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CPE 426 Computer Networks

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CPE 426 Computer Networks Week 16: Last Chapter 16: Wireless NW Technologies TOPICS Chapter 16 Wireless NW Technologies Introduction ISM PAN ISM Bands WLAN Standard ... – PowerPoint PPT presentation

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Title: CPE 426 Computer Networks


1
CPE 426 Computer Networks
  • Week 16 Last
  • Chapter 16 Wireless NW Technologies

2
TOPICS
  • Chapter 16 Wireless NW Technologies
  • Introduction
  • ISM
  • PAN
  • ISM Bands
  • WLAN
  • Standard
  • Architecture
  • Contension
  • Wireless MAN and WiMax
  • Wireless WAN
  • Cellular Technologies
  • VSAT
  • GPS

3
16.2 Wireless Networks Taxonomy
  • ??????????????????????????????????????????????????
    ????????
  • ????????????????????????? License ????????
    License
  • ??????? Wireless Technologies ????????? PAN ?????
    WAN

4
16.2 Wireless Networks Taxonomy
5
16.3 Personal Area Network
  • ??????????????????????? ??????????????????????????
    ???????????????????
  • Handset ??? Telephone
  • Mouse ??? Keyboard
  • ?????????????? 3 ????

6
16.4 ISM Wireless Bands Used By LANs and PANs
  • ?????????????????????????????????????????????????
    Industrial, Scientific ??? Medical Group
    ?????????????????????? License ???????????????
    WLAN ??? PAN

7
16.5 Wireless LAN Technologies ??? WIFI
  • ??????????????????? IEEE 802.11
  • ?? 1999 ??????????????????? Wireless
    ??????????????????? Wi-Fi Alliance
  • Non-Profit Organization ??????????????????????????
    ? Wireless ???????????????? IEEE 802.11
  • ??????????????????? Wi-Fi Alliance ????????????

8
16.5 Wireless LAN Technologies ??? WIFI
9
16.6 Spread Spectrum Techniques
  • ??????????????????? Spread Spectrum ?????
  • ????? Performance ???????
  • ??????????????????????? Noise
  • ??? Bandwidth ????????????????????????
  • ?? 3 Technologies
  • DSSS ???????????? Digital ?????????(Exclusive
    OR) Code ????????? Pseudorandom Sequence
  • FHSS ????????? Analog ???????????????????????????
    ?????????????????????????????
  • OFDM ????????? FDM ???????? ?????????????????????
    ?????????????? Orthogonal ??? ????????????????????
    ?????????????

10
16.6 Spread Spectrum Techniques
11
16.7 Wireless LAN Standard ????? (IEEE
802.11-2007)
12
16.8 Wireless LAN Architecture
  • ?????????? Access Point (Base Station),
    Interconnection Mechanism (Switch or Router) ???
    Nodes (Wireless Station)
  • ???????????????????????
  • Ad Hoc Wireless Host ?????????????????????????
    Base Station
  • Infrastructure ???? Host ???????????????????
    Base Station
  • Set ??? Computer ??????????????????????????????
    Access Point ????? BSS (Basic Service Set)

13
16.8 Wireless LAN Architecture
14
16.9 Overlap, Association and 802.11 Frame Format
  • ??? Access Point ????????????????? ???????????
    Dead Zone
  • ?????? Access Point ???????????????????????
    Overlap ???? Host ??????????????????????????????
    Access Point
  • ???????????? Host ????????????? Association
    ????????????? Access Point
  • Frame ??? 802.11 ?????????????? MAC Address
    ??????? Access Point ??? Router

15
16.9 Overlap, Association and 802.11 Frame Format
16
16.10 Coordination ??????? Access Point
  • Access Point ??????????????????????
    ?????????????????????????????????????
    ???????????????????????????? ?????????????????????
  • Handoff (Hand Over) ???????????????????????????
    ????????????? Association ????? AP ???????
  • ????????????? Signal Strength ??????????????????
  • ?? AP ???????????? ???????? Mechanism ??? Access
    Point ???????? Computer ??????????????????????????
    ????? ???????? Association ??? Access Point
    ????????????????????

