Training@Siemens

Industrial Training@SIEMENS


SUMMER TRAINING REPORTON

“SYNCHRONOUS DIGITAL HIERARCHY”

Submitted byRAHUL CHAUHAN Ambedkar Institute Of AdvancedComm. Technologies And ResearchDelhi


Contents1) Company Profile

Introduction History

2) Plesiochronous Digital Hierarchy (PDH) Introduction Multiplexing Hierarchy Limitations

3) Synchronous Digital Hierarchy Introduction SDH advantages over PDH Multiplexing Levels Network Elements Multiplexing frame

16) Summary17) References


Company ProfileLOGO

HISTORY

Siemens Ltd. is a Indian subsidiary of Siemens AG based in Germany; Siemens AG is Europe's largest engineering conglomerate. Siemens International headquarters are located in Berlin, Munich and Erlangen, Germany. The company has three main business sectors: Energy, Industry, and Healthcare; with a total of 16 divisions.

Worldwide Siemens and its subsidiaries employ approximately 420,800 people in nearly 190 countries and reported global revenue of 76.651 Billion Euros as of 2009. Siemens AG is listed on the Frankfurt Stock Exchange, and has been listed on the New York Stock Exchange since March 12, 2001.

Siemens was founded by Werner von Siemens on 12 October 1847. Based on the telegraph, his invention used a needle to point to the sequence of letters, instead of using Morse code. The company, then called Telegraphen-Bauanstalt von Siemens & Halske,opened its first workshop on October 12.

In 1848, the company built the first long-distance telegraph line in Europe; 500 km from Berlin to Frankfurt am Main. In 1850 the founder's younger brother, Carl Wilhelm Siemens started to represent the company in London.


In the 1850s, the company was involved in building long distance telegraph networks in Russia. In 1855, a company branch headed by another brother, Carl Heinrich von Siemens, opened in St Petersburg, Russia. In 1867,

Siemens completed the monumental Indo-European (Calcutta to London) telegraph line.

In 1881, a Siemens AC Alternator driven by a watermill was used to power the world's first electric street lighting in the town of Godalming, United Kingdom. The company continued to grow and diversified into electric trains and light bulbs. In 1890, the founder retired and left the company to his brother Carl and sons Arnold and Wilhelm. Siemens & Halske(S&H) was incorporated in 1897. In 1907 Siemens had 34,324 employees and was the

seventh-largest company in the German empire by number of employees.

In 1919, S&H and two other companies jointly formed the Osram Light Bulb Company. A Japanese subsidiary was established in 1923.

During the 1920s and 1930s, S&H started to manufacture radios, television sets, and electron microscopes.

In the 1930s Siemens constructed the Ardnacrusha Hydro Power station on the River Shannon in the then Irish Free State, and it was a world first for its design. The company is remembered for its desire to raise the wages of its under-paid workers only to be overruled by the Cumann na nGaedhael government.

In the 1982s and from their new base in Bavaria, S&H started to manufacture computers, semiconductor devices, washing machines, and pacemakers. Siemens AG was incorporated in 1966. The company's first digital telephone exchange was produced in 1980. In 1988 Siemens and GEC acquired the UK defense and technology company Plessey. Plessey's holdings were split, and Siemens took over the avionics, radar and traffic control businesses — as Siemens Plessey.

In 1991, Siemens acquired Nixdorf Computer AG and renamed it Siemens Nixdorf Informationssysteme AG.

In October 1991, Siemens acquired the Industrial Systems Division of Texas Instruments,Inc, based in Johnson City, Tennessee. This division was


organized as Siemens Industrial Automation, Inc., and was later absorbed by Siemens Energy and Automation,Inc.

In 1997 Siemens introduced the first GSM cellular phone with color display. Also in 1997 Siemens agreed to sell the defense arm of Siemens Plessey to British Aerospace (BAe) and a UK government agency, the Defense Analytical Services Agency (DASA). BAe and DASA acquired the British and German divisions of the operation respectively.

In 1999, Siemens' semiconductor operations were spun off into a new company known as Infineon Technologies. Also, Siemens Nixdorf Informationssysteme AG formed part of Fujitsu Siemens Computers AG in that year. The retail banking technology group became Wincor Nixdorf.

In February 2003, Siemens reopened its office in Kabul.In 2005 Siemens sold the Siemens mobile manufacturing business to BenQ, forming the BenQ-Siemens division.

In 2006, Siemens announced the purchase of Bayer Diagnostics, which was incorporated into the Medical Solutions Diagnostics division on 1 January 2007.

