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Wireless LAN IEEE802.11 Tutorial. Maximilian Riegel ICM Networks, Advanced Standardization. Prolog: The ubiquitous WLAN. Railway Station. Airport. Public WLAN. Campus. Today’s road worriers require access to the Internet everywhere.

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Wireless lan ieee802 11 tutorial

Wireless LANIEEE802.11 Tutorial

Maximilian Riegel

ICM Networks, Advanced Standardization


Prolog the ubiquitous wlan

Prolog:The ubiquitous WLAN

Railway Station

Airport

PublicWLAN

Campus

  • Today’s road worriers require access to the Internet everywhere.

  • WLAN is more than just cable replacement, it provides hassle-free broadband Internet access everywhere.

  • Coverage in ‘hot-spots’ sufficient.

  • IEEE802.11b meets the expectations for easiness, cost and bandwidth.

Office

Hospital

Office

Congress hall,Hotel

Semi-publicWLAN

Corporate WLAN

Plant

Remote Access

HomeWLAN

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Prolog wlan has taken off

Prolog:WLAN has taken off ...

  • Lots of serious WLAN activities have been started

    • All big players have products (Cisco, Intel, …)

    • Integrated WLAN solutions appearing (Apple, IBM, ...)

  • The prediction have been exceeded by actual market.For comparison:Total PC world market in ‘01: ~ 120 Mio pcs.; > 30 % portable.

  • Ruling technology is IEEE802.11b (Wi-Fi) [11Mb/s, 2.4 GHz].

Source: Frost&Sullivan (2000-03)

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Outline

Outline

  • Part 1: Wireless Internet System Architecture

  • Part 2: IEEE802.11 Overview

  • Part 3: Physical Layer

  • Part 4: Medium Access Control

  • Part 5: MAC Layer Management

  • Part 6: WLAN Mobility

  • Part 7: WLAN Security

  • Part 8: Public Hotspot Operations

  • Part 9: WLAN – UMTS Interworking

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Part 1 wireless internet system architecture

Part 1: Wireless Internet system architecture

  • Generic Internet network architecture

  • Layering means encapsulation

  • IEEE802.11 – seamless integration into the Internet

  • IP based network architecture

  • Wireless LAN IEEE802.11 basic architecture

  • What is unique about wireless?

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Generic internet n etwork a rchitecture

Generic Internet network architecture

Internet

Policy Server

AAA Server

WLAN Access

Peer

(Client)

Peer

(Web-Server)

Internet/Web Applications

www

www

http

http

tcp

tcp

ip

ip

ip

ip

ip

ip

ip

ip

802.2

802.2

802.2

802.2

link

link

link

link

link

link

802.11

802.11

802.3

802.3

phy

phy

phy

phy

phy

phy

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Layering means encapsulation

Layering means encapsulation

HTML

user data

http

appl. header

tcp

tcp header

application data

TCP segment

ip

ip header

IP datagramm

802.2

Ethernet

ip header

tcp header

appl. header

user data

14 bytes

20 bytes

20 bytes

Ethernet frame

64 - 1500 bytes

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Ieee802 11 seamless integration into the internet

IEEE802.11 - seamless integration into the Internet

html

xml

xsl

smil

www

W3C

HTTP

FTP

SMTP

M3UA

NFS

DNS

SNMP

TCP

SCTP

UDP

IP

PPP

ARP

encap

Internet

IETF

802.2

ITU

ETSI

ATMF

ISDN

ATM

SDH

GSM

802.3

802.4

802.5

802.11

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Ip based network architecture

IP based network architecture

Internet

www

www

TOS (pre-diffserv)

http

http

0

0

D

T

R

tcp

tcp

D: Delay

T: Throughput

R: Reliability

“1”= precedent

link

link

link

link

link

link

link

link

phy

phy

phy

phy

phy

phy

phy

phy

193.175.26.92

131.34.3.35

N-DATA.indication

N-DATA.request

N-DATA

N-DATA

N-DATA

ip

ip

ip

ip

ip

ip

ip

ip

ip =connectionless,non-reliable,end-to-end,packet-orienteddata delivery service

1

2

3

4

Version

Length

Type of Service

Total Length

Identification

FLAGS

Fragmentoffset

Time-to-live

Protocol

Header checksum

Source IP Address (32bit)

Destination IP Address (32 bit)

Options (if any)

Data

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Wireless lan ieee802 11 basic architecture

Wireless LAN IEEE802.11basic architecture

local distribution network

internet

Netscape

apache

http

http

tcp

tcp

ip

ip

ip

ip

ip

802.2

ppp

802.2

802.2

802.2

802.2

ppp

802.11

Bluetooth

802.11

802.3

802.3

802.3

Bluetooth

802.3

IEEE802.11

Client

Access Point

Access Router

Server

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


What is unique about wireless

What is unique about wireless?

