High Density & High Availability in Wireless … Density & High Availability in Wireless Deployment ... is determined by uplink link budget (Handset ... is between downlink-uplink

9/30/2014

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Fast Innovation requires Fast IT

High Density & High Availability in Wireless Deployment

MinSe Kim,

Sr. Technical Marketing Engineer, Cisco Systems

9/30/2014

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Agenda WiFi Operation Today

WLAN RF Design Fundamental

Physical AP Placement Tips

Configuration Best Practices

Wired-Wireless Integration for HD WiFi

WiFi operation Today

9/30/2014

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© 2014 Cisco and/or its affiliates. All rights reserved. Cisco Public

Why High Density Wi-Fi?

Wireless has become the preferred access technology -- and in many cases the only practical one

The need for high density started with stadiums and auditoriums – but has reached every network

The explosion of smart devices and increasing connection counts per seat are everywhere

Application demands are increasing

Even with advances - wireless is still a shared half-duplex medium and requires efficient use to succeed.

2 to 3 devices per user


What are Some Typical Challenges?

Interference from other WiFi networks in the venue

Interference from non-WiFi systems operating in the same band

Co-channel interference: Many APs in the venue, but effectively no more capacity

Clients operating at low data rates (ex. 802.11b) pull down the performance of the network

Clients mistakenly choose a 2.4 GHz radio (louder signal) instead of 5 GHz (less load)

Sticky Clients: Clients mistakenly stay on the same AP, even when person has moved from one end of the venue to another

Limitations on AP installable location. Hard to put APs where you want them

Probe storms: 2.4 GHz clients probe on all 11 overlapping channels

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Signal Quality

Inevitable Interference from neighboring WiFi or from unknown sources

Interference from Neighboring WiFi is impacting user experience

Interference from Non-WiFi is also increasing

5GHz adoption is progressing but still less then 50%

Neighboring AP is going louder and louder everyday


Signal Quality Issue –Higher Tx Power means better coverage?

Not always. Balanced link (make LinkBudget between UL and DL to be as closest as possible) provides most reliable performance

WiFi coverage characteristic is determined by uplink link budget (Handset dependent)

Max. Tx Power

per antenna

Number of Tx

chain

Number of

Rx chain

Ant. Gain

(Omni)

# of Tx:Rx

antenna

Cisco AP2600 20 dBm 3 TX 4 RX 4 dBm 3:4

Cisco AP3700 20 dBm 4 TX 4 RX 4/7 dBm 4:4

iPhone 5 20 dBm 1 TX 1 TX -1.5 dBm 1:1

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Balanced Link budget for Better Quality, Load-balanced link

Differences in Rx Sensitivity and Tx Power makes client to deem out of coverage AP as closer then what it actually located.

Hence, Client roaming is not occurred, User exposed many problem

– Load Balancing doesn’t work

– Roaming involves service outage.

– Increasing Packet Loss

– Network throughout drop

AP1 AP2

RSSI for

Client-1 : -84 dBm

AP’s perspective

on iPhone-A

coverage

RSSI for

AP-1 : -73 dBm

Client-1

-76 dBm!

RSSI’s still okay!

..I’ll stay here30 dBm EIRP

from AP

22.5d Bm EIRP

from iPhone

-84 dBm, Seriously?!

Come on-

You need to roam!


802.11n Myth

What we hear from the ―industry‖

―802.1n will deliver 300Mbps, 450Mbps, 600Mbps … 900 Mbps…‖

So Can WLC get chocked up as WLC will become bottleneck?

Most of 802.11n supported Mobile device

Supports 20Mhz, Long Guard Interval

Single Tx / Rx

Max Datarate = 65Mbps

98% of mobile device until Mid.2012.

20% Datarate

increase from

802.11a/g

Oversubscription is between downlink-uplink is typical in wired design (100Mbps x 24 : 1Gbps 24 Gbps x 20 : 2-20Gpbs)

Required Network performance is application driven, not device driven

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Mobile device WiFi Max Data rate

0

100

200

300

400

500

600

700

800

900

1000

iPhone 1 iPhone 3G iPhone 3GS iPhone 4 iPhone 4s iPhone 5 iPhone 5s iPhone 6

iPhone

Samsung

Galaxy S5

Galaxy S4

Galaxy S3


Client Association Storm

In Subway Station, hundreds to thousandpeople can flood in/out

Delay should be minimized, andimmediate IP address assignment shouldhappen

Cisco’s Association rate (CPS)

Cisco DHCP Server(CNR) can assign 47,000 IP address in a seconds

8500 WiSM2 vWLC

Open 385 385 371

WPA2 (EAP) 387 125 61

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Link Reliability during the roam

Roaming must includes handoff and message exchange between AP-to-Client, between AP-to-AP

Cisco Device

support Caveats

Average Roaming

delay

OKC Yes Windows Limited to few

Android device

0.5 sec

Sticky Key Caching

(802.11i)

Yes Apple,

Android

Scalability

issue

0.5 sec

802.11r Yes Apple iOS 6.0+ Can cause

Legacy

interoperability

0.1 sec

CCKM Yes CCX compatible

device

(eg. Samsung Galaxy

S3)

Limited support

on Mobile

device

0.1 sec

WLAN RF DesignFundamental

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Channel Utilization—What Made the Difference?

