1. VOIP and the “Last Mile”1

2. Voice over IP (VoIP)
You may use Skype or some other program to talk over the Internet at low cost or even no cost.
This is called voice over IP, because you are using an IP network, namely the Internet.
Companies also use VoIP, both within their buildings and outside their buildings.
They do not always use the Internet for transmission. 2 2

3. Voice over IP (VoIP) 6-3 In voice over IP (VoIP), calls are digitized,
packetized, and transported over an IP network:
either an internal IP network or the Internet.
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4. Voice over IP (VoIP) A media gateway connects
a VoIP network to the PSTN.
This gives VoIP users access
To PSTN users.
The media gateway must translate
between both signaling technology
and transport technology.
Voice over IP (VoIP)
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5. VoIP
VoIP means that a firm does not have to maintain two networks—an IP network for data and a circuit- switched voice network.
This should reduce costs considerably by only requiring the maintenance of a single network.
In addition, VoIP’s packet switching should be more efficient than the PSTN’s circuit switching.
But companies have concerns about sound quality and the high availability expected of telephone service.
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6. VoIP Signaling and Transport
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Again, signaling is the transmission
of supervisory messages.
Transport is the actual
transmission of voice.
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7. VoIP Signaling and Transport
VoIP transport consists of a stream of VoIP packets.
Each VoIP packet contains a short amount codec-encoded voice.
There is no time to wait for error correction, so UDP is used.
The Real Time Protocol (RTP) header “fixes” weaknesses of UDP.
First, the RTP has a sequence number to place packets in order.
Second, RTP has a time stamp so that the voice steam
can be played back at the correct time.
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8. VoIP Codecs The two phones must use the same codec
to encode and decode voice.
They must agree on
one of several standard
codec protocols
through negotiation.
Generally,
more compression
gives lower
sound quality but
lowers transmission cost
Codec
Transmission Rate
G.711
64 kbps
G.721
32 kbps
G.722
48, 56, 64 kbps
G.722.1
24, 32 kbps
G.723
5.33, 6.4 kbps
G.723.1A
5.3, 6.3 kbps
G.726
16, 24, 32, 40 kbps
G.728
16 kbps
G.729AB
8 kbps
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9. Wired “Last Mile” Services
Telephone Modems
ADSL Modem Service
Cable Modem Service
Fiber to the Home
You need to get to the Internet from your home or apartment.
Businesses need to get to the Internet from their sites.
We will begin looking at three traditional ways to connect to the Internet.
All of them used wired transmission. 9 9

