Notes
-
Upload
electronink -
Category
Documents
-
view
71 -
download
1
Transcript of Notes
1
Brought to you by
Welcome to CWNA –
Certified Wireless Network
Administrator
Objectives
In this video…
• About Your Instructor and Train Signal
• What’s Covered in this Course
About your Instructor and Train Signal
About Ed Liberman
• CWNT, CWNA, MCT, MCP, MCSA, MCSE, MCDST, MCTS, MCITP, A+, NET+, SERVER+
• Have worked in technology for about 20 years
• Have been certified and instructing IT for over 10 years
• Volunteer time in my local community as a math tutor for struggling grade school children
About Train Signal
• Casual Training Method
• Scenario-Based Training
2
What’s Covered in this Course
2. WLAN Standards
3. RF Fundamentals
4. RF Math
5. Antennas
6. RF Regulatory Domains
7. Wireless LAN Operation
8. Power over Ethernet (PoE)
9. 802.11 Service Sets
10. WLAN Analysis
11. Medium Access
12. 802.11n Amendment
13. Site Surveying
14. Basic WLAN Security
Videos…
What’s Covered in this Course
1. Network Topologies
2. OSI Model
3. TCP/IP Fundamentals
4. Network Devices
5. Network Security
Bonus Videos…
Are you ready to get started?
Let’s go!!!
3
Brought to you by
Introduction to
WLAN Standards
Objectives
In this video…
• Discuss the standards organizations responsible for shaping the 802.11 Wireless LAN protocol
• Learn how standards compliance is enforced for 802.11 WLAN vendors• Examine the 802.11 standard and various amendments• Discuss additional networking standards that are commonly used to
enhance 802.11 WLANs
IEEE
www.ieee.org
•Institute of Electrical and Electronics Engineers
•ISO (International Organization for Standardization)
•OSI Model
4
Wi-Fi Alliance®
Cross-vendor standards compliance and
interoperability testing organization
www.wi-fi.com
IEEE 802.11 Working Groups
• Original standard created in 1997 and modified in 1999
• Various amendments and supplements were rolled into a new standard called 802.11-2007
• Amendments not rolled into the -2007 standard are still called by their amendment name (e.g. 802.11n)
http://grouper.ieee.org/groups/802/11/QuickGuide_IEEE_802_WG_and_Activities.htm
802.11 Amendments
• Since the 802.11 amendment names are still used in the market, it’s advantageous to understand how each amendment modified the 802.11 standard.
• When the 802.11-2007 standard was ratified, many amendments became obsolete because their content was now part of the new standard.
5
802.11 Amendments
• 802.11a specifies use of OFDM technology using the 5 GHz UNII bands
• Obsolete: Rolled into 802.11-2007
• 802.11b specifies HR-DSSS using the 2.4 GHz band and is backwards compatible with DSSS
• Obsolete: Rolled into 802.11-2007
802.11 Amendments
• 802.11g specifies use of OFDM technology in the 2.4 GHz ISM band and offers backwards compatibility with HR/DSSS and DSSS
• Obsolete: Rolled into 802.11-2007
• Transmit Power Control (TPC)• Dynamic Frequency Selection (DFS)• UNII band spectrum management enhancement• Obsolete: Rolled into 802.11-2007
802.11 Amendments
• Specified multiple QoS mechanisms that can interoperate with legacy (non-QoS aware) devices
• Obsolete: Rolled into 802.11-2007
• Strong authentication with 802.1X/EAP and Preshared keys
• Strong encryption using CCMP/AES• Obsolete: Rolled into 802.11-2007
6
802.11 Amendments
• Changes to the 802.11 MAC and PHY to conform with new Japanese 4.9 and 5 GHz bands
• Obsolete: Rolled into 802.11-2007
• Defines physical layer requirements to extend 802.11 to new regulatory domains (countries)
• Obsolete: Rolled into 802.11-2007
• Adds MAC bridging functionality to 802.11 WLANs• Obsolete: Rolled into 802.11-2007
Active 802.11 Amendments
• Enhancements to the 802.11 MAC layer to minimize the amount of time data connectivity between the Station (STA) and the Distribution System (DS) is absent during a Basic Service Set (BSS) transition while maintaining strong security
• 802.11n offers data rates up to 600 Mbps (theoretical) and throughput in excess of 100 Mbps in both the 2.4 GHz ISM and 5 GHz UNII bands using MIMO technology.
Active 802.11 Amendments
• The amendment enables interoperable formation and operation of an ESS Mesh and allows for alternative path selection based on application requirements
• Defines Radio Resource Measurement enhancements to provide interfaces to higher layers for radio and network measurements.
7
Active 802.11 Amendments
• Supports communication between vehicles and the roadside and between vehicles while operating at speeds up to a maximum of 200 km/h for communication ranges up to 1000 meters
• Provides a set of performance metrics enabling measuring and predicting the performance of 802.11 WLAN devices and networks
• This is a recommended practice, not actually an amendment
Active 802.11 Amendments
• Amends the 802.11 MAC and PHY to enable Interworking with external networks
• Provides wireless network management enhancements to the 802.11 PHY and MAC to extend prior work in radio measurement to enable a complete and coherent upper layer interface for managing 802.11 devices in wireless networks
Active 802.11 Amendments
• Provides enhancements to the IEEE 802.11 MAC layer to make available mechanisms that enable data integrity, data origin authenticity, replay protection, and data confidentiality for selected IEEE 802.11 management frames
8
Related Standards: 802.1X
• Provides a framework for authenticating users connecting to a (W)LAN port
• Calls for 3 roles:
– Supplicant
– Authenticator
– Authentication Server
… is for Port-based Access Control
• Defines an authentication
framework which supports
multiple authentication methods
• There are many EAP
authentication protocols used in
802.11 WLANs… is for Extensible
Authentication Protocol
Related Standards: EAP
Related Standards: 802.3-2005, Clause 33
• Support for optionally powering a
10BASE-T,100BASE-TX, or
1000BASE-T DTE device via the
Power Interface (PI) using physical
layers
… is for Power-over-Ethernet
9
Related Standards: RADIUS
• A protocol for carrying authentication, authorization, and configuration information between an authenticator (WLAN Controller or AP) and an authentication server (RADIUS Server) for the purpose of authenticating users and optionally assigning them to roles.
… is for Remote Authentication Dial In User Service(… not just for dial-up anymore …)
Review
In this video we discussed:
• The standards organizations responsible for shaping the 802.11 Wireless LAN protocol.
• How standards compliance is enforced for 802.11 WLAN vendors.• The 802.11 standard and various amendments.• Additional networking standards that are commonly used to enhance
802.11 WLANs
Brought to you by
RF Fundamentals
10
Objectives
• Physical aspects of RF propagation
• Types of losses and attenuation that affect
RF communications
• Types of modulation and coding schemes
(MCS) used for 802.11 communications
• How channels and bandwidth are related to
each other in wireless networks
• Types of Spread Spectrum used in 802.11
networking
In this video...
Sine Waves
Current Flow
11
Photons
Wavelength
Frequency
Lower Frequency
Higher Frequency
12
Wavelength & Frequency
• Wavelength and Frequency are inverselyrelated through these formulas:
• f is frequency;
• is wavelength;
• c is the speed of
light—about 300,000
km/s
Wavelength Calculation
• 2.45 GHz = 4.82 inches (12.24 cm)
• 5.775 GHz = 2.04 inches (5.19 cm)
Formulas to calculate RF wavelengths:
Wavelength (in.) = 11.811/Frequency (GHz)
Wavelength (cm) = 30/Frequency (GHz)
Amplitude (Power Level)
Original Signal
Amplitude Increased
13
Phase
Signals 180 degrees out of phase
Phase is a relationship between two signals based on when their alternating current levels are rising and falling.
RF Loss
Loss as seen by an
Oscilloscope
Peak Amplitude before Loss
Peak Amplitude after Loss
Loss of DSSS as seen by a
spectrum analyzer
Loss – the main signal decreases in amplitude
(size or intensity) due to external
interference or attenuation.
RF Loss: Reflection
Reflection - occurs when an RF signal bounces off of a smooth, non-
absorptive surface, changing the direction of the signal.
14
RF Loss: Refraction
Refraction - occurs when an RF
signal changes speed and is bent
while moving between media of
different densities. How much this
happens depends on the Refraction
Index of each medium.
RF Loss: Diffraction
Diffraction – a change in
the direction (bending)
and intensity of a group
of waves after passing by
the edge of an obstacle.
RF Loss: Scattering
Scattering - occurs when the RF signal strikes an uneven surface
causing the signal to be scattered in such a fashion that the
resultant signals are less significant than the original signal.
15
RF Loss: Absorption
Absorption - occurs when the RF
signal striking an object is
absorbed into the material of the
object in such a manner that it
does not pass through, reflect off,
or bend around the object.
