Siemens IEEE802.11 Operation instructions

Maximilian Riegel
ICM Networks, Advanced Standardization

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 2 © Siemens, 2002
Prolog:
The ubiquitous WLAN
nToday’s road worriers require access to the Internet
everywhere.
nWLAN is more than just cable replacement, it provides
hassle-free broadband Internet access everywhere.
nCoverage in ‘hot-spots’ sufficient.
nIEEE802.11b meets the expectations for easiness, cost
and bandwidth.
Public
WLAN
Airport
Railway
Station
Campus
Plant
Semi-public
WLAN
Office Hospital
Congress hall,
Hotel
Corporate
WLAN
Office
Home
WLAN
Remote
Access

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 3 © Siemens, 2002
Prolog:
WLAN has taken off ...
nLots of serious WLAN activities have been started
– All big players have products (Cisco, Intel, …)
– Integrated WLAN solutions appearing (Apple, IBM, ...)
nThe prediction have been exceeded by actual market.
For comparison:
Total PC world market in ‘01: ~ 120 Mio pcs.; > 30 % portable.
nRuling technology is IEEE802.11b (Wi-Fi) [11Mb/s, 2.4 GHz].
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WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 4 © Siemens, 2002
Outline
nPart 1: Wireless Internet System Architecture
nPart 2: IEEE802.11 Overview
nPart 3: Physical Layer
nPart 4: Medium Access Control
nPart 5: MAC Layer Management
nPart 6: WLAN Mobility
nPart 7: WLAN Security
nPart 8: Public Hotspot Operations
nPart 9: WLAN – UMTS Interworking

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 5 © Siemens, 2002
Part 1:
Wireless Internet system architecture
nGeneric Internet network architecture
nLayering means encapsulation
nIEEE802.11 – seamless integration into the Internet
nIP based network architecture
nWireless LAN IEEE802.11 basic architecture
nWhat is unique about wireless?

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 6 © Siemens, 2002
Internet/Web Applications
Generic Internet network architecture
link
phy
ip
tcp
http
www
link
phy
ip link
phy
ip
link
phy
ip link
phy
ip
802.2
 link
phy
ip
802.2

ip
tcp
http
www
Peer
(Client) Peer (Web-Server)
802.2
802.3
ip
802.2
802.3
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WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 7 © Siemens, 2002
user data
appl. header
tcp header application data
ip header
Ethernet ip header tcp header appl. header user data
HTML
http
tcp
ip
802.2
TCP segment
IP datagramm
Ethernet frame
64 - 1500 bytes
14 bytes 20 bytes 20 bytes
Layering means encapsulation

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 8 © Siemens, 2002
IEEE802.11 - seamless integration into
the Internet
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WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 9 © Siemens, 2002
link
phy
link
phy link phy
link
phy link phy
link
phy link phy
link
phy
tcp
http
www
tcp
http
www
IP based network architecture
ipip ipip ipip ipip
N-DATA.request N-DATA.indication
N-DATA N-DATA N-DATA
ip = connectionless,
non-reliable,
end-to-end,
packet-oriented
data delivery service
193.175.26.92 131.34.3.35
Version Length Type of Service Total Length
Identification
)/$*6
Fragment offset
Time-to-live Protocol Header checksum
Source IP Address (32bit)
Destination IP Address (32 bit)
Options (if any)
1234
Data
00
RTD
D: Delay
T: Throughput
R: Reliability
“1”= precedent
TOS (pre-diffserv)

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 10 © Siemens, 2002
http
tcp
ip
ppp
Bluetooth
Netscape
ip
802.2
 802.2  802.3 802.2 802.3 802.2 802.3
http
tcp
ip
ppp
Bluetooth
apache
ip
802.2
802.3
ip
IEEE802.11
local distribution network internet
Client Access Point Access Router Server
Wireless LAN IEEE802.11
basic architecture

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 11 © Siemens, 2002
What is unique about wireless?
nDifficult media
– interference and noise
– quality varies over space and time
– shared with “unwanted” 802.11 devices
– shared with non-802 devices (unlicensed spectrum, microwave ovens)
nFull connectivity cannot be assumed
– “hidden node” problem
nMobility
– variation in link reliability
– battery usage: requires power management
– want “seamless” connections
nSecurity
– no physical boundaries
– overlapping LANs
nMultiple international regulatory requirements

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 12 © Siemens, 2002
Part 2: IEEE802.11 Overview
nWireless IEEE802.11 Standard
nIEEE802.11 Configurations
nIEEE802.11 Architecture Overview
nIEEE802.11 Protocol Architecture
nWireless LAN Standardization

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 13 © Siemens, 2002
Wireless IEEE802.11 Standard
nOperation in the 2.4GHz ISM band
– North America: FCC part 15.247-15.249
– Europe: ETS 300 - 328
– Japan: RCR - STD-33A
nSupports three PHY layer types:
DSSS, FHSS, Infrared
nMAC layer common to all 3 PHY layers
nRobust against interference
nProvides reliable, efficient wireless data
networking
nSupports peer-to-peer and
infrastructure configurations
nHigh data rate extension IEEE802.11b
with 11 Mbps using existing MAC layer
Approved June 1997
802.11b approved September 1999

