Documents
Resources
Learning Center
Upload
Plans & pricing Sign in
Sign Out

Wireless_ Guide to Wireless Communications

VIEWS: 182 PAGES: 13

BREW stands for Binary Runtime Environment for Wireless. From the basic level,, BREW platform is a handheld device, embedded chip or operating system interface abstraction layer. You can use it as a PC environment, Microsoft Windows, Win32 API. BREW platform is a set of local implementation and to compile and link the binary library, optimized to make use of wireless services, applications and resources. It controls the flow or the flow of events into the application, according to the corresponding event to start, stop, suspend or resume the application. BREW execution environment can be found in the run-time application and any related extensions.

More Info
									Wireless# Guide to Wireless Communications   10-1




Chapter 10
Wireless Wide Area Networks

At a Glance

Instructor’s Manual Table of Contents
•   Overview

•   Objectives

•   Teaching Tips

•   Quick Quizzes

•   Class Discussion Topics

•   Additional Projects

•   Additional Resources

•   Key Terms

•   Technical Notes for Hands-On Projects
Wireless# Guide to Wireless Communications                                                     10-2



Lecture Notes

Overview
        Chapter 10 describes wireless wide area networks (WWANs) and how they are used.
        Students will learn the applications that can be used on a digital cellular telephone.
        Next, students will learn how cellular telephony functions. Chapter 10 also lists features
        of the various generations of cellular telephony. Finally, students will learn how satellite
        transmissions work.


Objectives
    •   Describe wireless wide area networks (WWANs) and how they are used
    •   Describe the applications that can be used on a digital cellular telephone
    •   Explain how cellular telephony functions
    •   List features of the various generations of cellular telephony
    •   Discuss how satellite transmissions work


Teaching Tips
Cellular Telephone Applications
    1. Describe various applications of digital cellular telephones, including:
          a. Browse the Internet
          b. Send and receive short messages and e-mails
          c. Participate in videoconferencing
          d. Receive various sorts of information
          e. Run a variety of business applications
          f. Connect to corporate networks
          g. Watch television or on-demand movies
          h. Take and transmit pictures and short movies
          i. Locate family members and employees using GPS

    2. Explain that Short Message Services (SMS) is one of the most widely used applications
       today. SMS allows for the delivery of short, text-based messages between wireless
       devices. SMS messages are limited to about 160 characters.

    3. Describe some of the applications of SMS, such as:
          a. Person-to-person
          b. Agent-to-person
          c. Information broadcast services
          d. Software configuration
          e. Advertising
Wireless# Guide to Wireless Communications                                                     10-3


Teaching
                Read more about SMS at: http://en.wikipedia.org/wiki/Short_message_service.
Tip



How Cellular Telephony Works
    1. Mention that there are two keys to cellular telephone networks: cells, and the fact that
       all transmitters and cell phones operate at a low power level.

    2. Explain that in a typical city, the cells measure approximately 10 square miles. At the
       center of each cell is a cell transmitter connected to a base station. Each base station is
       connected to a mobile telecommunications switching office (MTSO), which is a link
       between the cellular network and the wired telephone world. The MTSO controls all
       transmitters and base stations. Use Figure 10-1 to show a cellular network.

    3. Explain that all transmitters and cell phones operate at a low power level. This feature
       enables the signal to stay confined to the cell. A signal at a specific frequency does not
       go far beyond the cell area, so the same frequency can be used in other cells at the same
       time, except in adjacent cells. Use Figure 10-2 to illustrate your explanation.

    4. Mention that cell phones have special codes associated with them. Use Table 10-1 to
       describe these codes.

    5. Use Figure 10-3 to describe the differences between handoff and roaming, as explained
       in this section.

    6. Describe the steps to receive a call. Use Figure 10-4 to illustrate your explanation.


Teaching        Learn more about cellular networks at:
Tip             http://en.wikipedia.org/wiki/Cellular_network.



Digital Cellular Telephony
    1. This section describes the main characteristics of digital cellular telephony.

First Generation Cellular Telephony

    1. Explain that the first generation of wireless cellular technology is known, appropriately
       enough, as First Generation (1G). 1G uses analog signal modulated using FM, and is
       based on Advanced Mobile Phone Service (AMPS).
Wireless# Guide to Wireless Communications                                                 10-4



Teaching        Read more about Advanced Mobile Phone Service (AMPS) at:
Tip             http://en.wikipedia.org/wiki/Advanced_Mobile_Phone_System.