Interference (corruption)
Basic Types of Modulation
• Amplitude Modulation– A method of combining an
information signal and an RF carrier by varying the amplitude (power) of the carrier wave in proportion to the information signal
• Frequency Modulation– A method of combining an
information signal and an RF carrier by varying the frequency of the carrier wave in proportion to the information signal
• Phase Modulation– A method of combining an
information signal and an RF carrier by varying the phase of the carrier wave in proportion to the information signal
16
DSSS and HR/DSSS MCS
Spreading
Code
Modulation
Technology
Data
Rate
2.4 GHz
DSSS &
HR/DSSS
Barker Code DBPSK 1 Mbps
Barker Code DQPSK 2 Mbps
CCK DQPSK 5.5 Mbps
CCK DQPSK 11 Mbps
OFDM MCS
Coding
Technique
Modulation
Technology
Convolution
Code Ratio
Data
Rate
OFDM DBPSK 1/2 *6 Mbps
OFDM DBPSK 3/4 9 Mbps
OFDM DQPSK 1/2 *12 Mbps
OFDM DQPSK 3/4 18 Mbps
OFDM 16QAM 1/2 *24 Mbps
OFDM 16QAM 3/4 36 Mbps
OFDM 64QAM 2/3 48 Mbps
OFDM 64QAM 3/4 54 Mbps
* The standard requires support for these data rates
Spectral Mask: DSSS & HR/DSSS
17
Spectral Mask: OFDM
Clause 17 (802.11a) and 19 (802.11g) OFDM
transmissions both use this spectral mask.
2.4 GHz ISM Band and Channels
The 2.4 GHz ISM band has 14 channels, 11 of
which are available in the U.S. regulatory
domain.
Non-overlapping HR/DSSS channels are
highlighted.
UNII Bands and Channels
Bands are divided into channels as shown
36 40 44 48 52 56 60 64
(lower) (middle) (extended) (upper)
18
DSSS Coding
X
=
“symbol”
“Barker” sequence
Result of multiplication
Symbol time ts
“1” “0”
Chip time tc
With an 11 chip spreading code, the required transmit channel
bandwidth increases from 1 MHz to 11 MHz however 802.11 uses 22
MHz channels to improve receiver synchronization procedures.
DSSS Coding
OFDM FEC Coding
19
Objectives
• The physical aspects of RF propagation.
• The different types of losses and attenuation
that affect RF communications.
• The different types of modulation and coding
schemes (MCS) used for 802.11
communications.
• How channels and bandwidth are related to
each other in wireless networks
• The different types of Spread Spectrum used
in 802.11 networking.
In this video we discussed:
Brought to you by
RF Math
Objectives
• RF units of measure
• Basic RF math
• RF signal measurements
• Link budgets
In this video…
20
Inverse Square Law
Free Space Path Loss (FSPL)
Units of Measure
• mW - milliwatt
• dB - decibel
• dBi – decibel relative to an isotropic radiator
• dBm – decibel relative to a milliwatt
Units
21
Rule of 10s and 3s
-40
dBm
-30
dBm
-20
dBm
-10
dBm0
dBm
+10
dBm+20
dBm
+30
dBm+40
dBm
100
nW
1
uW10
uW
100
uW1
mW
10
mW100
mW
1,000
mW
10,000
mW
-12
dBm
-9
dBm
-6
dBm
-3
dBm
0
dBm
+3
dBm
+6
dBm
+9
dBm+12
dBm
62.5
uW125
uW
250
uW
500
uW
1
mW
2
mW4
mW
8
mW
16
mW
RF Numbers: Infinitely Large to Infinitesimally Small
• Voyager 1 was launched in 1977
• It is currently 9+ billion miles from Earth
• Voyager communicates continuously to Earth with an X-band (8.4 GHz) transmitter
• The received signal is billions of times less powerful than the transmitted signal
Conversion Chart dBm/mW
0 dBm 1.0 mW 11 dBm 12.6 mW 22 dBm 158.5 mW
1 dBm 1.3 mW 12 dBm 15.8 mW 23 dBm 199.5 mW
2 dBm 1.6 mW 13 dBm 20.0 mW 24 dBm 251.2 mW
3 dBm 2.0 mW 14 dBm 25.1 mW 25 dBm 316.2 mW
4 dBm 2.5 mW 15 dBm 31.6 mW 26 dBm 398.1 mW
5 dBm 3.2 mW 16 dBm 39.8 mW 27 dBm 501.2 mW
6 dBm 4.0 mW 17 dBm 50.1 mW 28 dBm 631.0 mW
7 dBm 5.0 mW 18 dBm 63.1 mW 29 dBm 794.3 mW
8 dBm 6.3 mW 19 dBm 79.4 mW 30 dBm 1000 mW
9 dBm 7.9 mW 20 dBm 100.0 mW 40 dBm 10000 mW
10 dBm 10.0 mW 21 dBm 125.9 mW 43 dBm 19952.6
mW
22
Gains and Losses
AbsoluteAmplitude
in dBm
RelativeAmplitude
in dB
RelativeFrequency
Frequency
2X Amplification (Rule of 3s)
Amplifier #1
Signal Level In: 1
Signal Level Out: 2
Amplifier #2
Signal Level In: 2
Signal Level Out: 4
Amplifier #3
Signal Level In: 4
Signal Level Out: 8
+3 dB+3 dB
+3 dB
2X Attenuation (Rule of 3s)
Attenuator #1
Signal Level In: 8
Signal Level Out: 4
Attenuator #2
Signal Level In: 4
Signal Level Out: 2
Attenuator #3
Signal Level In: 2
Signal Level Out: 1
-3 dB-3 dB -3 dB
23
10X Amplification (Rule of 10s)
Amplifier #1
Signal Level In: 1
Signal Level Out: 10
Amplifier #2
Signal Level In: 10
Signal Level Out: 100
Amplifier #3
Signal Level In: 100
Signal Level Out: 1000
+10 dB+10 dB +10 dB
10X Attenuation (Rule of 10s)
Attenuator #1
Signal Level In: 1000
Signal Level Out: 100
Attenuator #2
Signal Level In: 100
Signal Level Out: 10
Attenuator #3
Signal Level In: 10
Signal Level Out: 1
-10 dB-10 dB -10 dB
RF Math: Problem
24
Receiver Sensitivity
Receiver sensitivity
varies by device
and manufacturer.
In this example you
can see that this
radio is capable of
clearly
distinguishing very
small signals from
the noise floor.
Example:
Signaling
Rate
Receiver
Sensitivity
Threshold
11 Mbps -82 dBm
5.5 Mbps -87 dBm
2 Mbps -91 dBm
1 Mbps -94 dBm
Equivalent Isotropically Radiated Power (EIRP)
Will the link work?
16.5 dBm28.5 dBm-75.5 dBm-63.5 dBm
-67 dBm
25
Review
• Different RF units of measure.
• How to do basic RF math.
• Different RF signal measurements.
• How to calculate link budgets.
In this video we discussed:
Brought to you by
Antennas
Objectives
• Antenna Polarization and Gain
• Types of antennas and antenna systems
commonly used in 802.11 WLANs
• Antenna implementation and safety
• Antenna accessories
In this video…
26
Isotropic Radiator
Visualizing Beam Patterns
Polarization of an Antenna
27
Understanding Polarization
Passive Gain
Low Gain Omni Antennas
28
High Gain Omni Antennas
Indoor Range ExtenderGain = 5 dBi
H Beam = 360°V Beam = 15°
Omni Gain = 4 dBi
H Beam = 360°V Beam = 50°
Slim OmniGain = 12 dBi
H Beam = 360°V Beam = 8°
Compact OmniGain = 8.5 dBiH Beam = 360°V Beam = 15°
Omni Antenna Examples
Mini-Mobile Magnetic Mount
Gain = 3 dBiH Beam = 360°V Beam = 30°
Omni ProfessionalGain = 15 dBi
H Beam = 360°V Beam = 8°
Images: 2007www.hyperlinktech.com
Outdoor Range Extenderwith Magnetic Base
Gain = 5 dBiH Beam = 360°V Beam = 60°
Omni Antenna Examples
Compact Ceiling Mount OmniGain = 3 dBi
H Beam = 360°V Beam = 45°
Compact Ceiling Mount OmniGain = 3.5 dBi H Beam = 360°V Beam = 90°
Compact Tri-band Ceiling Mount Omni
Gain = 3 dBiH Beam = 360°V Beam = 90°
Images: 2007www.hyperlinktech.com
29
Semi-Directional Antennas: Patch/Panel
Outdoor Directional Panel WLAN Antenna Gain = 15.5 dBi
H Beam = 25° V Beam = 25°
Images: 2007www.hyperlinktech.com
Patch Antennas
Single element patch
antennas may increase the RF
signal from 3-8 dBi. Multiple
element patch antennas may
increase the RF signal from
12-18 dBi.