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 14 © Siemens, 2002
Station
AH3
Station
Station
AH1
AH2
Ad Hoc Network
IEEE802.11 Configurations
nIndependent
– one “Basic Service Set”, BSS
– “Ad Hoc” network
– direct communication
– limited coverage area
nInfrastructure
– Access Points and stations
– Distribution System interconnects
Multiple Cells via Access Points
to form a single Network.
• extends wireless coverage area
Station
Station Station
Station
A1
A2 B1
B2
BSS-A
BSS-B
A
AP AP
B
Server
DISTRIBUTION SYSTEM

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 15 © Siemens, 2002
IEEE802.11 Architecture Overview
nOne common MAC supporting multiple PHYs
nTwo configurations
– “Independent” (ad hoc) and “Infrastructure”
nCSMA/CA (collision avoidance) with optional “point coordination”
nConnectionless Service
– Transfer data on a shared medium without reservation
– data comes in bursts
– user waits for response, so transmit at highest speed possible
– is the same service as used by Internet
nIsochronous Service
– reserve the medium for a single connection and provide a continues stream of bits, even
when not used
– works only when cells (using the same frequencies) are not overlapping.
nRobust against noise and interference (ACK)
nHidden Node Problem (RTS/CTS)
nMobility (Hand-over mechanism)
nSecurity (WEP)
nPower savings (Sleep intervals)

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 16 © Siemens, 2002
IEEE802.11 Protocol Architecture
nStation Management
– interacts with both MAC Management
and PHY Management
nMAC Layer Management Entity
– power management
– handover
– MAC MIB
nMAC Entity
– basic access mechanism
– fragmentation
– encryption
nPHY Layer Management
– channel tuning
– PHY MIB
nPhysical Layer Convergence Protocol (PLCP)
– PHY-specific, supports common PHY SAP
– provides Clear Channel Assessment signal (carrier sense)
nPhysical Medium Dependent Sublayer (PMD)
– modulation and encoding
MAC
Sublayer
PLCP Sublayer
PMD Sublayer
MAC Layer
Management
PHY Layer
Management Station
Management
LLC = 802.2
MAC
PHY

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 17 © Siemens, 2002
Wireless LAN Standardization
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Current standardization topics
HiperLAN/2
DFS & TPC
5 GHz
54 Mbit/s
ETSI BRAN
8076,QWHJUDWLRQ 802.11f: Inter Access Point Protocol
IEEE 802.11
IEEE 802.11
2,4 GHz
2 Mbit/s
802.11b
2,4 GHz
11Mbit/s
802.11g
2,4 GHz
54Mbit/s
802.11a
5 GHz
54Mbit/s
802.11e: 4R6(QKDQFHPHQWV
802.11i: 6HFXULW\(QKDQFHPHQWV
802.11h
DFS & TPC
WIG
Wireless
Interworking Group

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 18 © Siemens, 2002
Part 3: Physical layer
nIEEE802.11 2.4 GHz & 5 GHz Physical Layers
nFrequency Hopping Spread Spectrum
nDirect Sequence Spread Spectrum
nDSSS Transmit Spectrum and Channels
nIEEE802.11a 5GHz PHY Layer
nIEEE802.11g: Further Speed Extension for the 2.4 GHz Band
nSpectrum Designation in the 5GHz range
nIEEE802.11h: Spectrum and Transmit Power Management
n... when will 5 GHz WLANs come?
nPHY Terminology
nPhysical Layer Convergence Protocol (PLCP)

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 19 © Siemens, 2002
IEEE802.11
2.4 GHz & 5 GHz Physical Layers
Time
Frequency
n2.4 GHz Frequency Hopping Spread Spectrum
– 2/4 FSK with 1/2 Mbps
– 79 non overlapping frequencies
of 1 MHz width (US)
Frequency
Power
Frequency
Power
spreading
n2.4 GHz Direct Sequence Spread Spectrum
– DBPSK/DQPSK with 1/2 Mbps
– Spreading with 11 Bit barker Code
– 11/13 channels in the 2.4 GHz band
n2.4 GHz High Rate DSSS Ext. (802.11b)
– CCK/DQPSK with 5.5/11 Mbps
Frequency
Power
n5 GHz OFDM PHY (802.11a)
– Basic parameters identical to
HiperLAN2 PHY
– European regulatory issues
n Baseband IR, 1 and 2Mbps, 16-PPM and 4-PPM

, © Siemens, 2002
AMPLITUDE
FREQUENCY
TIME
123456789101112 f1
f2 f3
f4 f5
Frequency Hopping Spread Spectrum
n2.4GHz band is 83.5MHz wide (US & Europe)
nBand is divided into at least 75 channels
nEach channel is < 1MHz wide
nTransmitters and receivers hop in unison among
channels in a pseudo random manner
nPower must be filtered to -20db at band edge