15

5% After

60% Before


Maximize the SpectrumLeveraging PHY Rate Tuning

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Size your cells to allow elimination of low rates (i.e., <12mbps)

Eliminate 11b rates

Recommend NOT disabling any MCS rates due to interoperability issues with some clients

– Disabling MCS rates, especially 0-7, can cause significant client issues

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Cell Size – Higher Power ≠ Larger Coverage

Higher power does not always meanhigher SNR…

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Assuming 10% PER

Speed Required SNR AP Sensitivity

1 0 -91

2 3 -91

5.5 6 -91

6 2 -87

11 9 -88

12 6 -86

24 11 -85

36 13 -85

48 17 -78

54 19 -77

This for data, for voice, add 25 dB to SNR


Cell Size – Depends on Protocol and Rates

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Data rates decrease with the increase of distance from the radio source and client power will increase

Individual throughput (performance) varies with the number of users

Performance degrades with radio interference from other sources

Critical deployment design goal is to achieve high data rate at cell boundary

‒ High signal AND low noise

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2.4-GHz Network Design

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Conclusion: try to design small cells, with clever overlap…


Designing for Efficient RF Relationships

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How AP’s hear each other

AP to Client

Client to AP

AP to AP

How AP’s hear clients

How clients hear AP’s

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Channel Coverage Sizing Recommendations

Coverage must be designed for your Client Devices

Not all clients are created equal !!!

1. Live call test with the actual client to determine its coverage

Removing legacy DSSS data rates and slower OFDM data rates from the WLC configuration equals:

1. Less Co-Channel Interference

2. Better throughput in the cell

3. More usage of ClientLink and MRC

4. Smaller coverage cells

Smaller Coverage Cell Sizes equals:

1. More cells in a given coverage area

2. More cells equals more call with better voice and video quality

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Physical AP Placement Tips

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AP Mounting Orientation

Best Practice – Place APs pointing

down for APs with internal antenna

Incorrect

AP Orientation

Correct

AP Orientation


Internal antenna version Access PointsDesigned for Horizontal Mounting

Internal antenna versions of Access Points work best when mounted horizontally on the ceiling

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AP Antenna Vertical coverage

RF Radiation is focused to downward direction

Ceiling


Installation use case

To maximize AP’s performance, AP installation location is highly recommended at ceiling mount as exposed.

If customer must install AP inside ceiling, customer can consider external antenna model.

External Antenna with AP

inside ceiling

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Where is the best location to place AP?


Bad AP Placement : AP around corner

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1

3

2A B

C

At ―A‖ the phone is connected to AP 1

At ―B‖ the phone has AP 2 in the neighbor list, AP 3 has not yet been scanned due to the RF shadow caused by the elevator bank

At ―C‖ the phone needs to roam, but AP 2 is the only AP in the neighbor list

The phone then needs to rescan and connect to AP 3

– 200 B frame @ 54 Mbps is sent in 3.7 μs

– 200 B frame @ 24 Mbps is sent in 8.3 μs

– Rate shifting from 54 Mbps to 24 Mbps can waste 1100 μs

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Good AP Placement – AP on Intersection

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AB

C

1

2

3

At point A the phone is connected to AP 1

At point B the phone has AP 2 in the neighbor list as it was able to scan it while moving down the hall

At point C the phone needs to roam and successfully selects AP 2

The phone has sufficient time to scan for AP 3 ahead of time


Avoid Reflections

Highly reflective environments

Multipath distortion/fade is a consideration

Legacy SISO technologies (802.11a/b/g) are most prone

802.11n improvements with MIMO

Devices are susceptible

Things that reflect RF

– Irregular metal surfaces

– Large glass enclosures/walls

– Lots of polished stone

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AP Placement in Hallways

Incorrect

AP Placement

Correct

AP Placement

Best Practice – Place APs within the Room


AP Placement in Multi-story Building

Incorrect

AP Placement

Correct

AP Placement

Best Practice – Place APs in Zig-Zag on Alternate Floors

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WiFi Best Practices


Lower 2.4 speeds not turned off -1,2,5.5,6,9 Meg

Enable 2.4 GHz and 5 GHz bands

Guest & Admin on separate SSIDs and VLANs

802.11n throughout most of the property

802.11ac in spaces with high device density

General RF Recommendations

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Wired-Wireless Integration for HD WiFi


