Mobile & Wireless

Communications
CoSc 5132

Tesfa Tegegne (PhD)

Course overview
1. Introduction
2. Wireless Transmission
3. Media Access Control
4. Wireless Telecommunication / Cellular
Network
5. Satellite Systems ----Personal Reading
6. Wireless LAN
7. Mobile Network Protocols/Mobile IP
8. Mobile Ad hoc Networks and Sensor
Networks
Evaluation

• Reading assignments

• Article/chapter review (three reviews

&Presentation)

• Short paper for publication in a conference or journal

• Final exam
 References
• Mobile communications 2nd Edition, Jochen Schiller

• Introduction to Wireless and Mobile Systems (Second Edition) Dharma P.

Agrawal – University of Cincinnati Qing-An Zeng – University of Cincinnati ,
2006

• Fundamentals of Mobile and Pervasive Computing,

Frank Adelstein , Sandeep KS Gupta (Author), Golden
Richard III (Author), Loren Schwiebert (Author)

• IEEE/ACM journals and conference

Introdcution

• Wireless communications and mobility

• History of wireless/mobile communications
• Market penetration and growth
• Areas of research
 Computers for the next decade
• Computers are integrated (>95% embedded systems!)
• small, cheap, portable, replaceable - no more separate devices (see M.
Weiser/invisible computer)
• Technology is in the background
• computer are aware of their environment and adapt (“location awareness”)
• computer recognize the location of the user and react appropriately (e.g., call
forwarding, message forwarding, “context awareness”)
• Advances in technology
• more computing power in smaller devices
• flat, lightweight displays with low power consumption
• new user interfaces due to small dimensions
• more bandwidth per cubic meter
• multiple wireless interfaces: NFC, piconets, wireless LANs, wireless WANs,
regional wireless telecommunication networks, VLC etc.
Mobile Communications
• Two aspects of mobility:
• user mobility: users communicate (wireless) “anytime, anywhere, with anyone”
• device portability: devices can be connected anytime, anywhere to the network

• Wireless vs. mobile Examples

/ ✓  high performance cluster
✓ ✓ notebook in a hotel, on-board networks
✓  wireless LANs in historic buildings, ad-hoc
infrastructure replacement
✓ ✓ Smartphone

• The demand for mobile communication created already decades ago the need for
integration of wireless networks into existing fixed networks:
• local area networks: standardization of IEEE 802.11
• Internet: Mobile IP extension of the internet protocol IP
• wide area networks: e.g., internetworking of GSM and ISDN, VoIP over WLAN and POTS
 Applications
• Vehicles
• transmission of news, road condition, weather, music/video via DAB+/DVB-
T2/LTE
• personal communication using GSM/UMTS/LTE
• positioning via GPS/Galileo/Glonass/Beidou
• local ad-hoc network with vehicles close-by to prevent accidents, guidance
system, redundancy
• vehicle data (e.g., from busses, high-speed trains) can be transmitted in
advance for maintenance
• Emergencies
• early transmission of patient data to the hospital, current status, first
diagnosis
• replacement of a fixed infrastructure in case of earthquakes, hurricanes,
fire etc.
• crisis, war, ...
 Vehicular Ad hoc Networks (VANET)
• Vehicles Transformed into “Computers on the Wheels” or
“Networks on the Wheel”
• Vehicular Communication System (VCS):- Tow main types of
communications:
– Vehicle to Vehicle (V2V) communication:
– Vehicle to Infrastructure (V2I) communication:
• VCS provides real-time and safety applications
• Real-time applications:
– Traffic congestion and routing information
– Mobile infotainment (combined information and entertainment)
– High-speed tolling and many others
• Safety applications:
– Emergency
– Collision
– Car accident and other safety warnings
Typical application: road traffic

UMTS, WLAN,
DAB+, LTE, GSM,
cdma2000, TETRA, ...