17
16.11 Contention-Free Access
  • PCF (Point Coordination Function) ?????? AP
    ???????????????? BSS ?????????????????????????????
    ???????????????????? ??????????????????????????
    ?????????????????? WLAN
  • DCF (Distributed Coordinated Function)
    ?????????????????? BSS ????? Random Access
    Protocol ????????? 802.11 ????? CSMA/CA ???
    ??????????????????????? RTS(Request to Send)
    ????????????? CTS (Clear to Send) ???? ???????????

18
16.11 Contention-Free Access
  • CSMA/CA Timing ????????? 802.11
  • Host ???????? ????????? Channel ???????????? DIFS
    Distributed Inter-Frame Space 50 Microsecond
    (SIFS2 Slot Time)
  • Host ?????????????????????? RTS
  • AP(???? Host ???????) ??????????? RTS
    ??????????????????? SIFS (Short Inter-Frame Space
    10 us) ??????? CTS ??????
  • Host ??????????? CTS ?????????????????? SIFS
    ????????????????????????????????? Slot Time
  • ????? Slot Time 20 us
  • ??????????????????????????? ??????????? SIFS
    ?????? Ack
  • ???????????? Ack ?????????????? ??????? Backoff
    ??? Retransmission

19
16.11 Contention-Free Access
20
16.12 Wireless MAN Technologies and WiMax
  • ?????????????????????????????????????????? ???
    IEEE 802.16 ???????????? WiMax ???????????????????
    ????????????? WiMax Forum ????????????????????????
    ?
  • ????? Version ???????????????????????
  • Fixed WiMax, IEEE 802.16-2004 ?????????????????
    Access Point ???????????????? Handoff
    ??????????????????????????????????????????????????
    ?????????
  • Mobile WiMax, IEEE 802.16e-2005 ????? Handoff
    ??????? AP ??????????????????? Laptop ???? Cell
    Phone ???
  • WiMax ??????????????????????????????? Last Mile
    ???????????????? Backhaul ????????????????????????
    ??? Site ???????????

21
16.12 Wireless MAN Technologies and WiMax
22
16.12 Wireless MAN Technologies and WiMax
  • The key features of WiMAX can be summarized as
    follows
  • Uses licensed spectrum (i.e., offered by
    carriers)
  • Each cell can cover a radius of 3 to 10 Km
  • Uses scalable orthogonal FDM
  • Guarantees quality of services (for voice or
    video)
  • Can transport 70 Mbps in each direction at short
    distances
  • Provides 10 Mbps over a long distance (10 Km)

23
16.13 PAN Technologies and Standard
  • IEEE 802.15

24
16.13 PAN Technologies and Standard
  • Bluetooth
  • The IEEE 802.15.1a standard evolved after vendors
    created Bluetooth technology as a short-distance
    wireless connection technology
  • The characteristics of Bluetooth technology are
  • Wireless replacement for cables (e.g., headphones
    or mouse)
  • Uses 2.4 GHz frequency band
  • Short distance (up to 5 meters, with variations
    that extend the range to 10 or 50 meters)
  • Device is master or slave
  • Master grants permission to slave
  • Data rate is up to 721 Kbps

25
16.13 PAN Technologies and Standard
  • Ultra Wideband (UWB)
  • The idea behind UWB communication is that
    spreading data across many frequencies
  • requires less power to reach the same distance
  • The key characteristics of UWB are
  • Uses wide spectrum of frequencies
  • Consumes very low power
  • Short distance (2 to 10 meters)
  • Signal permeates obstacles such as walls
  • Data rate of 110 at 10 meters, and up to 500 Mbps
    at 2 meters
  • IEEE unable to resolve disputes and form a single
    standard

