1. ECEN5553 Telecom Systems Dr. George Scheets
ECEN5553 Telecom Systems Dr. George Scheets Week 10 Read [19] ""Evolution of Packet-Optical Integration in Backbone and Metropolitan High-Speed Networks" [20a] "Great Leaps of Light" [20b] "Breaking the Light Barrier" [21a] "Is the U.S. Stock Market Rigged" [21b] "The Multinational Study of Brain Tumors in Cell Phone Users' Heads" Exam #2: Covers Internet thru Fiber Optics pages will be from Fall 2015 Exam #2 Next Time (Live & Local DL) No Later than 31 October (Remote DL)

2. The Legacy Phone System...
4 Wire to 2 Wire Conversion at Central Office Hybrids can cause some problems
Singing (Cure: Attenuation)
Echoes (Cure: Echo Canceler)
Analog to Digital Conversion points also cause some problems
CO Switch filters on analog voice lines, necessary to limit noise and interference on voice circuits, limit dial-up modem data speeds to about 33 Kbps
Trend is to an all-digital system
U.S. long haul POTS voice circuits use digital Time Division Multiplexing or VOIP

3. TDM 1 2 3 time 1 etc. One 8 bit time slot provided for each
phone call every 1/8000th second.
frequency 1
1/8000 second
(192 Kbps)
24 bits in 2 3
time 1
etc.

4. Integrated Services Digital Network
Copper
Local
Loop
Copper
Local
Loop
Fiber
Optic
Trunk CO CO
Phone
Phone
4 Wire
2 Wire
‘4 Wire’
2 Wire
4 Wire
Digital TDM
64 Kbps

5. PC Modems & POTS
Band Pass Filter suppresses energy outside voice bandwidth (about 3,500 Hz)
A/D Converter
Twisted
Pair Cable
Band Pass Filter
≈ 3.5 KHz
Sampler
Fs = 8 KHz
Code
8 bits/sample
Quantize
256 levels
64 Kbps

6. PC Dial-Up Modems & POTS
PC Bit Stream has a significant amount of energy outside 3.5 KHz filter BW.
Modems squash the energy into the pass band of the filter (at a much reduced bit rate).
A/D Converter
Twisted
Pair Cable PC
Band Pass Filter
≈ 3.5 KHz)
Sampler
Fs = 8 KHz
Code
8 bits/sample
Quantize
256 levels
64 Kbps

7. PSTN Digital Hierarchy
Now obsolete except for some T1 & T3 on Local Loops

8. North American Digital Hierarchy
Obsolete except for ‘last mile’ connectivity
T1 byte interleaved, > T1 bit interleaved
T1 Frame (Format for 1/8000th second)
A 4 Wire T1 Connection:
is Full Duplex (1.544 Mbps in two directions)
Carriers often sell bandwidth in T1 & T3 chunks (& fractions thereof)

9. Digital Carriers North American T-Carrier ITU DS-0 64 Kbps
T Mbps
24 phone calls
T Mbps
28 T-1
ITU
E Mbps
30 phone calls

10. Switching
Crosspoint Switches Used for Space Division Switching Key component of CO switches
Time Slot Interchange Used for Time Division Switching
CO switches perform Space Division Switching
Any POTS switch handling TDM lines (such as a Tandem) performs Time & Space Division Switching

11. Switching
Packet Switches Handle Statistically Multiplexed traffic Require Buffers May use Crosspoints or Busses to switch between input/output lines
Cross Connects Under Network Control Long Term Trunk Switching Circuit Switching & TDM

12. Telephone Space Switching
Version 1.0
Human Operator
source: Salt Lake City Tribune

13. Telephone Space Switching
Version 2.0 Mechanical Crosspoint Switch
(a.k.a. Crossbar Switch)
source: wikipedia.com & ebay.com

14. Telephone Space Switching
Version 3.0 Transistorized Crosspoint Switch
←5ESS
sources: english.turkcebilgi.com , porticus.org, &