Patch/Panel Antenna Examples
Dual Cable / Dual Diversity Flat Patch Gain = 11 dBi
H Beam = 60° V Beam = 30°Diversity
Smoke-Detector Round Patch Gain = 8 dBi
H Beam = 75° V Beam = 65°
Directional Patch Range Extender Gain = 8 dBi
H Beam = 75° V Beam = 65°
Images: 2007www.hyperlinktech.com
30
Patch/Panel Antenna Examples
Flat Patch Gain = 14 dBi
H Beam = 30° V Beam = 30°
Heavy Duty Panel Gain = 18 dBi
H Beam = 22° V Beam = 17°
Mini Panel Gain = 12 dBi
H Beam = 65° V Beam = 34°
Images: 2007www.hyperlinktech.com
Horizontally Polarized Sector Panel Gain = 14 dBi H Beam = 90°V Beam = 20°
Sector Panel Gain = 17 dBi H Beam = 120°V Beam = 6.5°
Sector Panel Antennas
Images: 2007www.hyperlinktech.com
Sectorized Antenna System
31
Dual 180°Dual-Antenna Array
Gain = 15 dBiH Beam = 180° each
V Beam = 10°
Tri 120°Tri-Antenna Array
Gain = 14 dBiH Beam = 120° each
V Beam = 15°
Sectorized Antenna Systems
Images: 2007www.hyperlinktech.com
Quad 90°Quad-Antenna
Array Gain = 17 dBiH Beam = 90°
each
Semi-Directional Antennas: Yagi
Yagi Antennas
Radome Yagi Gain = 9 dBi H Beam = 60°V Beam = 60°
Radome YagiGain = 14 dBi H Beam = 30°V Beam = 30°
Diversity
Radome YagiGain = 12 dBiH Beam = 45°V Beam = 45°
Images: 2007www.hyperlinktech.com
32
Highly-Directional Antennas: Parabolic Dish or Grid
Dish Gain Examples:
25 cm – 15 dBi1m x 50 cm – 24 dBi1m full – 27 dBi2m full – 31 dBi3m full – 37 dBi
High Performance Parabolic Dish Gain = 28 dBiH Beam = 6°V Beam = 6°
Images: 2007www.hyperlinktech.com
Dish/Grid Antennas
Backfire WLAN Directional Antenna
Gain = 14 dBi H Beam = 25°V Beam = 25°
Mini-Reflector Grid Gain = 15 dBi H Beam = 16°V Beam = 21°
RemovableRadome
Images: 2007www.hyperlinktech.com
Dish/Grid Antennas
Parabolic Dish Gain = 20.5 dBiH Beam = 14°V Beam = 14°
Reflector Grid Gain = 30 dBiH Beam = 5.3°V Beam = 5.3°
Images: 2007www.hyperlinktech.com
33
Antenna Mounting Accessories
60 Degree Tilt and Swivel Bracket
Window Mount Kit
Heavy Duty Standoff Mount
Images: 2007www.hyperlinktech.com
Antenna Mounting Examples
Mini Panel WLAN Antenna with Mast-Mounting Hardware
Backfire WLAN Directional Antenna with Mast-Mounting hardware
Compact Omni-directional Antenna with Mast-Mounting Hardware
Images: 2007www.hyperlinktech.com
Antenna Mounting Examples
Horizontally Polarized Sector Panel
with Mast-Mounting HardwareSectorized Antenna Array
with Tri-Sector Mounting Hardware
Radome Yagi Antenna with 60 Degree Tilt and Swivel
Mounting Hardware
Images: 2007www.hyperlinktech.com
34
Voltage Standing Wave Ratio
Antenna Characteristics
When choosing an antenna, evaluation of the following points is highly recommended:
• Gain
• Beam widths (horizontal and vertical)
• Rear lobe coverage
• Polarization
• Cost
• Intended use
• Manufacturer
• Impedance, VSWR, and other electrical characteristics
• Attached cable and connector types
• Available mounting gear
Simple Diversity Systems
Tip:
Diversity antennas should not be used to provide coverage in two different areas.
35
Diversity Transmit Systems
Line-of-Sight (LoS)
Fresnel Zone
36
Fresnel Zone
1FZ
2FZStrongest Signal
(Point Source)
Tx Rx
1FZ
2FZ
What a person with RF goggles sees from the side
What the Receiver sees when looking at the Transmitter
1FZ
If antenna gain changes, FZ size
does not change because the FZ
is based only on distance and
frequency.
Calculating 1FZ Size & Minimum Clearance
To calculate the Height (Radius) of the First Fresnel Zone:
H = Height (Radius) of the First Fresnel Zone (in feet)
D = Distance between the antennas (in miles)
F = Frequency in GHz
F
DH
42.72
Calculating 1FZ Size & Minimum Clearance
To calculate Fresnel Zone minimum clearance (60% of
entire 1FZ):
H = Height (Radius) of 60% of the First Fresnel Zone (in feet)
D = Distance between the antennas (in miles)
F = Frequency in GHz
F
DH
43.43
37
Free Space Path Loss (FSPL)
• FSPL is always the single greatest loss factor in an
RF system
• When the Fresnel Zone is blocked:
– Raise the antenna tower(s)
– Remove obstacles
Clear Line-of-Sight
(no Fresnel Zone
obstructions)
required to assure
FSPL calculation is
correct
Free Space Path Loss (FSPL)
Free Space Path Loss (FSPL)
To calculate Free Space Path Loss where
the distance between antennas is
measured in kilometers:
Lp = 32.4 + (20 log10 F) + (20 log10 D)
Lp = free-space path loss between
antennas (in dB)
F = frequency in MHz
D = path length in kilometers
To calculate Free Space Path Loss where
the distance between antennas is
measured in miles:
Lp = 36.6 + (20 log10 F) + (20 log10 D)
Lp = free-space path loss between
antennas (in dB)
F = frequency in MHz
D = path length in miles
38
Earth Bulge
Calculating Antenna Height for Links >7 miles
H = Height of earth bulge (in feet)
D = Distance between antennas (in miles)
F = Frequency in GHz
To calculate additional antenna height
required to compensate for curvatureTo calculate minimum antenna height
required to compensate for curvature
H = Height of earth bulge (in feet)
D = Distance between antennas (in miles)
F = Frequency in GHz
8
2
43.43
DF
DH
8
2
DH
Antenna Downtilt
39
Antenna Safety
http://www.sitesafe.com
Read factory manuals
Do not touch an active antenna surface
Avoid metal obstructions
Consider professional installers
Avoid power lines
Use grounding rods
RF Health and Safety Classes
Antenna Accessories: RF Cables
FCC Part 15.204
Amendment
• Recent FCC Regulations now
allow the use of third party
antennas
FCC Regulations
• Proprietary connectors are still
required
Proprietary Connectors
• Home built systems are still
prohibited
Home Built Systems
40
Antenna Accessories: Pigtail Cables
Antenna Accessories: Pigtail Cables
Pigtails are short RF cable
adapters with a common or
generic connector-type on
one end and a
―Proprietary‖ connector-
type on the other end.
Pigtails are used to allow
generic antennas to be
connected to various
WLAN cards.
Common RF Connectors
Images: 2007www.hyperlinktech.com
41
Lightning Arrestors
Lightning arrestors use bi-metal
conductors or gas discharge tubes to
sense incoming over-voltages induced by
nearby lightning strikes and shunt the
current to earth ground. Lightning
arrestors cannot fully protect against a
direct lightning strike.
Gas discharge tube protectors feature
easily replaced gas tube elements,
multi-strike capability and bi-
directional protection.
Coaxial Gas Discharge Tube Surge Protectors
Lightning Protection
Review
• Antenna Polarization and Gain
• Different types of antennas and antenna
systems commonly used in 802.11 WLANs
• Antenna implementation and safety
• Different antenna accessories
In this video we discussed:
42
Brought to you by
RF Regulatory Domains
Objectives
• International, regional, and local RF spectrum management organizations
• RF channels in the unlicensed 2.4 GHz and 5 GHz frequency ranges as designated by the European Radiocommunications Commission (ERC) and the U.S. Federal Communications Commission (FCC)
• View specific examples of how power output limitations are enforced by the FCC for Point-to-Multipoint (PtMP) and Point-to-Point (PtP) wireless connections
In this video…
International RF Spectrum Management Hierarchy
International Telecommunications Union
– Radiocommunication Sector (ITU-R)
http://www.itu.int/ITU-R/
43
Regional Spectrum Management Groups - CITEL
• InterAmerican
Telecommunication
commission (CITEL)
• ITU-R Administrative Region
―A‖
• http://www.citel.oas.org
AntiguaBarbudaArgentinaBahamasBarbadosBelizeBolivia
ColombiaCosta RicaCubaDominicaEcuadorEl SalvadorGrenada
HondurasJamaicaMexicoNicaraguaPanamaParaguayPeru
Saint Vincent the GrenadinesSurinameTrinidad & TobagoUruguayVenezuelaUnited States of America
Regional Spectrum Management Groups - CEPT
• European Conference of
Postal and
Telecommunications
Administration (CEPT)
• ITU-R Administrative
Region ―B‖
• http://www.cept.org
AlbaniaAndorraAustriaAzerbaijanBelarusBelgiumBosnia & HerzegovinaBulgaria
Czech RepublicDenmarkEstoniaFinlandFranceGermanyGreeceHungary
ItalyLatviaLiechtensteinLithuaniaLuxembourgMaltaMoldovaMonaco
Serbia & MontenegroSlovakiaSloveniaSpainSwedenSwitzerlandthe former Yugoslav Republic of Macedonia
Regional Spectrum Management Groups - RCC
• Regional Commonwealth
in the field of
Communications (RCC)
• ITU-R Administrative
Region ―C‖
• http://www.rcc.org
ArmeniaBelarusBulgariaGeorgiaMoldovaRussia
44
Regional Spectrum Management Groups - ATU
• African
Telecommunications
Union (ATU)
• ITU-R Administrative
Region ―D‖
• http://www.atu-
uat.org
North Africa:AlgeriaEgyptLibyaMoroccoTunisiaMauritania
East Africa:ComorosDjiboutiEthiopiaKenyaMadagascarMauritiusSomalia
West Africa:BeninBurkina FasoCote d’IvoireGambiaGhanaGuinea
Southern Africa:LesothoMalawiSouth AfricaSwazilandZambiaZimbabwe
Central Africa:AngolaBurundiCameroonCentral African Rep.ChadCongoDemocratic Rep. of Congo
Central Africa:Guinea BissouLiberiaMaliNigerNigeriaSenegalSierra Leone
Regional Spectrum Management Groups - APT
• Asia-Pacific
Telecommunity
• ITU-R Administrative
Region ―E‖
• http://www.aptsec.org
AfghanistanAustraliaBangladeshBhutanBruneiDarussalamChina
IranJapanKorea DPRKorea, Rep.Lao PDRMalaysiaMaldives
MyanmarNauruNepalNew ZealandPakistanPalauPapua New Guinea
Sri LankaThailandTongaVietnamAssociate Members:Cook IslandsHong Kong
Examples of Local RF Regulatory Bodies
Japan
(MKK)
TELEC 33B
TELEC ARIB STD-T71
Canada ISC RSS-210
Europe
(ETSI)
ETS 300.328
ETS 301.893
USA FCC (47 CFR) Part
15C, Section 15.247
FCC (47 CFR) Part
15C, Section 15.407
China RRL/MIC
Notice 2003-13
Israel MOC
Singapore IDA/
TS SSS Issue 1
Taiwan PDT
45
Channel
Number
Frequency
(GHz)Americas EMEA Israel* China Japan
2.4 GHz ISM Band
1 2.412 x x x x x
2 2.417 x x x x x
3 2.422 x x x x x
4 2.427 x x x x x
5 2.432 x x x x x
6 2.437 x x x x x
7 2.442 x x x x x
8 2.447 x x x x x
9 2.452 x x x x x
10 2.457 x x x x x
11 2.462 x x x x x
12 2.467 x x x
13 2.472 x x x
14 2.484 x
*Israel allows channels 5-13 outdoors, but 1-13 indoors.
