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Chapter 16 Wireless WANs: Cellular Telephone and Satellite Networks

Cellular telephony is designed to provide communications between two moving units, called mobile stations (MSs), or between one mobile unit and one stationary unit, often called a land unit. | Chapter 16 Wireless WANs: Cellular Telephone and Satellite Networks Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 16. 16-1 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, often called a land unit. Frequency-Reuse Principle Transmitting Receiving Roaming First Generation Second Generation Third Generation Topics discussed in this section: 16. Figure 16.1 Cellular system 16. Figure 16.2 Frequency reuse patterns 16. AMPS is an analog cellular phone system using FDMA. Note 16. Figure 16.3 Cellular bands for AMPS 16. Figure 16.4 AMPS reverse communication band 16. Figure 16.5 Second-generation cellular phone systems 16. Figure 16.6 D-AMPS 16. D-AMPS, or IS-136, is a digital cellular phone system using TDMA and FDMA. Note 16. Figure 16.7 GSM bands 16. Figure 16.8 GSM 16. Figure 16.9 Multiframe components 16. GSM is a digital cellular phone system using TDMA and FDMA. Note 16. Figure 16.10 IS-95 forward transmission 16. Figure 16.11 IS-95 reverse transmission 16. IS-95 is a digital cellular phone system using CDMA/DSSS and FDMA. Note 16. The main goal of third-generation cellular telephony is to provide universal personal communication. Note 16. Figure 16.12 IMT-2000 radio interfaces 16. 16-2 SATELLITE NETWORKS 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. Orbits Footprint Three Categories of Satellites GEO Satellites MEO Satellites LEO Satellites Topics discussed in this section: 16. Figure 16.13 Satellite orbits 16. 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. Example 16.1 (continued) Solution The Moon is located approximately 384,000 km above the Earth. The radius of the Earth is 6378 km. Applying the formula, we get. 16. 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 Solution Applying the formula, we get 16. 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. Figure 16.14 Satellite categories 16. Figure 16.15 Satellite orbit altitudes 16. Table 16.1 Satellite frequency bands 16. Figure 16.16 Satellites in geostationary orbit 16. Figure 16.17 Orbits for global positioning system (GPS) satellites 16. Figure 16.18 Trilateration 16. Figure 16.19 LEO satellite system 16. Figure 16.20 Iridium constellation 16. The Iridium system has 66 satellites in six LEO orbits, each at an altitude of 750 km. Note 16. Iridium is designed to provide direct worldwide voice and data communication using handheld terminals, a service similar to cellular telephony but on a global scale. Note 16. Figure 16.20 Teledesic 16. Teledesic has 288 satellites in 12 LEO orbits, each at an altitude of 1350 km. Note 16.