  • Difficult 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)

  • Full connectivity cannot be assumed

    • “hidden node” problem

  • Mobility

    • variation in link reliability

    • battery usage: requires power management

    • want “seamless” connections

  • Security

    • no physical boundaries

    • overlapping LANs

  • Multiple international regulatory requirements

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Part 2 ieee802 11 overview

Part 2: IEEE802.11 Overview

  • Wireless IEEE802.11 Standard

  • IEEE802.11 Configurations

  • IEEE802.11 Architecture Overview

  • IEEE802.11 Protocol Architecture

  • Wireless LAN Standardization

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Wireless ieee802 11 standard

Wireless IEEE802.11 Standard

  • Operation in the 2.4GHz ISM band

    • North America: FCC part 15.247-15.249

    • Europe: ETS 300 - 328

    • Japan: RCR - STD-33A

  • Supports three PHY layer types: DSSS, FHSS, Infrared

  • MAC layer common to all 3 PHY layers

  • Robust against interference

  • Provides reliable, efficient wireless data networking

  • Supports peer-to-peer and infrastructure configurations

  • High 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


Ieee802 11 configurations

IEEE802.11 Configurations

  • Independent

    • one “Basic Service Set”, BSS

    • “Ad Hoc” network

    • direct communication

    • limited coverage area

  • Infrastructure

    • Access Points and stations

    • Distribution System interconnectsMultiple Cells via Access Points to form a single Network.

      • extends wireless coverage area

Station

AH2

Station

Ad Hoc Network

AH3

Station

AH1

Server

DISTRIBUTION SYSTEM

AP

AP

A

B

BSS-B

Station

A1

Station

B2

Station

Station

BSS-A

A2

B1

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Ieee802 11 architecture overview

IEEE802.11 Architecture Overview

  • One common MAC supporting multiple PHYs

  • Two configurations

    • “Independent” (ad hoc) and “Infrastructure”

  • CSMA/CA (collision avoidance) with optional “point coordination”

  • Connectionless 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

  • Isochronous 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.

  • Robust against noise and interference (ACK)

  • Hidden Node Problem (RTS/CTS)

  • Mobility (Hand-over mechanism)

  • Security (WEP)

  • Power savings (Sleep intervals)

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Ieee802 11 protocol architecture

IEEE802.11 Protocol Architecture

  • Station Management

    • interacts with both MAC Management and PHY Management

  • MAC Layer Management Entity

    • power management

    • handover

    • MAC MIB

  • MAC Entity

    • basic access mechanism

    • fragmentation

    • encryption

  • PHY Layer Management

    • channel tuning

    • PHY MIB

  • Physical Layer Convergence Protocol (PLCP)

    • PHY-specific, supports common PHY SAP

    • provides Clear Channel Assessment signal (carrier sense)

  • Physical Medium Dependent Sublayer (PMD)

    • modulation and encoding

LLC = 802.2

MAC Layer

Management

MAC Sublayer

MAC

PHY Layer

Management

PLCP Sublayer

Station

Management

PHY

PMD Sublayer

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Wireless lan standardization

Wireless LAN Standardization

ETSI BRAN

UMTS Integration

HiperLAN/2

DFS & TPC

5 GHz

54 Mbit/s

WIG

Wireless Interworking Group

IEEE 802.11

802.11f: Inter Access Point Protocol

802.11e: QoS Enhancements

MAC

802.11i: Security Enhancements

IEEE 802.11

802.11h

DFS & TPC

802.11a

5 GHz

54Mbit/s

802.11g

2,4 GHz

54Mbit/s

802.11b

2,4 GHz

11Mbit/s

PHY

2,4 GHz

2 Mbit/s

Current standardization topics

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Part 3 physical layer

Part 3: Physical layer

  • IEEE802.11 2.4 GHz & 5 GHz Physical Layers

  • Frequency Hopping Spread Spectrum

  • Direct Sequence Spread Spectrum

  • DSSS Transmit Spectrum and Channels

  • IEEE802.11a 5GHz PHY Layer

  • IEEE802.11g: Further Speed Extension for the 2.4 GHz Band

  • Spectrum Designation in the 5GHz range

  • IEEE802.11h: Spectrum and Transmit Power Management

  • ... when will 5 GHz WLANs come?

  • PHY Terminology

  • Physical Layer Convergence Protocol (PLCP)

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Ieee802 11 2 4 ghz 5 ghz physical layers

IEEE802.112.4 GHz & 5 GHz Physical Layers

  • 2.4 GHz Frequency Hopping Spread Spectrum

    • 2/4 FSK with 1/2 Mbps

    • 79 non overlapping frequencies of 1 MHz width (US)

  • 2.4 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

  • 2.4 GHz High Rate DSSS Ext. (802.11b)

    • CCK/DQPSK with 5.5/11 Mbps

Power

Power

spreading

Frequency

Frequency

Frequency

  • 5 GHz OFDM PHY (802.11a)

    • Basic parameters identical toHiperLAN2 PHY

    • European regulatory issues

Power

Frequency

Time

  • Baseband IR, 1 and 2Mbps, 16-PPM and 4-PPM

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Frequency hopping spread spectrum

Frequency Hopping Spread Spectrum

  • 2.4GHz band is 83.5MHz wide (US & Europe)

  • Band is divided into at least 75 channels

  • Each channel is < 1MHz wide

  • Transmitters and receivers hop in unison among channels in a pseudo random manner

  • Power must be filtered to -20db at band edge

f5

f4

AMPLITUDE

f3

FREQUENCY

f2

f1

1

2

3

4

5

6

7

8

9

10

11

12

TIME

,


Direct sequence spread spectrum

Direct Sequence Spread Spectrum

RF Energy is Spread by XOR of Data with PRN Sequence

0

1

Data

1 bit period

0100100011110110111000

Out

11 Bit Barker Code (PRN*)

1011011100010110111000

11 chips

1 bit

period

PRN

11 chips

* PRN: Pseudorandom Number

Signal Spectrum

Receiver baseband signal before matched filter (Correlator)