5 GHz Unlicensed Bands
Americas / EMEA UNII-1 Band
(5.15 - 5.25)
4 36
40
44
48
5180
5200
5220
5240
Americas / EMEA UNII-2 Band
(5.25 - 5.35)
4 52
56
60
64
5260
5280
5300
5320
Americas / EMEA UNII-2e Band
(5.470 - 5.725)
11 100, 104, 108,
112, 116, 120,
124, 128, 132,
136, 140
5500, 5520, 5540,
5560, 5580, 5600,
5620, 5640, 5660,
5680, 5700
Americas /
EMEA (with
restrictions)
UNII-3 Band
(5.725 - 5.825)
4 149
153
157
161
5745
5765
5785
5805
Americas ISM
(5.725 - 5.850)
1 165 5825
Band (GHz)Regulatory
DomainCenter FrequencyChannel Number# of Channels
FCC 2.4 GHz PtMP Rules
Referred to as ―1:1 Rule‖
46
FCC 2.4 GHz PtMP Rules
PtMP EIRP in the 2.4 GHz band may not exceed 36 dBm
FCC 2.4 GHz PtMP Rules
PtMP EIRP in the 2.4 GHz band may not exceed 36 dBm
FCC 2.4 GHz PtMP Rules
PtMP EIRP in the 2.4 GHz band may not exceed 36 dBm
47
FCC 2.4 GHz PtMP Rules
PtMP EIRP in the 2.4 GHz band may not exceed 36 dBm
FCC 2.4 GHz PtMP Rules
PtMP EIRP in the 2.4 GHz band may not exceed 36 dBm
FCC 2.4 GHz PtMP Rules
PtMP EIRP in the 2.4 GHz band may not exceed 36 dBm
48
Americas / EMEA 5 GHz Band Rules
FCC 5 GHz PtMP Rules: UNII-1
1:1 Rule applies to UNII-1 band
FCC 5 GHz PtMP Rules: UNII-2
1:1 Rule applies to UNII-2 band
FCC power output rules for the UNII-2e band
(5.470 – 5.725 GHz) are identical to rules for the
UNII-2 band (5.250 – 5.350 GHz)
49
FCC 5 GHz PtMP Rules: UNII-3
1:1 Rule applies to UNII-3 band
FCC 2.4 GHz PtP Rules
Referred to as ―3:1 Rule‖ 36 dBm = 4 Watts
FCC 2.4 GHz PtP Rules
3:1 Rule applies to 2.4 GHz PtP connections38 dBm = 6.3 Watts
50
FCC 2.4 GHz PtP Rules
3:1 Rule applies to 2.4 GHz PtP connections40 dBm = 10 Watts
FCC 2.4 GHz PtP Rules
3:1 Rule applies to 2.4 GHz PtP connections42 dBm = 16 Watts
FCC 2.4 GHz PtP Rules
3:1 Rule applies to 2.4 GHz PtP connections44 dBm = 25 Watts
51
FCC 2.4 GHz PtP Rules
46 dBm = 40 Watts3:1 Rule applies to 2.4 GHz PtP connections
FCC 2.4 GHz PtP Rules
3:1 Rule applies to 2.4 GHz PtP connections48 dBm = 63 Watts
FCC 2.4 GHz PtP Rules
50 dBm = 100 Watts3:1 Rule applies to 2.4 GHz PtP connections
52
FCC 2.4 GHz PtP Rules
3:1 Rule applies to 2.4 GHz PtP connections52 dBm = 158 Watts
FCC 5 GHz PtP Rules: UNII-3
PtP rules for the UNII-1, UNII-2, and UNII-2e band are the SAME as for PtMP
Review
• International, regional, and local RF spectrum management organizations
• RF channels in the unlicensed 2.4 GHz and 5 GHz frequency ranges as designated by the European Radiocommunications Commission (ERC) and the U.S. Federal Communications Commission (FCC)
• Specific examples of how power output limitations are enforced by the FCC for Point-to-Multipoint (PtMP) and Point-to-Point (PtP) wireless connections
In this video we discussed:
53
Brought to you by
Wireless LAN Operation
Objectives
• WLAN Hardware Devices• WLAN Software• Ad Hoc & Infrastructure Connectivity Operation• WLAN Management Systems (WNMS)• WLAN Controller Deployments• WLAN Profiles• AP Modes• Bridging & Repeating• Evolution of WLAN Architecture
In this video…
WLAN Radios
CardBusCompact Flash (CF)
Secure Digital (SDIO)
Universal Serial Bus (USB) Mini PCIe
PCI BusMini PCI Express Card
54
Client Utilities
Enterprise-Class Client Utilities
Some client utilities
are more robust
than others. Look
for authentication
and encryption
support that meets
the needs of your
implementation.
Access Points
55
Access Points as MAC Bridges
Frame Forwarding Between Physical Interfaces
Ad Hoc Mode
56
Infrastructure Mode
Wireless Network Management Systems (WNMS)
A WNMS can be used to
manage single- or multi-
vendor infrastructures
consisting of autonomous
APs, WLAN controllers
with lightweight APs,
WLAN Arrays, mesh
networks, or all of the
above.
WLAN Controllers
57
WLAN Controller: Core
WLAN Controller: Distribution
WLAN Controller: Access
58
WLAN Profiles
ESSID
Controller Capacity
Blah
QoS
VLAN
Security
Remote Office WLAN Controllers
Wireless Workgroup Bridges
59
Workgroup Bridges
Wireless Bridges
Bridging Repeaters
60
Access Point: Root Mode
Access Point: Repeater ModeWireless Distribution System
(WDS)
Point-to-Point (PtP) Connections
61
Point-to-Point Bridging
Point-to-Multipoint (PtMP) Connections
Point-to-Multipoint Bridging
62
Line-of-Sight (LoS)
LoS
Near
LoS
Non
LoS
Wireless Residential Gateways
Wireless VPN Routers
63
Enterprise Encryption Gateways (EEGs)
EEGs are sometimes
called Security
Controllers
Using EEGs
WLAN Arrays
64
WLAN Arrays
Location Tracking
Real-Time Location
Services (RTLS) is
widely used in
today’s market.
Location tracking
software may be
implemented as a
software-only
solution or as an
appliance solution.
Evolution of WLAN Architecture
65
Evolution of WLAN Architecture: Multi-Channel
Architecture (MCA)
Hexagonal tiling, often called ―channel re-use‖ is required for MCA
systems to avoid co-channel and adjacent channel interference. This
system has been used since the earliest days of WLAN deployments and
is still in use today by the majority of vendors.
Evolution of WLAN Architecture: Single Channel
Architecture (SCA)
Each WLAN operates interference free on a single channel. This allows dense
WLAN deployments using multiple channels. This is referred to as ―channel
spanning‖, ―channel blankets‖, and even ―channel stacking.‖
Wireless Mesh Networks
Wireless mesh routers communicate with each
other using proprietary layer 2 routing protocols,
forming a self-healing wireless infrastructure.
66
Review
• WLAN Hardware Devices• WLAN Software• Ad Hoc & Infrastructure Connectivity Operation• WLAN Management Systems (WNMS)• WLAN Controller Deployments• WLAN Profiles• AP Modes• Bridging & Repeating• Evolution of WLAN Architecture
In this video we discussed:
Brought to you by
Power over Ethernet
(PoE)
Objectives
• The two standards currently available for PoE
• Recognize the two types of devices used in Power
over Ethernet (PoE)
• Recognize the differences between the two types of
Power Sourcing Equipment (PSE)
• How is power delivered using PoE
• The importance of planning to maximize the
efficiency of Power over Ethernet
In this video…
67
A Tale of Two Standards
• Formerly 802.3af
•15.4 Watts maximum
power
• Widely-deployed in a
number of industries
including 802.11 WLANs
802.3-2005, Clause 33
• Currently in Draft
• 59 Watts maximum
power
• Draft-compliant
equipment currently
available, but not
widely deployed
•Often called ―PoE Plus‖
802.3at
PoE Overview
Powered Device (PD)
Power Sourcing Equipment (PSE)
Powered Device (PD)
68
Power Sourcing Equipment
Endpoint – Switch with
integrated power-supplying
equipment
Midspan – Passthrough
device with integrated
power-supplying
equipment (single-port or
multi-port)
• To determine classification, the PSE applies up to 20.5 VDC to PD
• The PD Classification Signature is determined by the returning current
802.3af PD Classification Signature
802.3af PSE Power Classes & PD Power Consumption
Class Usage Power Output at the PSE Maximum Power Levels at
the Powered Device
0 Default 15.4W 0.44 W to 12.95 W
1 Optional 4.0 W 0.44 W to 3.84 W
2 Optional 7.0 W 3.84 W to 6.49 W
3 Optional 15.4 W 6.49 W to 12.95 W
4 Reserved for
Future Use
Treat as Class 0 Reserved for Future Use: A
class 4 signature cannot be
provided by a compliant
powered device
The power difference between PSE output power and PD maximum power draw is
due to the resistance of the Ethernet cable. Power that is allocated but not used
is wasted.