In March 2007 a Siemens board member was temporarily arrested and accused of illegally financing a business-friendly labour association which competes against the union IG Metall. He has been released on bail. Offices of the labour union and of Siemens have been searched. Siemens denies any wrongdoing.

In April 2007, the Fixed Networks, Mobile Networks and Carrier Services divisions of Siemens merged with Nokia’s Network Business Group in a 50/50 joint venture, creating a fixed and mobile network company called Nokia Siemens Networks. Nokia delayed the merger due to bribery investigations against Siemens.

In July 2008, Siemens AG announced a joint venture of the Enterprise Communications business with the Gores Group. The Gores Group holding a majority interest of 51% stake, with Siemens AG holding a minority interest of 49%.


In April 2009, Fujitsu Siemens Computers became Fujitsu Technology Solutions as a result of Fujitsu buying out Siemens' share of the company.

Organization structure

The company is divided into 3 sectors and a total of 16 divisions.

Industry Sector Drive Technology Industry Automation Building Technologies Industry Solutions Water Technologies Metal Technology Division Mobility OSRAM Market Specific Solutions Financial Solutions IT Solutions and Services (This division is scheduled to no

longer be a part of

Siemens AG starting July 1, 2010. It is rumored that it will be purchased by a number of different organizations including Infosys and the BBC.)

Communication Networks Energy Sector Fossil Power Generation Renewable Energy Oil & Gas Service Rotating Equipment Power Transmission Power Distribution Financial Solutions IT Solutions and Services

Healthcare Sector


Diagnostic Imaging and Therapy Laboratory Diagnostics Infrastructure Solutions Hearing Instruments Financial Solutions IT Solutions and Services

Key business areas and subsidiary

Siemens' five operational business areas

Automation & Control (Automation & Drives, Industrial Solutions & Services,Siemens Building Technologies)

Power, *Transportation Rail (see Siemens Transportation Systems) Automotive

Medical (Siemens Medical Solutions) Information & Communication (Siemens Communications, Siemens

IT Solution and Services) Lighting (OSRAM GmbH, OSRAM Sylvania).

The company is also active in Financing (Siemens Financial Services), Real Estate (Siemens Real Estate), Home Appliances (BSH), Water Technologies (SWT) and Business Services.

Energy

Power Generation

Renewable

Power Transmission

Transformers HVDC

Consumer products


Hearing Instruments Home Appliances Lighting (OSRAM)

Plesiochronous Digital Hierarchy


IntroductionTo get the higher bit rates the technique to mux together TDM signals (tributaries) is known as Plesiochronous Digital Hierarchy (PDH).

Transport tributary with its own clock across a higher speed network with a different clock(without spoiling remote clock recovery).

For Clocked Data stream following terms are used:

1). Synchronous (synchronized)All of the clocks are synchronized to a master clock. They may be out of phase with each other but they will run at exactly the same frequency.

2). Plesiochronous (almost synchronized) All of the clocks run at the same frequency to a defined precision. These clocks are not synchronized to each other so the data streams will run at slightly different rates.

3). Isochronous (synchronized) An isochronous data stream had the timing information embedded in it. These data stream can be carried over Synchronous or plesiochronous networks.

4). Asynchronous (not synchronized )The clocks are not synchronized. The transmitter and the receiver have independent clocks that have no relationship with each other.

In a PDH network you have different levels of Multiplexers.

1). 2Mbit/s to 8Mbits/s2). 8Mbit/s to 34Mbit/s


3). 34Mbit/s to 140Mbit/s

So to carry a 2Mbit/s data stream across the 140Mbit/s trunk requires it to be multiplexed up through the higher order multiplexers into the 140Mbit/s trunk and then to be multiplexed down through the lower order multiplexers.

Because Plesiochronous is not quite Synchronous each of the multiplexer need a little bit of overhead on their high speed trunks to cater for the slight differences in data rates of the streams on the low speed ports.

PDH Multiplexing Hierarchy

Figure shows the PDH hierarchy. It is different for US and Japan The common base for the multiplex levels of plesiochronous bearers is represented by the 64 Kbit/s channel. Starting from this common base, the hierarchical levels are divided into different branches.

One branch describes the multiplex levels of plesiochronous bearers in the

Japanese standard, one further branch shows the multiplex levels of the American standard and a third one describes the conditions of the European standard. Within the European standard the multiplex level 1 is made up of bearers with a data rate of 2.048 Mbit/s. This rate is formed by the PCM-30 frame.