Transmitter baseband signal before spreading

Receiver baseband signal after matched filter (De-spread)

Transmitter baseband signal after spreading

,


Dsss transmit spectrum and channels

DSSS Transmit Spectrum and Channels

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Ieee802 11a 5ghz phy layer

IEEE802.11a 5GHz PHY Layer

  • Specifications

    • Modulation type OFDM

    • Data rates: 6, 12, 18, 24, 36, 48, 54Mbps

    • 48 sub-carriers

    • Sub-carrier modulation: BPSK, QPSK, 16QAM, 64QAM

    • Bit interleaved convolutional coding, K=7, R=1/2, 2/3, 3/4

    • OFDM frame duration: 4µs guard interval: 0.8ms

    • 18MHz channel spacing, 9-10 channels in 200MHz bandwidth

  • Key milestones

    • First letter ballot by working group from November 1998 meeting

    • January 1999 joint meeting with ETSI-BRAN

,


Ieee802 11g further speed extension for the 2 4ghz band

IEEE802.11g: Further Speed Extension for the 2.4GHz Band

Upcoming

  • Mandatory: CCK w/ short preample (802.11b) and OFDM (802.11a applied to 2.4 GHz range).

  • Optional:PBCC proposal for 22 Mbit/s from Texas Instruments

  • Optional:CCK-OFDM proposal for up to 54 Mbit/s from Intersil

Range vs. throughput rate comparison of

  • CCK (802.11b),

  • OFDM(“802.11a”),

  • PBCC,

  • CCK-OFDM

    (Batra, Shoemake; Texas Instruments; Doc: 11-01-286r2)

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Spectrum designation in the 5 ghz range

Spectrum Designation in the 5 GHz range

5.150

5.250

Japan

5.150

5.350

5.725

5.825

Max peak Tx power

USA

Indoor 200 mW / Outdoor 1 W EIRP

Outdoor 4 W EIRP

DFS & TPC

DFS & TPC

5.350

5.150

5.470

5.725

Max mean Tx power

Europe

Indoor 200 mW EIRP

Outdoor 1W EIRP

5.100

5.300

5.400

5.500

5.600

5.700

5.800

5.900

5.200

DFS: Dynamic Frequency Selection

TPC:Transmit Power Control

  • Many European countries are currently opening the 5 GHz range for radio LANs.

Freq./GHz

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Ieee802 11h spectrum and transmit power management

IEEE802.11h: Spectrum and Transmit Power Management

AP 2

AP 1

  • DFS (Dynamic Frequency Selection)

    • AP‘s make the decision

    • STA‘s provide detailed reportsabout spectrum usage at theirlocations.

AP 3

STA

Upcoming

  • TPC (Transmission Power Control)

    • supports interference minimisation, power consumption reduction, range control and link robustness.

    • TPC procedures include:

      • AP‘s define and communicate regulatory and local transmit power constraints

      • Stations select transmit powers for each frame according to local and regulatory constraints

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


When will 5 ghz wlans come

… when will 5 GHz WLANs come?

  • IEEE802.11b (2.4 GHz) is now taking over the market.

  • There are developments to enhance IEEE802.11b for

    • more bandwidth (up to 54 Mbit/s)

    • QoS (despite many applications do not need QoS at all)

    • network issues (access control and handover).

  • 5 GHz systems will be used when the 2.4 GHz ISM band will become too overcrowded to provide sufficient service.

    • TCP/IP based applications are usually very resilient against ‘error proune’ networks.

  • Issues of 5 GHz systems:

    • Cost: 5 GHz is more expensive than 2.4 GHz

    • Power: 7dB more transmission power for same distance

    • Compatibility to IEEE802.11b/g necessary

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Phy terminology

PHYTerminology

  • FHSSFrequency Hoping Spread Spectrum

  • DSSSDirect Sequence Spread Spectrum

  • OFDMOrthogonal Frequency Division Multiplex

  • PPMPulse Position Modulation

  • GFSKGaussian Frequency Shift Keying

  • DBPSKDifferential Binary Phase Shift Keying

  • DQPSKDifferential Quadrature Phase Shift Keying

  • CCKComplementary Code Keying

  • PBCCPacket Binary Convolutional Coding

  • QAMQuadrature Amplitude Modulation

,


Physical layer convergence protocol plcp

Physical Layer Convergence Protocol (PLCP)

  • SYNC(gain setting, energy detection, antenna selection, frequency offset compensation)

  • SFD(Start Frame Delimiter; bit synchronization)

  • SIGNAL(rate indication; 1, 2, 5.5, 11 Mbit/s)

  • SERVICE(reserved for future use)

  • LENGTH(number of octets in PSDU)

  • CRC(CCITT CRC-16, protects signal, service, length field)

PLCP Protocol Data Unit

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Part 4 medium access control

Part 4: Medium Access Control

  • Basic Access Protocol Features

  • CSMA/CA Explained

  • CSMA/CA + ACK protocol

  • Distributed Coordination Function (DCF)

  • „Hidden Node“ Provisions

  • IEEE802.11e: MAC Enhancements for Quality of Service (EDCF)

  • Point Coordination Function (PCF)

  • IEEE802.11e: MAC Enhancements for Quality of Service (HCF)

  • Frame Formats

  • Address Field Description

  • Summary: MAC Protocol Features

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Basic access protocol features

Basic Access Protocol Features

  • Use Distributed Coordination Function (DCF) for efficient medium sharing without overlap restrictions.

