top 10 ways for next gen wlan to improve user experience

doc.: IEEE 802.11-13/0545r1

Submission

May 2013

Veli-Pekka Ketonen (7signal) Slide 1

WLAN QoE, End User Perspective

Opportunities to Improve

Date: 2013-05-15

Name Company Address Phone email Veli-Pekka Ketonen 7signal Solutions, Inc. 526 S. Main Street,

Akron, Ohio, USA

+1 330 8618150 veli-pekka.ketonen

@7signal.com

Authors:

doc.: IEEE 802.11-13/0545r1

Submission

May 2013

Slide 2 Veli-Pekka Ketonen (7signal)

Abstract

Presentation for 802.11HEW SG in Hawaii May 12th-17th

Interim meeting

Includes data from various anonymous networks from

7signal Sapphire automated client device QoE

measurements for performance optimization and

management work

Bottlenecks in current networks and suggestions for

improvements are presented as background for further

HEW SG work

doc.: IEEE 802.11-13/0545r1

Submission

The Key Challenge

May 2013


doc.: IEEE 802.11-13/0545r1

Submission

In live networks, high max performance does not

translate to sufficient user experience*

• Capacity, range and end user experienced quality do not any more meet needs

• Example from University. Nw. vendor has less impact, network config. higher impact

• * = these are hourly average values from an area of multiple APs/SSID over a week time


doc.: IEEE 802.11-13/0545r1

Submission

Key findings

May 2013


doc.: IEEE 802.11-13/0545r1

Submission

#1. Too aggressive rate control,

average retrys often exceed 50% (1/2)

May 2013


• With 802.11n products, regularly

30-50% of packets require at least

one retry. Often even more.

Too high rate selected

A lot of retries,

multiplied by MIMO-X factor

High utilization

Lower SNR

More radio retries,

up to 7 times/packet

No air time & lost packets

Capacity and TCP

throughput collapse

doc.: IEEE 802.11-13/0545r1

Submission

#1. Too aggressive rate control,

less aggressive has been proven better (2/2)

May 2013


• Individual network behavior impacts

also all other nearby networks

• 802.11ac has much more demanding

requirements than 802.11n

• Suggestions:

• Use clearly less aggressive rate control

• Make rate control dynamic, adjusting

based on observed radio conditions (like

continuous Bluetooth)

• 802.11 to specify proper rate control

schemes, instead of leaving this to vendors

RX-level during this part of the route: -70 – -88 dBm

Original link adaptation

Optimized link adaptation

-> Reason for improvement:

•Using more MCS-8 instead of MCS-9

RX-level

RX-level

Past findings from Nokia Networks

EDGE link adaptation (Public, Ref [1])

Throughput

Throughput

doc.: IEEE 802.11-13/0545r1

Submission

#2 Automated channel control algorithms

need clear improvements • Automated features, like

channel selection do not

work properly

• Continuous channel

hopping in the whole

network and no stable

state

• Impacts also surrounding

networks

• Suggestion:

• 802.11 to specify more in

more detail requirements

May 2013


doc.: IEEE 802.11-13/0545r1

Submission

#3. Already available radio settings are not

utilized since their impacts are not understood • Radio should more accurately and

dynamically operate its settings, like

– Data rates; supported, default, control

– Management/control traffic data rates,

– Fragmentation process, MTU

– QoS

– Ack/block ack schemes usage

– Long/short pre-amble configuration

– RTS/CTS process

– Supported 802.11 standards

– Minimum limit for probe response

– Load balancing, etc

• Suggestions

– Performance management practices

– Automated operation

– 802.11 to specify in more detail

May 2013


doc.: IEEE 802.11-13/0545r1

Submission

#4. Interference due to lacking channel

coordination and Bluetooth devices • Channel plans are almost random in

public areas

– Resulting packet loss, jitter

• Proper radio operation in the mid-

term still requires significantly better

channel plans

• Suggestions

– Better, proven automated algorithms

for channel negotiation

– Cloud based control

– Regulation for allowed channels

– Better industry defaults

– Adhoc channel selection

limited/guided

May 2013


doc.: IEEE 802.11-13/0545r1

Submission

#5. Too dense beacons load air unnecessarily • In practice solely 100ms used

globally with 1 Mbit/s as

mandatory rate in consumer grade

APs. This congests air

significantly everywhere

• In 100ms, a person walking full

speed moves ~10 inches (~ 25cm).

Is this dense beaconing necessary?

May 2013


• Suggestions

• Define default beacon intervals longer, ~300ms

• Dynamic/adaptive beaconing, beacon interval automatically dependent on the

observed time between roaming.