    2. Explain that AMPS operates in the 800-900 MHz frequency spectrum. Each channel is
       30 KHz wide with a 45 KHz passband. There are 832 frequencies available. AMPS uses
       Frequency Division Multiple Access (FDMA). FDMA allocates a single cellular
       channel with two frequencies to one user at a time. Use Figure 10-5 to illustrate your
       explanation.

    3. Mention that 1G networks use circuit-switching technology. Circuit-switching makes a
       dedicated and direct physical connection between the caller and the recipient.

Teaching
                Learn more about 1G at: http://en.wikipedia.org/wiki/1G.
Tip

Second Generation Cellular Telephony

    1. Describe the main characteristics of 2G networks. 2G networks transmit data between
       9.6 Kbps and 14.4 Kbps in the 800 MHz and 1.9 GHz frequencies. 2G networks are also
       circuit-switching, but use digital transmissions.

    2. Describe some of the benefits of using digital transmission, such as:
          a. Uses the frequency spectrum more efficiently
          b. Over long distances, the quality of the voice transmission does not degrade
          c. Difficult to decode and offers better security
          d. On average, digital transmissions use less transmitter power
          e. Enables smaller and less expensive individual receivers and transmitters

    3. Use Figure 10-6 and Figure 10-7 to illustrate the multiple access technologies supported
       by 2G networks, including:
          a. Time Division Multiple Access (TDMA)
          b. CDMA
          c. Global System for Mobile communications (GSM)

Teaching
                For more information about GSM, visit: www.gsmworld.com/index.shtml.
Tip

2.5 Generation Cellular Telephony

    1. Define 2.5 Generation as an interim step between 2G and 3G technologies. 2.5G
       operates at a maximum speed of 384 Kbps. 2.5G networks are packet-switched.
Wireless# Guide to Wireless Communications                                                  10-5

    2. Describe the advantages of packet switching over circuit switching, including:
          a. Packet switching is much more efficient since it can handle more transmissions
              over a given channel
          b. Permits an always-on connection

    3. Describe the following three 2.5G network technologies:
          a. General Packet Radio Service (GPRS)
          b. Enhanced Data rates for GSM Evolution (EDGE)
          c. CDMA2000 1xRTT

Teaching
                Learn more about GPRS at: http://en.wikipedia.org/wiki/GPRS.
Tip

Third Generation Cellular Telephony

    1. Explain that 3G is intended to be a uniform and global standard for cellular wireless
       communication. Describe the standard data rates defined by this technology, including:
          a. 144 Kbps for a mobile user
          b. 386 Kbps for a slowly moving user
          c. 2 Mbps for a stationary user

    2. Describe the following network technologies supported by 3G networks:
          a. CDMA2000 1xEVDO
          b. CDMA2000 1xEVDV
          c. Wideband CDMA (W-CDMA)
          d. High-Speed Downlink Packet Access (HSDPA)

Teaching
                For more information about 3G networks, visit: http://en.wikipedia.org/wiki/3G.
Tip

    3. Use Figure 10-8 to show the digital cellular migration path. Use Table 10-2 to compare
       the different digital cellular technologies. Finally, use Figure 10-9 to compare the data
       rates between cellular technologies.


Quick Quiz 1
    1. ____________________ (SMS) allows for the delivery of short, text-based messages
       between wireless devices, such as cellular telephones and pagers.
       Answer: Short Message Services

    2. The ____________________ (MTSO) is the link between the cellular network and the
       wired telephone world, and controls all transmitters and base stations in the cellular
       network.
       Answer: mobile telecommunications switching office
Wireless# Guide to Wireless Communications                                               10-6

    3. 1G technology is based on the ____________________ (AMPS).
       Answer: Advanced Mobile Phone Service

    4. True or False: W-CDMA adds a packet-switched data channel to a circuit-switched
       voice channel.
       Answer: True


Client Software
    1. This section introduces the most common types of digital cellular client software: WAP,
       i-mode, Java, and BREW. These technologies will enable business applications to be
       used in virtually any location.

Wireless Application Protocol (WAP and WAP Version 2)

    1. Explain that Wireless Application Protocol (WAP) and WAP2 provide a standard way
       to transmit, format, and display Internet data for devices such as cell phones.

    2. Describe the main characteristics of WAP. WAP was developed in 1997, and enables
       devices to send and receive Internet text-only data. A WAP cell phone runs a tiny
       browser program called a microbrowser that uses Wireless Markup Language (WML)
       instead of HTML. Use Figure 10-10 to show a WAP display.

    3. Define a WAP gateway, sometimes called WAP proxy, as a computer running special
       conversion software used to translate between WML and HTML. Many features of
       HTML are not supported in WML.