    • Use CSMA with Collision Avoidance derivative.

    • Based on Carrier Sense function in PHY called Clear Channel Assessment (CCA).

  • Robust for interference.

    • CSMA/CA + ACK for unicast frames, with MAC level recovery.

    • CSMA/CA for Broadcast frames.

  • Parameterized use of RTS / CTS to provide a Virtual Carrier Sense function to protect against Hidden Nodes.

    • Duration information is distributed by both transmitter and receiver through separate RTS and CTS Control Frames.

  • Includes fragmentation to cope with different PHY characteristics.

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Csma ca explained

CSMA/CA Explained

Busy Medium

  • Reduce collision probability where mostly needed.

    • Stations are waiting for medium to become free.

    • Select Random Backoff after a Defer, resolving contention to avoid collisions.

  • Efficient Backoff algorithm stable at high loads.

    • Exponential Backoff window increases for retransmissions.

    • Backoff timer elapses only when medium is idle.

  • Implement different fixed priority levels

IFS: Inter Frame Space

Free access when medium

DIFS

is free longer than DIFS

Contention Window

PIFS

DIFS

SIFS

Backoff-Window

Next Frame

Slot time

Select Slot and Decrement Backoff as long as medium is idle.

Defer Access

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Csma ca ack protocol

CSMA/CA + ACK protocol

  • Defer access based on Carrier Sense.

    • CCA from PHY and Virtual Carrier Sense state.

  • Direct access when medium is sensed free longer then DIFS, otherwise defer and backoff.

  • Receiver of directed frames to return an ACK immediately when CRC correct.

    • When no ACK received then retransmit frame after a random backoff (up to maximum limit).

DIFS

Data

Src

SIFS

Contention Window

Dest

Ack

DIFS

Other

Next MPDU

Backoff after Defer

Defer Access

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Distributed coordination function dcf

Distributed Coordination Function (DCF)

Short interval ensures ACK is sent while other stations wait longer

Short deferral

ACK to STA1

STA 3’s back-off is shorter thanSTA 4’s therefore it begins transmission first

Distributed inter-frame deferral

Random back-off

Distributed inter-frame deferral

Detects channel busy

Tx Data

Distributed inter-frame deferral

Random back-off

Distributed inter-frame deferral

Detects channel busy

Detects channel busy

Station 1

Tx Data to STA 2

Station 2

Rx data from STA 1

Station 3

Detects channel busy

Detects channel busy

Station 4

,


Hidden node provisions

“Hidden Node” Provisions

Access Point

DIFS

Data

RTS

STA A

Ack

CTS

AP

STA “B” cannot detect carrier from STA “A”

Next MPDU

STA B

Time period to defer accessis based on duration in CTS

Back off after defer

Problem – Stations contending for the medium do not Hear each other

Solution – Optional use of the Duration field in RTS and CTS frames with AP

CTS-Range

STA “B” cannot receive data from STA “A”

RTS-Range

STA “B”

STA“A”

,


Ieee802 11e mac enhancements for quality of service edcf

IEEE802.11e: MAC Enhancementsfor Quality of Service (EDCF)

Upcoming

  • differentiated DCF access to the wireless medium for prioritized traffic categories (4 different traffic categories)

  • output queue competes for TxOPs using EDCF wherein

    • the minimum specified idle duration time is a distinct value

    • the contention window is a variable window

    • lower priority queues defer to higher priority queues

  • EDCF (Enhanced Distributed Coordination Function)

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Point coordination function pcf

Point Coordination Function (PCF)

  • Optional PCF mode provides alternating contention free and contention operation under the control of the access point

  • The access point polls stations for data during contention free period

  • Network Allocation Vector (NAV) defers the contention traffic until reset by the last PCF transfer

  • PCF and DCF networks will defer to each other

  • PCF improves the quality of service for time bounded data

CFP repetition interval

Contention Period

Contention Free Period

Access

Point

Beacon

D1+Poll

D2+Poll

CF end

U1+ACK

U2+ACK

Stations

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Ieee802 11e mac enhancements for quality of service hcf

IEEE802.11e: MAC Enhancements for Quality of Service (HCF)

Upcoming

  • only usable in infrastructure QoS network configurations

  • to be used during both the contention period (CP) and the contention free period (CFP)

  • uses a QoS-aware point coordinator („hybrid coordinator“)

    • by default collocated with the enhanced access point (QAP)

    • uses the point coordinator's higher priority to allocate transmission opportunities (TxOPs) to stations

  • meets predefined service rate, delay and/or jitter requirements of particular traffic flows.

  • HCF (Hybrid coordination function)

  • Caused long delays in standardization process due to its complexity

  • Recently widely supported „Fast –Track“ proposal to come to a conclusion in TGe

    • Most complex functions eliminated, streamlined HCF, ...

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Frame formats

Frame Formats

  • MAC Header format differs per Type:

    • Control Frames (several fields are omitted)

    • Management Frames

    • Data Frames

  • Includes Sequence Control Field for filtering of duplicate caused by ACK mechanism.

802.11 MAC Header

Bytes:

2

2

6

6

6

2

6

0-2312

4

Frame

Frame

Duration

Sequence

Addr 1

Addr 2

Addr 3

Addr 4

CRC

Body

Control

ID

Control

Bits: 2

2

4

1

1

1

1

1

1

1

1

Protocol

To

From

More

Pwr

More

Type

SubType

Retry

WEP

Rsvd

Version

DS

DS

Frag

Mgt

Data

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Address field description

Address Field Description

  • Addr 1 = All stations filter on this address.