15. Telephone Space Switching
V4.0 IP Routers & Gateways
IP device to IP device
→ Straight VoIP
IP device to PSTN phone
→ VoIP Provider (Such as Skype)
→ VoIP Gateway
(Corporate owned Interface box)
Server (IP PBX)
→ Provides PBX-like
functionality
Image source:

16. PSTN TDM The system was designed to move voice
But can & does haul other traffic
Bytes organized into frames
8,000 frames/second
Phone call bytes occupy specified slots in each frame
slots are byte sized
T-1 has 24 slots per frame

17. Switching Example
Two Phone calls Stillwater to Enid Tulsa to Stillwater

18. CO Connectivity Enid CO CO Tulsa 3 17 TO 6 3 Stillwater CO CO
Hierarchical
Direct Connect
2nd Route
Minimum of two
diverse routes out
of Central Office.

19. 2D Switching: The Animation
To:
Stillwater
From:
Stillwater 6 3
TSI
Enid
Enid
TSI
Crosspoint
Tulsa
Tulsa 3
TSI
Watch this one
From Stillwater (3) to Enid (17)
From Tulsa (3) to Stillwater (6)
From Stillwater (6) to Tulsa (3)
From Enid (17) to Stillwater (3)

20. 2D Switching: The Animation
To:
Stillwater
From:
Stillwater 6 3
TSI
Enid
Enid
TSI
Crosspoint
Tulsa
Tulsa 3
TSI
From Stillwater (3) to Enid (17)
From Tulsa (3) to Stillwater (6)
From Stillwater (6) to Tulsa (3)
From Enid (17) to Stillwater (3)

21. 2D Switching: The Animation
To:
Stillwater
From:
Stillwater 6 3 3
TSI
Enid
Enid 3
TSI
Crosspoint
Tulsa
Tulsa 3
TSI
From Stillwater (3) to Enid (17)
From Tulsa (3) to Stillwater (6)
From Stillwater (6) to Tulsa (3)
From Enid (17) to Stillwater (3)

22. 2D Switching: The Animation
To:
Stillwater
From:
Stillwater 6 3
TSI
Enid
Enid 3
TSI
Crosspoint
Tulsa
Tulsa
TSI
From Stillwater (3) to Enid (17)
From Tulsa (3) to Stillwater (6)
From Stillwater (6) to Tulsa (3)
From Enid (17) to Stillwater (3)

23. 2D Switching: The Animation
To:
Stillwater
From:
Stillwater 6
TSI
Enid
Enid
TSI
Crosspoint
Tulsa
Tulsa
TSI
From Stillwater (3) to Enid (17)
From Tulsa (3) to Stillwater (6)
From Stillwater (6) to Tulsa (3)
From Enid (17) to Stillwater (3)

24. 2D Switching: The Animation
To:
Stillwater
From:
Stillwater 6 3
TSI
Enid
Enid
TSI
Crosspoint
Tulsa
Tulsa 6 3
TSI
From Stillwater (3) to Enid (17)
From Tulsa (3) to Stillwater (6)
From Stillwater (6) to Tulsa (3)
From Enid (17) to Stillwater (3)

25. 2D Switching: The Animation
To:
Stillwater
From:
Stillwater 3
TSI
Enid
Enid 3
TSI
Crosspoint
Tulsa
Tulsa 6
TSI
From Stillwater (3) to Enid (17)
From Tulsa (3) to Stillwater (6)
From Stillwater (6) to Tulsa (3)
From Enid (17) to Stillwater (3)

26. 2D Switching: The Animation
To:
Stillwater
From:
Stillwater 3
TSI
Enid
Enid 3
TSI
Crosspoint
Tulsa
Tulsa
TSI
From Stillwater (3) to Enid (17)
From Tulsa (3) to Stillwater (6)
From Stillwater (6) to Tulsa (3)
From Enid (17) to Stillwater (3)

