Synchronization in (telecom) networks is the process of aligning the time scales of transmission and switching equipment, so equipment operations occur at the correct time and in the correct order. Synchronization requires the receiver clock to acquire and track the periodic timing information in a transmitted signal.

The transmitted signal consists of data that is clocked out at a rate determined by the transmitter clock. Signal transitions between zero and peak values contain the clocking information and detecting these transitions allows the clock to be recovered at the receiver. The recovered clock is used to write the received data into a buffer, also called elastic store or circular shift register, to reduce jitter. The data is then read out of the buffer onto a digital bus for further multiplexing or switching.

Synchronization at AimValley

Synchronization is a fundamental technology building block with AimValley for many years already. Practically every service provider network requires it, not because networks require the synchronization but mainly to provide, at the edge of the network, a frequency or phase/Time of Day synchronization singal to end-customers.

The performance of the traditional wired T1/E1, SONET and SDH networks are based upon constrained clock control theory and PLL design and deliver a frequency synchronization to the edge of the network. Also Circuit Emulated Services (CES) require frequency synchronization at the edge of the network to recover the emulated service via Differential Clock Recovery (DCR) methods.

In today’s networks end-equipment, like 4G and 5G base stations, require Time of Day (ToD) synchronization which allows to synchronize all base stations to a common wall-clock. Also standards like Audio Video Bridging (AVB) and Time Sensitive Networking (TSN) require ToD synchronization at the edge of the network to overcome Packet Delay Variation (PDV) and recover signals based on a provisioned ‘presentation time’.

The synchronization signal is disciplined by electronic circuits to provide the frequency accuracy, stability, phase movement control, wander filtering and edge jitter (phase noise) levels specified in volumes of various Standards documents. Each ‘end customer service’ has a specific set of performance requirements detailed in these documents. This performance is defined by the various international standards bodies and is well understood.

Presented at Conferences
ITSF 2014, ITSF 2015, WSTS 2015

Topics presented
IEEE1588 BC versus TC
PRTC Architectural Options in a Telecom Network

AimValley Synchronization Expertise

AimValley provides a wide range of expertise regarding synchronization. From helping you to interpret and understand the various Standards to architectural support.

SONET/SDH/CES/CEP transmission technologies

Legacy Technologies
* Timing architecture of various systems
* Core ASICs used in various systems

Current Technologies
* SEC/Stratum-3 built into AimValley ASICs (Maximux, Matterhorn)
* IP blocks with Circuit Emulation Services (FPGA)
* Smart SFPs with CES (E1, DS1, 155Mb/s, 622Mb/s, 2488Mb/s

Ethernet Switches

Architecture and implementation of products
* EEC-1/EEC-2 clocks
* SyncE
* Calculation of PLL bandwidth for synchronization function

Audio Video Bridging & Time Sensitive Networking

Standard 802.1AS
Standard 02.1Qat
Standard 802.1Qav