Transcript Document

Chapter 16
Other Wireless
Networks
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
16-1 WiMAX
The IEEE 802.16 Worldwide Interoperability
for Microwave Access.
16.2
16-1 WiMAX
WiMAX provides the last mile of broadband
wireless connectivity.
16.3
16-1 WiMAX
WiMAX provides wireless access up to 50Km
for fixed stations, 15Km for mobile stations
16.4
16-1 WiMAX
Sprint and Clearwire have deployed the
WiMAX technology .
Sprint will retire the service in 2015 in favor of
LTE
16.5
16-1 WiMAX
It has been successful in Russia, Pakistan, and
Mongolia.
Available to about 30million people in 27 cities
worldwide.
16.6
16-1 WiMAX
WiMAX frequency band is from 2-66GHz and
has bandwidth up to 75Mbps.
Actual field tests show bandwidth comparable
to DSL service (5-10Mbps).
16.7
Figure 16.1: Fixed WiMAX
16.8
Figure 16.2: Mobile WiMAX
16.9
16-1.2 LTE
Long Term Evolution
Marketed as 4G LTE.
16.10
16-1.2 LTE
Long Term Evolution
Service was first established in Dec 2009
(Europe),
2011 in North America.
16.11
16-1.2 LTE
LTE supports roaming internet access from
mobile phones.
LTE supports Voice over IP.
16.12
Vocabulary
MSC = mobile switching center, searches for
phones by paging until found.
Handoff = transferring a call between cells.
Roaming = agreements between providers
to help complete calls.
16-2 Cellular Telephony
Cellular telephony is designed to provide
communications between two moving units,
called mobile stations (MSs), or between one
mobile unit and one stationary unit.
16.14
16-2 Cellular Telephony
A service provider must be able to:
locate and track a caller,
●assign a channel to the call,
●and transfer the channel from base station to
base station as the caller moves out of range.
●
16.15
Figure 16.6: Cellular system
16.16
Figure 16.7: Frequency reuse patterns
16.17
16.2.2 First Generation (1G)
Cellular telephony is now in its fourth generation. The
first
generation
was
designed
for
voice
communication using analog signals.
AMPS was the first generation cellular technology in
North America. (Advanced Mobile Phone Service)
AMPS has a reuse factor of 7.
16.18
1G Cell math
25 MHz bandwidth
30 KHz per channel
832 channels
42 channels used for control
1/7 of the channels per cell
112 simultaneous calls per cell.
Figure 16.8: Cellular bands for AMPS
16.20
16.2.3 Second Generation (2G)
To provide higher-quality (less noise-prone) mobile
voice communications, the second generation of the
cellular phone network was developed.
1G is for analog service
2G supports digital service
Three major systems evolved in the
generation: D-AMPS, GSM, and IS-95.
16.21
second
2G D-AMPS
Combined TDMA → QPSK → and FDMA.
Trios of calls are interleaved in TDMA frames
before being converted to an analog signal
on one channel. Has about 3 times the call
capacity of 1G-AMPS.
D-AMPS has a cell reuse factor of 7.
2G-GSM
The Global System for Mobile service was
developed in Europe.
GSM has a cell reuse factor of 4
TDMA → GMSK → and FDMA
2G-GSM Capacity
8 calls per TDMA channel
25-MHz of bandwidth
200 KHz per channel
124 channels
About 31 channels per cell.
No more than 248 calls per cell.
Figure 616.11: GSM bands (Global System for Mobile Service)
16.25
Figure 16.12: GSM
16.26
2G IS-95
Interim Standard 95 used throughout North
America for 2G service.
Uses GPS to synchronize base stations.
Has a cell reuse factor of 1.
2G IS-95
Station to phone CDMA → QPSK → FDMA
Phone to station DSSSS → QPSK → FDMA
2G IS-95
25 MHz band
1.228 MHz per channel
20 channels per cell
64 calls per channel using CDMA
1280 calls per cell
Figure 16.14: IS-95 forward transmission
16.30
Figure 16.15: IS-95 reverse transmission
16.31
16.2.4 Third Generation (3G)
The third generation of cellular telephony refers to a
combination of technologies that provide both digital
data and voice communication.
16.32
16.2.4 Third Generation (3G)
Using a small portable device, a person is able to talk
to anyone else in the world with a voice quality
similar to that of the existing land line telephone
network.
A person can download and watch a movie, download
and listen to music, surf the Internet or play games,
have a video conference, etc.
16.33
3G
3G calls for, …
2 Mbps stationary bandwidth
144 to 384 Kbps moving bandwidth
3G-CDMA vs 3G-TDMA
CDMA providers
Verizon
Sprint
MetroPCS
Cricket
US Cellular
TDMA providers
AT&T
T-Mobile
16.2.5 Fourth Generation (4G)
The fourth generation of cellular telephony is
expected to be a complete evolution in wireless
communications. 4G-LTE appears to be the current
trend.
16.36
4G
1 Gbps stationary bandwidth
100 Mbps moving bandwidth
CDMA → 64-QAM → IFDMA or OFDMA
16-3 Satellite Network
A satellite network is a combination of nodes,
some of which are satellites, that provides
communication from one point on the Earth to
another. A node in the network can be a satellite,
an Earth station, or an end-user terminal or
telephone.
16.38
Figure 16.17: Satellite orbits
16.39
Figure 16.18: Satellite orbit altitudes
16.40
Figure 16.19: Satellites in geostationary orbit
16.41
Geostationary Orbit
C = 2pi(35700km + 6300)
Speed = C / 24 hrs ~ 11,000km/hr
Example: weather satellite, satellite TV.
16.3.3 MEO Satellites
Medium-Earth-orbit (MEO) satellites are positioned
between the two Van Allen belts. A satellite at this
orbit takes approximately 6 to 8 hours to circle the
Earth.
16.43
Figure 16.20: Orbits for global positioning system (GPS) satellites
16.44
MEO Satellites: GPS
GPS employs 24 satellites
Trilateration: 3 satellite positions are used to
locate any point on the earths surface.
Figure 16.21: Trilateration on a plane
16.46
Figure 16.22: LEO satellite system
16.47
LEO Satellites
Periods range from 90min to 120min to
circle the earth.
LEO is preferred for phone service due to
less delay compared to MEO or GEO
satellites.
LEO Satellites
Globalstar – 48 satellites divided into 6 polar
orbits. 8 satellites per orbit.
Iridium – 66 satellites divided into 6 polar
orbits. 11 satellites per orbit. Used by
DoD.