periodically measuring downlink timing, and adjusting uplink timing without explicit uplink signaling, thereby reducing the need for frequent radio resource usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If periodic transmission of preamble codes and timing difference information is performed to maintain uplink timing synchronization, then timing synchronization accuracy is improved, but radio resource overhead increases
Solution Approach 1:
The UE autonomously determines uplink timing by measuring downlink timing and applying timing advance based on stored reference values, without requiring periodic network instructions. The system serves itself by using the relationship between downlink and uplink propagation delays to self-correct timing drift, eliminating the need for continuous network intervention and reducing signaling overhead.
Solution Approach 2:
The network provides initial uplink timing synchronization information during the connection establishment phase, before actual data transmission begins. This preliminary timing calibration allows the UE to maintain synchronization for an extended period without frequent re-synchronization signaling, reducing overall radio resource consumption while preserving timing accuracy.
2Reliability
If frequent uplink timing adjustment signaling is performed, then uplink timing synchronization is maintained, but system complexity increases
Solution Approach 1:
The UE independently calculates timing adjustments by measuring downlink timing and applying stored timing advance values, eliminating the need for complex network-side timing management and frequent signaling exchanges. This self-service approach simplifies the overall system architecture while maintaining reliable synchronization.
Solution Approach 2:
Instead of continuous or event-driven timing adjustment signaling, the system uses periodic timing maintenance based on pre-configured timing advance values and downlink timing measurements. This periodic self-adjustment reduces signaling frequency and system complexity while ensuring timing synchronization is maintained throughout the transmission session.
3Measurement precision
If periodic measurement and adjustment of uplink timing is performed, then timing accuracy is improved, but transmission time is consumed
Solution Approach 1:
The system performs initial timing synchronization and stores reference timing values during the connection setup phase, before actual data transmission begins. This preliminary calibration establishes a timing baseline that can be used for an extended period, reducing the frequency of subsequent timing measurements and adjustments, thereby minimizing time loss during data transmission.
Solution Approach 2:
The UE continuously uses the stored timing advance values and downlink timing measurements to maintain uplink synchronization without interrupting data transmission for frequent re-synchronization. This continuous timing maintenance approach ensures timing accuracy is preserved while minimizing the time lost to synchronization procedures during the actual data transmission phase.
Data Source
AI summary
Disclosed is a method for maintaining uplink timing synchronization by a User Equipment (UE) in a mobile communication system, without uplink transmission of a preamble from a UE or without transmission of uplink timing difference information from an Evolved Node B (E-NB) to solve the inefficient use problem of radio resources, occurring due to periodic transmission of uplink signaling and downlink signaling during maintenance of the uplink timing synchronization, and a UE apparatus for the same.