Teaching
                Read more about WAP at: http://en.wikipedia.org/wiki/WAP.
Tip

    4. Explain that WML is based on the Extensible Markup Language (XML). Defined by the
       World Wide Web Consortium (W3C), XML is similar to HTML, which uses tags to
       describe how an item should be displayed on the screen. A WML document is called a
       deck that contains one or more blocks, known as cards. Use Figure 10-11 to illustrate
       your explanation.

    5. Describe the main characteristics of WAP2. WAP2 is based on XHTML (an extension
       of HTML version 4), and can display graphics and multiple font styles on color screen
       equipped mobile devices. WAP2 includes a protocol stack that allows it to support
       TCP/IP directly. WAP2 defines a new profile, an extension of XML, specifically to
       support mobile devices. WAP2 is backward compatible with WAP version 1.

i-Mode

    1. Define i-mode as an Internet access system owned by the Japanese corporation NTT
       DoCoMo. i-mode is based on compact HTML (cHTML), a subset of HTML designed
       for mobile devices. cHTML has its own set of tags and attributes
Wireless# Guide to Wireless Communications                                                     10-7

    2. Mention that i-mode users pay for the service by the amount of information downloaded
       plus a service charge.


Teaching        For more information about i-mode, visit:
Tip             www.i-mode.com/services/imode/index.html.


Java

    1. Explain that the Java programming language was developed by Sun Microsystems as an
       object-oriented language used for general-purpose business programming, as well as
       interactive Web sites.

    2. Define Java 2 Micro Edition (J2ME) as a subset of Java specifically developed for
       programming wireless devices, which enables a cellular phone to access remote
       applications and e-mail as well as run programs on the cellular phone itself.

Teaching
                Learn more about J2ME at: http://en.wikipedia.org/wiki/J2me.
Tip

Binary Runtime Environment for Wireless (BREW)

    1. Define BREW as a thin software environment, a very small program that resides on a
       wireless device and is capable of running applications that can be downloaded by the
       device on demand. BREW is compatible with Java, C, and C++.

    2. Explain that BREW efficiently uses the limited amount of memory available. It
       occupies only a small amount of flash memory and dynamically allocates RAM for
       applications. BREW can also be used with other applications and software.

Teaching
                For more information about BREW, visit: http://brew.qualcomm.com/brew/en/.
Tip



Digital Cellular Challenges and Outlook
    1. This section describes the challenges still faced by digital cellular communications.

Competing Technologies

    1. Describe the problems of a lack of global standards, as explained in this section.
Wireless# Guide to Wireless Communications                                                    10-8

Limited Spectrum

    1. Explain why spectrum is the single largest factor limiting the development of 3G,
       especially in the United States, where the U.S. Department of Defense currently uses
       the 1.7 GHz band for satellite control and military purposes.

Costs

    1. Explain that 3G monthly service fees for data transmission can run high. User cost for
       3G pales in comparison to costs for the carriers to build entire 3G networks.

Other Wireless Options

    1. Compare the advantages and disadvantages of using 3G networks and WLANS, as
       explained in this section.

    2. Describe the impact of WiMAX in the use and deployment of 3G networks.


Satellite Broadband Wireless
    1. Explain that the use of satellites for personal wireless communication is fairly recent.

    2. Use Figure 10-12 to describe the following broad categories of satellite use:
       a. Satellites are used to acquire scientific data and perform research in space
       b. Satellites look at Earth from space
       c. Satellites includes devices that are simply reflectors

Satellite Transmissions

    1. Explain that satellites generally send and receive on one of four frequency bands. Use
       Table 10-3 to describe these bands.

    2. Explain that the frequency band affects the size of the antenna. Use Figure 10-13 to
       illustrate your explanation.

    3. Describe the two classes of service provided by satellites:
       a. Consumer class service
       b. Business class service

    4. Use Figure 10-14 to explain the types of connectivity offered by satellites, including:
       d. Point-to-point
       e. Point-to-multipoint
       f. Multipoint-to-multipoint
Wireless# Guide to Wireless Communications                                                    10-9

    5. Describe the modulation techniques used by satellite communications, including:
       a. Binary phase shift keying (BPSK)
       b. Quadrature phase shift keying (QPSK)
       c. Eight-phase shift keying (8-PSK)
       d. Quadrature amplitude modulation (QAM)

    6. Describe the multiplexing techniques used by satellite communications, including:
       a. Permanently assigned multiple access (PAMA)
       b. Multi-channel per carrier (MCPC)
       c. Demand assigned multiple access (DAMA)


Low Earth Orbit (LEO)

    1. Explain that LEO satellites circle the Earth at an altitude of 200 to 900 miles. LEO
       satellites must travel at high speeds so that the Earth’s gravity will not pull them back
       into the atmosphere. LEO satellites’ area of Earth coverage (called the footprint) is
       small. Use Figure 10-15 to illustrate your explanation.