69
Where is the Power?
In a Midspan PSE
configuration, two
active pairs of
conductors carry the
Ethernet signal to the
end station (PD) …
… while the two unused
pairs are used to carry the
electrical power to the PD.
MDI – Medium Dependent Interface
PHY – Physical Layer Device
PI – Power Interface
PSE – Power Sourcing Equipment
In an Endpoint PSE
configuration, the
Ethernet signal and
electrical power both
travel on the same two
pairs.
802.3af Power Interface
Above cutaway cable was constructed specifically
to illustrate T568B conductor pinouts.
The generic term that refers to the
mechanical and electrical interface
between the PSE or PD and the
transmission medium.
Power is sent from the PSE to the PD
over the Ethernet cable (MDI)
Can use data lines
Orange Pair (Org/Wht and Org)
Green Pair (Grn/Wht and Grn)
Can use unused conductors
Blue Pair (Blu/Wht and Blu)
Brown Pair (Brn/Wht and Brn)
Power Interface
Note: Color code assumes use of T568B pinouts
PSE Endpoint Alternative A
SwitchPowered End
Station
Endpoint PSE – Alternative A
Endpoint PSE Alternative A uses the data conductors for electrical power
70
PSE Endpoint Alternative B
SwitchPowered End
Station
Endpoint PSE – Alternative B
Endpoint PSE Alternative B uses the spare conductors for electrical power
PSE Midspan
Midspan PSE – Alternative B
Midspan PSE -Alternative B uses the spare conductors for electrical power
• The PD must be able to accept power from the PSE using either Alternative A
or Alternative B
• The PD must be able to accept either electrical polarity that may be in use
by the PSE.
802.3af PD Pinout
71
High Density PoE Requires Planning
Each 802.3af-compliant 48-port PoE line card requires 739.2 W if all ports are active
at default class (15.4W)
High-density PoE requires high-power feeds and much
cooling
Two of these power
supplies will be in
operation in a single
switch, yielding a total of
~72,000 BTUs per hour at
capacity per switch
Each of these power
supplies radiates ~36,000
BTUs per hour at capacity
Use of Management Protocols
72
Where PoE is used in WLANs
WLAN controllers
Ethernet switches
Access Points
Midspan Injectors
Non-WLAN uses of PoE
Smart Card readersGas detectors
IP PhonesRFID readersClocks
IP Cameras
PoE Diagnostics
PoE Diagnostic Devices
73
Powering 802.11n
Dual 802.3af Ports
802.3af Port, upgradeable
to 802.3at
802.3af Port, proprietary
enhancement
Proprietary AC Power Plug
Review
• The two standards currently available for PoE
• Recognize the two types of devices used in Power
over Ethernet (PoE)
• The differences between the two types of Power
Sourcing Equipment (PSE)
• How is power delivered using PoE
• The importance of planning to maximize the
efficiency of Power over Ethernet
In this video we discussed:
Brought to you by
802.11 Service Sets
74
Objectives
In this video…
• The three types of service sets defined for use within 802.11 WLANs
• 802.11 authentication and association• 802.11 network infrastructure• Roaming within a WLAN• Load-balancing as a method to improve
congestion in WLANs
802.11 Service Sets
Independent Basic Service Set
• IBSS
• Ad Hoc
• Peer-to-Peer
75
IBSS Process
IBSS Process
Basic Service Set (BSS)
76
BSS Selection
Some client utilities allow
the user to configure the
client to join:
____________________
Only an IBSS network
Only a BSS network
Any network
The more ―automatic‖ the BSS selection is,
the higher the security risk.
Extended Service Set
The Network Infrastructure
Infrastructure: The infrastructure includes the distribution system medium (DSM), access point
(AP), and portal entities. It is also the logical location of distribution and integration service
functions of an extended service set (ESS). An infrastructure contains one or more APs and zero
or more portals in addition to the distribution system (DS).
77
Integration Service
Integration Service: The
service that enables
delivery of medium access
control (MAC) service data
units (MSDUs) between the
distribution system (DS)
and an existing, non-IEEE
802.11 local area network
(via a portal).
Distribution System
Distribution System: A system used to interconnect a set
of basic service sets (BSSs) and integrated LANs to create
an extended service set (ESS).
Wireless Distribution System (WDS)
78
802.11 State Machine
Joining a Service Set – State 1 (Discovery)
Joining a Service Set – State 1 (Discovery)
79
Joining a Service Set – State 1 (Open System Auth)
Joining a Service Set – State 1 (Shared Key Auth)
Joining a Service Set – State 2 (Association)
80
802.1X/EAP Authentication –State 3 (all frames)
Disassociation
Note: Disassociation is always successful,
from the sender’s perspective. The receiver
is not required to respond. That’s why
Disassociation is known as a Notification,
not a Request.
Deauthentication
81
Roaming (BSS Transition)
Load Balancing
Review
In this video we discussed:
• The three types of service sets defined for use within 802.11 WLANs
• 802.11 authentication and association• 802.11 network infrastructure• Roaming within a WLAN• Load-balancing as a method to improve
congestion in WLANs
82
Brought to you by
Basic WLAN Analysis
Objectives
• Protocol Analysis
• 802.11 Frame Types– Data Frames
– Control Frames
– Management Frames
• Protection Mechanisms
• Power Saving Operations
• Transmission Rates
In this video…
WLAN Protocol Analyzers
83
Handheld Protocol Analyzers
Handheld Protocol Analyzers
AirMagnet Handheld
Fluke OptiView III
BV Systems Yellowjacket
Tamosoft CommView for Wi-Fi PPC
802.11 Frame Format
Carry Data• Simple Data• QoS Data• Data + CF-Ack• QoS Data + CF-Ack• Data + CF-Poll• QoS Data + CF-Poll• Data + CF-Ack + CF-Poll• QoS Data + CF-Ack + CF-
Poll
Data Frames
Two types of Data frames:
• First group is used to carry data
• Second group does not carry data
Do Not Carry Data
• Null
• QoS Null
• CF-Ack
• CF-Poll
• QoS CF-Poll
• CF-Ack + CF-Poll
• QoS CF-Ack + CF-Poll
84
Null Frames
Control Frames
1
2
3
PS-Poll
Used to request data frames in Power Save mode
4
5
CF-End, CF-End+CF-Ack
Used to signal the end of a service period
Ack, CF-End+CF-Ack, BlockAck, BlockAckReq
Used to acknowledge or request acknowledgement of correctly received frames
RTS, CTS
Used to reserve the RF medium
Control Wrapper
Used to carry any other control frame together with an HTC field
Hidden Node - Obstructions
85
Hidden Node – Signal Strength
Hidden Node – Signaling Methods
Using RTS/CTS
86
RTS/CTS Exchange
Without RTS/CTS With RTS/CTS
RTS/CTS Exchange – cont’d
Protection Mechanisms
Is there an 802.11b station
associated with this 802.11g AP?
Should this AP tell the 802.11g
stations associated with it to use
protection mechanisms?
87
Power Management Modes
Some client utilities let
the user configure how
much the client will doze
while in Power Save mode.
TIM and DTIM
The DTIM Period field indicates the number
of Beacon intervals between successive
DTIMs. If all TIMs are DTIMs, the DTIM
Period field has the value 1. The DTIM
Period value 0 is reserved.
AIDs in the TIM indicate to individual
stations whether or not they have traffic
buffered at the AP. AIDs are assigned to
clients by the AP during association and
have a maximum value of 2007.
ATIM & ATIM Window
ATIM Window
Beacon Interval
Beacon
Station A
Station B
Tx ATIM Tx Data
Tx Ack Tx Ack
88
Legacy Power Save and U-APSD
Legacy Power SaveU-APSD
Management Frames
• Management
– Beacon
– Probe Request
– Probe Response
– Authentication
– Association Request
– Association Response
– Reassociation Request
– Reassociation Response
– Disassociation
– Deauthentication
– ATIM
– Action
– Action, No Ack
Beacons
89
Probe Requests / Responses
Open Authentication
Shared Key Authentication
90
Association Request / Response
Reassociation Request / Response
Disassociation
91
Deauthentication
Acknowledgement (Ack) Frames
Basic and Supported Rates
92
Transmission Rates
Review
• Protocol Analysis
• 802.11 Frame Types– Data Frames
– Control Frames
– Management Frames
• Protection Mechanisms
• Power Saving Operations
• Transmission Rates
In this video we discussed:
93
Brought to you by
802.11 Medium Access
Objectives
• Differences between CSMA/CD and CSMA/CA
• Distributed Coordination Function (DCF)– Network Allocation Vector (NAV)
– Clear Channel Assessment (CCA)
– Interframe Spacing (IFS)
– Contention Window (CW)
• Point Coordination Function (PCF)
• Hybrid Coordination Function (HCF)
In this video…
CSMA/CD
94
CSMA/CA
Distributed Coordination Function (DCF)
Virtual Carrier Sense
Duration/ID field indicates
how long it will take to
complete the present frame
exchange. This value is
processed by all stations in
a BSA except the station to
which the frame is directed.
