9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.
-
Upload
percival-bates -
Category
Documents
-
view
224 -
download
2
Transcript of 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.
![Page 1: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/1.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 1
Telephone Communications
![Page 2: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/2.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 2
Internet Communications
• Largely carried on telephone network
• Lately quite a bit of privately owned fiber– communication carriers– electric companies– private organizations
• Some carried over television cables
• New conveyance by wireless providers
![Page 3: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/3.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 3
Present Telephone Conveyance
• ATM backbone (long distance)
• ATM switching at core
• T1 data lines to businesses (1.544 Mb/s)
• Copper “last mile”– voice grade lines– DSL possible using residual bandwidth outside
the voice channel - has distance limitations
![Page 4: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/4.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 4
Terms
• ATM - Asynchronous Transfer Mode
• DSL - Digital Subscriber Line
• DSLM - DSL Modem
• DSLAM - DSL Access Module
• POTS - Plain Ordinary Telephone System
• SONET - Synchronous Optical NETwork
![Page 5: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/5.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 5
TelCo Network Interface
ATM
ATM
ATM
CS
DSLAM
R R
S
S
S
...
CoreSwitching
EdgeSwitching
Access(Local Loop)
OC 192 Backbone T1
Copper
Copper
DSLM
![Page 6: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/6.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 6
Residential Data Lines• POTS line with modem
– 56 kb/s– rate depends on line quality
• DSL line with splitter/modem*– Advanced, up to 1.5M / 128K $59.95/month– Premium, up to 384K / 384K $69.95/month– Professional, up to 1.5M / 384K$79.95/month
-------------------------------------------------------------* Speed depends on distance to TelCo office
![Page 7: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/7.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 7
Digital Data Transmission
• Binary data
• Transmitted as pulses
• Pulses shaped by line bandwidth
• Pulses have high frequency components
• Limiting bandwidth limits data rate
![Page 8: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/8.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 8
Fourier Series of Bandlimited Pulse
![Page 9: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/9.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 9
Fourier Transform of Pulse
![Page 10: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/10.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 10
Notes:
• First crossover of spectral amplitude is at B
• 2B is effective bandwidth needed to transmit through noiseless channel.
![Page 11: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/11.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 11
Nyquist Bit Rate
• Relates three transmission variables:– Channel Capacity (C)– Bandwidth (B)– Signal levels (L) – quantization levels– Formula:
C = 2Blog2[L]
• Noise-free channel assumed
![Page 12: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/12.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 12
Nyquist Example:
• Formula: 2BLog2[L]
• Example:
L = 1 (binary signals)
B = 3000 Hz (300 – 3300 Hz)
C = 2*6000*1 = 6000 [bits/s]
Note: Applies to noise-free channel only
![Page 13: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/13.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 13
Shannon Formula
• C = B log2(1 + SNR)
• Example:– B = 3000 Hz (300 – 3300 Hz)– SNR = 3163 (35 dB power ratio)– C = 34,882 [bits/s]
![Page 14: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/14.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 14
All Digital Telephony
• Voice-to-Digital conversion coding at transmitter
• Digital transmission
• Digital-to-Voice code conversion at receiver
• Conversions performed by COder-DECoder (CODEC) module at each end of line
![Page 15: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/15.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 15
Voice-Data Conversion
CODEC CODECVoice Data Voice
(8 bits)
![Page 16: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/16.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 16
Digital Data Frame on T1 Line
• Voice lines are low-pass filtered to 3.1 KHz
• CODEC output is 8 bits wide
• Sampling rate is about 8000 samples/s
• Data rate is thus about 64000 bits/sec
• 24 lines carried on T1 link (1.544 Mb/s)
![Page 17: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/17.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 17
T1 Time-Division Multiplexing• Data frame starts with framing bit
• Data samples (8 bits each)
• 24 lines each supply a data sample every 125 microseconds (0.000125 sec)
• Samples are sequentially multiplexed
• 193 bits per data frame
• 1.544 Mb/s total data rate
![Page 18: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/18.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 18
Time Division Multiplexing
Multiplexer
Line 1
Line 2
Line n
...
Line 1
Line 2
Line n
...
![Page 19: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/19.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 19
Time Division De-Multiplexing
De-Multiplexer
Line 1
Line 2
Line n
...
Line 1
Line 2
Line n
...