    2. Mention that LEO systems have a low latency and use low-powered terrestrial devices
       (RF transmitters). LEO systems’ round trip time is between 20 to 40 milliseconds.

    3. Describe the following two groups of LEO satellites:
       a. Big LEO
       b. Little LEO


Teaching        Read more about Low Earth Orbit (LEO) at:
Tip             www.thetech.org/exhibits_events/online/satellite/4/4a/4a.1.html.


Medium Earth Orbit (MEO)

    1. Explain that (MEO) satellites orbit the Earth at altitudes between 1,500 and 10,000
       miles. Some MEO satellites orbit in near-perfect circles, have a constant altitude, and
       travel at a constant speed. Other MEO satellites revolve in elongated orbits called
       highly elliptical orbits (HEOs).

    2. Describe the advantages of MEO satellites, including:
       a. Can circle the Earth in up to 12 hours
       b. Have a bigger Earth footprint; use Figure 10-16 to illustrate this point

    3. Explain that one of the main disadvantages of MEO satellites is that higher orbit
       increases the latency. MEO round trip time is between 50 to 150 milliseconds.

    4. Describe the main characteristics of HEO satellites. HEO satellites have a high apogee
       (maximum altitude) and a low perigee (minimum altitude) and can provide good
       coverage in extreme latitudes. Orbits typically have a 24-hour period.
Wireless# Guide to Wireless Communications                                                   10-10



Teaching        Read more about elliptical orbit at:
Tip             www.thetech.org/exhibits_events/online/satellite/4/4d/4d.1.html.


Geosynchronous Earth Orbit (GEO)

    1. Explain that GEO satellites are stationed at an altitude of 22,282 miles. A GEO
       satellite’s orbit matches the rotation of the Earth and moves as the Earth moves. GEO
       satellites can provide continuous service to a very large footprint (only three GEO
       satellites are needed to cover the entire Earth). GEO satellites have high latencies of
       about 250 milliseconds and require high-powered terrestrial sending devices.


Teaching        Read more about geosynchronous equatorial orbit at:
Tip             www.thetech.org/exhibits_events/online/satellite/4/4c/4c.1.html.


    2. Use Table 10-4 to summarize some of the satellites in use today, their purpose, and the
       companies that operate them.

    3. Use Table 10-5 to provide a summary of satellite orbits, advantages, and disadvantages.

Experimental Technology

    1. Explain that NASA has been experimenting with ultra-lightweight, solar-powered,
       high-flying aircraft since the 1990s that can be used in place of a satellite or ground-
       based antenna tower infrastructure.

Satellite Technology Outlook

    1. Explain that satellites can provide wireless communication service in areas not covered
       by cellular or WiMAX. Satellites today are enabling carriers to offer Internet access and
       voice calls to passengers and crews across large oceans, as well as in high latitudes and
       remote corners of the Earth. Satellites can also make these services available in many
       other unpopulated areas.


Quick Quiz 2
    1. A WML document is called a deck that contains one or more blocks, known as
       ____________________.
       Answer: cards

    2. The ____________________ programming language was developed by Sun
       Microsystems as an object-oriented language used for general-purpose business
       programming, as well as interactive Web sites.
       Answer: Java
Wireless# Guide to Wireless Communications                                                 10-11

    3. The single largest factor limiting the development of 3G is ____________________.
       Answer: spectrum

    4. ____________________ (LEO) satellites circle the Earth at an altitude of 200 to 900
       miles (321 to 1,448 kilometers).
       Answer: Low earth orbit


Class Discussion Topics
    1. In a cellular network, what are the differences between handoff and roaming?

    2. What is the Extensible Markup Language (XML)?


Additional Projects
    1. Instruct your students to call a local cellular telephony company and ask for the
       coverage area and the prices for local coverage and roaming services.

    2. Ask your students to use the Internet to research other types of earth orbits used by
       satellite communications and write a report with the most important points, including
       advantages and disadvantages of each type of orbit.


