TLMN625 CLASS 4 Spring 2003

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TLMN625 CLASS 4Spring 2003

• Digital Transmission Access

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SESSION 5 Digital Transmission Access (Consumer,
Business)

• Introduction
• -Preliminary- Multiplexing
• Subscriber loop review (analog vs. digital
  lines)
• T1, channel banks, CSUs
• Digital Subscriber lines (xDSL), ISDN
• Cable Modems
• Wireless (LMDS, MMDS)

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Internet AccessSurvey CNN Feb.27, 2001

• Cable Modem 33
• Modem 29
• DSL 22
• T-1 14
• ISDN 3

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Review of Fundamentals
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Multiplexing
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Time Division Multiplexing
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Digital Transmission

• Amplifiers Boost the energy in the signal
• Also boost the noise (used for analog signalling)
• Repeaters Recover the digital pattern and
  retransmit it
• Do not retransmit the noise
• Advantages of digital transmission
• Compression, Store and Hold, (Buffers)
• Better multiplexing
• Security (e.g. mobile )
• Integration of analog and digital data

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Figure 8-17
Telephone Network
? The McGraw-Hill Companies, Inc., 1998
WCB/McGraw-Hill
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Figure 8-18
? The McGraw-Hill Companies, Inc., 1998
WCB/McGraw-Hill
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Figure 8-19
? The McGraw-Hill Companies, Inc., 1998
WCB/McGraw-Hill
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Figure 8-20
Analog Switched Service
? The McGraw-Hill Companies, Inc., 1998
WCB/McGraw-Hill
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Figure 8-21
Analog Leased Service
? The McGraw-Hill Companies, Inc., 1998
WCB/McGraw-Hill
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Figure 8-22
Analog Hierarchy
? The McGraw-Hill Companies, Inc., 1998
WCB/McGraw-Hill
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Figure 8-23
? The McGraw-Hill Companies, Inc., 1998
WCB/McGraw-Hill
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Figure 8-24
Switched/56 Service
? The McGraw-Hill Companies, Inc., 1998
WCB/McGraw-Hill
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Figure 8-25
DDS
? The McGraw-Hill Companies, Inc., 1998
WCB/McGraw-Hill
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Figure 8-26
DS Hierarchy
? The McGraw-Hill Companies, Inc., 1998
WCB/McGraw-Hill
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Figure 8-27
T-1 Line
? The McGraw-Hill Companies, Inc., 1998
WCB/McGraw-Hill
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Figure 8-28
T-1 Frame
? The McGraw-Hill Companies, Inc., 1998
WCB/McGraw-Hill
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Figure 8-29
Fractional T-1 Line
? The McGraw-Hill Companies, Inc., 1998
WCB/McGraw-Hill
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DS-1 Transmission (T1)

• Frame size 193 bits.
• 4 wire Full Duplex (2 twisted pairs)
• Voice
• 24 voice chs. 8 bits each 1 frame bit
• PCM voice 8 KHz 8000 frames / sec
• 8 bit PCM (every 6th frame, each channel has 7
  bit PCM)
• Data
• 23 channels 1 byte for frame sync.
• 7 bits per channel, 56 Kbps per channel

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Channel Banks

• filtering to 3400 Hz for each signal
• sampling 8000 times a second
• coding to 8 bit accuracy
• multiplexing, synchronization

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TDM Carrier Standards
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LEASED-LINE TELEPHONE TECHNOLOGIES Name
Bandwidth Notes ----
--------- ----------------------------------
------- DS-0 64 kbps Equal
to one voice phone connection. DS-1
1.544 Mbps Used for T1. Old primary
Internet backbone. DS-2
6.312 Mbps Only used for microwave
transmitters. DS-3 44.736 Mbps
Used for T3. OC-1 51.840 Mbps
SONET level 1. OC-3 155.530 Mbps
SONET level 3. M560 560.000 Mbps
Proprietary. Current telephone backbone. OC-48
2,488.32 Mbps Future telephone
backbone. OC-192 9,953.28 Mbps
Currently unavailable.
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T1 Costs

• Quest LCI 6000/month (coast to coast)
• Frontier 9000/ month (coast to coast)
• Big three around 14,000/month (c. to c)
• Above are published rates. Significant discounts
  are now being offered as competition comes from
  alternatives such as VOIP, Frame Relay, DSL etc.
  Especially true for T1 access to Internet portals
  

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Leased Line Costs
1)InternetTypically phone companies charge T1
400-600 per month about 125 for 56 k.
2) Leased-line pricing varies among
carriers, expect to pay around 2,000 per
month for a T1 line that traverses 50 miles.
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(No Transcript)
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DSLAM
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Transmission Spectrum
The VDSL spectrum usually ranges from 200 kHz to
30 MHz
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Business Opportunities for xDSL

• Internet Connectivity Services
• Corporate Branch Office Connectivity
• Telecommuting Services
• Business- to- Business Services
• Symmetric Voice- T1 Replacement

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VDSL 52 Mbps downstream and 13
Mbps upstream,
Source Telecominvestor Magazine August
1999 VDSL useful for TV, video conferencing
Limited to 4500 feet
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Cable Modem
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(No Transcript)
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Questions relating to the following?

• Why is the Frame Relay curve flat?
• What is the breakpoint in moving from one telecom
  service to the other?
• What does this say about the two services as when
  the services should be utilized?

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Cost Comparison
300
1000