27. Crosspoint Switch: Time Slot 6
From:
Stillwater
Crosspoint
Closed (On)
Enid
Crosspoint
Open (Off)
Tulsa
Byte
To:
Stillwater
To:
Tulsa
Enid

28. 2D Switching: The Animation
To:
Stillwater
From:
Stillwater 6
TSI
Enid
Enid
TSI
Crosspoint
Tulsa
Tulsa
TSI
From Stillwater (3) to Enid (17)
From Tulsa (3) to Stillwater (6)
From Stillwater (6) to Tulsa (3)
From Enid (17) to Stillwater (3)

29. Simplified Central Office Switch
Space
Switch
TDM
deMux
D/A
Local Loops
Echo
Canceler
Hybrid +
A/D
TDM
Mux
POTS Time & Space Switching
Local Loops
Space
Switch
TDM
deMux
D/A
Echo
Canceler
Hybrid +
A/D
TDM
Mux

30. Carrier Leased Line Network
Trunks
Leased Line
Cross-Connect
Carrier reserves BW from pool for our use.
Cross-Connects assign N byte sized time slots
8,000 times/second = N*8*8000 bps.

31. Cross Connect: Same Innards
To:
Stillwater
From:
Stillwater 6
TSI
Enid
Enid
TSI
Crosspoint
Tulsa
Tulsa
TSI
From Stillwater (3) to Enid (17)
From Tulsa (3) to Stillwater (6)
From Stillwater (6) to Tulsa (3)
From Enid (17) to Stillwater (3)

32. Packet Switch using Crosspoint Switching
Input:
Line 1
Crosspoint
Closed (On)
Line 2
Crosspoint
Open (Off)
Line 3
Packet
Output:
Line 1
Line 3
Line 2

33. POP's... Customers can tie into Carrier's Network Here
Mix all sorts of traffic onto the fiber
Use either
Cross Connects to allocate trunk bandwidth via Circuit Switching & Time Division Multiplexing
Routers & Switches to allocate trunk bandwidth via Packet Switching and StatMux
Lambda Switches to allocate entire light waves via Circuit Switching
Or a mixture of these

34. Hybrid TDM Trunking (Potentially most efficient network)
Fixed Rate
TDM
Switch
Packet Switch
SONET
OTN
Bursty Data
Fixed Rate traffic assigned sufficient bytes every 1/8000th second Bursty Data Traffic is aggregated and StatMuxed onto a
common fabric (such as Internet routers).
Aggregate streams are TDM cross connected onto fiber.

35. Hybrid POP offers best potential Carrying Capacity...
Cell Switch
StatMux
Packet Switch
StatMux
Circuit Switch
TDM
0% Data % Data
100% TST % TST
Offered Mix

36. Hybrid Network Trunks Leased Line Cross-Connect Byte Aware
Fixed Rate Traffic: CSTDM bandwidth based on Peak Rates
Bursty Traffic: Access lines aggregated onto higher load trunk. Packet Switch StatMux Trunks are CSTDM.

37. A Typical Hybrid POP Mixes all sorts of traffic onto the fiber...
...using Cross Connects & multiplexers Circuit Switching Time Division Multiplexing
Fiber BW is dedicated to each service
May have other switches (Voice, Ethernet, Routers, SONET, OTN)
POP doesn’t have switch needed? Traffic is back-hauled to nearest switch. Trade-off: Fiber Bandwidth vs Cost of more Switches

38. Backhauling... Tulsa POP OKC POP If a OKC Customer wants an Ethernet
connection & the nearest switch is in Tulsa,
the carrier will cross connect the leased line
to the Tulsa switch.
Ethernet Switch
Customer Switch
Ethernet Trunk
Dallas POP
Backhauled Line
Fiber in the ground
Leased Line

39. Backhauling... Tulsa POP OKC POP If a OKC Customer wants an Ethernet
connection & the nearest switch is in Tulsa,
the carrier will cross connect the leased line
to the Tulsa switch.
Ethernet Switch
Customer Switch
Ethernet Trunk
Dallas POP
Backhauled Line
Fiber in the ground
Leased Line