26
16.13 PAN Technologies and Standard
  • Zigbee
  • The Zigbee standard (802.15.4) arose from a
    desire to standardize wireless remote control
    technology
  • especially for industrial equipment
  • Because remote control units only send short
    command
  • high data rates are not required
  • The chief characteristics of Zigbee are
  • Wireless standard for remote control, not data
  • Target is industry as well as home automation
  • Three frequency bands used (868 MHz, 915 MHz, and
    2.4 GHz)
  • Data rate of 20, 40, or 250 Kbps, depending on
    frequency band
  • Low power consumption
  • Three levels of security being defined

27
16.14 Short Distance Communication Technologies
????
  • ?????????? InfraRED ??? RFID
  • InfraRED
  • InfraRED technology is often used in remote
    controls
  • and may be used as a cable replacement (e.g., for
    a wireless mouse)
  • The Infrared Data Association (IrDA) has produced
    a set of standards that are widely accepted
  • The chief characteristics of the IrDA technology
    are
  • Family of standards for various speeds and
    purposes
  • Practical systems have range of one to several
    meters
  • Directional transmission with a cone covering 30
    Degree
  • Data rates between 2.4 Kbps (control) and 16 Mbps
    (data)
  • Generally low power consumption with very-low
    power versions
  • Signal may reflect from surfaces
  • but cannot penetrate solid objects

28
16.14 Short Distance Communication Technologies
????
  • Radio Frequency Identification (RFID)
  • RFID technology uses an interesting form of
    wireless communication to create a mechanism
  • A small tag contains identification information
  • that a receiver can pull from the tag
  • Some features of RFID
  • Over 140 RFID standards exist for a variety of
    applications
  • Passive RFIDs draw power from the signal sent by
    the reader
  • Active RFIDs contain a battery
  • which may last up to 10 years
  • Limited distance
  • although active RFIDs extend farther than passive
  • Can use frequencies from less than 100 MHz to
    868-954 MHz
  • Used for
  • inventory control, sensors, passports, and other
    applications

29
16.15 Wireless WAN Technologies
  • ????????
  • Cellular Communication System
  • Satellite Communication System

30
16.15.1 Cellular Communication System
  • ????????????????????? Voice ?????? Mobile Phone
  • ?????????? Cell ???????????? PTN
  • ??????????????????????????????????? Data ????
  • Architecture ????? Cell ??????????
  • Tower
  • ???????? Tower ?????????????? Mobile Switching
    Center ?????????????????????????????????????
    Handoff ??????? Cell
  • Tower ????? Omnidirectional Antenna
    ??????????????????? (??????????)
  • Cell ????? Cell ?????????????????????????
    ?????????
  • ???????????????????? Cell ?????????
    ???????????????????????

31
16.15.1 Cellular Communication System
32
16.16 Cell Clusters and Frequency Reuse
  • ???????? Cell ???????????????????????????????????
    ????? Cell ???????????? Cluster ????? Cluster
    ???????????????????????????????
  • ????????????????????????????????? Cell
    ??????????????
  • 7 cell cluster ???????????????????? ?????????????

33
16.16 Cell Clusters and Frequency Reuse
34
16.17 Generations of Cellular Technologies
  • 1G, 2G, 2.5G, 3G, 3.5G, 4G
  • 1G
  • Began in the late 1970s, and extended through the
    1980s
  • Originally called cellular mobile radio
    telephones
  • used analog signals to carry voice 
  • 2G and 2.5G
  • Began in the early 1990s and continues to be used
  • The main distinction between 1G and 2G arises
  • because 2G uses digital signals to carry voice
  • The label 2.5G is used for systems that extend a
    2G system
  • to include some 3G features

35
16.17 Generations of Cellular Technologies
  • 1G, 2G, 2.5G, 3G, 3.5G, 4G
  • 3G and 3.5G
  • Began in the 2000s
  • Focuses on the addition of higher-speed data
    services
  • A 3G system offers download rates of 400 Kbps to
    2 Mbps, and is intended to support applications
    such as web browsing and photo sharing
  • 3G allows a single telephone to roam across the
    world
  • 4G
  • Began around 2008
  • Focuses on support for real-time multimedia
  • such as a television program or high-speed video
  • They include multiple connection technologies
  • such as Wi-Fi and satellite
  • at any time, the phone automatically chooses the
    best connection technology available

