National Time Service Center of Chinese Academy of Sciences

Description

The National Time Service Center (NTSC) of the Chinese Academy of Sciences is China's national time service authority, responsible for generating, maintaining, and disseminating the national standard time, UTC(NTSC), which is aligned with Coordinated Universal Time (UTC). Within the context of 3GPP specifications, the NTSC is recognized as an example of a trusted external time source. Telecommunications networks require highly accurate and reliable time references for various functions, including synchronization of base stations, timestamping of network events, and supporting security protocols like secure time distribution for Lawful Interception.

In 3GPP architecture, a network's Time Distribution Function (TDF) can acquire UTC time from an external source such as the NTSC. The TDF would typically connect to the NTSC's time dissemination services, which may use methods like Network Time Protocol (NTP), Precision Time Protocol (PTP), or satellite-based signals. The acquired time is then considered trustworthy because it originates from a national metrology institute. The 3GPP specifications, such as those for LTE Positioning Protocol (LPP) in TS 36.355 and its counterparts, may reference the NTSC as an entity that provides timing assistance data or as an exemplar of a reliable time server.

The role of the NTSC in the network ecosystem is to act as a primary stratum-1 time source. Its time signal integrity and traceability to international standards are critical. For network operators, especially in China, using the NTSC as a time source ensures compliance with national regulations and provides a common time baseline. This is essential for synchronizing Time Division Duplex (TDD) systems, coordinating handovers, and ensuring that timestamps for security events and lawful interception are accurate and legally defensible. The reference to NTSC in 3GPP docs provides a concrete real-world example of how networks can interface with national time authorities to achieve secure synchronization.

Purpose & Motivation

The inclusion and recognition of the NTSC in 3GPP specifications serve to provide a standardized reference to a credible, national-level time authority. This addresses the problem of networks relying on arbitrary or unverified time sources, which could lead to synchronization errors, security vulnerabilities, and non-compliance with legal requirements for time-stamping intercepted communications. Historically, networks might use various commercial or less-traceable NTP servers, lacking the assurance of metrological traceability.

The motivation stems from the need for interoperability and regulatory compliance, particularly in regions with strict national standards. By specifying an entity like the NTSC, 3GPP provides a model for how network equipment can integrate with official time services. This is especially important for functions like positioning (where accurate time is needed for OTDOA), secure time distribution (NTP-UTC), and network operation in regulated markets. Referencing the NTSC helps equipment vendors and operators design systems that can connect to similar national time services worldwide, ensuring a consistent approach to sourcing trusted time. It solves the limitation of having no standardized reference for what constitutes a 'trusted external time source' in deployment scenarios.

Key Features

• National authority for generating and maintaining UTC(NTSC)
• Provides traceable time references aligned with international standards
• Disseminates time via multiple methods (e.g., NTP, PTP, satellite signals)
• Referenced in 3GPP as a trusted external time source for network synchronization
• Supports legal and regulatory requirements for accurate time-stamping
• Enables network synchronization for TDD operation and positioning services

Evolution Across Releases

Defining Specifications