hostile environments: wireless lan design for warehouse wlpc

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CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved Hostile Environments Wireless LAN Design for Warehouses Charlie Clemmer Consulting Systems Engineer Twitter: @charlieclemmer CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved

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Page 1: Hostile Environments: Wireless LAN Design for Warehouse WLPC

CONFIDENTIAL

© Copyright 2014. Aruba Networks, Inc.

All rights reserved

CONFIDENTIAL

© Copyright 2014. Aruba Networks, Inc.

All rights reserved

Hostile Environments

Wireless LAN Design for Warehouses

Charlie Clemmer

Consulting Systems Engineer

Twitter: @charlieclemmer

CONFIDENTIAL

© Copyright 2014. Aruba Networks, Inc.

All rights reserved

Page 2: Hostile Environments: Wireless LAN Design for Warehouse WLPC

CONFIDENTIAL

© Copyright 2014. Aruba Networks, Inc.

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Agenda

• Characteristics of a Warehouse

• Planning for Deployment

• RF Fundamentals

• Troubleshooting

• Q&A

Page 3: Hostile Environments: Wireless LAN Design for Warehouse WLPC

CONFIDENTIAL

© Copyright 2014. Aruba Networks, Inc.

All rights reserved

CONFIDENTIAL

© Copyright 2014. Aruba Networks, Inc.

All rights reserved

Characteristics of a Warehouse

Page 4: Hostile Environments: Wireless LAN Design for Warehouse WLPC

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How Are Warehouses Unique?

The Good, The Bad, and The Ugly

• Typically low bandwidth requirements

– Usually handheld scanner or forklift mounted terminal

• High ceilings

• Tall shelving packed with goods of varying density

• Potentially hostile temperatures (both extremes)

• Seasonal variability with stock levels

• Frequent layout changes

Page 5: Hostile Environments: Wireless LAN Design for Warehouse WLPC

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Characteristics of a Warehouses

• Physical

– Tall metal shelving, limited LOS to ceiling

– Long aisles, limited AP installation options

– Freezers, firewalls, building additions

• Technical

– Incorrect antenna aiming

– Tend to be older clients

• Outdated OS/firmware

• Limited protocol support (LEAP/802.11b?)

• Operational

– Product pickers incented based on speed

– Varying stock levels/rack configuration

Page 6: Hostile Environments: Wireless LAN Design for Warehouse WLPC

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© Copyright 2014. Aruba Networks, Inc.

All rights reserved

CONFIDENTIAL

© Copyright 2014. Aruba Networks, Inc.

All rights reserved

Planning for Deployment

Page 7: Hostile Environments: Wireless LAN Design for Warehouse WLPC

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Planning for Deployment

• Inventory wireless devices

• Quantify facility requirements

• Develop coverage and client density model

• Perform RF plan and spectrum clearing

walkthrough

• Perform passive site survey post deployment to

verify coverage

• Perform client testing to verify operations

• Fine tune plan/documentation for next site

Page 8: Hostile Environments: Wireless LAN Design for Warehouse WLPC

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Inventory Wireless Devices

• Identify all client device make/models/apps

• Capture all device limitations (TX

power/Encryption)

• Capture best firmware level

• Worksheets used for RF and Security designs

Page 9: Hostile Environments: Wireless LAN Design for Warehouse WLPC

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Quantify Facility Requirements

• Intended use(s)

• Ceiling height / building square footage

• Unique coverage areas? Freezers?

• WAN backhaul/redundancy

• Local compute resources

Page 10: Hostile Environments: Wireless LAN Design for Warehouse WLPC

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Selecting a Target Cell Edge Data Rate

• Manufacturers of

some voice and data

devices recommend

“minimum SNR”

• Applications typically

determine data rate

• Each 802.11 data rate

requires a minimum

SNR to demodulate

Page 11: Hostile Environments: Wireless LAN Design for Warehouse WLPC

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Match AP Output Power to Clients

• Match AP output power to least capable client device

• Reasons why this is important

– If the AP transmits at higher power than the client, the client may

hear the AP, but may not have sufficient transmit power so the AP

can hear the client

– APs have greater receive sensitivity than do clients

Page 12: Hostile Environments: Wireless LAN Design for Warehouse WLPC

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© Copyright 2014. Aruba Networks, Inc.

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AP Location & Antenna Selection

• Vertical coverage is especially important in

warehouse environments to get coverage in between

shelving to ensure that intended signals reach the

clients

• Low gain, downtilt omnidirectional antennas are

ideal for warehouse and high-ceiling environments

because:

– Low gain limits range to a predictable area around the AP and

reduces AP-AP interference

– Low gain limits users per AP to a controlled area

– Downtilt omni pattern provides users at ground level a higher

signal than Aps see from each other

Page 13: Hostile Environments: Wireless LAN Design for Warehouse WLPC

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AP Location – Adjust for High Shelves

• As shelving gets higher, place Aps more closely

together to overcome attenuation from shelving

Page 14: Hostile Environments: Wireless LAN Design for Warehouse WLPC

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AP Guidelines for Warehouses

• For general dry goods, overhead mounting is

recommended

• For cold/frozen storage, wall mount strategy is more

typical and every row should have 1 AP with clear

line of sight

• Use down-tilt omnidirectional antennas when

ceilings are above 25 feet

Page 15: Hostile Environments: Wireless LAN Design for Warehouse WLPC

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© Copyright 2014. Aruba Networks, Inc.