  • Addr 2 = Transmitter Address (TA)

    • Identifies transmitter to address the ACK frame to.

  • Addr 3 = Dependent on To and From DS bits.

  • Addr 4 = Only needed to identify the original source of WDS (Wireless Distribution System) frames.

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Summary mac protocol features

Summary: MAC Protocol Features

  • Distributed Coordination Function (DCF) provides efficientmedium sharing

    • Use Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA)

    • MAC uses the PHY layer Clear Channel Assessment (CCA) function for CSMA/CA

  • Robust for interference

    • CSMA/CA + ACK for unicast frames, with MAC level recovery

    • CSMA/CA for broadcast frames

  • Virtual carrier sense function provided to protect againsthidden nodes

  • Includes fragmentation to cope with different PHY characteristics

  • Point Coordination Function (PCF) option for time bounded data

  • Frame formats to support multiple configurations and roaming

,


Part 5 mac layer management

Part 5: MAC layer management

  • Infrastructure Beacon Generation

  • Timing Synchronization Function

  • Scanning

  • Active Scanning Example

  • Power Management Considerations

  • Power Management Approach

  • Power Management Procedure

  • MAC Management Frames

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Infrastructure beacon generation

Infrastructure Beacon Generation

  • APs send Beacons in infrastructure networks.

  • Beacons scheduled at Beacon Interval.

  • Transmission may be delayed by CSMA deferral.

    • subsequent transmissions at expected Beacon Interval

    • not relative to last Beacon transmission

    • next Beacon sent at Target Beacon Transmission Time

  • Timestamp contains timer value at transmit time.

Beacon Interval

"Actual time" stamp in Beacon

Time Axis

X

X

X

X

Busy Medium

Beacon

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Timing synchronization function tsf

Timing Synchronization Function (TSF)

  • All stations maintain a local timer.

    • Used for Power Management

      • All station timers in BSS are synchronized

    • Used for Point Coordination Timing

      • TSF Timer used to predict start of Contention Free burst

  • Timing Synchronization Function (TSF)

    • keeps timers from all stations in synch

    • AP controls timing in infrastructure networks

    • distributed function for Independent BSS

  • Timing conveyed by periodic Beacon transmissions

    • Beacons contain Timestamp for the entire BSS

    • Timestamp from Beacons used to calibrate local clocks

    • not required to hear every Beacon to stay in synch

    • Beacons contain other management information

      • also used for Power Management, Roaming

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Scanning

Scanning

  • Scanning required for many functions.

    • finding and joining a network

    • finding a new AP while roaming

    • initializing an Independent BSS (ad hoc) network

  • 802.11 MAC uses a common mechanism for all PHY.

    • single or multi channel

    • passive or active scanning

  • Passive Scanning

    • Find networks simply by listening for Beacons

  • Active Scanning

    • On each channel

      • Send a Probe, Wait for a Probe Response

  • Beacon or Probe Response contains information necessary to join new network.

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Active scanning example

Active Scanning Example

  • Initial connection to an Access Point

    • Reassociation follows a similar process

Steps to Association:

Station sends Probe.

Access Point C

Access Point A

APs send Probe Response.

Station selects best AP.

Station sends Association

Request to selected AP.

AP sends Association

Response.

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Power management considerations

Power Management Considerations

  • Mobile devices are battery powered.

    • Power Management is important for mobility.

  • Current LAN protocols assume stations are always ready to receive.

    • Idle receive state dominates LAN adapter power consumption over time.

  • How can we power off during idle periods, yet maintain an active session?

  • 802.11 Power Management Protocol:

    • allows transceiver to be off as much as possible

    • is transparent to existing protocols

    • is flexible to support different applications

      • possible to trade off throughput for battery life

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Power management approach

Power Management Approach

  • Allow idle stations to go to sleep

    • station’s power save mode stored in AP

  • APs buffer packets for sleeping stations.

    • AP announces which stations have frames buffered

    • Traffic Indication Map (TIM) sent with every Beacon

  • Power Saving stations wake up periodically

    • listen for Beacons

  • TSF assures AP and Power Save stations are synchronized

    • stations will wake up to hear a Beacon

    • TSF timer keeps running when stations are sleeping

    • synchronization allows extreme low power operation

  • Independent BSS also have Power Management

    • similar in concept, distributed approach

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Power management procedure

Power Management Procedure

  • Stations wake up prior to an expected DTIM (Delivery Traffic Indication Message).

  • If TIM indicates frame buffered

    • station sends PS-Poll and stays awake to receive data

    • else station sleeps again

  • Broadcast frames are also buffered in AP.

    • all broadcasts/multicasts are buffered

    • broadcasts/multicasts are only sent after DTIM.

    • DTIM interval is a multiple of TIM interval

TIM-Interval

DTIM interval

Time-axis

Busy Medium

TIM

TIM

DTIM

TIM

TIM

DTIM

Broadcast

AP activity

Broadcast

PS Station

Tx operation

PS-Poll

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Mac management frames

MAC Management Frames

  • Beacon

    • Timestamp, Beacon Interval, Capabilities, ESSID, Supported Rates, parameters

    • Traffic Indication Map

  • Probe

    • ESSID, Capabilities, Supported Rates

  • Probe Response

    • Timestamp, Beacon Interval, Capabilities, ESSID, Supported Rates, pars

    • same for Beacon except for TIM

  • Association Request

    • Capability, Listen Interval, ESSID, Supported Rates

  • Association Response

    • Capability, Status Code, Station ID, Supported Rates

  • Reassociation Request

    • Capability, Listen Interval, ESSID, Supported Rates, Current AP Address

  • Reassociation Response

    • Capability, Status Code, Station ID, Supported Rates

  • Disassociation

    • Reason code

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Part 6 wlan mobility

Part 6: WLAN Mobility

  • IEEE802.11 Ad Hoc Mode

  • IEEE802.11 Infrastructure Mode

  • Mobility inside a WLAN ‚hotspot‘ by link layer functions...

