Student Workbook

Presentation Graphics

Notes Areas

Glossary

Presenter – Keith R. Parsons, CWNE #3

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802.11n Planning and Optimization Workshop

Outline

• Section I: 802.11 Fundamentals – Review of ‘Legacy’ 802.11a/b/g • Section II: 802.11n Concepts, Terms, Features • Section III: 802.11n Analysis • Section IV: 802.11n Design

Section I: 802.11 Fundamentals AirMagnet Product Family

Evolution of 802.11 Standards

Comparison of 2.4GHz and 5GHz Radio Waves

2.4GHz Channel Overlap

Want – Don’t Want – Don’t Care (Signal Strength)

RF Power and Distance

So, What *is* an Access Point Anyway?

Where 802.11 is in the OSI Model – Physical and Data Link

802.11 MAC Header

To DS and From DS Bits Diagram

MAC Header Frame Details

802.11 ‘classic’, b, a, g Available Data Rates

Protection ‘Penalty’ for b/g Mixed Mode

Effects of Multipath

Section II: 802.11n Overview 802.11n is Complex!

How Detailed do you want to get?

PHY Enhancements

Multiple Input, Multiple Output (MIMO) - “My Moe”

Spatial Division Multiplexing (SDM)

Space-Time Block Coding (STBC)

Transmit BeamForming (TxBF)

 

Antenna Selection (ASEL)

Short Guard Interval (SGI)

Maximum Ratio Combining (MRC)

More Subcarriers Available in 802.11n – with 40MHz Channels

Forward Error Correction (FEC)

40MHz Channels in the 2.4GHz Band 3 4 5 6 7 8 9

Channels defined for 2.4 GHz band, showing common 20 MHz channel plan and 40 MHz options

1Channel 2 3 4 5 6 7 8 9 10 11

1 6 11

12 132412Center Frequency 2417 2422 2427 2432 2437 2442 2447 2452 2457 2462 2467 2472

40MHz Channels in the 5GHz Band

MAC Layer Enhancements

Frame Aggregation

Frame Aggregation Examples

Aggregation Analysis

Multiple Traffic ID Block Acknowledgements (MTBA)

Power Save Methods

Legacy Support Modes

High-Throughput Mode (Greenfield)

Legacy Mode

HT Mixed Mode

L-SIG TxOP Protection

RTS – CTS Mode

Phase Coexistence Operation (PCO)

Legacy Protection Analysis

Modulation and Coding Schemes

Granulation and Additional Speeds with 802.11n

HT Informational Element

802.11n Decodes

Section III: 802.11n Analysis

New Features of WiFi Analyzer (formally called Laptop Analyzer)

New 802.11n Alarms

Affects of Channel Occupancy

New Start Columns to Support 802.11 n Fields

New 802.11n information in STA and AP detail

802.11n Efficiency Tool

802.11n Analysis Tool

802.11n WLAN Throughput Simulator

802.11n WLAN Throughput Simulator Results

802.11n Tools – Device Throughput Calculator (Overhead)

Device Throughput Calculator Results

Section IV: 802.11n Design

Skills you’ll need for 802.11n Deployments

Migration Issues

New Features of AirMagnet Survey PRO

Throughput Simulator

802.11 n Heatmaps

– Color-coded by 'n'

– Channel Width

– Max MCS

– Operating Mode

– Measured PHY Data

– Predictive PHY Data

Updated AirWise

iPerf Survey

'n' Active Survey

'n' Passive Survey

Updated Heatmaps

@ 2008 - AirMagnet 9  

Updated AirWISE Categories

Open Source iPerf – Throughput Tester

Importance of an Active Survey

802.11n Design Issues

Where to go from here?

Further Questions?