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RF Fundamentals

Page 16: Hostile Environments: Wireless LAN Design for Warehouse WLPC

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RF Fundamentals – Design Considerations

• The Goods Stored

• Coverage vs Coverage Reliability

• Antennas and Antenna Patterns

• Managing AP to AP Interference

Page 17: Hostile Environments: Wireless LAN Design for Warehouse WLPC

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Characterizing Goods: Absorption

Microwave Absorption Analysis

• Goods are placed in a reverberation chamber and

excited simultaneously by multiple modes and random

incidence wave fronts of varying frequency

• During the test, the specific absorption rate is

monitored to determine the absorption characteristic

Page 18: Hostile Environments: Wireless LAN Design for Warehouse WLPC

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Characterizing Goods: Absorption

Alternatively, if limited to 2.4GHz studies, this

reverberation chamber is usually more accessible

• Check the break room

Page 19: Hostile Environments: Wireless LAN Design for Warehouse WLPC

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The Goods: Absorption & Reflection

• All products have different RF characteristics and

can be thought of in relative terms with respect to

their Absorption and Reflection characteristics

– Absorption Goods

• Low Absorption – Air, low density paper goods, apparel

• Higher Absorption – Rubber, plastics, general dry goods

• Highest Absorption – Liquids, frozen goods, butter

– Reflection Goods

• Metal parts and machinery/handling equipment

• In general, High Absorption goods affect RF much

more than High Reflection goods

• In stacks of goods, waves propagate in both the

materials and spaces of air. Variations can have

significant effects

Page 20: Hostile Environments: Wireless LAN Design for Warehouse WLPC

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Coverage Vs Coverage Reliability

• Most warehouses contain goods of varying

absorption characteristics

– Coverage affected differently in different areas of the

warehouse

– Coverage varies day to day due to changing in stock levels

• The ability of an RF coverage design to survive

these changes is called “Coverage Reliability”

Page 21: Hostile Environments: Wireless LAN Design for Warehouse WLPC

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Coverage Reliability Basics

• Reliable Coverage requires the following:

– Actual AP or Client Power minimum

– Actual antenna gain in the direction of clients

– Loss due to materials and walls/racks

– Higher minimum desired SNR for day to day variation in stock

• Because dB is a logarithmic scale, small changes

can make a big difference on the end result

• Coverage Reliability must be a DESIGN

requirement and not exclusively a survey

validation

• Typical Site Survey is only one snapshot in time

Page 22: Hostile Environments: Wireless LAN Design for Warehouse WLPC

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Design Considerations - Antennas

• Radiation Pattern

– All antennas radiate in 3 dimensions

– Antennas do not create or destroy

power

– Antennas focus energy into a tighter

region of 3D space

• Gain

– Higher gain = more tightly focused

– Higher gain typically focuses in the

vertical direction

– High gain antennas are typically no

appropriate where both horizontal

and vertical coverage is needed

Page 23: Hostile Environments: Wireless LAN Design for Warehouse WLPC

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Omni-directional Antenna Patterns

Azimuth (H-plane) Elevation (E-plane)

High Gain Antenna

10 dBi

Vert BW: 8o

Max Range: 500m

Lower Gain Antenna

5dBi

Vert BW: 18o

Max Range: 285m

Down Tilt Antenna

3dBi

Vert BW: 60o

Centered at -45

Max Range: 226m

Page 24: Hostile Environments: Wireless LAN Design for Warehouse WLPC

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Wall Mounted Antennas

• The antenna on the

left is 13 dBi, on the

right is a 5 dBi

antenna

• The darker area is a

coverage hole close

to the AP, caused by

the high gain antenna

pattern

Page 25: Hostile Environments: Wireless LAN Design for Warehouse WLPC

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Wall Mounted Antennas – 3D View

High Gain Antenna Pattern

(narrow vertical beamwidth)Low Gain Antenna Pattern

(wide vertical beamwidth)

Page 26: Hostile Environments: Wireless LAN Design for Warehouse WLPC

CONFIDENTIAL

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Antennas (Summary)

• Vertical coverage is critical in high ceiling

environments

• Low gain, down-tilt omni-directional antennas are

ideal

– Low gain limits range to a predictable area

– Reduces AP-AP interference

– Focuses signal towards users at ground level

Page 27: Hostile Environments: Wireless LAN Design for Warehouse WLPC

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© Copyright 2014. Aruba Networks, Inc.

All rights reserved

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Troubleshooting

Page 28: Hostile Environments: Wireless LAN Design for Warehouse WLPC

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Troubleshooting User Issues

• What symptoms are being reported?

• Where in the network flow is the problem

occurring?

– Can the client establish an association with the AP?

– Can the client authentication if 802.1X is being used?

– Did the client get an IP address?

– Does the problem happen while the client is stationary, or while

the client is roaming?

– What is the SNR between the client and the AP?

– Did any network events occur at the time of the problem?

– Is there any interference on the RF spectrum?

Page 29: Hostile Environments: Wireless LAN Design for Warehouse WLPC

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Troubleshooting Roaming Issues

• Are all APs on a consistent power level?

• How many APs can a client hear?

– Does AP power setting match the EIRP of the client?

– Are Aps a mix of legacy a/b/g and 802.11n?

– Do clients support 802.11k? Is it enabled?

– Can a probe response threshold be used on the AP?

Page 30: Hostile Environments: Wireless LAN Design for Warehouse WLPC

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Troubleshooting Installation Issues

• Has the AP power level(s) changed?

- Are APs at full power?

• Are antennas aimed correctly?

- Are the correct antennas being used?

• Has stock levels changed dramatically?

• Has the warehouse layout been reconfigured?

• Has a new wireless service been introduced?

Page 31: Hostile Environments: Wireless LAN Design for Warehouse WLPC

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Q&A

Page 32: Hostile Environments: Wireless LAN Design for Warehouse WLPC

CONFIDENTIAL

© Copyright 2014. Aruba Networks, Inc.

All rights reserved

CONFIDENTIAL

© Copyright 2014. Aruba Networks, Inc.

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Thank You