  • IEEE802.11f: Inter-Access Point Protocol (IAPP)

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Ieee802 11 ad hoc mode

IEEE802.11 Ad Hoc Mode

  • Independent networking

    • Use Distributed Coordination Function (DCF)

    • Forms a Basic Service Set (BSS)

    • Direct communication between stations

    • Coverage area limited by the range of individual stations

Peer-to-Peer Network

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Ieee802 11 infrastructure mode

IEEE802.11 Infrastructure Mode

  • Access Points (AP) and stations (STA)

  • BSS (Basic Service Set): a set of stations controlled by a single coordination function

  • Distribution system interconnects multiple cells via access points to form a single network

  • Extends wireless coverage area and enables roaming

Distribution System (DS)

Server

BSS-A

BSS-B

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Mobility inside a wlan hotspot by link layer functions

Mobility inside a WLAN ‘hotspot’ by link layer functions...

  • Station decides that link to its current AP is poor

  • Station uses scanning function to find another AP

    • or uses information from previous scans

  • Station sends Reassociation Request to new AP

  • If Reassociation Response is successful

    • then station has roamed to the new AP

    • else station scans for another AP

  • If AP accepts Reassociation Request

    • normally old AP is notified through Distribution System

    • AP indicates Reassociation to the Distribution System

local distribution network

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Ieee802 11f inter access point protocol iapp

IEEE802.11f: Inter-Access Point Protocol (IAPP)

Upcoming

  • IAPP defines procedures for

    • context transfer between APs when stations move

    • automatic configuration handling of access points

RADIUS Server

Distribution System

Server

IAPP-ADD

IAPP-MOVE

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Part 7 wlan security

Part 7: WLAN security

  • IEEE802.11 Privacy and Access Control

  • WEP privacy mechanism

  • Shared key authentication

  • Shortcomings of plain WEP security

  • IEEE802.11i: Robust Security Network (RSN)

  • A last word about WLAN security:

  • Summary: MAC Functionality

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Ieee802 11 privacy and access control

IEEE802.11 Privacy and Access Control

  • Goal of 802.11 was to provide “Wired Equivalent Privacy” (WEP)

    • Usable worldwide

  • 802.11 provides for an authentication mechanism

    • To aid in access control.

    • Has provisions for “OPEN”, “Shared Key” or proprietary authentication extensions.

  • Shared key authentication is based on WEP privacy mechanism

    • Limited for station-to-station traffic, so not “end to end”.

    • Uses RC4 algorithm based on:

      • a 40 bit secret key

      • and a 24 bit IV that is send with the data.

      • includes an ICV to allow integrity check.

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Wep privacy mechanism

WEP privacy mechanism

Secret Key

IV

IV

WEPPRNG

IV

WEPPRNG

TX

Secret Key

Plaintext

+

+

Ciphertext

Ciphertext

Plaintext

Integrity Algorithm

ICV'=ICV?

ICV

ICV

Integrity Algorithm

PLCPHeader

Preamble

MAC Header

Payload

CRC

Encrypted

IV(4)

K-ID

Cyphertext

ICV (4)

  • WEP bit in Frame Control Field indicates WEP used.

    • Each frame can have a new IV, or IV can be reused for a limited time.

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Shared key authentication

Shared key authentication

Station sends authentication request

AP sends challenge text generatedwith the WEP algorithm

Station encrypts challenge textand sends it to the AP

AP decrypts the encrypted challenge text.Authentication successful if text matches original

  • Shared key authentication requires WEP

  • Key exchange is not specified by IEEE802.11

  • Only one way authentication

Station

Access Point

Secret Key Loaded Locally

Secret Key Loaded Locally

,


Shortcomings of plain wep security

Shortcomings of plain WEP security

  • WEP unsecure at any key length

    • IV space too small, lack of IV replay protection

    • known plaintext attacks

  • No user authentication

    • Only NICs are authenticated

  • No mutual authentication

    • Only station is authenticated against access point

  • Missing key management protocol

    • No standardized way to change keys on the fly

    • Difficult to manage per-user keys for larger groups

  • WEP is no mean to provide security for WLAN access,

    • … but might be sufficient for casual uses.

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Ieee802 11i robust security network rsn

IEEE802.11i:Robust Security Network (RSN)

Associate

EAP Identity Request

AuthenticationServer

EAP Identity Response

Access Request

EAP Request

Access Challenge

EAP Response

Access Request

EAP Success

Access Accept

Upcoming

Additional enhancement to existing IEEE802.11 functions:

  • Data privacy mechanism:

    • TKIP (Temporal Key Integrity Protocol) to enhance RC4-based hardware for higher security requirements, or

    • WRAP (Wireless Robust Authenticated Protocol) based on AES (Advanced Encryption Standard) and OCB (Offset Codebook)

  • Security association management:

    • RSN negotiation procedures for establishing the security context

    • IEEE802.1X authentication and key management

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


A last word about wlan security

A last word about WLAN security:

Even IEEE802.11i may not be sufficient for public hot-spots:

Only VPN technologies (IPSEC, TLS, SSL) will fulfil end-to-end security requirements in public environments.

