Wireless Communication Systems

1
Wireless Communication Systems
Background of Wireless Communication
Wireless Communication Technology
Wireless Networking and Mobile IP
Wireless Local Area Networks
Wireless Personal Area Networks
Wireless Metropolitan Area Networks
Wireless Wide Area Networks
Wireless Communication Technologies
2
Objectives

• Review various wireless networks
• List the technologies of a wireless metropolitan
  area network
• Describe the features of a wireless wide area
  network
• Discuss the future of wireless networking

3
Wireless Personal Area Networks

• Wireless networks classified into four broad
  categories
• Wireless personal area network (WPAN) Hand-held
  and portable devices slow to moderate
  transmission speeds
• Wireless local area network (WLAN) i.e., IEEE
  802.11a/b/g/n
• Wireless metropolitan area network (WMAN) Range
  up to 50 kilometers
• Wireless wide area network (WWAN) Connects
  networks in different geographical areas

4
Wireless Personal Area Networks (continued)
Figure 12-1 Wireless network distances
5
Wireless Personal Area Networks (continued)
Figure 12-2 Point-to-point transmission
6
Wireless Personal Area Networks (continued)
Figure 12-3 Point-to-multipoint transmission
7
Wireless Personal Area Networks (continued)

• WPANs encompass technology designed for portable
  devices
• PDAs, cell phones, tablet or laptop computers
• Low transmission speeds
• Three main categories
• IEEE 802.15 standards
• Radio frequency ID (RFID)
• IrDA

8
WPANs IEEE 802.15.1 (Bluetooth)

• Bluetooth uses short-range RF transmissions
• Users can connect wirelessly to wide range of
  computing and telecommunications devices
• Rapid and ad hoc connections between devices
• 802.15.1 adapted and expanded from Bluetooth
• Designed for area of about 10 meters
• Rate of transmission below 1 Mbps
• Two types of 802.15.1 network topologies
• Piconet
• Scatternet

9
WPANs IEEE 802.15.1 (continued)

• Piconet When two 802.15.1 devices come within
  range, automatically connect
• Master Controls wireless traffic
• Slave Takes commands from master
• Piconet has one master and at least one slave
• Active slave Connected to piconet and sending
  transmissions
• Parked slave Connected but not actively
  participating

10
WPANs IEEE 802.15.1 (continued)
Figure 12-4 Piconet
11
WPANs IEEE 802.15.1 (continued)
Figure 12-5 Slave device detected by a master
device
12
WPANs IEEE 802.15.1 (continued)

• Devices in piconet can be in one of five modes
• Standby Waiting to join a piconet
• Inquire Device looking for devices to connect to
• Page Master device asking to connect to specific
  slave
• Connected Active slave or master
• Park/Hold Part of piconet but in low-power state
• Scatternet Group of piconets in which
  connections exist between different piconets
• 802.15.1 uses FHSS

13
WPANs IEEE 802.15.1 (continued)
Figure 12-6 Scatternet
14
WPANs IEEE 802.15.1 (continued)
Table 12-1 Comparison of 802.15.1 speed
15
WPANs IEEE 802.15.3

• Created in response to limitations of 802.15.1
• High-rate WPANs
• Two main applications
• Video and audio distribution for home
  entertainment systems
• High-speed digital video transfer
• High-density MPEG2 transfer between video
  players/gateways and multiple HD displays
• Home theater
• PC to LCD projector
• Interactive video gaming
• High speed data transfer

16
WPANs IEEE 802.15.3 (continued)

• Differences between 802.15.3 and 802.15.1
• Quality of Service (QoS)
• Security
• High data rates
• Spectrum utilization
• Coexistence

Table 12-2 IEEE 802.15.3 security modes
17
WPANs IEEE 802.15.3 (continued)

• 802.15.3a Will support data transfers up to 110
  Mbps between max of 245 devices at 10 meters
• Ultrawideband (UWB)
• Intended to compete with USB 2.0 and FireWire
• IEEE 802.15.3b task group working on improving
  implementation and interoperability of 802.15.3
• IEEE 802.15.3c task group developing alternative
  physical layer standard that could increase
  speeds up to 2 Gbps

18
WPANs IEEE 802.15.4 (ZigBee)

• Sometimes preferable to have low-speed, low-power
  wireless devices
• Size can be dramatically reduced
• IEEE 802.15.4 standard addresses requirements for
  RF transmissions requiring low power consumption
  and cost

Table 12-3 IEEE 802.15.4 data rates and
frequencies
19
WPANs IEEE 802.15.4 (continued)

• ZigBee Alliance Industry consortium that
  promotes 802.15.4 standard

Figure 12-7 ZigBee and IEEE 802.15.4
20
WPANs Radio Frequency ID (RFID)
Figure 12-8 RFID tag
21
WPANs Radio Frequency ID (continued)

• Passive RFID tags No power supply
• Can be very small
• Limited amount of information transmitted
• Active RFID tags Must have power source
• Longer ranges/larger memories than passive tags

Table 12-4 RFID tags
22
WPANs IrDA

• Infrared Data Association
• IrDA specifications include standards for
  physical devices and network protocols they use
  to communicate
• Devices communicate using infrared light-emitting
  diodes
• Recessed into device
• Many design considerations affect IrDA performance

23
WPANs IrDA (continued)
Figure 12-9 IrDA diodes in device
24
WPANs IrDA (continued)

• IrDA drawbacks
• Designed to work like standard serial port on a
  personal computer, which is seldom used today
• Cannot send and receive simultaneously
• Strong ambient light can negatively impact
  transmissions
• Angle and distance limitation between
  communicating devices

25
Wireless Metropolitan Area Networks

• Cover an area of up to 50 kilometers (31 miles)
• Used for two primary reasons
• Alternative to an organizations wired backhaul
  connection
• i.e., T1, T3, T4 lines
• Fiber Optics
• Very expensive to install backhaul connections
• Often less expensive to use a WMAN to link remote
  sites

26
Wireless Metropolitan Area Networks (continued)

• Used for two primary reasons (continued)
• Overcome last mile connection
• Connection that begins at a fast Internet service
  provider, goes through local neighborhood, and
  ends at the home or office
• Slower-speed connection
• Bottleneck

27
Wireless Metropolitan Area Networks Free Space
Optics

• Optical, wireless, point-to-point, line-of-sight
  wireless technology
• Able to transmit at speed comparable to Fiber
  Optics
• Transmissions sent by low-powered IR beams
• Advantages compared to fiber optic and RF
• Lower installation costs
• Faster installation
• Scaling transmission speed
• Good security
• Atmospheric conditions can affect transmission

28
Wireless Metropolitan Area Networks Local
Multipoint Distribution Service (LMDS)

• LMDS provides wide variety of wireless services
• High-frequency, low-powered RF waves have limited
  range
• Point-to-multipoint signal transmission
• Signals transmitted back are point-to-point
• Voice, data, Internet, and video traffic
• Local carrier determines services offered
• LMDS network is composed of cells
• Cell size affected by line of site, antenna
  height, overlapping cells, and rainfall

29
Wireless Metropolitan Area Networks LMDS
(continued)
Figure 12-11 LMDS cell
30
Wireless Metropolitan Area Networks Multichannel
Multipoint Distribution Service (MMDS)

• Many similarities to LMDS
• Differs in area of transmission
• Higher downstream transmission, lower upstream
  transmission, greater range
• In homes, alternative to cable modems and DSL
  service
• For businesses, alternative to T1 or fiber optic
  connections
• MMDS hub typically located at a very high point
• On top of building, towers, mountains

31
Wireless Metropolitan Area Networks MMDS
(continued)

• Hub uses point-to-multipoint architecture
• Multiplexes communications to multiple users
• Tower has backhaul connection
• MMDS uses cells
• Single MMDS cell as large as 100 LDMS cells
• Receiving end uses pizza box antenna
• Advantages
• Transmission range, cell size, low vulnerability
  to poor weather conditions
• Still requires line-of-site, not encrypted

32
Wireless Metropolitan Area Networks IEEE 802.16
(WiMAX)

• High potential
• Can connect IEEE 802.11 hotspots to Internet
• Can provide alternative to cable and DSL for last
  mile connection
• Up to 50 kilometers of linear service area range
• Does not require direct line of sight
• Provides shared data rates up to 70 Mbps
• Uses scheduling system
• Device competes once for initial network entry