Smartphone,
Laptop, Tablet, LTE,
GSM, UMTS, WLAN,
Bluetooth, NFC ...
Mobile and wireless services – Always Best Connected

LTE LAN
DSL/ GSM/GPRS 53 kbit/s 10 Mbit/s 1 Gbit/s,
WLAN Bluetooth 500 kbit/s WLAN
50 Mbit/s 300 Mbit/s

UMTS
2 Mbit/s

GSM/EDGE 384 kbit/s,

DSL/WLAN 6 Mbit/s
UMTS, GSM
384 kbit/s
 Application II
• Traveling salesmen
• direct access to customer files stored in a central location
• consistent databases for all agents
• mobile office

• Replacement of fixed networks

• remote sensors, e.g., weather, earth activities
• flexibility for trade shows
• LANs in historic buildings

• Entertainment, education, ...

• outdoor Internet access
• intelligent travel guide with up-to-date location dependent information
• ad-hoc networks for multi user games
Location dependent services
• Location aware services
• what services, e.g., printer, phone, server etc. exist in the local environment

• Follow-on services
• automatic call-forwarding, transmission of the actual workspace to the current
location

• Information services
• “push”: e.g., current special offers in the supermarket
• “pull”: e.g., where is the Black Forrest Cheese Cake?

• Support services
• caches, intermediate results, state information etc. “follow” the mobile device
through the fixed network

• Privacy
• who should gain knowledge about the location
Mobile Devices

Specialized PDAs Laptop/Notebook/Converti

• graphical displays ble
• character recognition • fully functional
• application specific • standard applications
• ruggedized

Sensors,
embedded
controllers

Smart Smartphone/Tablet
Classical mobile phones • tiny virtual keyboard
dust
• voice, data • voice recognition
• simple graphical displays • simple(r) versions
• robust, water proof of standard applications

performance
 Effects of device portability
• Power consumption
• limited computing power, low quality displays, small disks due to limited battery capacity
• CPU: power consumption ~ CV²f
• C: internal capacity, reduced by integration
• V: supply voltage, can be reduced to a certain limit
• f: clock frequency, can be reduced temporally

• Loss of data
• higher probability, has to be included in advance into the design (e.g., defects, theft)

• Limited user interfaces

• compromise between size of fingers and portability
• integration of character/voice recognition, abstract symbols

• Limited fast memory (always in relation to e.g. PCs)

• Limited/no usage of mass memories with moving parts
• flash-memory or ? as alternative
Wireless networks in comparison to fixed networks
• Higher loss-rates due to interference
• emissions of, e.g., engines, lightning

• Restrictive regulations of frequencies

• frequencies have to be coordinated, useful frequencies are almost all occupied

• Lower transmission rates

• local some Mbit/s, regional sometimes only, e.g., 53kbit/s with GSM/GPRS or about 150 kbit/s
using EDGE – some Mbit/s with LTE (shared!) – compare country side vs. downtown

• Higher delays, higher jitter

• connection setup time with GSM in the second range, several hundred milliseconds for other
wireless systems – in ms range with LTE

• Lower security, simpler active attacking

• radio interface accessible for everyone, base station can be simulated, thus attracting calls from
mobile phones

• Always shared medium

• secure access mechanisms important
Early history of wireless communication

• Many people in history used light for communication

• heliographs, flags (“semaphore”), ...
• 150 BC smoke signals for communication;
(Polybius, Greece)
• 1794, optical telegraph, Claude Chappe

• Here electromagnetic waves are

of special importance:
• 1831 Faraday demonstrates electromagnetic induction
• J. Maxwell (1831-79): theory of electromagnetic Fields, wave equations
(1864)
• H. Hertz (1857-94): demonstrates with an experiment the wave character
of electrical transmission through space (1886, in Karlsruhe, Germany)

Prof. Dr.-Ing. Jochen H. Schiller

www.jochenschiller.de Mobile
Communications
History of wireless communication I
• 1896 Guglielmo Marconi
• first demonstration of wireless telegraphy (digital!)
• long wave transmission, high transmission power necessary (> 200kW)

• 1907 Commercial transatlantic connections

• huge base stations (30 100m high antennas)

• 1915 Wireless voice transmission New York - San Francisco

• 1920 Discovery of short waves by Marconi

• reflection at the ionosphere
• smaller sender and receiver, possible due to the invention of the vacuum tube (1906, Lee DeForest
and Robert von Lieben)