95
Virtual Carrier Sense
STA-1 and STA-2 cannot hear each other’s
transmissions.
Physical Carrier Sense
Inter-Frame Spacing
96
Interframe Spacing
Random Backoff Algorithm
Point Coordination Function (PCF)
97
802.11e MAC Architecture
HCF Controlled Channel Access (HCCA)
Enhanced Distributed Channel Access (EDCA)
98
WMM Access Categories (AC)
WMM Transmission Queues
WMM Power Save (WMM-PS)
99
Review
• Differences between CSMA/CD and CSMA/CA
• Distributed Coordination Function (DCF)– Network Allocation Vector (NAV)
– Clear Channel Assessment (CCA)
– Interframe Spacing (IFS)
– Contention Window (CW)
• Point Coordination Function (PCF)
• Hybrid Coordination Function
In this video we discussed:
Brought to you by
The 802.11n Amendment
Objectives
• Challenges addressed by 802.11n
• 802.11n PHY/MAC layer enhancements
• MIMO and SISO systems
• 802.11n coexistence mechanisms
• 802.11n integration and deployment
considerations
• 802.11n site surveying and analysis
In this video…
100
Time to File Transfer
0 2 4 6
11n
11g
Throughput Reliability Predictability
Laptop Rotational Spin
0
5
10
15
20
0 20 40 60Time
Th
rou
gh
pu
t 11n
11g
Roving Laptop Comparison
8
10
12
14
16
18
20
22
24
0 50 100 150 200 250
Time
Packet
Retr
ies
11n
11g
Why 802.11n?
Throughput Reliability Predictability
Enhanced file transfer and
download speeds for large files
Lower latency for mobile
communications
More consistent coverage and throughput for
mobile applications
5x more throughput 2x more reliable 2x more predictable
PHY Comparison
802.11b 802.11a 802.11g 802.11n
Amendment Approved
July 1999 July 1999 June 2003Draft 2.0
February 2007
Maximum Data Rate 11 Mbps 54 Mbps 54 Mbps300 - 600
Mbps
Supported Modulation
HR/DSSS OFDMHR/DSSS &
OFDMHR/DSSS &
OFDM
RF Band 2.4 GHz 5 GHz 2.4 GHz 2.4 / 5 GHz
Number of Spatial Streams
1 1 1 1 - 4
Channel Width 22 MHz 20 MHz 20 MHz 20 / 40 MHz
Average Burst Data Rate (Mbps)
6050403020100
MIMO
AP
Average Burst Data Rate (Mbps)
6050403020100
SISO
AP
Reliable Connectivity
• Higher average throughput, more reliable connectionsBetter reliability, better user experience
Predictable throughput and coverage
Fewer help desk calls
101
Performance penalty caused by multipath and interference from metal shelves, elevator shafts, corridors, and machinery
Challenge
MIMO uses multipath to its advantage to reduce coverage holes
Hospitals
Manufacturing facilities
Factory floors
Warehouse
Most AffectedHow 802.11n Helps
Challenging RF Environments
Challenge
Most AffectedHow 802.11n Helps
Bandwidth Intensive Environments
Limited wireless bandwidth for heavy data transfers
MIMO offers two spatial streams for greater throughput
40MHz channels
Frame aggregation improves payload efficiencies
Healthcare (digital imaging, patient records)
Engineering (CAD, imaging)
Education (research, file sharing)
Challenge
Most AffectedHow 802.11n Helps
Voice and Video Readiness
Delivering a quality wireless voice experience over a network optimized for latency sensitive traffic
Healthcare
Retail stores
Warehouses
MIMO decreases frame retries, maintaining low latency throughput
MIMO provides more consistent coverage
102
Challenge
Most AffectedHow 802.11n Helps
Mixed Client Environments
Delivering optimal performance and compatibility in a wireless network with a mix of existing 802.11abg and 802.11n clients
802.11n requires backwards compatibility with existing 802.11abg clients
Benefits of MIMO for reliability and predictability extend to 11abg clients
Education
Hospitability (Guest networks)
MIMO
Transmit
Beamforming
(TxBF)
Maximal Ratio
Combining (MRC)
Spatial
Multiplexing (SM)
Space Time Block
Coding (STBC)
802.11n Enhancements
SISO vs. MIMO
Simple receive diversity has one
radio with two antennas
Dual-frequency capable
AP with 3x3 MIMO
Two radio cards, 6
radios, 6 antennas
103
MIMO
There are two variations
between SISO and MIMO
Single Input Single Output (SISO)
Destructive Interference
Am
plit
ud
e
Time Time
Am
plit
ud
e
Am
plit
ud
e
Time
SISO and Multipath
=
Pow
erPo
wer
Inter-Symbol Interference
MIMO Radio Card
• Analog/Digital
Conversion
• Baseband
Processing
• MAC Functions
• PC Interface
(CardBus, Mini-
PCIe, etc.)
• 2-4 Dual-Band
Radios
• 2-4 Dual-Band
Antennas
104
MIMO “Uses” Multipath
Performance
MIMO: Tx Beam Forming
Performed by
transmitter
Ensures signal is
received in-phase
Increases SNR Works with
non-MIMO and
MIMO clients
HALLWAY
Without Tx Beam Forming Transmissions Arrive out of Phase
With Tx Beam Forming Transmissions Arrive in Phase, Increasing Signal Strength
MIMO AP
TxBF sends the same data on all participating radios, but has the effect of ―focusing‖
transmissions at a target station by changing the phase of each transmission at the transmitter
MIMO: Tx Beam Forming
123456789
MIMO AP
123456789
MIMO STA
123456789
123456789
123456789
105
Path Delay
Path Delay
Am
plitu
de
Time
Am
plitu
de
Time
Am
plitu
de
Time
Signal Transmission
with Phase Offset
Signal Reception (combined,
in-phase) – improved SNR
TxBF causes constructive interference
MIMO: Tx Beam Forming
MRC takes multiple received signals (from multipath) and combines
them in a way that significantly boosts signal strength.
MIMO: Maximal Ratio Combining
123456789
Legacy STA
123456789
MIMO AP
123456789
123456789
123456789
MIMO: Maximal Ratio Combining
106
Transmitter and Receiver Participate
Concurrent Transmission on Same Channel
Increases Throughput
Requires MIMO Clients
Performance
stream 1
stream 2
Information is split and transmitted on multiple streams
MIMO AP
MIMO: Spatial Multiplexing
• Conventional SISO systems transmit and receive on a single radio
chain
• SM can provide an N-fold increase in throughput by using N streams
• Advanced signal processing and additional radio chains are required
for Tx and Rx
MIMO: Spatial Multiplexing
123456789
MIMO AP
123456789
MIMO STA
456
789
123
Time
Time
Transmitted SignalReceived Signal
Time
Pow
erPo
wer
Pow
er
Pow
er
MIMO: Spatial Multiplexing
107
PHY Enhancements: Effect on Throughput Example
MIMO: Space-Time Block Coding (STBC)
•Uses more antennas than spatial streams
•Increases reliability at the receiver
•SM and STBC can be used together
•Think ―RAID for RF‖
Tx RxAB ->BC -> ABCCA ->
SM + STBC Data Flow
Data flow in this direction
Space-time
BlockCoder
SpatialDivision
Multiplexor
SpatialDivision
Multiplexor
Space-timeBlock
Decoderand
MaximalRatio
Combiner
MACetc.
RFchannel MAC
etc.
Split again
into N STS
space-time
streams
Split into
NS
spatial
streams
Original
data
stream
Original
data
stream
Rebuilt
into NS
spatial
streams
Recieved
signals from
available
antennas
108
PHY Enhancements
40 MHz Channels
Channel Bonding
More Subcarriers
Non-HT Duplicate
Format
Optional Short
Guard Intervals
Modulation Rates
Antenna
Selection
802.11n Enhancements
20 MHz Channel Mask
20 MHz Channel Width
40 MHz Channel Mask
40 MHz Channel Width
109
20 MHz
20 MHz
40 MHzGained Space
20 MHz vs. 40 MHz Channels
Moving from 2 to 4 lanes
40 MHz = two aggregated 20 MHz channels - takes advantage of the reserved channel space through bonding to gain more than double the data rate of two 20 MHz channels
2.4 GHz Channel Selection
1 2 6 113 4 5 7 8 9 12 13 1410
40MHz 802.11n channel2.402 GHz 2.483 GHz
Channel Bonding (2.4 & 5 GHz)
5.25
GHz
5.35
GHz
5.470
GHz
5.725
GHz
5.825
GHz
5.15
GHz
UNII-1 UNII-2 UNII-3UNII-2e
110
Channel Bonding in 5 GHz
802.11a/g
52 subcarriers in 20-
MHz Channel
56 subcarriers in 20-MHz
Channel
802.11n
114 subcarriers in 40-MHz HT
Mode Channel
OFDM Subcarriers
More subcarriers means more data can be crammed into a channel
Non-HT Duplicate Mode
802.11n
Non-HT
Duplicate
Format
52
subcarriers
in
20-MHz
Channel56 subcarriers in HT 20 MHz
Channel
5.25
GHz
5.15
GHz Adjacent 20 MHz, 52 subcarrier
channels are used simultaneously to
carry the same information
111
Guard Interval Reduction
TimeISI
Time
800 ns
The Problem
The 802.11a/g/n Solution The Optional 802.11n Solution
Time
400 ns
Guard Interval Reduction
800 ns (standard)400 ns (optional)
Antenna Selection (ASEL)
• When there are more antennas than transmit and/or receive radio chains, ASEL can be used to increase signal diversity, and effectively SNR, at the receiver.
