Terms and Abbreviations for 1588v2, SMPTE-2059-2, and G.8275.1

Synchronization

On a modern communications network, in most cases, the proper functioning of telecommunications services requires network clock synchronization, meaning that the frequency offset or time difference between devices must be kept in an acceptable range. Network clock synchronization includes time synchronization and frequency synchronization.

• Time synchronization

  Time synchronization, also called phase synchronization, refers to the consistency of both frequencies and phases between signals. This means that the phase offset between signals is always 0.

• Frequency synchronization

  Frequency synchronization, also called clock synchronization, refers to a strict relationship between signals based on a constant frequency offset or a constant phase offset, in which signals are sent or received at the same average rate in a valid instance. In this manner, all devices on the communications network operate at the same rate. That is, the phase difference between signals remains a fixed value.

IEEE 1588v2

PTP

1588v2, defined by the Institute of Electrical and Electronics Engineers (IEEE), is a standard for Precision Clock Synchronization Protocol for Networked Measurement and Control Systems. The Precision Time Protocol (PTP) is used for short.

Clock domain

Logically, a physical network can be divided into multiple clock domains. Each clock domain has a reference time, with which all devices in the domain are synchronized. Different clock domains have their own reference time, which is independent of each other.

Clock node

Each node on a time synchronization network is a clock. The 1588v2 protocol defines three types of clocks: OC, BC, and TC.

Clock reference source

Clock source selection is a method to select reference clocks based on the clock selection algorithm.

One-step mode

In one-step mode, Sync messages in Delay mode and PDelay_Resp messages in PDelay mode are stamped with the time when messages are sent.

Two-step mode

In two-step mode, Sync messages in Delay mode and PDelay_Resp messages in PDelay mode only record the time when messages are sent and carry no timestamps. The timestamps are carried in the messages, such as Follow_Up and PDelay_Resp_Follow_Up messages.

1588v2

Precision Time Protocol

IP RAN

Internet Protocol Radio Access Network

GSM

Global System for Mobile communications

WCDMA

Wideband Code Division Multiple Access

TD-SCDMA

Time Division-Synchronous Code Division Multiple Access

WiMax FDD

Worldwide Interoperability for Microwave Access Frequency Division Duplex

WiMax TDD

Worldwide Interoperability for Microwave Access Time Division Duplex

NTP

Network Time Protocol

GPS

Global Position System

LTE

Long Term Evolution

BC

Boundary Clock

OC

Ordinary Clock

TC

Transparent Clock

BMC

Best Master Clock

BITS

Building Integrated Time Supply System