VPN technologies might even be used in corporate WLAN networks.

IPSEC, TLS, SSL

tcp

tcp

802.11

802.11

WEP

802.11

802.11

Netscape

apache

http

http

tcp

tcp

ip

ip

ip

ip

ip

802.2

ppp

802.2

802.2

802.2

802.2

ppp

802.3

802.3

802.3

802.3

Bluetooth

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Summary mac functionality

Summary: MAC Functionality

  • Independent and Infrastructure configuration support

    • Each BSS has a unique 48 bit address

    • Each ESS has a variable length address

  • CSMA with collision avoidance

    • MAC-level acknowledgment

    • allows for RTS/CTS exchanges (hidden node protection)

    • MSDU fragmentation

    • “Point Coordination” option (AP polling)

  • Association and Reassociation

    • station scans for APs, association handshakes

    • Roaming support within an ESS

  • Power management support

    • stations may power themselves down

    • AP buffering, distributed approach for IBSS

  • Authentication and privacy

    • Optional support of “Wired Equivalent Privacy” (WEP)

    • Authentication handshakes defined

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Part 8 public hotspot operation

Part 8: Public hotspot operation

  • Serving customers in public hot spots...

  • One solution for every place (hotspot)

  • Becoming a WLAN operator is easy.

  • Selling WLAN access in public hot-spots: Probably to consider...

  • Using a web page for initial user interaction

  • How does it work: Web based access control

  • Web based access control: Enabler for mCommerce and location based services

  • Functions of an integrated access gateway (User Management)

  • Functions of an integrated access gateway (Network services)

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Serving customers in public hot spots

Serving customers in public hot spots...

Office

Hospital

Railway Station

Airport

Campus

Congress hall,Hotel

  • Do not touch customer equipment

  • Address all customers

  • Make access procedure self explaining

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


One solution for every place hotspot

One solution for every place (hotspot)

Railway Station

Airport

PublicWLAN

Campus

  • There is a wide variety of notebooks each having more or less its unique configuration.

  • Only a very common dominator can be assumed for the software installations available on all notebooks.

  • Most WLAN-enabled notebooks will use DHCP for basic IP configuration.

  • A web-browser will likely be available on all notebooks.

Office

Hospital

Office

Congress hall,Hotel

Semi-publicWLAN

Corporate WLAN

Plant

Remote Access

HomeWLAN

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Becoming a wlan operator is easy

Becoming a WLAN operator is easy.

  • Legal aspects (in Germany):

    • Usage of license free spectrum (2,4 GHz ISM band)

    • No telecommunication license necessary, as long as

      • not providing telephony services,

      • not providing network access across borders of private premises.

  • Cost issues:

    • The lower bound:Investment: WLAN Access Point /w DSL Router (~ 350 €)Monthly operation cost: ~ 60 € for DSL Flat Rate

    • Most commercial installations are much more expensive due to charging and billing.

  • It is very easy and extremely cheap to become a WLAN operator, but most people did not yet know about it.

    ...but wait until they have installed WLAN in their living rooms!

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Selling wlan access in public hot spots probably to consider

Selling WLAN access in public hot-spots:Probably to consider …

  • How does your favorite storefront look like?

Too much security might hinder your business!

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Using a web page for initial user interaction

Using a web page for initial user interaction

Free

local content

services

Authentication for Internet access

Selection of billing method

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


How does it work web based access control

How does it work:Web based access control

Username:

Password:

html

N

auth

RADIUS

client

auth

Mobile

Client

max.riegel

**********

DHCP

Server

AAA

Server

Access

Gateway

internet

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Web based access control enabler for mcommerce and location based services

Web based access control: Enabler for mCommerce and location based services

  • Puting a mCommerce application into a web-page for WLAN access control enables further services to be billed.

    => there is far more business for the operator than just WLAN access

  • Due to its limited coverage services delivered by WLAN in hot-spots can easily tailored to their locations.

    => Operators can start with location based services without huge investments for full geographic coverage.

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Functions of an integrated access gateway user management

Functions of an integrated access gateway (User management)

  • Authentication via secure (HTTPS) web-based GUI for registered and unknown users based on

    • External database, supports ISP roaming via RADIUS

    • Integrated LDAP directory

    • GSM phone (Transmission of one-time passwords by SMS)

    • Credit card

  • Authorization based on user profiles assigned to different user groups having particular access

    • Dynamic subscribtion to additional services

    • Personalized portal page

  • Real-time accounting based on service, duration and volume

    • Instant user feedback on portal page or by SMS

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Functions of an integrated access gateway network services

Functions of an integrated access gateway (Network services)

  • DHCP server for assigning IP addresses to WLAN clients

    • Retaining session if user is temporarily out of WLAN coverage

    • Detection of session end

  • Policy engine

    • Loadable user profiles

    • User-specific routing configuration

    • Dynamic firewalling rules

  • IP router with NAT engine

    • Assignment of private addresses for free services

    • Must allow IPSEC connections

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Part 9 wlan umts interworking

Part 9: WLAN – UMTS Interworking

  • UMTS and Wireless LAN are different

  • WLAN – UMTS Interworking: Ancient approach: ‚tight coupling‘

  • WLAN as an exension of a mobile network

  • WLAN is much cheaper than 2G/3G

  • Conclusions for Mobile Network Operators

  • WLAN – UMTS Interworking: Now widely accepted: ‚loose coupling‘

  • WLAN loosely coupled to a Mobile Network

  • E.g.: Web based authentication and mobile network security

  • Standards for WLAN – UMTS Interworking

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Umts and wireless lan are different

UMTS and Wireless LAN are different.