112
802.11n MCS (Data) Rates
MAC Enhancements
Frame
Aggregation
Block ACKs
RIFS
SMPS
PSMP
802.11n Enhancements
802.11 Protocol Stack
113
802.11 Encapsulation
Frame Aggregation
Carpooling is more efficient than driving alone
Without Frame Aggregation
Data Unit
Frame
802.11n Overhead
Data Unit
Frame
802.11n Overhead
Data Unit
Frame
802.11n Overhead
With Frame Aggregation
Data Unit
Frame
802.11n Overhead
FrameFrame
40-MHz Channels:802.11n supports both 20- and 40-MHz wide channelsWider channels means more BW per AP
Frame Aggregation:Combine multiple data units into one frameSaves on 802.11n and MAC overhead
20 MHz
20 MHz
40 MHz
Auto Analogy:Twice the traffic lanes, twice the cars
Auto Analogy:Car pooling is more efficient than driving by yourself
Without FrameAggregation
With FrameAggregation
802.11nOverhead
Data Unit
Payload
802.11nOverhead
Data Unit
Payload Payload Payload
802.11nOverhead
Data Unit
Payload802.11n
Overhead
Data Unit
Payload
Frame Aggregation
114
Frame Aggregation: A-MSDU
Layer 3
MAC
PLCP
PMD
MAC HeaderMSDU
MSDU MSDU MSDU
MSDU MSDU
max 4 KB
max 2304 Bytes
MPD
U
PLCP
Header
MAC HeaderMSDU MSDU MSDU PPD
U
By reducing frame header overhead, 802.11n
stations can increase throughput substantially
Frame Aggregation: A-MPDU
MAC HeaderMSDU
PLCP Header
MAC HeaderMSDU
MSDU MSDU MSDU
MAC HeaderMSDU
MAC HeaderMSDU
MAC HeaderMSDU
MAC HeaderMSDU
max 65 KB
max 2304 Bytes
MPD
U
Layer 3
MAC
PLCP
PMD
Frame Aggregation Efficiency
Efficiency at 300
Mbps for:
• No Aggregation
• Maximum A-MSDU
Aggregation
• Maximum A-MPDU
115
Frame Aggregation Efficiency
Efficiency at 600
Mbps for:
• No Aggregation
• Maximum A-MSDU
Aggregation
• Maximum A-MPDU
Block Acknowledgements
Block Acknowledgements
(BlockAcks) are used as lists of
data frames being acknowledged.
BlockAcks allow selective
retransmission of data frames.
Block Acknowledgements
Time
ACK
F1
F2
ACK
F3
ACK
Data – Ack – Data – Ack
BEFORE
116
Time
F1
F2
F3
ACK-1, 2, 3
F1 F1 F1
ACK-1, 2, 3
Time
Block Acknowledgements
AFTER
Reducing MAC Overhead
DIFS/AIFS PIFS
SIFSContention Window
Back-Off
Time (t)
Busy Medium Next Frame
RIFS is used in a
very limited
number of
situations in
802.11n
deployments
• SIFS
• PIFS
• DIFS
• AIFS
• EIFS
• RIFS
Short Interframe Space
PCF Interframe Space
DCF Interframe Space
Arbitration Interframe Space
Extended Interframe Space
Reduced Interframe Space
Power Save: SMPS & PSMP
Spatial Multiplexing Power Save
Dynamic
Static
Power Save Multi-Poll
Unscheduled
Scheduled
(PSMP)(SMPS)
117
SMPS: Static
SMPS: Dynamic
Unscheduled PSMP (U-PSMP)
BUFFE
R
BUFFER
sleep trigger/data ACK/sleep
data data data
AP
CLIENT
118
Scheduled PSMP (S-PSMP)
BUFFER A
& B
TSpe
c
Req
AP
STAsTSpe
c
Req
Dat
a
A
Dat
a
B
DTT BUFFER A &
B
Dat
a
Dat
a
UTT
NAV
prevents
transmission
Sched
ule
STA-A
(PSMP)
STA-B
(PSMP)
STA-C
(Non-PSMP)
802.11n Coexistence
2.4GHz 5GHz
802.11a/b/g clients interoperate with 802.11n andexperience performance improvements
802.11n Operates in Both Frequencies
PPDU Frame Formats
L Legacy (non-HT)
STF Short Training Field
LTF Long Training Field
SIG Signal
HT High Throughput
L-STF L-LTF L-SIG
8us 4us8us
Data
L-STF L-LTF L-SIG HT-SIGHT-
STFHT-LTF
8us 8us 4us 8us 4us
Data
HT-GF-STF HT-LTF1 HT-SIG
Non-HT
(Legacy)
Mixed
Format
HT
Greenfield
8us 8us 8us
4us
.. HT-LTF(E)
HT-LTF
(E)
HT-LTF..
HT-LTF Data
4uS per
LTF 4us
.. HT-LTF(E)
HT-LTF
(E)
HT-LTF..
4uS per
LTF
4uS per
LTF
4uS per
LTF
119
Mode 0: (called ―Greenfield‖ Mode) - if all stations in a
20/40 MHz BSS are 20/40 MHz HT capable or if all stations in
the BSS are 20 MHz HT stations in a 20 MHz BSS.
Mode 1: (called HT non-Member Protection Mode) - used if
there are non-HT stations or APs using the primary and/or
secondary channels
Mode 2: (called HT 20 MHz Protection Mode) - if only HT
stations are associated in the 20/40 MHz BSS and at least
one 20 MHz HT station is associated.
Mode 3: (called HT Mixed Mode) - used if one or more non-
HT stations are associated in the BSS.
802.11n HT Protection Modes
The ―Operating Mode‖ value should
actually be decoded as ―HT
Protection‖ (per 802.11n-d4.00,
Section 7.3.2.58), and it contains
valuable information about what is
happening in the WLAN.
802.11n HT Protection Modes
20/40 MHz Mode
• AP must declare 20 MHz or 20/40 MHz
support in Beacons
• STAs must declare 20 MHz or 20/40 MHz in association or reassociation frames
• STAs must reassociate between 20 MHz and 20/40 MHz modes
• If 20/40 MHz capable STAs transmit using a single 20 MHz channel, it MUST be on the primary channel
5.25
GHz
5.15
GHz
UNII-1
20/40 MHz BSS Mode
20 MHz 802.11a/g/n stations and 40 MHz
capable 802.11n stations can operate within
the same cell at the same time.
120
PCO BSS Mode
Phased Coexistence Operation (PCO) is an optional coexistence mechanism in which an AP
divides time into alternating 20 MHz and 40 MHz phases. Although PCO improves
throughput in some circumstances, PCO might also introduce jitter.
Dual CTS
Stations send RTS to AP for uplink transmissions AP responds to RTS with HT and Legacy CTS frames APs use CTS-to-Self frames to accomplish the same
goal for downlink transmissions
Dual CTS Protection
L-SIG Legacy stations can read the L-SIG field in a mixed
mode PHY frame header 802.11n stations use the L-SIG field to indicate to
legacy stations how long to be silent
L-SIG TXOP Protection
121
40 MHz Intolerant
Can be indicated by an AP in Beacons and Probe Response Frames in the HT Capabilities Info field
Can be indicated by Stations in their HT Capabilities Info field in various frames
40 MHz Intolerant
Wi-Fi Certification for Draft 2.0
Feature AP / STA Mandatory Tested if implemented
2 spatial streams in Tx mode AP X
2 spatial streams in Rx mode AP/STA X
A-MPDU & A-MSDU AP/STA X
Block ACK AP/STA X
2.4 GHz operation AP/STA X
5 GHz operation AP/STA X
40 MHz channel in 5 GHz band AP/STA X
Greenfield preamble AP/STA X
Short GI in 20 & 40 MHz bands AP/STA X
Concurrent 2.4 and 5 GHz operation AP X
WMM QoS AP/STA X
WPA/WPA2 with Extended EAP AP/STA X
802.11n Considerations
802.11n Deployment Considerations
Core/Distribution/
Edge Switching
Speed
PoE, Cable Plant
Certification (or
Replacement)
Backward
Compatibility
Effects
RF Spectrum Design
and On-going
Management
Deployment
Strategy
Client PHY
Population
Expected vs.
Actual Speed
Enhancements
Increasing WLAN
Use
Migration
Strategy
Mesh Deployments
Site Survey Requirements
Controller Capacity
2.4 GHz vs. 5 GHz
Architecture Scalability
122
Backhaul Speeds
Power over Ethernet (PoE)
• Dual-, triple-, or quad-radio 802.11n APs often require more power than 802.3af PSE devices can provide.
• Most dual- or quad-radio 802.11n APs can operate in a diminished capacity while operating on 802.3af power.
• This could mean operating at 2x3 or 2x2 MIMO instead of 3x3.
• This could also mean full operation of only a single radio in the AP.
802.3af? 802.3at? Proprietary?
Cable Plant Certification
Since multi-band 802.11n APs can put 200-400 Mbps
onto the Ethernet backhaul connection, it is important
to verify that the cable plant is providing high quality
connectivity.