10. “Traditional” Technologies for the Last Mile
The access line to your home
Traditionally, a 1-pair VG UTP line from the telephone company
In the 1960s, a few businesses started getting 2-pair data-grade UTP and optical fiber
Given the cost of upgrading the 1-pair VG UTP plant, 1- pair VG UTP seemed eternal
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11. “Traditional” Technologies for the Last Mile
Telephone Service and Cable TV
1950s brought cable television service
Used coaxial cable with a central wire and a coaxial conductive ring or mesh
Telephone companies controlled broadcast telephone service
Cable companies controlled television delivery service
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12. “Traditional” Technologies for the Last Mile
Telephone modems obsolete(I hope nobody uses it anymore)
Limited to 33.6 kbps sending / 56 kbps receiving
Cannot use your telephone for calls while using the telephone modem
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13. Asymmetric Digital Subscriber Line (ADSL)
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Like telephone modems,
ADSL also uses the existing 1-pair voice-grade
UTP line going to the home;
but it offers higher speeds than telephone modems
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14. Telephone Modems and ADSL
Both use the 1-pair VG UTP line running to the subscriber’s home
Already installed, so no extra cost of running a new line
Telephone modems send analog signals
This is what the traditional telephone system expects
ADSL
Send digital signals for data (digital subscriber line)
Requires special equipment at the end office switch (DSLAM)
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15. Asymmetric Digital Subscriber Line (ADSL)
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Unlike telephone modem services,
ADSL provides simultaneous voice and data.
The phone line is not tied up
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16. Asymmetric Digital Subscriber Line (ADSL)
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Speed is asymmetric.
Faster downstream (to home) speed
than upstream (from the home) speed.
This is ideal for World Wide Web downloads.
Speeds are increasing rapidly in both directions.
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17. Asymmetric Digital Subscriber Line (ADSL)
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Home user needs a splitter for each
telephone outlet
Connects a phone to the splitter voice port
Connects an ADSL modem
To the splitter data port
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18. Cable Modem Service
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Optical fiber brings signals to and from the neighborhood.
Thick coaxial cables carry signals in the neighborhood.
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19. ADSL Versus Cable Modem Service
Generally, cable modem service is somewhat faster and not more expensive than ADSL service
However, price and performance ranges overlap
And performance is increasing rapidly
In cable modem service, all subscribers in a neighborhood must share the speed
However, cable modem speed to the neighborhood is very high, so cable modem subscribers usually still get higher-than-ADSL speeds
And other subscribers cannot read a subscriber’s transmissions, which are encrypted
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20. Fiber to the Home
Some carriers are beginning to replace their 1-pair voice grade UTP residential wiring with optical fiber
This is called fiber to the home or fiber to the premises
Download speeds vary. See Verizon FIOS.
Not more expensive than DSL service.
See FIOS and COMCAST comparison.
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21. Wireless Access Service
Wireless Technologies for the Last Mile
We have looked at wired access to the Internet.
We will no look at wireless access technologies to get you to the Internet. 21 21

22. Wireless for the Last Mile
3G Cellular Data Transmission
3G cellular was created to send data faster
current services offer DSL speeds at higher prices
2 Mbps to 3 Mbps speeds are even more expensive
Consumer usage is dominating with downloading music, videos, and games
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23. Wireless for the Last Mile
Cellular companies are still using many 3G technologies
Cellular companies are introducing faster 4G service
100 Mbps or more
Using Long-Term Evolution (LTE)
Which is IP-based
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24. Wireless for the Last Mile
WiMAX Metropolitan Area Networks
Designed to compete with DSL, cable modem service, and 3G and 4G cellular service
Designed to serve a metropolitan area
Users can get service anywhere, not just at hotspots
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25. Wireless for the Last Mile
WiMAX Metropolitan Area Networks
Promised to be faster than 3G service at lower cost
Mobile subscribers with omnidirectional antennas could receive speeds at the lower end
Fixed subscribers in homes with directional antennas could receive at the higher end
The largest WiMAX network was created by Clearwire in the US.
Sprint acquired Clearwire and converted their users for LTE and will shutdown WiMAX in 2015.
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26. 4G LTE Services Standards are the same as for cellular 4G LTE
Evolving market offerings
Verizon 4G LTE Internet (Installed)
a variety of Internet and routers providing wireless connection to home and office.
see link at bottom of the page.
AT&T Wireless Home Phone & Internet
prices vary based on data usage.
Mobile hotspots
an alternative to have Internet connection for devices without a 4G LTE antenna (e.g. Laptops, tablets, etc).
Cost of the device, plus provider monthly fee.
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27. Wireless for the Last Mile
Satellite Access Service
Very expensive because of long transmission distance to satellites
Hundreds to thousands of miles from the user site
One-way transmission, which is used in television delivery, is not too expensive
Two-way data transmission is complex and therefore expensive
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28. The Market Situation
Having looked at technologies, we need to turn the situation in the marketplace for services.
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29. The Market Situation The Triple Play The goal of access carriers
Telephony companies
Cable television companies
Wireless access companies
Provide telephony, data, and video in a package
Video is the hardest
People want multiple incoming TV signals
They also want HDTV
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30. The Market Situation The International Situation
United States ranks 9th internationally in broadband speed and availability
Korea and Japan provide 500 Mbps speeds or faster at prices comparable to U.S. prices (for lower speeds)
Leadership in speed brings leadership in applications
See link at the bottom of the page for a recent report.
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