40. Hypothetical Hybrid POP
Optical Switch
Fiber
2.5, 10, 40 or 100 Gbps
Fiber
TD Mux
TD Mux
Cross
Connects
Leased Lines
CO Trunks
Internet
Router
Best Potential
Carrying Capacity
of any switched
network.
POTS
TimeSpace Switch

41. Hypothetical Hybrid POP
Fiber
Fiber
Mux
Mux
Cross
Connects
Leased Lines
CO Trunks
Internet
Router
POTS
TimeSpace Switch
Will likely see...
Through Traffic

42. Hypothetical Hybrid POP
Fiber
Fiber
Mux
Mux
Cross
Connects
Leased Lines
CO Trunks
Internet
Router
POTS
TimeSpace Switch
May see...
Digitized TV

43. Hypothetical Hybrid POP
Fiber
Fiber
Mux
Mux
Cross
Connects
Leased Lines
CO Trunks
Internet
Router
POTS
TimeSpace Switch
May see...
ISP Trunks

44. Hypothetical Hybrid POP
Fiber
Fiber
Mux
Mux
Cross
Connects
Leased Lines
CO Trunks
Internet
Router
POTS
TimeSpace Switch
Will likely see...
ISP
Local Connections

45. Hypothetical Hybrid POP
Fiber
Fiber
Mux
Mux
Cross
Connects
Leased Lines
CO Trunks
Internet
Router
POTS
TimeSpace Switch
Will likely see...
Leased Lines

46. CO Connectivity CO TO CO TO CO CO Hierarchical Direct Connect
2nd Route
Minimum of two
diverse routes out
of Central Office.

47. Hypothetical Hybrid POP
Fiber
Fiber
Mux
Mux
Cross
Connects
Leased Lines
CO Trunks
Internet
Router
POTS
TimeSpace Switch
May see...
CO Direct
Connections

48. Hypothetical Hybrid POP
Fiber
Fiber
Mux
Mux
Cross
Connects
Leased Lines
CO Trunks
Internet
Router
POTS
TimeSpace Switch
Will likely see...
Tandem POTS
Switch Traffic

49. Circuit Switch TDM Trunking (Eighties ‘Private Line’ Network Model Evolved into Hybrid Network)
Fixed Rate Traffic
TDM
Switch
Trunk
Bursty Data Traffic
Fixed Rate traffic assigned sufficient bytes every 1/8000th second Bursty Data Traffic receives dedicated trunk BW based
on peak input (line) rates.

50. Circuit Switched TDM Network POP
Copper, RF,
Fiber
Copper, RF,
Fiber
Mux
Mux
Cross
Connects
Leased Lines
CO Trunks
No effort is made to
aggregate bursty data
leased line traffic onto
fewer high speed packet
switched StatMuxed
trunks...
‘80’s Network Model.
Evolved to Hybrid.
POTS
TimeSpace Switch

51. Hybrid POP Mux Mux Cross Connects Leased Lines CO Trunks Internet
Fiber
Fiber
Mux
Mux
Cross
Connects
Leased Lines
CO Trunks
Internet
Router
Best Potential
Carrying Capacity
of any switched
network.
POTS
TimeSpace Switch
... which is done in a
Hybrid network.

52. ATM StatMux Trunking (Tomorrow's Network Model? Nope.)
Fixed Rate Traffic
ATM
Switch
SONET OC-N
Bursty Data Traffic
Assumptions:
Fixed Rate Traffic assigned to CBR VC's.
CBR traffic gets near-TDM like service.
Data Traffic is StatMuxed onto the remaining trunk BW.