GSM/GPRS/UMTS

anytime / everywhere

voice, realtime messaging

QoS

precious bandwidth

carrier grade

operator driven

huge customer base

high revenues

WLAN IEEE802.11

sometimes / somewhere

standard web applications

best effort

cheap bandwidth

corporate technology

market driven

casual users

low revenues

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Wlan umts interworking ancient approach tight coupling

WLAN – UMTS Interworking: Ancient approach: ‘tight coupling’

LNP

SCP

IN

MSCS

MSCS

VLR

HSS

PSTN

AUC

BSC

RNC

BTS

BTS

wlan local access network

Node B

Node B

TDM / ATM / IP

PLMN core

GGSN

SGSN

PLMN access

internet

WLAN as just another radio access technology of UMTS

  • All UMTS services become available over WLAN.

    but:

  • PLMN is burdened with high bandwidth WLAN traffic.

  • Wi-Fi does not provide all the functionality needed (QoS, security).

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Wlan as an extension of a mobile network

WLAN as an extension of a mobile network

  • WLAN just as another radio access technology

  • MNOs are the WLAN operators

    • OA&M

    • agreement with siteowner

    • very dense PLMN

  • Full competition with open ISP market.

  • Mobile network is carrier of the WLAN traffic.

  • Dynamics of growth may differ.

  • very complex

    • SIM / USIM cards required

    • new standards necessary

tight coupling

AP

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Wlan is much cheaper than 2g 3g

WLAN is much cheaper than 2G/3G

*based on current IP volume prices of 40€ /GByte.Time based pricing results in similar costs,e.g. MobileStar Pulsar pricing plan: $0,10/min

Transfer cost/duration of an 1 Mbytes .ppt/.doc/.xls File...

logarithmic scale

4 min

4 min

5 sec

-99,6%

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Conclusions for mobile network operators

Conclusions for Mobile Network Operators

  • The most complicated and appealing task of a WLAN operator is charging and billing.

  • MNOs have large customer bases, secure authentication and accounting facilities and they like to go into mobile business.

  • Providing electronic payment services to WLAN operators can be an important market entry into mobile business for MNOs.

  • There is no time to wait!The WLAN access market is exploding, and WLAN access may be ‘for free’ in many hot-spots in a few years (~3-5 years).

When you can’t stop them, when you can’t beat them,then you should join them.

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Wlan umts interworking now widely accepted loose coupling

WLAN – UMTS Interworking: Now widely accepted: ‘loose coupling’

LNP

SCP

IN

MSCS

MSCS

VLR

HSS

PSTN

AUC

internet

BSC

RNC

BTS

BTS

wlan local access network

Node B

Node B

Siemens contributed ‚loose coupling‘ to standardization.

TDM / ATM / IP

PLMN core

Authentication

Accounting

SGSN

PLMN access

Only Authentication, Authorization and Accounting of WLAN access is performed by the mobile network operator.

  • Revenues without competing against aggressive WLAN operators.

  • Perfect model for leveraging the huge customer base and establishing a widely accepted platform for mobile commerce.

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Wlan loosely coupled to a mobile network

WLAN loosely coupled to a Mobile Network

Each hotspot is SS7 endpoint

SIM cards required

SGSN or MSC functionalityat access network

Tight userbase to HLR

Standalone capability

Flexibility in security

SIM

HLR

loose coupling (SIM)

loose coupling (RADIUS)

HLR

SGSN

RADIUS

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


E g web based authentication and mobile network security

E.g.: Web based authentication and mobile network security

SMS containing Password

Username:

Password:

html

N

auth

RADIUS

client

auth

HLR

Mobile

Client

0172-3456789

**********

mobile

network

DHCP

Server

AAA

Server

Access

Gateway

internet

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


Standards for wlan umts interworking

Standards for WLAN/UMTS interworking

  • 3GPP

    • R5: SA1Requirements of 3GPP system – WLAN interworking.

    • R6: SA2Continuation with architectural considerations

  • ETSI BRANSubgroup on “Interworking between HiperLAN/2 and 3rd generation cellular and other public systems”.

    • Detailed architectural description mainly based on the Siemens ‘loose coupling’ principle established

    • IEEE802.11 and MMAC are now joining this effort.=> Wireless Interworking Group (WIG).

  • WECA (Wireless Ethernet Compatibility Alliance)‘Wireless ISP Roaming Initiative’

    • Detailed functional specification for roaming (loose coupling) between IEEE802.11 WLAN networks available.

    • Mainly aimed for roaming between ISPs but also applicable for MNOs.

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


The end

The end

  • Thank you for your attention.

  • Questions and comments?Maximilian Riegel ([email protected])

    Literature:

  • The IEEE 802.11 Handbook – A Designer‘s CompanionBob O‘Hara, Al Patrick; IEEE press, ISBN 0-7381-1855-9

  • 802.11 Wireless Networks – The Definitive GuideMatthew S. Gast; O‘ Reilly, ISBN 0-596-00183-5

WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt


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