16.1

Chapter 16

Wireless WANs: Cellular Telephone

and Satellite Networks

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

16.2

16-1 CELLULAR TELEPHONY16-1 CELLULAR TELEPHONY

Cellular telephonyCellular telephony is designed to provide is designed to provide communications between two moving units, called communications between two moving units, called mobile stations (MSs), or between one mobile unit and mobile stations (MSs), or between one mobile unit and one stationary unit, often called a land unit. one stationary unit, often called a land unit.

Frequency-Reuse PrincipleTransmittingReceivingRoamingFirst GenerationSecond GenerationThird Generation

Topics discussed in this section:Topics discussed in this section:

16.3

Figure 16.1 Cellular system

16.4

Figure 16.2 Frequency reuse patterns

16.5

16.6

16.7

1G 2G 2.5G 2.75G 3G 3.5G 4G

AMPS D-AMPS

IS-136

GSMGPRS

30-50 kbps

iDEN

Nextel

CDMA

IS-95

EDGE

75-135kbps

iPhone (1st

generation)

UMTS

Wideband-CDMA

Wireless-CDMA

384kbps; AT&T,

T-Mobile

HSPA

High speed

packet access

400-700kbps

(or 3G ?)

LTE?

Long-term

Evolution

3-5 Mbps

1xRTT

CDMA2000

1x

IS-2000

144 kbps

CDMA2000

EV-DO

1xEV

EV

IS-856

2.5 Mbps down

154 kbps up

Verizon, Sprint

CDMA2000

EV-DV

Dead?

3.1 Mbps down

1.8 Mbps up

UMB ??

Ultra-

Mobile

Broadband

WiMax??

Wi-Fi???

EV-DO Rev.A

Up to 3.1Mbps

AT&T, Verizon, and Alltel now support LTE.

What about WiMax for 4G?

16.8

AMPS is an analog cellular phone system using FDMA.

Note

16.9

Figure 16.3 Cellular bands for AMPS

16.10

Figure 16.4 AMPS reverse communication band

16.11

Figure 16.5 Second-generation cellular phone systems

16.12

Figure 16.6 D-AMPS

16.13

D-AMPS, or IS-136, is a digital cellular phone system using TDMA and FDMA.

Note

16.14

Figure 16.7 GSM bands

16.15

Figure 16.8 GSM

GSM uses TDMA and FDMA concepts

GMSK (Gaussian minimum shift keying):

a form of FSK used in European systems

16.16

Figure 16.9 GSM Multiframe components

Lots of overhead!!

16.17

Figure 16.10 IS-95 CDMA forward (base to mobile) transmission

ESN is used to generate 2^42 pseudorandom chips, each having

42 bits. Decimator chooses 1 bit out of the 64, and then is

scrambled with digitized voice to create privacy.

19.2 ksps = 19.2 kilosignals per second

19.2 ksps signal converted to 64-chip

sequence, giving 1.228 Mcps (mega-chips)

ESN: electronic serial

number of handset

16.18

Figure 16.11 IS-95 CDMA reverse (mobile to base) transmission

Note: CDMA not used here because no way of syncing all mobile devices together!

Frequency reuse is 1, since neighboring channels cannot interfere with CDMA or

DSSS transmission.

Each 6 symbols are used to index into a 64x64 Walsh matrix; thus each 6-symbol chunk

is replaced (not multiplied as it would be with CDMA) with a 64-chip code.

A 42-bit unique code is generated by the mobile

hand set and combined with the 307.2 kcps signal

creating a 1.228 Mcps signal.

