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Chapter 16
Other WirelessNetworks
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
16.2
16-1 WiMAX16-1 WiMAX
The IEEE 802.16 Worldwide Interoperability for Microwave Access.
16.3
16-1 WiMAX16-1 WiMAX
WiMAX provides the last mile of broadband wireless connectivity.
16.4
16-1 WiMAX16-1 WiMAX
WiMAX provides wireless access up to 50Km for fixed stations, 15Km for mobile stations
16.5
16-1 WiMAX16-1 WiMAX
Sprint and Clearwire have deployed the WiMAX technology .
Sprint will retire the service in 2015 in favor of LTE
16.6
16-1 WiMAX16-1 WiMAX
It has been successful in Russia, Pakistan, and Mongolia.
Available to about 30million people in 27 cities worldwide.
16.7
16-1 WiMAX16-1 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).
16.8
Figure 16.1: Fixed WiMAX
16.9
Figure 16.2: Mobile WiMAX
16.10
16-1.2 LTE16-1.2 LTE
Long Term Evolution
Marketed as 4G LTE.
16.11
16-1.2 LTE16-1.2 LTE
Long Term Evolution
Service was first established in Dec 2009 (Europe),
2011 in North America.
16.12
16-1.2 LTE16-1.2 LTE
LTE supports roaming internet access from mobile phones.
LTE supports Voice over IP.
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.
16.14
16-2 Cellular Telephony16-2 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.
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16-2 Cellular Telephony16-2 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.
16.16
Figure 16.6: Cellular system
16.17
Figure 16.7: Frequency reuse patterns
16.18
16.2.2 First Generation (1G)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.
1G Cell math
25 MHz bandwidth30 KHz per channel832 channels 42 channels used for control1/7 of the channels per cell112 simultaneous calls per cell.
16.20
Figure 16.8: Cellular bands for AMPS
16.21
16.2.3 Second Generation (2G)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 service2G supports digital service
Three major systems evolved in the second generation: D-AMPS, GSM, and IS-95.
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 channel25-MHz of bandwidth200 KHz per channel124 channelsAbout 31 channels per cell.No more than 248 calls per cell.
16.25
Figure 616.11: GSM bands (Global System for Mobile Service)
16.26
Figure 16.12: GSM
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 band1.228 MHz per channel20 channels per cell64 calls per channel using CDMA1280 calls per cell
16.30
Figure 16.14: IS-95 forward transmission
16.31
Figure 16.15: IS-95 reverse transmission
16.32
16.2.4 Third Generation (3G)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.
16.33
16.2.4 Third Generation (3G)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.
3G
3G calls for, …
2 Mbps stationary bandwidth144 to 384 Kbps moving bandwidth
3G-CDMA vs 3G-TDMA
CDMA providers TDMA providersVerizon AT&TSprint T-MobileMetroPCSCricketUS Cellular
16.36
16.2.5 Fourth Generation (4G)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.
4G
1 Gbps stationary bandwidth100 Mbps moving bandwidth
CDMA → 64-QAM → IFDMA or OFDMA
16.38
16-3 Satellite Network16-3 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.
16.39
Figure 16.17: Satellite orbits
16.40
Figure 16.18: Satellite orbit altitudes
16.41
Figure 16.19: Satellites in geostationary orbit
Geostationary Orbit
C = 2pi(35700km + 6300)Speed = C / 24 hrs ~ 11,000km/hr
Example: weather satellite, satellite TV.
16.43
16.3.3 MEO Satellites16.3.3 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.
16.44
Figure 16.20: Orbits for global positioning system (GPS) satellites
MEO Satellites: GPS
GPS employs 24 satellites
Trilateration: 3 satellite positions are used to locate any point on the earths surface.
16.46
Figure 16.21: Trilateration on a plane
16.47
Figure 16.22: LEO satellite system
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.
