COURSE INTRODUCTION http://wireless.web.unc.edu Jasleen Kaur Fall - - PDF document
8/22/17 COMP 635: WIRELESS & MOBILE COMMUNICATIONS COURSE INTRODUCTION http://wireless.web.unc.edu Jasleen Kaur Fall 2017 1 Introductions q Names q BS/MS, First-year Grad, Senior Grad? q If youre new, where have you come from? q Your
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q Names q BS/MS, First-year Grad, Senior Grad? q If you’re new, where have you come from? q Your CS interests? q Why this course? q What are you expecting to learn from this course?
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q Two aspects of mobility:
Ø User mobility:
Ø Device portability:
q Wireless vs. mobile Examples
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20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015* Mobile cellular telephone subscriptions Fixed-telephone subscriptions Active Mobile-broadband subscriptions Fixed broadband subscriptions Internet Users
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q Unrestricted mobility
Ø Unplugged from power outlet
q Significantly lower cost
Ø No cable, low labor cost, low maintenance
q Ease
Ø Minimum infrastructure - scatter and play
q Ubiquity
Ø Available everywhere like water/air - holy grail
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q Personal communication q Replacement of fixed networks
Ø Access to remote areas Ø Sensors in difficult terrains (weather, earth activities) Ø Flexibility for trade shows Ø LANs in historic buildings
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q Location aware services
Ø Resource-discovery, e.g., printer, fax, phone, server etc.
q Follow-me services
Ø Call-forwarding, mobile desktop
q Information services
Ø “push”: e.g., current special offers in the supermarket Ø “pull”: e.g., where is the Black Forrest Cheese Cake?
q Privacy services
Ø Who should gain knowledge about the location? Ø What information should environment gain about you?
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q Vehicular Traffic:
Ø Personal communication using GSM/UMTS Ø News, road condition, weather, music via DAB/DVB-T Ø Position via GPS Ø Local ad-hoc network with vehicles close-by
Ø Transport networks (buses, trains)
q Emergencies
Ø Early transmission of patient data to the hospital
Ø Quick replacement of a fixed infrastructure in case of
Ø Crisis, war, ...
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q Traveling salesmen/employee
Ø Access to central (consistent) customer database Ø Mobile office Ø Location-aware services (call-forwarding, hotel printer)
q Entertainment, education, ...
Ø Outdoor Internet access Ø Intelligent travel guide with up-to-date location-
Ø Ad-hoc networks for multi user games
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q Wireless sensing
Ø Using RF signals for geolocation Ø Using RF signals to sense physical objects
Ø “Piggy-back” RF signals for no-power communication Ø …
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.-Ing. JochenH. Schiller www.jochenschiller .de MC - 2009
Pager
messages Mobile phones
PDA
Smartphone
Laptop/Notebook
Sensors, embedded controllers
www.scatterweb.net
No clear separation between device types possible (e.g. smart phones, embedded PCs, …)
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q Wide-area communications (cellular, satellite-based):
Ø GSM, AMPS, UMTS, cdma2000, DAB, DVB-T
q Wireless LANs:
Ø 802.11x series Ø Small-to-medium range, higher bit-rates
q Short-range:
Ø Bluetooth Ø Low bit-rates
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Courtesy: Romit Roy Choudhary, Duke University
QuickTime™ and a decompressor are needed to see this picture.Internet
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q Power consumption
Ø Low quality displays, small disks due to limited battery Ø Limited compute power: CPU power consumption ~ CV2f
q Limited memory
Ø Limited usage of mass memories with moving parts Ø Flash-memory as alternative
q Limited user interfaces
Ø Compromise between size of fingers and portability Ø Integration of voice recognition, abstract symbols
q Loss of data
Ø E.g., errors, theft
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q Providing seamless support for mobility
Ø Without disrupting users or applications
q Signal propagation:
Ø Signal attenuation (as signal propagates)
Ø Higher loss-rates due to interference
q Frequency-usage:
Ø Restrictive regulations of frequencies
Ø Spatial reuse (facilitated by signal attenuation)
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q Constraints on performance:
Ø Low transmission rates (few Mbps) Ø Higher delays, higher jitter
q Exploiting/dealing with diversity / dynamism:
Ø Antenna selection, Time diversity, Frequency selection
q Energy conservation:
Ø Wireless devices often battery-powered
q Security-related issues:
Ø Lower security, simpler active attacking
Ø Broadcast medium è easier to snoop or tamper with
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.-Ing. JochenH. Schiller www.jochenschiller .de MC - 2009
Application layer Transport layer Network layer Data link layer Physical layer service location new/adaptive applications multimedia congestion/flow control quality of service addressing, routing device location hand-over authentication media access/control multiplexing encryption modulation interference attenuation frequency
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q Background:
Ø Physical Layer (modulation, interference, attenuation) Ø MAC Protocols (coordinated access, random access) Ø Mobile IP Ø Ad-hoc Routing Protocols Ø TCP in Wireless
q Recent proposals:
Ø Enhance physical performance, make MAC more
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q Initial set of lectures (by me):
Ø Will cover all background material
q Review of recent publications
Ø Paper presentations (by you) Ø Critical reviews (by you)
q Semester-long projects (groups of 2 welcome)
Ø Topics: investigating, designing something new
Ø Preferably on one of the focus topics for this course
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q Project topics: investigating or designing something
Ø Experimental study
Ø Formal analysis
Ø Design and evaluation of new mechanisms/application
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q Paper Presentations: 25% q Critical Reviews: 20% q Projects (groups of 2 are welcome):
Ø Progress: 30% Ø Presentation + report: 10%
q Final Exam (oral): 15% q Class Participation:
Ø Will be used to potentially bump up (or down) half a
q All percentage points above are flexible by 5-10%
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q Several reputable texts for background material:
Ø Jochen Schiller, “Mobile Communications”. Ø William Stallings, “Wireless Communications &
Ø Theodore S. Rappaport, “Wireless Communications”. Ø Pahlavan & Krishnamurthy, “Principles of Wireless
q Unfortunately, none is sufficient by itself for this
q Nearly half the course will cover recent research
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