![Page 20: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/20.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 20
De-Multiplexing
• Data samples are redistributed into lines
• Low-pass filter recovers analog voice
![Page 21: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/21.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 21
High-Speed Backbone
• 28 T1 streams merged to T3 stream
• ATM cells repackage data at core– 53 octets/cell
• 5 octets of header information
• 48 octets of data
• SONET frames– 8 x 810 = 6480 bits sent 8000 times per second– 51.85 Mb/s data rate (some frame overhead)
![Page 22: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/22.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 22
ATM Cell Transmission
Time
ATM Cell ATM Cell ... ATM Cell
![Page 23: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/23.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 23
TelCo Standard Data Rates
• T1 1.544 Mb/s (24 voice circuits)• T3 44.736 Mb/s (672 voice circuits)• OC-3 155.52 Mb/s (2430 voice circuits)• OC-12 622.08 Mb/s (9720 voice circuits) • OC-48 2488.32 Mb/s (19440 voice circuits) • OC-192 9953.28 Mb/s (38880 voice circuits)
![Page 24: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/24.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 24
Future Network Interface
l 1
l n
l -R
l -R R
S
S
S
...
CoreSwitching
EdgeSwitching
Access
l - BACKBONE
Fiber
Fiber
Copper
Copper...
![Page 25: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/25.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 25
- Network
• Backbone fiber combines 16 OC-192 lines
• Each is given a different wavelength
• All data streams merged into single fiber
• Streams split by wavelength
• 16 OC-192 lines out
• Switches to TelCo customers
![Page 26: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/26.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 26
Optical-Data Conversion
LASER DIODECopper Fiber Copper
()
![Page 27: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/27.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 27
Optical Data Conversion
• Data on wire drives tunable laser
• Laser emits photon pulses
• Photons propagate down fiber
• Photon energy activates receiving diode
• Diode produces voltage or current
• Amplifier drives wire
![Page 28: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/28.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 28
Transmission Problems
• Photons lost at fiber coupling
• Photons lost in fiber due to scattering
• Photons per pulse deteriorates with length
• Repeater amplifiers needed
![Page 29: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/29.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 29
Optical-Data Link
LASER DIODECopper
FiberCopper
()Repeater
Fiber
()
![Page 30: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/30.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 30
More Problems
• Repeaters require external power
• Photons need conversion to voltage, amplification, and then reconversion to photons - data rate bottleneck!
![Page 31: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/31.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 31
Repeater for Fiber Optic Line
Diode LaserFiber
CopperFiber
()Amplifier
Copper
()
![Page 32: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/32.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 32
Wave Division Multiplexing
LaserLine 1
Line 2
Line n
...
Laser
Laser
WDM Fiber
![Page 33: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/33.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 33
Wave Division Multiplexing
• Incoming data converted to photons
• Photon streams have individual frequencies
• Streams can be merged onto single fiber
• Streams propagate without interference
![Page 34: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/34.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 34
WDM Problems
• Limited number of “colors” of photons
• Repeaters must work on all “colors”
![Page 35: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/35.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 35
Repeaters for WDM
• Must amplify all photon “colors”
• Must not cause interaction between photon streams
![Page 36: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/36.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 36
Pumped Laser Repeater
Pumped LaserFiber Fiber
() ()
Pump
Photon Energy
![Page 37: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/37.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 37
Pumped Laser Repeater
• Rare-earth doped glass
• Pumped by external light
• Photons receive excitation and are amplified
• Amplification of all photon “colors”
![Page 38: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/38.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 38
WDM De-multiplexing
• Photon stream split by “colors”
• Separated streams may be converted to voltage pulses
![Page 39: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/39.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 39
Wave Division De-Multiplexing
Line 1
Line 2
Line n
...WDM Fiber
DIODE
DIODE
DIODE
1
2
n
![Page 40: 9/9/2015© 2010 Raymond P. Jefferis IIILect 02 - 1 Telephone Communications.](https://reader036.fdocuments.us/reader036/viewer/2022062301/56649e295503460f94b17157/html5/thumbnails/40.jpg)
04/21/23 © 2010 Raymond P. Jefferis III Lect 02 - 40
WDM Routing
• Data streams must be switched
• Ideally this should be optical
• Optical switching of SONET frames?
• Electro-optics?
• State-of-the-art - developments taking place rapidly (Lucent, Nortel, others)