08-16-2017, 09:27 PM
[attachment=7400]
Prepared by:Anuj Prabhakar Lakra
SYNCHRONOUS DIGITAL HIERARCHY (SDH)
ITI PROFILE
ITI UNITS IN INDIA
ITI LTD. NAINI
T.E.D. (Transmission Equipment Division)
T.I.D. (Telephone Instrument Division)
R & D (Research & Development)
Administrative Control Division
COMMUNICATION SYSTEM
Transmitter
Transmission channel
Receiver
PDH (Plesiochronous Digital Hierarchy)
Technology used to transfer large amounts of data over fibre optic or microwave band radio's.
Implementation of networks with transmission capacities of up to 140 Mbit/s.
The basic transfer rate of the data is 2048 kilobits per second.
LIMITATIONS IN PDH
There s no standardised definition of PDH bit rates greater than 140 Mbit/s.
Back to Back multiplexing
Inter Operas Ability of System Between Different Vendors
No optical interfaces world standard and without an optical level, networking is not possible
WHY SDH?
High Transmission Rates
Simplified Add & Drop Function
High Availability and Capacity Matching
Reliability
Future Proof Platform for New Services
Advantages of SDH
optical interfaces
world standard digital format
cost effective and easy traffic cross connection capacity and add and drop facility
reduced networking cost due to the transversal compatibility
Network resources are synchronised to a master clock.
STM-1 bit rate
The frame having a duration of 125 microseconds corresponds
to a matrix of 9 Rows by 270 x N columns whose elements are
bytes.
Data are sent line after line, from left to right and top to bottom.
To support 8 KHz sampled voice applications
Bytes organized into rows and columns Administrative channels
are rate decoupled for easier processing
STM-1 frame is organized into 270 (3 x 90) columns by 9 rows
Frame size is 2430 bytes
9 x 270 bytes/frame x 8 bits/byte x 8000 frame/s = 155.52 Mbit/s
STM-N
STM-N structure
Byte-interleaving STM-1 modules
No extra overhead introduced
Overhead of multiplexed signals taken over, but section overhead
(SOH) should be replaced with new information for the STS-N
multiplex section
Overhead is growing in absolute number of bits, but relative size
is the same
New overhead is bigger than necessary for regenerator and
multiplex section overheads, so some bytes are unused
Section overhead (SOH) is frame aligned
SPE (multiplexed VC-3 or VC-4 channels) is not frame
aligned
Three levels of Network Protection
Protection in Ring Network
Protection in Meshed Network
Shared Protection
SDH in future
The modern lifestyle requires high speed communication applications.
SDH provides large bandwidth that can meet the needs of this applications.
SDH networks have flexible routing ability for circuit protection thus allowing rapid circuit reallocation and high circuit availability.