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CS436: SPECIAL TOPICS IN COMPUTER NETWORKS Dr. Mustafa Y. ElNainay Department of Computer and Systems Engineering Alexandria University Email: [email protected] 1
CS436: SPECIAL TOPICS IN
COMPUTER NETWORKS
Dr. Mustafa Y. ElNainay
Department of Computer and Systems
Engineering
Alexandria University
Email: [email protected]
1
Welcome
Instructor: Dr. Mustafa Y. ElNainay
Email: [email protected]
Office
TA: Eng. Arsany Hany
Course Information
Network Topology , network architecture , Date link layer , IEEE
standars (Ethemet, Token bus & token Ring) , Packet Radio Network ,
Fast Ethernet , Distributed Queue Dual Bus , FDDI Network layer ,
Routing Routines & congestion control.
The Course Distribution Hours:
Weekly Hours Marks
Exam
Duratio
n
(Hours)
Lectures Tut Lab Total Class Lab Oral Final Total
4 1 5 25 25 75 125 3
Course Breakdown Week
Topic
Materials
Assignments
1 (7/2) Network 1 Revision +
Introduction to Mobile and
Wireless Networks
Kurose Ch 1 +
Case Study +
Schiller Ch1 +
Notes
2 (14/2) No lectures Setup NS3 if not yet
3 (21/2) Wireless and Mobile Transport
Layer Protocols
Schiller Ch9 NS3 Lab 1
4 (28/2) Mobile Network Layer Mobile IP
Kurose Ch6 +
Schiller Ch8 +
Perkins RFC5944
Sheet # 1
5 (7/3) No lectures Sheet#2
6 (14/3) Multi-hop Wireless Network
Ad Hoc Routing Protocol - 1
Notes + Papers NS3 Lab 2
Course Breakdown
5
7 (21/3) Wireless MAC Schiller Ch3 NS3 Lab 3 Sheet#3
8 (28/3) Midterm Exams
9 (4/4) Multimedia Networking Kurose Ch7 Sheet # 3
10 (11/4) Network Security Kurose Ch8 NS3 Lab 4 Sheet #4
11 (18/4) Network Management Kurose Ch9
12 (25/4) No lectures
13 (2/5) Advanced Topics (Introduction
to Software Defined Radio)
USRP Hands on
Lab
13 (9/5) Advanced Topics
14 (16/5) Revision
15 (23/5) Project Discussions
16 (30/5) Final Exams
Course Materials
Class presentations
Jochen Schiller, Mobile Communications, 2nd edition, Addison
Wesley, 2003, ISBN: 978-0321123817.
J. F. Kurose and K. W. Ross, Computer Networking: A Top-Down
Approach, 6th edition, Addison-Wesley, 2012. ISBN-13:
9780132856201.
Mischa Schwartz, Mobile Wireless Communications, Cambridge
University Press, 2005, ISBN: 0-521-84347-2.
Vijay K. Garg, Wireless Communications and Networking, Morgan
Kaufmann (Elsevier), 2007, ISBN: 978-0-12-373580-5.
Course Assessment
7
Labs 12% = 15
Assignments and Midterm 12% = 15
Project 16% = 20
Final Exam 60% = 75
Total 100%
Acknowledgment
The slides of this lecture are adopted from book slides of
Jim Kurose, Keith Ross, Computer Networking: A Top
Down Approach , 6th edition, Addison-Wesley, 2012, and
the lecture notes of Prof. Dr.-Ing. Jochen Schiller
8
9
Synthesis: a day in the life of a web request
journey down protocol stack complete! application, transport, network, link
putting-it-all-together: synthesis! goal: identify, review, understand protocols (at all
layers) involved in seemingly simple scenario: requesting www page
scenario: student attaches laptop to campus network, requests/receives www.google.com
10
A day in the life: scenario
Comcast network
68.80.0.0/13
Googles network 64.233.160.0/19 64.233.169.105
web server
DNS server
school network
68.80.2.0/24
web page
browser
router
(runs DHCP)
11
A day in the life connecting to the Internet
connecting laptop needs to get its own IP address, addr of first-hop router, addr of DNS server: use DHCP
DHCP
UDP
IP
Eth
Phy
DHCP
DHCP
DHCP
DHCP
DHCP
DHCP
UDP
IP
Eth
Phy
DHCP
DHCP
DHCP
DHCP DHCP
DHCP request encapsulated in UDP, encapsulated in IP, encapsulated in 802.3 Ethernet
Ethernet frame broadcast
(dest: FFFFFFFFFFFF) on LAN, received at router running DHCP server
Ethernet demuxed to IP demuxed, UDP demuxed to DHCP
router
(runs DHCP)
12
DHCP server formulates DHCP ACK containing clients IP address, IP address of first-hop router for client, name & IP address of DNS server
DHCP
UDP
IP
Eth
Phy
DHCP
DHCP
DHCP
DHCP
DHCP
UDP
IP
Eth
Phy
DHCP
DHCP
DHCP
DHCP
DHCP
encapsulation at DHCP server, frame forwarded (switch learning) through LAN, demultiplexing at client
Client now has IP address, knows name & addr of DNS
server, IP address of its first-hop router
DHCP client receives DHCP ACK reply
A day in the life connecting to the Internet
router
(runs DHCP)
13
A day in the life ARP (before DNS, before HTTP)
before sending HTTP request, need IP address of www.google.com: DNS
DNS
UDP
IP
Eth
Phy
DNS
DNS
DNS
DNS query created, encapsulated in UDP, encapsulated in IP, encapsulated in Eth. To send frame to router, need MAC address of router interface: ARP
ARP query broadcast,
received by router, which replies with ARP reply giving MAC address of router interface
client now knows MAC address of first hop router, so can now send frame containing DNS query
ARP query
Eth
Phy
ARP
ARP
ARP reply
router
(runs DHCP)
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DNS
UDP
IP
Eth
Phy
DNS
DNS
DNS
DNS
DNS
IP datagram containing DNS query forwarded via LAN switch from client to 1st hop router
IP datagram forwarded from campus network into comcast network, routed (tables created by RIP, OSPF, IS-IS and/or BGP routing protocols) to DNS server
demuxed to DNS server
DNS server replies to client with IP address of www.google.com
Comcast network
68.80.0.0/13
DNS server
DNS
UDP
IP
Eth
Phy
DNS
DNS
DNS
DNS
A day in the life using DNS
router
(runs DHCP)
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A day in the lifeTCP connection carrying HTTP
HTTP
TCP
IP
Eth
Phy
HTTP
to send HTTP request, client first opens TCP socket to web server
TCP SYN segment (step 1 in 3-way handshake) inter-domain routed to web server
TCP connection established! 64.233.169.105 web server
SYN
SYN
SYN
SYN
TCP
IP
Eth
Phy
SYN
SYN
SYN
SYNACK
SYNACK
SYNACK
SYNACK
SYNACK
SYNACK
SYNACK
web server responds with TCP SYNACK (step 2 in 3-way handshake)
router
(runs DHCP)
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A day in the life HTTP request/reply
HTTP
TCP
IP
Eth
Phy
HTTP
HTTP request sent into TCP socket
IP datagram containing HTTP request routed to www.google.com
IP datagram containing HTTP reply routed back to client
64.233.169.105
web server
HTTP
TCP
IP
Eth
Phy web server responds with
HTTP reply (containing web page)
HTTP
HTTP
HTTP HTTP
HTTP
HTTP
HTTP
HTTP
HTTP
HTTP
HTTP
HTTP
HTTP
web page finally (!!!) displayed
Computers for the next decades?
Computers are integrated small, cheap, portable, replaceable - no more separate devices
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, fax 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: wireless LANs, wireless WANs, regional wireless telecommunication networks etc. (overlay networks)
17
Terminology
Wired vs. Wireless
Wireless vs. Mobile
Infrastructure vs. Infrastructure-less Networks
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- Single hop networks
Cellular networks
Satellite networks
Service discovery
Home and office
Bluetooth master-slave
- Multi-hop networks
Sensor networks
Mesh networks for wireless
Internet access
Ad hoc networks
Mobile communication 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 stationary computer notebook in a hotel wireless LANs in historic buildings Personal Digital Assistant (PDA)
The demand for mobile communication creates the need for integration of wireless networks into existing fixed networks: local area networks: standardization of IEEE 802.11,
ETSI (HIPERLAN)
Internet: Mobile IP extension of the internet protocol IP
wide area networks: e.g., internetworking of GSM and ISDN
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Applications I
Vehicles
transmission of news, road condition, weather, music via DAB
personal communication using GSM
position via GPS
local ad-hoc network with vehicles close-by to prevent accidents, guidance system, redundancy (VANETs)
vehicle data (e.g., from busses, high-speed trains) can be transmitted in advance for maintenance
Automobile Safety
Emergencies early transmission of patient data to the hospital, current status, first
diagnosis (also patient recognition is a nice application)
replacement of a fixed infrastructure in case of earthquakes, hurricanes, fire etc.
crisis, war, ...
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Typical application: road traffic
UMTS, WLAN,
DAB, DVB, GSM,
cdma2000, TETRA, ...
Personal Travel Assistant,
PDA, Laptop,
GSM, UMTS, WLAN,
Bluetooth, ...
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Integration and Interoperability
Mobile and wireless services Always Best Connected
UMTS
2 Mbit/s
UMTS, GSM
384 kbit/s
LAN
100 Mbit/s,
WLAN
54 Mbit/s
UMTS, GSM
115 kbit/s
GSM 115 kbit/s,
WLAN 11 Mbit/s
GSM/GPRS 53 kbit/s
Bluetooth 500 kbit/s
GSM/EDGE 384 kbit/s,
DSL/WLAN 3 Mbit/s
DSL/ WLAN
3 Mbit/s
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Applications II
Travelling 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
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Location dependent services
Location aware services what services, e.g., printer, fax, 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 Cherry 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
24
Mobile devices
performance
Pager
receive only
tiny displays
simple text messages
Mobile phones
voice, data
simple graphical displays
PDA
graphical displays
character recognition
simplified WWW
Palmtop
tiny keyboard
simple versions
of standard applications
Laptop/Notebook
fully functional
standard applications
Sensors,
embedded
controllers
www.scatterweb.net
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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 memory limited value of mass memories with moving parts
flash-memory or ? as alternative
26
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
Low transmission rates local some Mbit/s, regional currently, e.g., 53kbit/s with GSM/GPRS
Higher delays, higher jitter connection setup time with GSM in the second range, several hundred
milliseconds for other wireless systems
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
27
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
(1888, in Karlsruhe, Germany, at the
location of todays University of Karlsruhe)
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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
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History of wireless communication II 1928 many TV broadcast trials (across Atlantic, color TV, 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 customer 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
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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, ...
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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 Telecommunication System) as European
proposals for IMT-2000
Iridium 66 satellites (+6 spare), 1.6GHz to the mobile phone
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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,
Wireless systems: overview of the development cellular phones satellites
wireless LAN cordless
phones
1992:
GSM
1994:
DCS 1800
2001:
IMT-2000
1987:
CT1+
1982:
Inmarsat-A
1992:
Inmarsat-B
Inmarsat-M
1998:
Iridium
1989:
CT 2
1991:
DECT 199x:
proprietary
1997:
IEEE 802.11
1999:
802.11b, Bluetooth
1988:
Inmarsat-C
analogue
digital
1991:
D-AMPS
1991:
CDMA
1981:
NMT 450
1986:
NMT 900
1980:
CT0
1984:
CT1
1983:
AMPS
1993:
PDC
4G fourth generation: when and how?
2000:
GPRS 2000:
IEEE 802.11a
200?:
Fourth Generation
(Internet based)
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Worldwide wireless subscribers (old prediction
1998)
0
100
200
300
400
500
600
700
1996 1997 1998 1999 2000 2001
Americas
Europe
Japan
others
total
Mobile phones per 100 people 1999
0 10 20 30 40 50 60
Finland
Sweden
Norway
Denmark
Italy
Luxemburg
Portugal
Austria
Ireland
Switzerland
Great Britain
Netherlands
France
Belgium
Spain
Greece
Germany
2005: 70-90% penetration in Western Europe
36
Worldwide cellular subscriber growth
0
2 0 0
4 0 0
6 0 0
8 0 0
1 0 0 0
1 2 0 0
1 9 9 2 1 9 9 3 1 9 9 4 1 9 9 5 1 9 9 6 1 9 9 7 1 9 9 8 1 9 9 9 2 0 0 0 2 0 0 1 2 0 0 2
Su
bs
crib
ers
[m
illi
on
]
Note that the curve starts to flatten in 2000 2004: 1.5 billion users
37
Cellular subscribers per region (June
2002)
A s ia P a c ific ;
3 6 ,9
E u ro p e ; 3 6 ,4
A m e ric a s (in c l.
U S A /C a n a d a );
2 2
A fric a ; 3 ,1
M id d le E a s t ;
1 ,6
2004: 715 million mobile phones delivered
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Mobile statistics snapshot (09/2002 /
12/2004) Total Global Mobile Users
869M / 1.52bn
Total Analogue Users 71M / 34m
Total US Mobile users 145M / 140m
Total Global GSM users 680M / 1.25T
Total Global CDMA Users 127M / 202m
Total TDMA users 84M / 120m
Total European users 283M / 343m
Total African users 18.5M / 53m
Total 3G users 130M / 130m(?)
Total South African users 13.2m / 19m
European Prepaid Penetration 63%
European Mobile Penetration 70.2%
Global Phone Shipments 2001 393m
Global Phone Sales 2Q02 96.7m
http://www.cellular.co.za/stats/stats-main.htm
#1 Mobile Country China (139M / 300m)
#1 GSM Country China (99m)
#1 SMS Country Philipines
#1 Handset Vendor 2Q02 Nokia (37.2%)
#1 Network In Africa Vodacom (6.6m)
#1 Network In Asia Unicom (153m)
#1 Network In Japan DoCoMo
#1 Network In Europe T-Mobile (22m / 28m)
#1 In Infrastructure Ericsson
SMS Sent Globally 1Q02 60T / 135bn
SMS sent in UK 6/02 1.3T / 2.1bn
SMS sent Germany 1Q02 5.7T
GSM Countries on Air 171 / 210
GSM Association members 574 / 839
Total Cost of 3G Licenses in Europe 110T
SMS/month/user 36
The figures vary a lot depending on the statistic, creator of the statistic etc.!
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Areas of research in mobile
communication 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
...
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Simple reference model used here
Application
Transport
Network
Data Link
Physical
Medium
Data Link
Physical
Application
Transport
Network
Data Link
Physical
Data Link
Physical
Network Network
Radio
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Influence of mobile communication to
the layer model service location
new applications, multimedia
adaptive applications
congestion and flow control
quality of service
addressing, routing, device location
hand-over
authentication
media access
multiplexing
media access control
encryption
modulation
interference
attenuation
frequency
Application layer
Transport layer
Network layer
Data link layer
Physical layer
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Overlay Networks - the global goal
regional
metropolitan area
campus-based
in-house
vertical
handover
horizontal
handover
integration of heterogeneous fixed and
mobile networks with varying
transmission characteristics
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Physical Layer
44
Limited bandwidth, Limited power (if battery) Position information (GPS receiver ?) One-to-all commun. (omni-directional antennas) One-to-many communication (directional antennas
with fixed or variable angular beam)
One-to-one communication (narrow beam directional/smart antennas, separate frequency)
Same frequency, different but fixed frequencies, frequency hopping (Bluetooth, ultra-wideband)
Laptops, sensors, cellular phones, palmtops,
Physical Layer Solutions
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Power management(battery operated) Wireless error controlchoose error correcting codes
suitable for wireless transfer
Wireless data compressioncompress data for faster wireless transfer
Channel modelingwhat is the interference model in cellular networks?
Smart antennas (e.g. directional) New technologies (e.g. ultra-wideband frequency hopping)
Medium Access Control
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IEEE 802.11 Bluetooth for personal short range networks 10m Ultra-wideband MAC with position information ?? Frequency allocation for cellular networks Neighbor discovery in ad hoc, sensor, Bluetooth Position discovery (GPS, indoor, relative, cell) Handoff in cellular networks Position based MAC Power adjusted MAC fixed or variable transmission
radii
Medium Access Control Solutions
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Call admission: which news calls to accept ? Handoff management: how to move ongoing call to new
cell, which calls to move to new frequencies or other
base station, which calls to terminate
Random access schemes:ALOHA like protocols generate delay of broadcast at random
Data broadcast: BS periodically broadcast desired data. Minimize average access delay.
CDMAcode division multiple access: use different codes over the same channel, small interference
Network Layer
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Neighbor discovery in multi-hop Network organization: choosing transmission radii for
desired connectivity
Data communication: Routing, broadcasting, geocasting, multicasting, QoS
routing
Service access in multi-hop = routing Connection rerouting in cellular = routing Paging and registration trade oof= location
management in cellular networks, cellular IP, mobile
IP
Transport Layer
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In wired networks, errors are mainly due to congestion In wireless networks, error rate is increaseddue to
MAC problems, disconnectionis possible due to
mobility or power failure
Wireless TCP different from TCP Choose best routes and choose best transmission
rates to avoid congestion
QoS issues Differentiated service: voice, data, multimedia
Applications
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Mobile, pervasive, ubiquitous, nomadic computing Computing anytime anywhere Distributed computing, CORBA Cellular and satellite networks Ad hoc networks: rescue, battlefield, conference Sensor networks: monitoring environment to detect
object movement or presence of chemicals, fire,
temperature reports
Mesh networks;: rooftop networks for multi-hop wireless Internet access
QUESTIONS?
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