Additional Resources
    1. Wireless Short Message Service (SMS):
       www.iec.org/online/tutorials/wire_sms/index.html

    2. How a GSM Network Operates:
       www.cellular.co.za/howagsm.htm

    3. Wi-Fi VoIP and Cellular Network Integration:
       www.verisign.com/static/031270.pdf

    4. AMPS:
       www.auditmypc.com/acronym/AMPS.asp

    5. GSM:
       http://en.wikipedia.org/wiki/GSM

    6. GPRS:
       www.m-indya.com/gprs/index.htm

    7. 3G Today:
       www.3gtoday.com/wps/portal/3ghome?page=home
Wireless# Guide to Wireless Communications                                           10-12

    8. Wireless Application Protocol (WAP):
       www.iec.org/online/tutorials/wap/index.html

    9. I-mode:
       http://en.wikipedia.org/wiki/I-mode

    10. Sun Java Wireless Toolkit for CLDC:
        http://java.sun.com/products/sjwtoolkit/

    11. Binary Runtime Environment for Wireless (BREW):
        http://en.wikipedia.org/wiki/BREW

    12. Geostationary Operational Environmental Satellite:
        http://en.wikipedia.org/wiki/GEOS_%28satellite%29


Key Terms
        Generation (2.5G) — An interim step between 2G and 3G digital cellular networks.
        8-PSK — A modulation technique in which the phase of the carrier is shifted in 45
        degree increments and 4 bits can be transmitted per phase change.
        Advanced Mobile Phone Service (AMPS) — The standard used for 1G analog cellular
        transmissions based on FDMA.
        Binary Runtime Environment for Wireless (BREW) — A thin software interface
        layer that resides on a wireless device and creates a runtime environment.
        cards — A small block of a WML document.
        CDMA2000 1xEVDO — The 3G digital cellular technology that is a migration from
        CDMA2000 1xRTT.
        CDMA2000 1xEVDV — The 3G digital cellular technology that is a migration from
        CDMA2000 1xEVDO.
        CDMA2000 1xRTT — A 2.5G digital cellular network technology that is a migration
        from CDMA (1xRTT stands for 1-times Radio Transmission Technology).
        cell — A smaller area of a mobile network.
        compact HTML (cHTML) — A subset of HTML that is designed for mobile devices.
        control channel — A special frequency that cellular phones use for communication
        with a base station.
        deck — A WML document.
        Enhanced Data rates for GSM Evolution (EDGE) — A 2.5G digital cellular network
        technology that boosts GPRS transmissions.
        Extensible Markup Language (XML) — A definition language that uses tags to
        describe the data.
        First Generation (1G) — The first generation of wireless cellular telephony that is
        transmitted at 9.6 Kbps using analog circuit-switched technology.
        General Packet Radio Service (GPRS) — A 2.5G network technology that can
        transmit up to 114 Kbps.
        geosynchronous earth orbit (GEO) satellites — Satellites that are stationed at an
        altitude of 22,282 miles (35,860 kilometers).
Wireless# Guide to Wireless Communications                                                 10-13

        GSM (Global Systems for Mobile communications) — One of three multiple access
        technologies that make up the 2G digital cellular system that uses a combination of
        FDMA and TDMA.
        i-mode — An Internet access system for digital cellular telephones.
        Java — An object-oriented programming language used for general-purpose business
        programming and interactive Web sites.
        Java 2 Micro Edition (J2ME) — A subset of Java specifically developed for
        programming wireless devices.
        latency — Delays caused by signals that must travel over a long distance.
        low earth orbit (LEO) satellites — Satellites that orbit the Earth at an altitude of 200
        to 900 miles (321 to 1,448 kilometers).
        medium earth orbit (MEO) satellites — Satellites that orbit the Earth at altitudes
        between 1,500 and 10,000 miles (2,413 to 16,090 kilometers).
        mobile telecommunications switching office (MTSO) — The connection between a
        cellular network and wired telephones.
        profile — An extension of the XML language.
        roaming — The automatic transfer of the RF signal when moving from one cellular
        network to another network.
        Second Generation (2G) — The second generation of cellular telephony that uses
        circuit-switched digital networks.
        Short Message Services (SMS) — A delivery system for short, text-based messages
        sent between wireless devices such as cellular telephones and pagers.
        Third Generation (3G) — Digital cellular wireless generation of cellular telephony
        with speeds up to 2 Mbps.
        Wideband CDMA (W-CDMA) — The 3G digital cellular technology that is a
        migration from EDGE.
        wireless wide area network (WWAN) — A network that spans a geographical area as
        large as an entire country or even the entire world.


Technical Notes for Hands-On Projects
Project 10-1: This project requires a pencil and a piece of paper.

Project 10-2: This project requires a Web browser, an Internet connection, and a WAP
              emulator.

Project 10-3: This project requires a Web browser and an Internet connection.

Project 10-4: This project requires a Web browser and an Internet connection.

Project 10-5: This project requires a Web browser and an Internet connection.

								
To top