Figure: PDH multiplexing hierarchy for European(E) for Japan(J)

The Japanese and American standards possess a data rate of 1.544 Mbit/s. In this case, 24 channels of 64 kbit/s each are multiplexed together. Multiplex level 2 is achieved by multiplexing 4 bearers of level 1. For the Japanese and American standards, this represents a multiplexed data rate of 6.321 Mbit/s. The European standard has a combined data rate of 8.448 Mbit/s for multiplex level 2. In the

European multiplex structure 4 bearers each of the corresponding hierarchical level are multiplexed together to obtain the bearer for the next higher multiplex level.The other thing to notice is that the different multiplexing levels are not multiplies of each other.


For example CEPT2 supports 120 calls but it requires more than 4 times the bandwidth of CEPT1 to acxheive this.

This is because PDH is not exactly synchronous and each multiplexing level requires extra bandwidth to perform Bit Stuffing to cater for the differences in clocks.

Drop and insert a 2Mbit/s streamTo drop & insert a 2Mbit/s stream from a 140Mbit/s trunk you need to break the 140Mbit/s trunk and insert a couple of “34Mbit/s to 140Mbit/s” multiplexers.You can then isolate the appropriate 34Mbit/s stream and multiplex the other 34Mbit/s streams back into the 140Mbit/s trunk.

Then demultiplex the 8Mbit/s stream isolate the 2Mbit/s stream that you have been looking for and multiplex the other 2Mbit/s stream up through the higher layer multiplexer into the 140Mbit/s trunk.

Limitations of PDH 1). PDH is not very flexible

As previously explained ,it is not easy to identify individual channels in a higher order bit stream.you must multiplex the high rate channel down through all multiplexing levels to find a

particular lower speed channel. This requires an expensive and complex “multiplexer mountain”.

2). Lack of Performance

It is not easy to provide good performance if you can’t monitor the performance in the first place. For PDH there is no international standard for performance monitoring and no agreed management


channels. There are some overhead bits that are used for management but they have limited bandwidth and are hard to locate in a 140 Meg stream without de-multiplexing

3). Lack of Standards

Not only PDH have two totally different multiplexing hierarchies but it is qyite weak on stANDARS. For example there are no standards for the data rates above 140Mbit/s and no standards for the line side of a “Line Transmission Terminal”.

Synchronous Digital HierarchyIntroduction


SONET(Synchronous Optical Network) or SDH(Synchronous Digital Hierarchy) as it's known in Europe, is a set of standards for interfacing Operating Telephone Company(OTC) optical networks.

They are a set of global standards for interfacing equipment from different vendors(One of the few where telephony is concerned).

SONET is the protocol for North America and Japan while SDH is the definition for Europe. The differences between SONET and SDH are slight.

SDH like PDH is based on a hierarchy of continuously repeating, fixed length frames designed to carry isochronous traffic channels. It is designed in a way that it would preserve a smooth internetworking with existing PDH networks.

SDH Advantages versus PDH

1). SDH is based on the principal of direct synchronous multiplexing.

2). Essentially, separate, slower signals can be multiplexed directly onto higher speed SDH signals without intermediate stages of multiplexing.

3). SDH is more flexible than PDH and provides advanced network management and maintenance features.

4). Can be used in the three traditional telecommunications areas: long-haul networks, local networks and loop carriers. It can also be used to carry CATV video traffic

SDH multiplexing levels


SDH Network ElementsThese are the elements required to make up the SDH network.1). Path Terminating Element These are the end point devices where the lower speed channelsenter and leave the SDH network.These are known as “PathLevel”devices.

2). Digital Cross Connect


These devices can cross X-connect at the STM level down to individual E1 stream .so an E1 stream on one STM trunk could be cross connected to another STM trunk.3).RegeneratorIt is a device that regenerates the signal.4). Add or Drop MultiplexerThe Add/Drop mux has the ability to breakout and insert low speed channels into an STM stream

SDH Multiplexing Frame

In order to facilitate the changeover from the plesiochronous to the synchronous technology, SDH technology allows the insertion of existing plesiochronous network structures into a synchronous network. To do this, the plesiochronous digital bearers are packed into predetermined SDH structures. This procedure is called mapping.The transport units for plesiochronous bearers within the SDH technology are called Container C. The SDH system define several containers for the plesiochronous bearers of the different hierarchical levels. If these containers are completed with additional information, Virtual Containers (VC) are created.

Bit Rates International organization defined standardized bit rates


Figure: Bit rates of STM frame

Training@Siemens

Documents

industrial training siemens

synchronous digital hierarchy

plesiochronous digital hierarchy

siemens ag

data rate

siemens plessey

data rates

sdh network