Carrier Systems, Multiplexing - Ohio University 16-20kHz 4kHz 4kHz 20 kHz 8-12kHz 12-16kHz 4kHz...
Transcript of Carrier Systems, Multiplexing - Ohio University 16-20kHz 4kHz 4kHz 20 kHz 8-12kHz 12-16kHz 4kHz...
Carrier Systems, Multiplexing
Reading: Pecar, O'Connor, Garbin, "Telecommunications Factbook", McGraw‐Hill, 1992, Chapter 3, Transmission SystemsTransmission Systems
Dodd, Chapter 5, pp. 248‐253
2From Pecar, O'Connor, Garbin, Ch. 3
3From Pecar, O'Connor, Garbin, Ch. 3
4From Pecar, O'Connor, Garbin, Ch. 3
5From Pecar, O'Connor, Garbin, Ch. 3
6From Pecar, O'Connor, Garbin, Ch. 3
7From Pecar, O'Connor, Garbin, Ch. 3
8Slide the work of Dr. Hans Kruse
4kHz
4kHz
4kHz Aggregate Signal4kHz
4kHz
4kHz
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4kHz
16-20kHz4kHz
4kHz 20 kHz 8-12kHz
12-16kHz
16 20kHz
4kHz
4kHz
4-8kHz
0-4kHz
4kHz
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4kHz codec 64kbps
4kH d 64kb
320kbps
4kHz codec 64kbps
4kHz codec 64kbps
4kHz codec 64kbps
4kHz codec 64kbps
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12Slide the work of Dr. Hans Kruse
•The Basic channel is a DS0 = 64kbpse as c c a e s a S0 64 bps•DS1 = 24 x DS0 plus framing = 1.544Mbps•DS1C = 2 x DS1•DS2 = 4 x DS1 •DS3 = 28 x DS13
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•Synchronous Optical NetworkSy c o ous Opt ca et o•STS‐n is the electrical standard, OC‐n the optical one•Basic channel STS‐1 = about 52Mbps5 p•OC‐3 = about 155Mbps•OC‐12 = about 600Mbpsp•OC‐48 = about 2500Mbps, etc.
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•Basic channel: DS0 = 64kbpsas c c a e : S0 64 bps•E1 = 30 x DS0 + 2 x 64kbps for signaling = 2,048Mbps•No signaling embedded in the user channels.g g
•Separate signaling channels very similar to ISDN PRI
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16Slide the work of Dr. Hans Kruse
•T1 and DS1 are synonymousa d S a e sy o y ous•To the end‐user, a T1 represents either
•a digital transmission path of 1.536Mbits/sec, g p 53•or 24 “channels”, with each channel capable of carrying a voice call or digital data up to 56kbits/sec.
•Channels are 64kbits/sec “wide”, more about that later…later…
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•Typical uses for the T1Typical uses for the T1•Voice trunks (ACDs)•Small Business Internet Access•Next higher speed after ISDN BRI
•T1 is a “mature” market with established manufacturers; growth is modest.
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24 Voice Trunks
T1 Facility
ChannelBankPBX
y
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Video Conference
T1 Facility
CSU/DSULAN Router
y
Voice
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•T1 facilities will continue to be in wide‐spread T1 facilities will continue to be in wide spread use.•T1 is being used to carry “Frame Relay” data g y ytraffic.•The next step after T1 (possibly multiple ones) is p (p y p )DS3=45Mbit/sec private lines and ATM (Asynchronous Transfer Mode) networks over SONET SONET.
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Data: 1 1 1 0 0 1 1 1 1Data: 1 1 1 0 0 1 1 1 1
Timing:
Transmit:
Receive:
Timing:
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What if:
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1 1 1 10 01 1 1 10 0
•Alternating polarity used to create net zero DC on the line
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Alternating polarity used to create net zero DC on the line•8 or 9 Volt pulses if you check source, lower at the other end•Regenerate after first 3,000 ft, and 6,000 ft thereafter
•A “Frame” consists of 8 bits for each channel, strung a e co s sts o 8 b ts o eac c a e , st u gone after the other
•8 bits/channel times 24 channels = 192 bits•One “Framing Bit” is added to each frame
•Total frame length is 193 bits•8000 frames are sent per second
•8,000 times 193 = 1,544,000 bps
•FYI: when the framing bits are removed at the destination, the channels only carry 1.536 Mbps of payload datachannels only carry 1.536 Mbps of payload data
•1,544,000 – 8,000 framing bits/sec = 1,536,000 bps
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Framing Bit8000 frames per
d Framing Bitbit 193
second
0.125 msec per frame
…
Channel 1 Channel 3Channel 1bits 1 to 8
Channel 2
Channel 3bits 17 to 24
Channel 24bits 9 to 16 bits 185 to 192
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•In the bit stream, there must never be more than 15 t e b t st ea , t e e ust e e be o e t a 5consecutive “0”s.•Over short periods of time, there must be at least 12.5% “1”s in the signal.
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•At the T1 levelt t e e e•“Superframe” signaling uses groups of 12 T1 frames to create timing and signaling patterns•“Extended Superframe” signaling uses 24 T1 frames to create timing, error detection, and signaling capabilitiescapabilities
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Superframe Signaling (Sequence of 12 framing bits):
100011011100100011011100
Extended Superframe (Sequence of 24 framing bits):
DCD0DCD0DCD1DCD0DCD1DCD1
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•Inside each channels de eac c a e•Voice channels use signaling bits to indicate on‐hook and off‐hook conditions•Data channels may include signaling bits and bits that enforce the “1”s density.
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Frame Bit 1 2 3 4 5 6 7 81 v v v v v v v v2 v v v v v v v v3 v v v v v v v v4 v v v v v v v v5 v v v v v v v v6 v v v v v v v A7 v v v v v v v v8 v v v v v v v v99 v v v v v v v v10 v v v v v v v v11 v v v v v v v v12 v v v v v v v B
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12 v v v v v v v B
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•Interface between the customer and the carrier te ace bet ee t e custo e a d t e ca ecircuit.•Regenerates the signal•Provides or recovers timing•Passes a T1 signal (DS1‐X) to the customer equipment
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•Receives a T1 signal from the CSUece es a s g a o t e CSU•Converts the signal to a “short‐haul” interface format
•RS‐2323•V.35•RS‐422
•Can access and “break out” individual channels.
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•Combines numerous voice and data input streams Co b es u e ous o ce a d data put st ea sinto a T1•May use the 24‐channel format•Often uses proprietary channel assignments
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•Used by carriers and large end‐usersUsed by ca e s a d a ge e d use s•Electronically connects T1s to each other, or•Connects channels from one T1 to channels in another T1.
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