Autonomous FlexConnect Centralized Converged Access

Traffic Distributed at AP Traffic Centralized at Controller

Traffic Distributed at SwitchStandalone APs

Target

PositioningSmall Wireless Network Branch Campus Branch and Campus

Purchase

DecisionWireless only Wireless only Wireless only Wired and Wireless

Benefit

• Simple and cost-effective

• Enterprise Class AP quality

• Provides Bridge functionality

• Highly scalable for

large number of branches

• No controller at branch

• Most feature rich

solution

• Wireless Traffic visibility

at the controller

• Wired & Wireless common operations

• One Enforcement Point

• One OS (IOS)

• Traffic visibility at every network layer

• Performance optimized for 11ac

Key

considerations

• Limited features

• First step to Controller based

• L2 roaming only

• Branch with WAN bw and

latency requirements

• Top Performance and

Scalability• Access layer refresh (3650/3850)

WAN

One Network: Wireless Deployment Modes

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Campus Design: Centralized, Controller-based

Components

• Wireless LAN controllers

• Aironet Access Points

• Management (Prime Infrastructure)

• Mobility Service Engine (MSE)

Principles

• Overlay Architecture

• Based on AireOS software

• AP must have CAPWAP connectivity with WLC

• Configuration downloaded to AP by WLC

• All Wi-Fi traffic is forwarded to the WLC

Wireless LAN

Controller

Aironet Access

Point

Cisco Prime

Infrastructure

MSE

Campus

Network


Converged Access – Deployment Overview

Mobility Domain MO

Sub-Domain

#1

Sub-Domain

#2

Mobility Group

SPG SPG

PIISE

MAMAMA MAMAMA

MCMC

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SimplicityFlexibility

ISE, Prime, APIC

Working towards architectural integration

Aironet

Catalyst

ISR / ASA

Cisco Enterprise

Cisco ONE Architecture

MR

MS

MX

Cisco Cloud Managed


Cloud and on-premise deployment configurations

Cisco

Enterprise

Cisco Enterprise

Campus & WAN

Cisco Cloud

Managed Branch

Cisco Cloud

Managed Edge

Cisco Enterprise

Core / Datacenter

Cisco

Cloud Managed

Mid-Market Business Enterprise and Mid-Market Business

Optimized for Ease of Management Optimized for Flexibility and ControlHybrid

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Constrain RF

– Directional Antennas, Down-Tilt

Good RF Layout/Design:

– Channels, Tx Power

Eliminate Interference

– Rogues and Non-Wi-Fi Interference

Minimize SSIDs

Disable Low Data Rates

– Helps with Sticky Clients, Improves capacity

Band Select

– Push dual-band clients to 5 GHz

RF Profiles

Rx-SOP Tuning

– Greatly improves capacity by reducing co-channel impact

– Also reduces sticky clients

Optimized Multicast Video

AdvancedSolid RF Design Basic Tuning

HD Wi-Fi -- Best Practices

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Backup Slides


Below or Above Ceiling?

WAP WAP

AP’s RF coverage is as site surveyed.

Coverage & performance is getting mostly close

its intended one. No attenuation

RF Signal from AP’s back panel is reduced from ceiling’s

attenuation. No impact on performanceExposed

Ceiling

Mount

WAPWAP

When Signal went through ceiling tile,

Signal level is lowered from attenuation

Lot of interferences

AP’s RRM tends to reduce Tx power as it see AP LoSAP

Inside

Ceiling

Mount

Automatic RF Power Control (TPC) can give less power then required

Higher Co-Channel Interference between AP-to-AP

Reduced Speed, Lowered Location accuracy

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Comparisons per AP’s installed area

Above Ceiling Below ceiling

Performance Lower Higher

Interference between

APs

Higher lower

RF Signal Strength Reduced to 50% (3dB) Maintain RF coverage and

strength as it’s planned

Custom enclosure and

Locker

Possible Possible

Location Accuracy Lower High

Maintenance Higher Lower

Installation Cost Higher ( Possibly, separate

bracket or enclosure)

Lower

(Mount kit is included w/ 0$)

Documents

High Density & High Availability in Wireless … Density & High Availability in Wireless Deployment ... is determined by uplink link budget (Handset ... is between downlink-uplink