123
802.11n Deployment Strategy
• 5 GHz Recommended for 802.11n
– More available spectrum; greater number of channels
– Benefits from 40 MHz channels, although 20 MHz still works well
• 2.4 GHz still benefits from MIMO and frame aggregation
– Ideal for legacy applications (handhelds, scanners, & medical applications)
1
2 3
2
1 3 5 7 9 11
4 6 8 10
5 GHz 40 MHz Channels2.4 GHz 20 MHz Channels
802.11n Migration Strategy
• All vendors implement 802.11n infrastructure differently
• Look to manufacturer’s design guides for optimal migration strategies
• Migrate to 802.11n client devices as early as possible (preferably before an infrastructure migration to 802.11n)
Client Population
• 802.11a? 802.11g? 802.11n?
• Internal or External Antennas?
• Capable of Fast BSS Transition (e.g. 802.11r)?
• Support for which 802.11n MIMO features?
• Maximum radio output power?
• DFS/TPC capable?
124
Site Survey Methodology
Site Survey Methodology
APs should be placed
to take advantage of
multipath
Client population
should be considered
Data Forwarding Scalability
L3 Core Switch
WLAN Controller
L2 Edge Switch
File Server
125
802.11n Tools: Analyzer
802.11n Tools: Calculator
802.11n Tools: Simulator
126
802.11n Tools: Efficiency
Analyzer: AP Detail
The top line indicates a strong 40 MHz signal using channel 3 as primary with the secondary channel located above channel 3.
Notice that the
channel-3 AP
affects every usable
channel in the
entire 2.4 GHz
spectrum because it
is using a 40 MHz
channel.
Channel Occupancy Effects
127
Review
• Challenges addressed by 802.11n
• 802.11n PHY/MAC layer enhancements
• MIMO and SISO systems
• 802.11n coexistence mechanisms
• 802.11n integration and deployment
considerations
• 802.11n site surveying and analysis
In this video we discussed:
MIMO
Transmit
Beamforming
(TxBF)
Maximal Ratio
Combining (MRC)
Spatial
Multiplexing (SM)
Space Time Block
Coding (STBC)
40 MHz Channels
Channel Bonding
More Subcarriers
Non-HT Duplicate
Format
Optional Short
Guard Intervals
Modulation Rates
Antenna Selection
PHY
Enhancements
MAC
Enhancements
Frame
Aggregation
Block ACKs
RIFS
SMPS
PSMP
802.11n Enhancements
Brought to you by
Site Surveying
128
Objectives
• What is an RF site survey?
• Spectrum Analysis
• Types of RF site surveys– Manual RF site surveys
• Passive
• Active
– Predictive Modeling
• Dense AP deployment
In this video…
What is an RF Site Survey?
The Survey Process
RF Coverage Model Review
Pre-deployment audit to verify
RF coverage plan
Post-deployment audit
Deployment
Design
Project Phasing
Final RF node adjustments
Gathering Information
Maintenance and management
Deployment quality is
proportional to the
quality of the initial
stakeholder meetings
The on-site RF site survey
is often the 5th step in
the survey process.
129
Understanding the customer’s requirements
• Purpose
• Available Resources
• Existing Networks
• Business Requirements
• Technical Requirements
• Security Requirements
• Application Requirements
Access and Documents
Access to wiring closets, digital or printed copies of floor plans, security badges
(when required), etc. is essential at the beginning of the survey.
Spectrum Analyzers
A quiet background is the foundation of a
reliable, resilient, high-performance RF link. The
design objective should be -95 dBm. A high and
unstable noise floor usually affects clients first,
then APs.
130
Portable, Traditional Spectrum Analyzers
Spectrum Analysis
Identifying Legacy and Non Wi-Fi 802.11 Transmissions
Proxim’s RangeLAN/2 FHSS Access
Point
BreezeCOM’s BreezeNET Pro.11 FHSS
Access Points
Belkin’s USB Bluetooth Adapter
131
Two Types of RF Site Surveys
Predictive Site Survey
Manual Site Survey
• Passive
• Active
Manual RF Site Surveys
Most manual site
survey tools allow
importing of raster
and vector graphical
floor plans.
There are many
available applications
for converting vector
floor plans to raster
format.
Manual RF Site Survey Applications
132
Manual Site Survey Kit
Predictive RF Site Surveys
Allows for ―what if‖ scenarios
Have extensive propagation
characteristic databases
Predictive RF Modeling Tools
133
General Survey Principles
Additional Factors
Frequency
Channel Reuse (MCA systems)
Antenna Patterns and Gain
Transmit Power
Physical Environment
Co-channel & Adjacent Channel Interference
Elements of Propagation
Quiet RF Background (Noise Floor)
Correct Amount of Bidirectional Output Power
Stable Power Throughout the Environment
Design Elements and Considerations
80% Use of Directional Antennas When Possible
-65 dBm Cell Edges for data
Audit Point Selection
Interference Detection & Mitigation
Surveying for the Clients (Roaming, PHY support, etc.)
Channel Reuse
MCA vs. SCA
Single Channel Architecture
(SCA)
Multiple Channel Architecture
(MCA)
134
Channel Reuse
Coverage vs. Capacity
It’s important to note
that there’s a point of
diminishing returns
when designing
―micro cell‖
networks. When APs
are too close
together, co-channel
interference
significantly affects
single-AP and
aggregate system
performance.
VoWLAN Surveying
The recommended AP cell overlap for VoWLAN deployments at 2.4 GHz
is 20%. For 5 GHz, 15-20% is recommended.
135
Surveying for SCA Systems
AP .11b/g Channel
1 6
2 6
3 6
AP1 AP2 AP3
Transmissions are coordinated by the controller so that only one AP is
transmitting in a particular area at a time.
Portability vs. Mobility
Recommended Rx Thresholds
Data Rates
(Mbps)
2.4 GHz
Receive Threshold
(dBm)
2.4 GHz
VoIP Traffic
Threshold (dBm)
5 GHz
Receive Threshold
(dBm)
54 -61 -56 -58
36 -63 -58 -63
24 -67 -62 -67
12/11 -72 -67 -72
6/5.5 -79 -74 -75
2 -81 -76 N/A
1 -84 -79 N/A
136
The Site Survey Report: The Deliverable
An electronic survey template
should be kept up-to-date by
the surveyor
Some completed by customer
RF Site Survey Forms
Some completed by surveyor
Customer interview results, AP/antenna mounting,
interference sources & types, power sources & types, etc.
Review
• What is an RF site survey?
• Spectrum Analysis
• Types of RF site surveys– Manual RF site surveys
• Passive
• Active
– Predictive Modeling
• Dense AP deployment
In this video we discussed:
137
Brought to you by
Basic WLAN Security
• The Importance of WLAN Security
• Security Policies
• Legacy WLAN Security Mechanisms
• Modern WLAN Security Mechanisms
• Baseline WLAN Security Practices
Objectives
In this video…
The Importance of WLAN Security
138
“… only as strong as the weakest link”
WLAN Security is…
Wi-Fi Worries at Home
Is Your WLAN Secure?
139
Network Security Components
General Security Policy
Image Area
• General Security Policy
– Statement of Authority
– Applicable Audience
– Violation Reporting Procedures and Enforcement
– Risk Assessment
– Security Auditing
Network security depends on having a comprehensive and flexible security policy
Image Area
• Functional Security Policy
– Password Policies
– Training Requirements
– Acceptable Usage
– Security Configurations for Devices
– Asset Management
Functional Security Policy
140
• Legislative Compliance– Dept. of Defense
• Directive 8100.2
– HIPAA– Sarbanes-Oxley– Gramm-Leach-Bliley Act
• Implementation is the responsibility of IT department
• Must be verifiable and auditable
• There may be penalties for non-compliance
Security Policy: Compliance
WLAN Discovery
SSID Hiding
141
• Legacy 802.11 equipment often implements:
– MAC address filtering
– Open System Authentication
– Shared Key Authentication
– Static WEP keys (for authentication and encryption)
– PPTP VPN connections
Legacy WLAN Security
Wi-Fi Protected Access
WPA and WPA2 are functionally different, and each
has two types: Personal and Enterprise
WPA Terminology
Wi-Fi Alliance
Security
Mechanism
Authentication
Mechanism
Cipher
Suite
Encryption
Mechanism
WPA-Personal Preshared Key TKIP RC4
WPA-Enterprise 802.1X/EAP TKIP RC4
WPA2-Personal Preshared Key CCMP (default)
TKIP (optional)
AES (default)
RC4 (optional)
WPA2-Enterprise 802.1X/EAP CCMP (default)
TKIP (optional)
AES (default)
RC4 (optional)
142
WPA2-Personal
Wi-Fi Protected Setup
Wi-Fi Protected Setup
143
Wi-Fi Protected Setup
Supplicant AuthenticatorAuthentication
Server
802.11 association
EAPoL-start
EAP-request/identity
EAP-response/identity (username) RADIUS-access-request
EAP-request (challenge) RADIUS-access-challenge
EAP-response (hashed resp.) RADIUS-access-request
EAP-success RADIUS-access-accept
Access Granted
Need
access!
Calculating
my key…
Calculating
this guy’s
key…
Access
blocked
Generic 802.1X Process
Role Based Access Control
144
WIDS/WIPS
Image Area
Written security policies can be
enforced using technical solutions
such as a WIDS/WIPS.
Protocol Analyzers
Baseline Practices: SOHO
Image Area
145
Baseline Practices: SMB
Image Area
Baseline Practices: Enterprise
Image Area
• The Importance of WLAN Security
• Security Policy
• Legacy WLAN Security Mechanisms
• Modern WLAN Security Mechanisms
• Baseline WLAN Security Practices
Review
In this video we discussed: