Sdh vs pdh - BSNL Durg SSA(Connecting India)
Download
Report
Transcript Sdh vs pdh - BSNL Durg SSA(Connecting India)
Technologies used in
telecommunication networks
PDH
:-PLESIOCHRONOUS DIGITAL
HIERARCHY.
A TECHNOLOGY USED IN
TELECOMMUNICATIONS NETWORK
TO TRANSPORT LARGE QUANTITY
OF DATA OVER DIGITAL
TRANSPORT EQUIPMENT SUCH AS
FIBRE OPTIC AND MICROWAVE
RADIO WAVE SYSTEMS.
THE
TERM “PLESIOCHRONOUS” IS
DERIVED FROM Greek plesio which
means near, and chronous, time.
IT MEANS THAT PDH NETWORKS RUN
IN A STATE WHERE DIFFERENT PARTS
OF THE NETWORK ARE ALMOST, BUT
NOT QUITE PERFECTLY
SYNCHRONISED.
SENDING
A LARGE QUANTITY OF DATA
ON FIBRE OPTIC TRANSMISSION
SYSTEM.
TRANSMISSION AND RECEPTION ARE
SYNCHRONIZED BUT TIMING IS NOT.
THE CHANNEL CLOCKS ARE DERIVED
FROM DIFFERENT MASTER CLOCKS
WHOSE RANGE IS SPECIFIED TO LIE
WITHIN CERTAIN LIMITS. THE
MULTIPLEXED SIGNAL IS CALLED A
“PLESIOCHRONOUS” SIGNAL.
PDH SIGNALS ARE NEITHER
SYNCHRONOUS NOR ASYNCHRONOUS.
THERE
ARE TWO VERSIONS OF PDH
NAMELY
1) THE EUROPEAN AND 2 ) THE
AMERICAN.
THEY DIFER SLIGHTLY IN THE DETAIL
OF THEIR WORKING BUT THE
PRINCIPLES ARE THE SAME.
EUROPEAN PCM = 30 CHANNELS
NORTH AMERICAN PCM = 24 CHANNELS
JAPANESE PCM = 24 CHANNELS
IN INDIA WE FOLLOW THE EUROPEAN
PCM OF 30 CHANNELS SYSTEM
WORKING
MUX
BIT RATE
2 Mbps
2.048 Mbps +/- 50
30
8 Mbps
ppm
8.448 Mbps +/- 30
ppm
120
34.368
Mbps
140 Mbps 139.264
Mbps
34 Mbps
PARTS
PER
MILLION
CHANNEL
S
+/- 20 ppm
480
+/- 15 ppm
1920
LOWER
CAPACITY.
ADD AND DROP DIFFICULT.
COMPLEX MULTIPLEXING AND
DEMULTIPLEXING.
NO UNIVERSAL STANDARD
INTERWORKING BETWEEN
HIERARCHIES COMPLEX
PDH
IS NO LONGER EFFICIENT TO
MEET THE DEMANDS PLACED ON IT.
BANDWIDTH LIMITATIONS – MAX
CAPACITY IS 566 MBPS ONLY.
NO COMMON STANDARDS AMONG
VENDORS
POINT TO POINT CONFIGURATION (
LINEAR WORKING ) ONLY IS
POSSIBLE.
IT DOES NOT SUPPORT HUB
Because
of the disadvantages in the
pdh technology, sdh technology is
developed which overcomes all the
drawbacks of an pdh technology.
thus
sdh is an advanced technology.
SYNCHRONOUS :
ONE MASTER CLOCK & ALL
ELEMENTS SYNCHRONISE WITH IT.
DIGITAL:
INFORMATION IN BINARY.
HIERARCHY:
SET OF BIT RATES IN A HIERARCHIAL
ORDER.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
SIMPLIFIED MULTIPLEXING/DEMULTIPLEXING
TECHNIQUES.
DIRECT ACCESS TO LOWER ORDER TRIBUTARIES.
ACCOMMODATES EXISTING PDH SIGNALS.
CAPABLE OF TRANSPORTING BROADBAND
SIGNALS.
MULTI-VENDOR, MULTI OPERATOR
ENVIRONMENT.
PROTECTION SWITCHING TO TRAFFIC IS
OFFERED BY RINGS.
ENHANCED BANDWIDTH.
NMS FACILITY.
UNLIMITED BANDWIDTH
GROWTH OF THE EXISTING TO THE HIGHER
ORDER SYSTEM IS SIMPLE.
LOW/HIGH
SPEED DATA
VOICE
INTERCONNECTION
COMPUTER
OF LAN
LINKS
FEATURE SERVICES LIKE HDTV
BROAD BAND ISDN TRANSPORT
SDH Levels
STM-1
STM-4
STM-16
STM-64
Bit rates in Kbps
155520
622080
2488320
96215043.28
The
different network elements
are
TERMINAL MULTIPLEXER
ADD/DROP MULTIPLEXER
REGENERATOR
SYNCHRONOUS DIGITAL
CROSS CONNECT
ADM
ADM
(STM1/STM4/STM16)
Aggregate signal
Tributary
(2/34/140Mbps/STM1(e)/ STM1(o))
signal
Pdh
is obsolete now a days and replaced by
sdh technology
Sdh has many advantage over pdh technology
Sdh encompasses features like hdtv ,isdn
services which pdh is incapable of
It also provides high speed data transfer