• 1926 Train-phone on the line Hamburg - Berlin

• wires parallel to the railroad track

Prof. Dr.-Ing. Jochen H. Schiller

www.jochenschiller.de Mobile
Communications
History of wireless communication II
• 1928 many TV broadcast trials (across Atlantic, color TV, news)
• 1933 Frequency modulation (E. H. Armstrong)
• 1958 A-Netz in Germany
• analog, 160MHz, connection setup only from the mobile station, no handover, 80%
coverage, 1971 11000 customers
• 1972 B-Netz in Germany
• analog, 160MHz, connection setup from the fixed network too (but location of the mobile
station has to be known)
• available also in A, NL and LUX, 1979 13000 customers in D
• 1979 NMT at 450MHz (Scandinavian countries)
• 1982 Start of GSM-specification
• goal: pan-European digital mobile phone system with roaming
• 1983 Start of the American AMPS (Advanced Mobile Phone System, analog)
• 1984 CT-1 standard (Europe) for cordless telephones

Prof. Dr.-Ing. Jochen H. Schiller

www.jochenschiller.de Mobile
Communications
History of wireless communication III
• 1986 C-Netz in Germany
• analog voice transmission, 450MHz, hand-over possible, digital signaling, automatic
location of mobile device
• was in use until 2000, services: FAX, modem, X.25, e-mail, 98% coverage

• 1991 Specification of DECT

• Digital European Cordless Telephone (today: Digital Enhanced Cordless
Telecommunications)
• 1880-1900MHz, ~100-500m range, 120 duplex channels, 1.2Mbit/s data transmission, voice
encryption, authentication, up to several 10000 user/km2, used in more than 50 countries

• 1992 Start of GSM

• in D as D1 and D2, fully digital, 900MHz, 124 channels
• automatic location, hand-over, cellular
• roaming in Europe - now worldwide in more than 200 countries
• services: data with 9.6kbit/s, FAX, voice, ...

Prof. Dr.-Ing. Jochen H. Schiller

www.jochenschiller.de Mobile
Communications
History of wireless communication IV
• 1994 E-Netz in Germany
• GSM with 1800MHz, smaller cells
• as Eplus in D (1997 98% coverage of the population)

• 1996 HiperLAN (High Performance Radio Local Area Network)

• ETSI, standardization of type 1: 5.15 - 5.30GHz, 23.5Mbit/s
• recommendations for type 2 and 3 (both 5GHz) and 4 (17GHz) as wireless ATM-networks (up to
155Mbit/s)

• 1997 Wireless LAN - IEEE802.11

• IEEE standard, 2.4 - 2.5GHz and infrared, 2Mbit/s
• already many (proprietary) products available in the beginning

• 1998 Specification of GSM successors

• for UMTS (Universal Mobile Telecommunications System) as European proposals for IMT-2000
• Iridium
• 66 satellites (+6 spare), 1.6GHz to the mobile phone

Prof. Dr.-Ing. Jochen H. Schiller

www.jochenschiller.de Mobile
Communications
History of wireless communication V
• 1999 Standardization of additional wireless LANs
• IEEE standard 802.11b, 2.4-2.5GHz, 11Mbit/s
• Bluetooth for piconets, 2.4GHz, <1Mbit/s
• decision about IMT-2000
• several “members” of a “family”: UMTS, cdma2000, DECT, …
• Start of WAP (Wireless Application Protocol) and i-mode
• first step towards a unified Internet/mobile communication system
• access to many services via the mobile phone
• 2000 GSM with higher data rates
• HSCSD offers up to 57,6kbit/s
• first GPRS trials with up to 50kbit/s (packet oriented!)
• UMTS auctions/beauty contests
• Hype followed by disillusionment (50 B$ paid in Germany for 6 licenses!)
• Iridium goes bankrupt
• 2001 Start of 3G systems
• Cdma2000 in Korea, UMTS tests in Europe, Foma (almost UMTS) in Japan