• Consider add few % variance to beacon intervals to avoid continuously repeating

collisions (compare to spread spectrum CPU clocking for EMI reduction)

• Consider impact to power save functionality

doc.: IEEE 802.11-13/0545r1

Submission

#6. Mobile networks interfere 2.4 GHz band

WLANs through 3rd harmonic distortion • When cellular network indoor antennas are near (30ft/10m) to WLAN APs

and/or clients, they may saturate the receiver with off band signals and

receiver generates distortion product that lands in the 2.4 GHz band

• Suggestion

– Add mandatory RF band-pass filtering to WLAN radios

– Receiver blocking test to FCC approval

May 2013


2.4 GHz 2.3 GHz 2.2 GHz 2.5 GHz 2.6 GHz 2.1 GHz 2.0 GHz 1.9 GHz 1.8 GHz 1.7 GHz

DCS-1800

(EUR, US)

PCS-1900 (EUR)

UMTS-1900 (US)

UMTS-2100 (EUR)

UMTS-1700 (US)

Distance appr. 300MHz => Harmonic distortion

lands at 300MHz

distance from source

WLAN

WLAN

signal

High power

mobile base

station signal

High power

mobile base

station signal

Ghost

signal

(noise)

=> Signal-to-noise ratio

degrades in WLAN receiver

and data transfer suffers

Verified to happen in

live network conditions

doc.: IEEE 802.11-13/0545r1

Submission

#7. Support for legacy devices (802.11b/a)

seriously degrades benefits of new standards • Protection mode is “contagious” and

highly inefficient

• Benefits of new standards are

limited if legacy devices are

overprotected. Important especially

in consumer grade equipment.

• Suggestions

– Better industry defaults

• 802.11b not supported

• 802.11a not supported

– Improvements to protection mode

– Prevent/limit protection mode

spreading with required minimum

signal levels

May 2013


doc.: IEEE 802.11-13/0545r1

Submission

#8. Lacking interoperability may take down

whole network performance • Introduction of new radio

devices increased average retry

rates to about 70%. Max

network capacity came down at

least 50%

May 2013


• Suggestions

– More exact requirements needed for

client-AP interoperability

– Live network performance

management capabilities need to

improve. All scenarios cannot ever

be tested upfront.

doc.: IEEE 802.11-13/0545r1

Submission

#9. Modest access point antenna solutions

• Omni-antennas with significant vertical coverage are widely used

• RF energy goes where it should not go and antennas try to receive it from

directions where are no clients

• Lacking antenna sophistication

– More gain towards users would benefit uplink quality

– Lack of antenna directivity creates more interference

• Suggestions

– Down-tilt beam patterns

• Fixed, “normal” antennas

• Electrically adjustable, like in mobile networks

– Wider use of beam steering

May 2013


doc.: IEEE 802.11-13/0545r1

Submission

#10. Performance Management is

completely missing • With WLAN networks, commonly accepted fact is that:

“It is not necessary to continuously know what kind of service end

users get from the network.

If we manage to make it work once, there is no need to look after

performance for several months/a year. It will take care of itself

automatically. We will troubleshoot when end users complain”

• This approach fundamentally prevents WLAN becoming a reliable media

• Mobile operators/telecom industry are used to manage networks based on

Meaningful Key Performance Indicators, KPIs, that accurately indicate and

predict User Experience (L1-L7) in the network. These are covered also in

standards. This is a good practice that should be brought to WLAN

• Beyond technology providing the required solutions, data and services, even

bigger change is required in attitudes.

May 2013


doc.: IEEE 802.11-13/0545r1

Submission

2-10x improvement available with these already Results: Controller Automation vrs First Manual Optimization Round

• University campus, dense WLAN network

• 2.4 GHz downlink throughput improvement Improvement – Area 1 7Mbit/s vrs. 25Mbit/s (+250%)

– Area 2 5Mbit/s vrs. 15Mbit/s (+200%)


• 2.4 GHz uplink throughput improvement – Area 1 7Mbit/s vrs. 20Mbit/s (+180%)



• 2.4 GHz downlink Voice Quality (MOS grade, max 4.0) improvement – Area 1 2.6Mbit/s vrs. 3.5Mbit/s (+0.9 MOS)

– Area 2 2.9Mbit/s vrs. 3.8Mbit/s (+0.9 MOS)


• 2.4 GHz uplink Voice Quality (MOS grade, max 4.0) improvement – Area 1 3.5Mbit/s vrs. 3.8Mbit/s (+0.3 MOS)



• 2.4 GHz jitter daily averages before vrs. after – Area 1 9% vrs. 1% (- 89%)

– Area 2 9% vrs. <<1% (> -90%)

– Area 3 7% vrs. 1% (-85%)

• Hourly minimum measured downlink throughput values increase 10X – Area1, Area 3 0.2 Mbit/s vrs. 2.5 Mbit/s (~1100%)

17 Veli-Pekka Ketonen (7signal.) Slide 17

doc.: IEEE 802.11-13/0545r1

Submission

May 2013

Slide 18

Areas looking for improvements based on data from current installations

1. Too aggressive rate control

2. Automated channel control algorithms need clear improvements

3. Already available radio settings are not utilized since their impacts are not understood

4. Interference due to lacking channel coordination and Bluetooth devices

5. Too dense beacons load air unnecessarily

6. