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Wireless and Mobile Networks
Lecture 1. Introduction and Overview
Lecture Objectives
• Motivate the study of Wireless and Mobile Networks
• Briefly introduce the different technologies and concepts that will be discussed in the unit
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MOTIVATION
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Wireless Comes of Age
• Guglielmo Marconi invented the wireless telegraph in 1896
• Communication by encoding alphanumeric characters in an analog signal • Sent telegraphic signals across the Atlantic Ocean
• Communications satellites launched in 1960s • Advances in wireless technology
• Radio, television, mobile telephone, communication satellites,… • More recently
• Wireless networking and cellular technology, mobile apps, Internet of Things
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Cellular (Mobile) Phone
• Started as a replacement to the wired telephone
• Early generations offered voice and limited data
• Current third and fourth generation systems • Voice
• Texting
• Social networking • Mobile apps
• Mobile Web
• Mobile commerce • Video streaming
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Global Cellular Network (1)
• Growth
• 11 million users in 1990 • Over 7 billion today
• Mobile devices • Convenient
• Location aware
• Only economical form of communications in some places
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Global Cellular Network (2)
Source: http://www.smh.com.au/technology/sci-tech/the-long-inexorable-decline-of-the-landline-in-australia-20161221-gtfjsp.html
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Global Cellular Network (3)
• 1G: analog
• Australia: 1987-1999
• 2G: digital voice, voice services with some moderate rate data services
• Australia: 1993-2017
• 3G: packet networks (Universal Mobile Phone Service – UMTS, CDMA2000)
• Australia: 2003-current
Image credits:
Redrum0486 – http://en.wikipedia.org/wiki/File:DynaTAC8000X.jpg (license: CC BY-SA 3.0)
Discostu – https://en.wikipedia.org/wiki/File:Nokia_3310_blue.jpg (public domain) Justin14-https://en.wikipedia.org/wiki/IPhone_3G#/media/File:IPhone_PSD_White_3G.png (license:CCBY-SA3.0)
Motorola DynaTAC 8000X (c. 1984)
Nokia 3310 (c. 2000)
Apple iPhone 3G (c. 2008)
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Global Cellular Network (4)
• 4G – New wireless approach (OFDM)
• Higher spectral efficiency
• 100 Mbps for high mobility users
• 1 Gbps for low mobility access
• LongTermEvolution(LTE)andLTE-Advanced
• 5G (beyond 2020): ongoing development. Goals: • Data rates up to 10 Gbps
• <10mslatency
• D2Dcommunication
• Better coverage, better energy efficiency
Image credits:
Rafael Fernandez - https://en.wikipedia.org/wiki/Pixel_2#/media/File:Pixel_2_and_Pixel_2_XL.svg (license: CC BY-SA 4.0)
Google Pixel 2 (c. 2017)
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Mobile device revolution (1)
• Originally just mobile phones
• Today’s devices
• Multi-megabit Internet access • Mobile apps
• High megapixel digital cameras
• Access to multiple types of wireless networks • Wi-Fi, Bluetooth, 3G, and 4G
• Several on-board sensors
• Key to how many people interact with the world around them
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Mobile device revolution (2)
• Better use of spectrum
• Decreased costs
• Limited displays and input capabilities
• Tablets provide balance between smartphones and PCs
• Long distance
• Cellular 3G and 4G
• Local areas • Wi-Fi
• Short distance
• Bluetooth, ZigBee
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Problems with Wireless (1)
• Wireless is convenient and less expensive, but not perfect
• Limitations and political and technical difficulties inhibit wireless
technologies
• Wireless channel
• Line-of-sight is best but not required
• Signals can still be received • Transmission through objects
• Reflections off objects
• Scattering of signals
• Diffraction around edges of objects
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Problems with Wireless (2)
• Wireless channel
• Reflections can cause multiple copies of the signal to arrive • At different times and attenuations
• Creates the problem of multipath fading
• Signals add together to degrade the final signal
• Noise
• Interference from other users
• Doppler spread caused by movement
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Combating Problems
• Modulation – use a signal format to send as many bits as possible
• Error control coding – add extra bits so errors are detected/corrected.