Prof. Dr.-Ing. Jochen H. Schiller

www.jochenschiller.de Mobile
Communications
 History
• 2007
• 2002 • over 3.3 billion subscribers for
mobile phones (NOT 3 bn people!)
• WLAN hot-spots start to spread
• 2008
• 2003 • “real” Internet widely available on
• UMTS starts in Germany mobile phones (standard browsers,
decent data rates)
• Start of DVB-T in Germany replacing • 7.2 Mbit/s HSDPA, 1.4 Mbit/s HSUPA
analog TV available in Germany, more than 100
operators support HSPA worldwide,
• 2005 first LTE tests (>100 Mbit/s)
• WiMax starts as DSL alternative (not • 2009 – the story continues with
mobile) netbooks, iPhone, VoIPoWLAN…
• first ZigBee products • 2010 – LTE available in some cities, new
frequencies allocated
• 2006 • Reuse of old analog TV bands, LTE as
• HSDPA starts in Germany as fast UMTS DSL replacement for rural areas
download version offering > 3 Mbit/s • 2015 – VoLTE, LTE@700MHz, LTE
• WLAN draft for 250 Mbit/s (802.11n) advanced
using MIMO • 2020 -2022– Start of 5G
• WPA2 mandatory for Wi-Fi WLAN devices • 2022-2023—standardized 6G
Questions & Tasks

• The history of wireless and mobile communication is not only a history of

successes, but also failures. Iridium, HiperLAN, WAP, WiMax are examples.
Find reasons for their failure (or at least limited success)!
• Check the current, newest standards for mobile communications (3gpp),
WLAN (IEEE), PANs (Zigbee, Bluetooth)

Prof. Dr.-Ing. Jochen H. Schiller

www.jochenschiller.de Mobile
Communications
Market for mobile communications

• Although the growth in wireless and mobile communication systems

has slowed down, these technologies have still a huge market
potential.

• The following figure shows the increasing number of subscribers to

mobile phone services
worldwide (2014)
Market for mobile communications

Number of mobile (cellular) subscriptions worldwide

from 1993 to 2021: 8.6 billion.
Internet uptake has accelerated during the pandemic
Percentage of individuals using the Internet, 2021*
5G Connections

2 billion 5G connections by 2025

Developed Asia & the US to lead the way
Marekt peneteration…
Market penetrartion…
Mobile Pentration rate in Ethiopia
 Recent Wireless Innovations
• 5G: Beyond 4G. 2020. 100X LTE • Super Wi-Fi: Long-distance internet access
using TV white spaces
• CognitiveRadio: Find unused channels
and use them • ZigBee: Trade name for 802.15.4 personal
• 802.11ac: 500Mbps-1 Gbps Wi-Fi area networks. Like Wi-Fi for 802.11

• Wi-Fi Direct: Point-to-Point Wi-Fi • 802.11ax: user throughput 4x 801.11ac

without access point
• Small Cells: 10m to 2km. Includes Micro • Low Powered Wide Area (LPWA): For IoT.
LTE Cat-M1, ECGSM-IoT, LTE Cat-NB1,
cells, Pico cells, Femto cells LoRa, Sigfox, RPMA, FlexNet, WiSUN,
Synergize
• 802.22: Wireless regional area network
using white spaces in TV channels
• Mobile Satellite Services: 500 kbps and up
Internet of Things

• More IoT devices than mobile phones in 2018

• 70% of wide-area IoT devices will use cellular
• Cisco predicts $457B by 2020 with a CAGR of 28%
• Statista predicts $8.9T in 2020
• Accenture estimates IIoT $14.2T by 2020
• Manufacturing dominates IoT connections
Challenges

• Security is a major concern.

• Authentication schemes.
• Encryption schemes.
• Payment schemes.
• E-tickets getting a service by producing a ticket.
• E-currency issues like anonymity, creditworthiness, non-repudiation,
etc. (bitcoin)

• Mobile agent security

Research Areas

Wireless Communication
– transmission quality (bandwidth, error rate, delay)
– modulation, coding, interference
– media access, regulations
– ...
Mobility
– location dependent services
– location transparency
– quality of service support (delay, jitter, security)
– ...
Portability
– power consumption
– limited computing power, sizes of display, ...
– usability