Glossary 802.11 Groups PHY/MAC ‘Classic’1 & 2 Mbps, 2.4GHz FH, DS, and IR .a PHY up to 54 Mbps in the 5GHz band .b PHY up to 11 Mbps in the 2.4GHz band .c MAC MAC-layer Bridging .d PHY Additional Regulatory Domains for .11b .e MAC Quality of Service (QoS) Improvements .f MAC Inter-Access-Point Protocal IAPP .g PHY Up to 54 Mbps in the 2.4GHz band .h MAC Dynamic Frequency Selection/Transmit Power Control for .11a .i MAC Security Enhancements .j PHY 4.9GHz Regulatory Issues for Japan .k MAC Radio Resource Measurement .m PHY/MAC Maintenance and Technical Corrections .n PHY/MAC Performance and High Throughput - MIMO .p PHY/MAC Wireless Access in Vehicular Environment (WAVE) .r MAC Fast Roaming – reducing latency during handoffs .s MAC Mesh – for both AP and STA .t MAC Testing and Performance Prediction .u MAC Interworking with External Networks .v MAC Network Management .w MAC Management Frame Security .y PHY Operation in the 3650-3700 MHz Band

ACK Frame A short frame sent by the receiving station to the transmitting station to confirm the receipt of the frame.

A-MPDU Aggregate MAC Protocol Data Unit

A-MSDU Aggregate MAC Service Data Unit

AP Access Point

ASEL Antenna Selection

Block ACK Block Acknowledgement - a method of sending a single Acknowledgement frame to confirm receipt of multiple frames

BSA Basic Service Area

BSS Basic Service Set

CODEC Coder/Decoder – an algorithm implemented either in software or hardware to encode the digitized voice, video or image for optimum transmission over the network.

CSD Cyclic Shift Diversity

CSD Cyclic Shift Diversity – type of Transmit diversity used to spread spatial streams across multiple antennas.

ESS Extended Service Set

FEC Forward Error Correction – a method to help with transmit diversity.

Frame Aggregation

A protocol for combining several frames into a single frame, thereby eliminates some inter-frame gaps to improve efficiency on the RF link.

GI Guard Interval – a period at the end of each OFDM symbol allocated to letting the signal dissipate prior to transmitting the next symbol to prevent overlap. Legacy devices 802.11 abg use 800ns.

HT High Throughput

HT-GF-STF High Throughput – Greenfield – Short Training Field

HT-LTF High Throughput – Long Training Field

HT-SFT High Throughput – Short Training Field

HT-SIG High Throughput – Signal Field

Interframe Space

Is the quiet time between packets transmitted on media

LDPC Low Density Parity Check

L-LTF Non-HT - Long Training Field

L-SIG Non-HT - Signal Field

L-STF Non-HT - Short Training Field

LTF Long Training Field

MCS Modulation Coding Scheme

MIMO Multiple Input, Multiple Output “My Moe”

MPDU MAC Protocol Data Unit

MRC Maximum Ratio Combining – a technique used by a receiver that is working with two or more diversity antennas to optimally combine signals received taking into account the SNR of each of the received signals.

MSDU MAC Service Data Unit

NAV Network Allocation Vector – An indicator used by STA and AP to know time periods when the wireless medium will not be available. NAV information can be derived from announcements in packets concerning how long they intend to occupy the medium.

Non-HT Non-High Throughput – legacy devices not capable of 802.11 n communications contained in the HT Information.

Non-HT Duplicate Mode

A method to protect legacy networks from disruption caused by 802.11 n protocols. Two packets are sent on both halves of the 40MHz channel simultaneously announcing the NAV to tell legacy STA how long to stay off the medium.

OFDM Orthogonal Frequency Division Multiplexing

PCO Phased Coexistence Operation

PSMP Power Save Multi-Poll

RFS Reduced Interframe Spacing

RSSI Receive Signal Strength Indicator

SGI Short Guard Interval – an optional use of 400ns GI in the 802.11 n specifications.

SISO Single Input, Single Output

SM Spatial Multiplexing

STA Station – Client device

STBC Space-Time Block Coding – Transmitter diversity technique of spreading the signal over multiple antennas to improve reception. STBC also incorporates Forward Error Correction (FEC) coding.

STBC/SM Space-Time Block Code/Spatial Multiplexing

TPC Transmit Power Control

TxBF Transmit Beamforming

WMM Wireless Multi-Media – the WiFi Alliance QoS Protocol for defining different priority levels for Voice, Video, Background and Best Effort Traffic. Based on 802.11e and incorporated in the updated 802.11/2007 edition.

Notes

Notes

Student DVD