Ilenia Tinnirello

wireless networks
Ilenia Tinnirello
[email protected]
Giuseppe Bianchi, Ilenia Tinnirello
Reti Radiomobili
Struttura corso
A: Pianificazione di sistemi cellulari
» Richiami propagazione/attenuazione; Ingegneria del traffico (Erlang)
» Applicazioni alle reti cellulari
(verificare cosa e’ noto e cosa no :-)
B: GSM / WiFi
» Interfaccia radio
» Protocolli
» Infrastrutture di rete e reti ad hoc
C: Tecnologie in evoluzione: UMTS/ LTE / IMS / WiMax
» … in aumento/evoluzione
» letteratura scientifica del settore
Giuseppe Bianchi, Ilenia Tinnirello
Supporti didattici
Forum
Per Q/A, discussioni, informazioni
Puntatori interessanti da studenti
Lucidi lezioni
Su web
Testi
2 capitoli libro Shankar per parte A
Testo monografico per GSM, WLAN, WiMax, UMTS
Articoli scientifici
Lucidi + testi lingua inglese
(qualche piccolo problema riscontrato)
Giuseppe Bianchi, Ilenia Tinnirello
Testi
(fotocopie disponibili)
-Shankar, “Introduction to Wireless Systems”, (cap. 2
e 4), Wiley, 2001
-Stallings, “Wireless Communications and Networks”,
Prentice Hall, 2001
(versioni elettroniche disponibili)
-Eberspacher, Vogel, Bettstetter, “GSM switching,
services & protocols”, Wiley, 2001
-Matthew Gast, “802.11 Wireless Networks: The
Definitive Guide”, O'Reilly
-Jeffreey G. Andrews, et al. “Fundamentals of
WiMax”, Prentice Hall
-Mikka Poikselka, “The IMS IP multimedia concepts
and services in the mobile domain”
Giuseppe Bianchi, Ilenia Tinnirello
Modalità esame (fino all’anno scorso..)
A+B o C+orale
Prova A “quantitativa”
Pianificazione di sistemi cellulari
Esercizi scritti (3)
Prova B su parte monografica
su GSM/WLAN
7/8 domande scritte e/o prova orale
Prova C su approfondimenti
2 esercizi su modelli e simulatore e 3 domande scritte
Prova orale su articolo scientifico
Giuseppe Bianchi, Ilenia Tinnirello
Modalità esame nuova
Unica prova scritta con:
3 esercizi su pianificazione di sistemi cellulare e/o modelli di
protocolli
7 domande su GSM/WLAN/WiMax/UMTS approfondimenti
(volete mantenere le due prove separate??)
Prova orale su articolo scientifico
selezionato dalla letteratura del
settore (da concordare con il
docente a fine corso)
Giuseppe Bianchi, Ilenia Tinnirello
History
Lecture 0
Giuseppe Bianchi, Ilenia Tinnirello
Wireless communication
Early wireless communication:
in the 400-900 TeraHertz Band!
150 BC smoke signals (Greece)
1794, optical telegraph, Claude Chappe
What is wireless communication:
Any form of communication that does not require the
transmitter and receiver to be in physical contact
Electromagnetic wave propagated through free-space
Radar, RF, Microwave, IR, Optical
Giuseppe Bianchi, Ilenia Tinnirello
types of communication
Simplex
one-way communication
radio, TV, etc
Half-duplex:
two-way communication but not simultaneous
push-to-talk radios, etc
Full-duplex:
two-way communication
cellular phones
Frequency-division duplex (FDD)
Time-division duplex (TDD): simulated full-duplex
Giuseppe Bianchi, Ilenia Tinnirello
Why wireless communication?
User Mobility
Reduced Cost (cheap infrastructure)
Cabling very critical
Developing nations utilize cellular telephony rather than
laying twisted-pair wires to each home
Flexibility
Can easily set-up temporary LANs
Disaster situations
Office moves
Only use resources when sending or
receiving a signal
Giuseppe Bianchi, Ilenia Tinnirello
Why wireless different than
wired?
Noisy, time-varying channel
BER varies by orders of magnitude
Environmental conditions affect transmission
Shared medium
Other users create interference
Must develop ways to share the channel
Bandwidth is limited
spectrum allocated by state rules
ISM band for unlicensed use
Giuseppe Bianchi, Ilenia Tinnirello
History of wireless
communication
1896: Marconi
first demonstration of wireless telegraphy
tx of radio waves to a ship at sea 29 km away
long wave transmission, high power req. (200 kW and +)
1901: Marconi
Telegraph across the atlantic ocean
Close to 3000 Km hop!
1907 Commercial transatlantic connections
huge ground stations (30 by100m antennas)
1915: Wireless telephony established
NY – S. Francisco
Virginia and Paris
1920 Marconi:
Discovery of short waves (< 100m)
reflection at the ionosphere
(cheaper) smaller sender and receiver, possible due to the invention of the
vacuum tube (1906, Lee DeForest and Robert von Lieben)
Giuseppe Bianchi, Ilenia Tinnirello
History of wireless
communication
1920's: Radio broadcasting became popular
1928: many TV broadcast trials
1930's: TV broadcasting deployment
1946: First public mobile telephone service in US
St. Louis, Missouri
Single cell system
1960's: Bell Labs developed cellular concept
brought mobile telephony to masses
1960’s: Communications satellites launched
Late 1970's: technology advances enable
affordable cellular telephony
entering the modern cellular era
1974-1978: First field Trial for Cellular System
AMPS, Chicago
Giuseppe Bianchi, Ilenia Tinnirello
1st generation mobile systems
Analog transmission
First generation: 1980’s
Frequency modulation
Several competing standards in
different countries
Various bands:
NMT (Nordic Mobile Telephone)
NMT:
Scandinavian standard; adopted in most
of Europe
First european system (Sweden, 1981)
TACS (Total Access Communication
Systems), starts in 1985
UK standard; A few of Europe, Asia,
Japan
AMPS (Advanced Mobile Phone
Service)
US standard
C-Netz (Only in Germany)
Radiocom 2000 (Only in France)
Giuseppe Bianchi, Ilenia Tinnirello
450 MHz first
900 MHz later
TACS
900 MHz
AMPS
800 MHz
Today still in use in lowtechnology countries
And not yet completely
dismissed in high-tech
countries
2nd generation mobile systems
4 systems
Basic bands:
Global System for Mobile (GSM)
900 MHz
Digital AMPS (D-AMPS), US
1800 MHz
Code Division Multiple Access
(Digital Cellular System:
(IS-95) – Qualcomm,US
DCS-1800)
Personal Digital Cellular
1900 MHz
(PDC),Japan
(Personal Communication
GSM by far the
System:PCS-1900,US only)
dominant one
Specifications for
Originally pan-european
GSM-400 (large areas)
Deployed worldwide
GSM-800 (north america)
(slow only in US)
Giuseppe Bianchi, Ilenia Tinnirello
Timing
1982: Start of GSM-specification in
Europe (1982-1990)
1983: Start of American AMPS
widespread deployment
1984 CT-1 standard (Europe) for
cordless telephones
1991 Specification of DECT
Digital European Cordless Telephone (today: Digital
Enhanced Cordless Telecommunications)
- ~100-500m range, 120 duplex channels, 1.2Mbit/s data
transmission, voice encryption, authentication
1992: Start of GSM operation Europewide
1994: DCS-1800
Giuseppe Bianchi, Ilenia Tinnirello
2 ½ generation mobile systems
GSM incremental extension
High speed circuit switched data
(HSCSD)
Circuit switched data communication
Uses up to 4 slots (1 slot = 9.6 or 14.4 Kbps)
General Packet Radio Service (GPRS)
Packet data (use spectrum only when needed!)
dial-up comparable speed
Enhanced Data-rates for Global Evolution
(EDGE)
Higher data rate available on radio interface (3x)
» Up to 384 Kbps (8 slots)
» Thanks to new modulation scheme (8PSK)
» May coexist with old GMSK
Giuseppe Bianchi, Ilenia Tinnirello
3rd generation mobile systems
UMTS (Universal Mobile
TelecommunicationSystem)
ITU standard: IMT-2000 (International Mobile
Telecommunication – 2000)
UMTS forum created in 1996
Later on 3GPP forum (bears most of
standardization activities)
Wideband CDMA radio interface
But several other proposals accepted as
“compatible”
Radio spectrum: 1885-2025 & 2110-2200 MHz
Long Term Evolutions
Giuseppe Bianchi, Ilenia Tinnirello
History of Wireless Data
Early Wireless LAN proprietary products
WaveLAN (AT&T) - the ancestor of 802.11
HomeRF (Proxim)
45% of the home network in 2000; 30% in 2001, … ε% today
Abandoned by major chip makers (e.g. Intel: dismissed in april 2001)
IEEE 802.11 Committee formed in 1990
Charter: specification of MAC and PHY for WLAN
First standard: june 1997
1 and 2 Mbps operation
Reference standard: september 1999
Multiple Physical Layers
2.4GHz Industrial, Scientific & Medical shared unlicensed band
» Legacy; 802.11b/g
5 GHz ISM (802.11a)
1999: Wireless Ethernet Compatibility Alliance
(WECA) certification
Later on named Wi-Fi
Boosted 802.11 deployment!!
Giuseppe Bianchi, Ilenia Tinnirello
WLAN speeds
802.11a: PHY for 5 GHz
802.11b: higher rate PHY for 2.4
GHz
802.11g: OFDM for 2.4 GHz
802.11n: ??? (Higher data rate)
Launched in september 2003
Minimum goal: 108 Mbps (but higher numbers
considered)
Giuseppe Bianchi, Ilenia Tinnirello
Why so much talking about of
802.11 today?
802.11: no more “just” a WLAN
Hot-spots
Where the user goes, the network is available: home,
school, office, hotel, university, airport, convention center…
Freedom to roam with seamless connectivity in every
domain, with single client device
May compete (complement) with 3G for
Wireless Internet access
Which of these two is the
proper (closer) picture
of Wireless Internet and
Mobile Computing?
Which technology is most suited?
Giuseppe Bianchi, Ilenia Tinnirello
The global picture
GPRS, 3G – UMTS
< 400 Kb/s Kms
Mobile Broadband Internet
Wide Area
Local Area
IEEE 802.11 (b)
> 10 Mb/s 100 m
WAN:
everywhere outside of
the hotspots, where
wireless Internet
802.11/UMTS connection are
provided
switching
Personal Area
Bluetooth
< 800 Kb/s 10 m
BT/802.11
switching
LAN:
collection of secure
“hot spot”
connections, providing
broadband access to
the Internet
PAN:
collection of secure
connections between
devices in a
“very” local area
Giuseppe Bianchi, Ilenia Tinnirello