33
Wireless Metropolitan Area Networks IEEE 802.16
(continued)

• Currently addresses only devices in fixed
  positions
• 802.16e will add mobile devices to the standard
• IEEE 802.20 (MBWA) standard Sets standards for
  mobility over large areas
• Will permit users to roam at high speeds
• WiMAX base stations installed by a wireless
  Internet service provider (wireless ISP) can send
  high-speed Internet connections to homes and
  businesses in a radius of up to 50 km (31 miles)

34
Wireless Wide Area Networks (WWANS)

• Wireless networks extending beyond 50 kilometers
  (31 miles)
• Two primary technologies
• Digital cellular telephony
• Satellites

35
Digital Cellular Telephony

• Two keys to cellular telephone networks
• Coverage area divided into cells
• Cell transmitter at center
• Mobile devices communicate with cell center via
  RF
• Transmitters connected to base station,
• Each base station connected to a mobile
  telecommunications switching office (MTSO)
• Link between cellular and wired telephone network
• All transmitters and cell phones operate at low
  power
• Enables frequency reuse

36
Digital Cellular Telephony (continued)
Figure 12-13 Frequency reuse
37
Satellites

• Satellite use falls into three broad categories
• Acquire scientific data, perform research
• Examine Earth
• Military and weather satellites
• Reflectors
• Relay signals
• Communications, navigation, broadcast

38
Satellites (continued)

• Satellite systems classified by type of orbit
• Low earth orbiting (LEO) Small area of earth
  coverage
• Over 225 satellites needed for total coverage of
  earth
• Must travel very fast
• Medium earth orbiting (MEO) Larger area of
  coverage than LEO
• Do not need to travel as fast
• Geosynchronous earth orbiting (GEO) orbit
  matches earths rotation
• Fixed position
• Very large coverage area

39
Satellites (continued)
Figure 12-14 LEO coverage area
40
The Future of Wireless Networks

• IEEE 802.11 subcommittees currently at work
• 802.11d Supplementary to 802.11 MAC layer
• Promote worldwide use of 802.11 WLANs
• 802.11f Inter-Access Point Protocol (IAPP)
• Will assist with faster handoff from one AP to
  another
• 802.11h Supplement to MAC layer to comply with
  European regulations for 5 GHz WLANs
• 802.11j Incorporates Japanese regulatory
  extensions to 802.11a standard
• 802.11s Defines a mesh wireless network
• Devices configure themselves and are intelligent

41
Summary

• WPANs encompass technology that is designed for
  portable devices, typically PDAs, cell phones,
  and tablet or laptop computers at transmission
  speeds lower than the other types of networks
• The IEEE 802.15 standards address wireless
  personal area networks
• RFID is not a standard but is a technology that
  uses RF tags to transmit information
• IrDA technology uses infrared transmissions to
  transmit data at speeds from 9,600 bps to 16 Mbps

42
Summary (continued)

• FSO is an optical, wireless, point-to-point
  wireless metropolitan area network technology
• LMDS can provide a wide variety of wireless
  services, including high-speed Internet access,
  real-time multimedia file transfer, remote access
  to local area networks, interactive video,
  video-on-demand, video conferencing, and
  telephone
• MMDS has many of similarities to LMDS, yet has a
  longer distance range

43
Summary (continued)

• The IEEE 802.16 (WiMAX) standard holds great
  promise for providing higher throughput rates for
  fixed location and mobile users
• Wireless wide area network (WWAN) technology
  encompasses digital cellular telephony and
  satellite
• The future of wireless networks is hard to
  predict, but most experts agree that wireless
  networks will be faster, more global, and easier
  to use in the years ahead

44
Acknowledgement

• Based on Chapter 12 of CWNA Guide to Wireless
  LANs, Second Edition
• Part of CWNA Curriculum for Certified Wireless
  Network Administrator

45
QA

• ?

46
Assignment 12

• Compare FSO, LMDS, MMDS, WiMAX with each other?
  Which WMAN technology do you think will be
  adopted in future and which will not be? Give
  Reasons to justify your judgment?