53. Cell Switched StatMux Network POP
SONET
Fiber
SONET
Fiber
Mux
Mux
ATM
Switch
Leased Lines
CO Trunks
Internet
Router
POTS
TimeSpace Switch
ATM Model

54. Packet Switch StatMux Trunking (Pure Internet Model)
Fixed Rate Traffic
Router
SONET or OTN
Bursty Data Traffic
Assumptions:
All Fixed Rate Traffic is packetized.
All traffic is Statistically Multiplexed onto the trunk BW.

55. Packet Switched StatMux Network POP
Fiber
Fiber
Mux
Mux
Routers
Leased Lines &
Local Connections
100% Internet Model
Voice Switch
Local Loops

56. Fiber Optic Cable SC
1 1/4 inch

57. 100 m Fiber Cable Suppose need to move 2.5 Gbps binary bit stream
Would use light pulses (very hi freq EM waves)
Energy centered up around 200,000 GHz
90% of power is within GHz of center freq
99% of power is within + 25 GHz of center freq
Fiber has Wide Bandwidth → Loss same at all freqs
0.2 dB/Km loss → 0.02 dB loss over 100 m
Power out = Power in *
To get 1 mwatt out need mwatt input

58. 100 m RG-58 Coax Cable Suppose need to move 2.5 Gbps binary bit stream
Would use square electrical pulses (lower freq EM waves)
90% of power is < 2.5 GHz
99% of power is < 25 GHz
Coax has Narrow Bandwidth → Loss not same at all freqs
At 0 Hz, suppose 0 dB loss over 100 m
Power out = Power in * 1
At 2.4 GHz, loss = 38.9 dB/100 feet (38.9 db/100 ft)(328.1 ft/100m) = dB
Power out = Power in * 173.7(10-15)
To get 1 mwatt out at 2.4 GHz, need to inject 5.8 Gwatts
High Frequency energy gets severely attenuated
Can't move a 2.5 Gbps bit stream 100m over RG-58 coax

59. Mechanical Fiber Splice
Corning CamSplice
Strip & Cleave Fibers
Insert until they touch
Twist cams until secure
Claims 3% - 7% Signal Loss
Short Haul splicing
source:

60. Fusion Fiber Splice Automatically Aligns fibers Electrically fuses
Claims < 1% Signal Loss
Long Haul splicing
source:

61. Elements of Optical Networks
Fiber
Ultra-pure Glass Typical Window absorbs ≈ 10% of light 2 Km of typical fiber absorbs ≈ 10% of light
Core/Cladding Boundary will totally reflect light from Core hitting at shallow angles
Bending limitations for fiber cables
Multi-Mode Fiber used on short hauls (LAN’s)
Single-Mode Fiber used on long hauls (WAN’s)

62. Elements of Optical Networks
Erbium Doped Fiber Amplifier (EDFA)
All optical amplifiers. Boost signal power.
Add some noise to the signal in the process
Regenerative Repeaters (Regens)
Cleans up optical signal and restores timing at the cost of occasional bit errors
Requires Optical-Electronic-Optical (OEO) conversion
Basically a Fiber Optic Receiver (photo & bit detector) and Laser Transmitter stuck back-to-back

63. Fiber Span Example
Assumptions: 1 mw in 0.2 db/Km 2.5 Gbps RCVR Single Sample Bit Detector
200 km → P(Bit Error) ≈ 50(10-9)
EDFA midway between XMTR & RCVR → 300 km has about same P(BE) → 200 km has P(BE) ≈ 0.0

64. Fiber Optic Transmission Systems
Short Haul
FOTS Transmitter...
...connected to fiber...
...connected to a FOTS Receiver.
Medium Haul
FOTS Transmitter connected to a fiber...
....connected to an EDFA followed by fiber... (1 or more times)
...connected to a FOTS Receiver

65. Fiber Optic Transmission Systems
Long Haul
FOTS Transmitter connected to a fiber...
....connected to an EDFA followed by fiber... (1 or more times)
...connected to a Regen followed by fiber...
(EDFA & Regen combo repeated 1 or more times)
...connected to a FOTS Receiver