16.19

2.5 Generation iDEN

iDEN (Integrated Dispatch Enhanced Network)

• Functionally the same as MIRS (Motorola Integrated Radio System)• A high-capacity digital trunked radio system providing integrated voice and data services to its users• Used by Nextel Communications

16.20

2.5 Generation GPRS

GPRS (General Packet Radio Service)

• The 2.5G version of GSM• Theoretically allows each user access to 8 GSM data channels at once, boosting data transfer speeds to more than 100 Kbps (30 Kbps in the real world since it only uses 2 GSM channels)• AT&T Wireless, Cingular, T-Mobile

16.21

2.5 Generation 1xRTT

1xRTT (CDMA2000) 1x Radio Transmission Technology

• The 2.5G backwards compatible replacement for CDMA• 1xRTT will replace CDMA and iDEN• 1x means that it requires only the same amount of spectrum as 2G networks based on CDMA (IS-95)•Sprint and Verizon

16.22

3rd Generation UMTS

UMTS (Universal MobileTelecommunications System)

• Also called Wideband CDMA• The 3G version of GPRS• UMTS is not backward compatible with GSM, so first UMTS phones will have to be dual-mode• Based on TDMA, same as D-AMPS and GSM

16.23

3rd Generation 1xEV

1xEV (1x Enhanced Version)

• The 3G replacement for 1xRTT• Will come in two flavors

• 1xEV-DO for data only• 1xEV-DV for data and voice

16.24

EDGE

EDGE (Enhanced Data rates for Global Evolution)

• Further upgrade to GSM• Possible 3G (no – 2.75G) replacement for GPRS• Uses improved modulation to triple the data rate where reception is clear

16.25

LTE

LTE (3GPP LTE – Long TermEvolution)• 3G upgrade to UMTS• 3GPP – third generation partnership project • LTE actually an architecture – contains EPS (evolved packet system), EUTRAN (evolved UTRAN), and EPC (evolved packet core)•OFDM, QPSK, 16QAM, 64QAM, MIMO

16.26

16-2 SATELLITE NETWORKS16-2 SATELLITE NETWORKS

A satellite network is a combination of nodes, some of A satellite network is a combination of nodes, some of which are satellites, that provides communication from which are satellites, that provides communication from one point on the Earth to another. A node in the one point on the Earth to another. A node in the network can be a satellite, an Earth station, or an end-network can be a satellite, an Earth station, or an end-user terminal or telephone. user terminal or telephone.

OrbitsFootprintThree Categories of SatellitesGEO SatellitesMEO SatellitesLEO Satellites

Topics discussed in this section:Topics discussed in this section:

16.27

Figure 16.13 Satellite orbits

16.28

What is the period of the Moon, according to Kepler’s law?

Example 16.1

Here C is a constant approximately equal to 1/100. The period is in seconds and the distance in kilometers.

16.29

Example 16.1 (continued)

SolutionThe Moon is located approximately 384,000 km above the Earth. The radius of the Earth is 6378 km. Applying the formula, we get.

16.30

According to Kepler’s law, what is the period of a satellite that is located at an orbit approximately 35,786 km above the Earth?

Example 16.2

SolutionApplying the formula, we get

16.31

This means that a satellite located at 35,786 km has a period of 24 h, which is the same as the rotation period of the Earth. A satellite like this is said to be stationary to the Earth. The orbit, as we will see, is called a geosynchronous orbit.

Example 16.2 (continued)

16.32

Figure 16.14 Satellite categories

16.33

Figure 16.15 Satellite orbit altitudes

16.34

Table 16.1 Satellite frequency bands

L: GPS

S: weather, NASA, Sirius/XM satellite radio

C: open satellite communications

Ku: popular with remote locations transmitting back to TV studio

Ka: communications satellites

16.35

Figure 16.16 Satellites in geostationary orbit

16.36

Figure 16.17 Orbits for global positioning system (GPS) satellites

16.37

Figure 16.18 Trilateration

16.38

Figure 16.19 LEO satellite system

UML: user mobile link

GWL: gateway link

ISL: intersatellite link

16.39

Figure 16.20 Iridium constellation

16.40

The Iridium system has 66 satellites in six LEO orbits, each at an

altitude of 750 km.

Note

16.41

Iridium is designed to provide direct worldwide voice and data

communication usinghandheld terminals, a service similar to cellular telephony but on a global scale.

Note

16.42

Figure 16.20 Teledesic

16.43

Teledesic has 288 satellites in 12 LEO orbits, each at an altitude of 1350 km.

Note