• Adaptive modulation and coding – dynamically adjust modulation and coding to current channel conditions.
• Equalization – counteract the multipath effects of the channel.
• Multiple-input multiple-output systems – use multiple antennas • Point signals strongly in certain directions
• Send parallel streams of data.
• Direct sequence spread spectrum – expand the signal bandwidth
• Orthogonal frequency division multiplexing – break a signal into many lower rate bit streams
• Each is less susceptible to multipath problems.
• Security techniques
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OVERVIEW OF OTHER TOPICS OF THE UNIT
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Wireless NIC and Access Point (AP)
• Each host on WLAN uses wireless network interface cards (NIC) with built-in antennas
• Wireless NICs send signals
• Among several hosts, all at the same level (ad hoc networking) • Through radio waves to a fixed access point (AP)
• AP may be attached to a wired LAN (infrastructure mode)
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Mobile IP
• Enable computers to maintain Internet connectivity while moving from one Internet attachment point to another
• Mobile – user's point of attachment changes dynamically and all connections are automatically maintained despite the change
• Nomadic - user's Internet connection is terminated each time the user moves and a new connection is initiated when the user dials back in
• New, temporary IP address is assigned
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Wireless Broadband Access
• Higher data rates: broadband wireless technology • Graphics, video, audio
• Same advantages as with all wireless services: convenience and reduced cost
• Service can be deployed faster than fixed service • No cost of cable plant
• Service is mobile, deployed almost anywhere
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• Started in 1999
WiMax (IEEE 802.16)
• The WiMAX (Worldwide Interoperability for Microwave Access) Forum
• Industryconsortium
• Formed to promote the 802.16 standards and to develop interoperability specifications
• Create wireless metropolitan area networks (WMANs)
• Provide public network service to fee-paying customers
• Use point-to-multipoint architecture with stationary rooftop or tower-mounted antennas
• Once considered a viable 4G implementation, WiMax is losing ground to LTE
• Still used to provide wireless Internet access
• Used to provide broadband wireless access in areas of South Australia not covered by fixed broadband
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Bluetooth and Personal Area Networks
• Wireless Personal Area Networks
• Short-range communication
• Low-cost, low-energy to provide long battery life
• Several standards have been provided
• Universal short-range wireless capability
• Available globally for unlicensed users
• Devices within 10 m can share up to 2.1 Mbps or 24 Mbps of capacity
• Supportsopen-endedlistofapplications
• Data, audio, graphics, video
• Started as IEEE 802.15.1
• New standards come from the Bluetooth Special Interest Group (Bluetooth SIG) • Industry consortium
• Bluetooth 2.0, 2.1, 3.0, and 4.0
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Wireless Sensor Networks
Cloud of Smoke
Radio Range
Predicted position for the Cloud of Smoke
Data Collection and Monitoring Agency
Path of the Response
Credit: D. P. Agrawal and Q-A Zeng, Introduction to Wireless & Mobile Systems, 4th Edition. CENGAGE, 2016.
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Wireless Mesh Networks
Internet
Backbone IGW 2
Mesh Clients
IGW 1 MR1
MR4
MR2 MR3
MR5
MR6
Credit: D. P. Agrawal and Q-A Zeng, Introduction to Wireless & Mobile Systems, 4th Edition. CENGAGE, 2016. Google WiFi image credit: The Verge, https://www.theverge.com/2016/12/6/13843536/google-wifi-review-mesh-router-system-vs-eero
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Unless otherwise stated:
Sources for this lecture
Cory Beard, William Stallings. Wireless Communication Networks and Systems, 1st edition. Pearson Higher Education, 2016
(mostly chapter 1)
All material copyright 2016
Cory Beard and William Stallings, All rights reserved
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