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Telecommunication Systems Spring 2010

Telecommunication Systems Spring 2010. ynchronous igital ierarchy. S. D. H. SDH. What is it ?? Synchronous Digital Hierarchy is the international standard for transmitting digital information over optical networks. SDH. The Concept !

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Telecommunication Systems Spring 2010

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  1. Telecommunication Systems Spring 2010

  2. ynchronous igital ierarchy S D H

  3. SDH What is it ?? Synchronous Digital Hierarchy is the international standard for transmitting digital information over optical networks

  4. SDH • The Concept ! • Signals with a higher transmission rate are obtained by multiplexing several low rate signal • Every signal in the hierarchy levels has a specific frame structure • All multiplex levels are positive integer multiples of the base signal

  5. SDH • Synchronous Signals !! • Data signals which have same nominal transmission rates, but come from different sources, controlled by a central clock frequency are clock aligned to each other

  6. SDH • Plesiochronous Signals !! • Data signals which have same nominal transmission rates, but come from different sources, have slightly higher or lower value than the nominal bit rate • There is a small amount of variation between them, such signals are almost synchronous to each other and therefore termed as Plesiochronous

  7. SDH • Plesiochronous Network • The individual link sections are not synchronous to each other • Synchronous Network • In synchronous network, the link sections are synchronous to each other

  8. SDH • PDH multiplex hierarchies !

  9. SDH • PDH multiplex hierarchies !

  10. STM-N Nx155.52Mbps STM-16 2.05 Gbps STM-4 622.08 Mbps SDH • What is STM-1?? • ITU-T defined the STM-1 (Synchronous transport module -1), 155.52 Mbps as base signal for SDH • All multiplex levels are positive integer multiples of this base signal (STM-1)

  11. SDH • Structure of an STM-1 frame !! • The two dimensional representation of an STM-1 frame includes 9 rows with 270 bytes each • The sequence of transmission is top left to bottom right

  12. SDH • Structure of an STM-1 frame !!

  13. SDH • Transmission rate of STM-1 ??

  14. SDH • Structure of an STM-1 frame !! • STM-1 frame has three types of blocks • Section Overhead • PTR (pointer) • Payload

  15. SDH • Multiplexing technique ! • Byte Interleaving (byte-by-byte multiplexing)

  16. SDH • Structure of an STM-1 frame !! • Every STM frame is transmitted 8000 times per second • Every byte in an STM-1 frame has a transmission capacity of 64 kbps

  17. SDH • Multiplexing technique !

  18. SDH • Mapping of ATM cells ! • Prior to their transmission, ATM cells are interleaved into the container C-4 (Mapping)

  19. SDH • Mapping of ATM cells ! • A C-4 is provided every 125 micro seconds • An ATM cell can be transmitted via two C-4

  20. SDH • Mapping of ATM cells ! • In order to transmit container C-4 in the STM-1, container specific supplementing is necessary • The C-4 receives a path over head with a size of 9 bytes

  21. SDH • Mapping of ATM cells ! • The block resulting from C-4 and POH is called virtual container VC-4

  22. SDH • MAPPING OF ATM CELLS ! • THERE IS A FLOATING EMBEDDING OF VC-4 INTO THE STM-1 FRAME PAYLOAD • PART OF THE VC-4 MAY BE TRANSMITTED IN ONE STM FRAME AND ANOTHER PART IN THE NEXT STM FRAME

  23. SDH • Mapping of ATM cells ! • The pointer indicates start of the Virtual container 4 in the payload

  24. SDH • Mapping of ATM cells ! • Component of the STM-1, inside which a VC-4 is able to float and which consists of the block PTR and payload is known as Administrative unit 4 (AU-4)

  25. SDH • Mapping of ATM cells ! • In the AU-4, pointer is abbreviated AU-4 PTR

  26. SDH • Mapping of ATM cells ! • To complete the STM-1 frame section overhead is added to AU-4

  27. SDH • Mapping of ATM cells ! • Individual steps of creating an STM-1

  28. SDH • Mapping of ATM cells ! • In SDH, containers with a fixed capacity are provided every 125 micro second • Incorporation of ATM cells into STM

  29. SDH • SDH Products !!

  30. Thank You

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