36
16.17 Generations of Cellular Technologies
  • A variety of standards have evolved
  • (many attempted to choose an approach and create
    a standard)
  • The European Conference of Postal and
    Telecommunications Administrators chose a TDMA
    technology known as Global System for Mobile
    Communications (GSM)
  • In the United States, each carrier created a
    network with its own technology
  • Motorola invented a TDMA system known as iDEN
  • Most US and Asian carriers adopted a CDMA
    approach that was standardized as IS-95A
  • Japan created a TDMA technology known as PDC
  • Figure 16.18 summarizes major 2G standards
  • and some of the 2.5G standards that evolved

37
16.17 Generations of Cellular Technologies
38
16.17 Generations of Cellular Technologies
  • The standards listed in the figure each provide a
    basic communication mechanism over which many
    services can operate
  • General Packet Radio Service (GPRS) for Internet
    access
  • Short Message Service (SMS) is used for texting
  • Wireless Application Service (WAP) is used to
    access Internet
  • Multimedia Messaging service (MMS) is used for
    multi-media
  • GPRS technologies have been further developed
    that use more sophisticated modulation and
    multiplexing techniques (to increase data rates)
  • Enhanced Data rate for GSM Evolution (EDGE)
  • known as Enchanced GPRS (EGPRS), offers higher
    transfer rates
  • EDGE Evolution provides higher rates

39
16.17 Generations of Cellular Technologies
  • Service providers pushed to make technologies
    interoperable
  • the industry consolidated many of the approaches
    from 2G into a few key standards
  • IS-136, PDC, IS-95A, and EDGE all influenced the
    design of UMTS, a technology that uses Wideband
    CDMA (WCDMA)
  • IS-95B was extended to produce CDMA 2000, as in
    Figure 16.19
  • Several standards evolved for 3G data services
  • EVDO (Evolution Data Optimized or Evolution Data
    Only) and EVDV emerged at approximately the same
    time
  • They combine CDMA and FDM to increase the overall
    performance
  • High-Speed Downlink Packet Access (HSDPA) offers
    download speeds of 14 Mbps

40
16.17 Generations of Cellular Technologies
41
16.18 VSAT Satellite Technology
  • ???????????????????????????????????????????
    ???????? ???????????????? Commercial ???????????
  • VSAT (Very Small Aperture Terminal)
    ?????????????????????????????????????????????
    ??????????
  • ??????????????????????????????????????????????????
    ???????????
  • VSAT ?????????????? 3 ???? ???????????????????????
    ?????????????????

42
16.18 VSAT Satellite Technology
43
16.19 GPS Satellites
  • Global Positioning System ????????????
    ????????????????????????
  • Accuracy between 2-20 meters
  • (military ones have higher accuracy)
  • 24 total satellites orbit the earth
  • Satellites arranged in six (6) orbital planes
  • Provides time synchronization
  • that can be used in some communications

44
HW 10(Last) Chapter 16
  • Download
  • ?????????????????????????? ???????????????????
    5-310

45
End of Chapter Week 16
  • Course Ends
  • Final Exam
  • Up to Week 16
  • ??????????? Midterm ???? MT ?????????
    ???????????? IP Address
  • No Calculator
  • ????????? Final 50 (6 ??? 60 ?????)
  • ??????????????????????? ????????
  • IP Subnet ????????????? ?????????? Midterm

46
End of Chapter Week 16
  • Final Exam List
  • 1. IP Address and Subnetting
  • 2. TCP/UDP
  • 3. Routing General
  • 4. IP Routing
  • 5. QoS and IP Telephony
  • 6. NW Security and WLAN
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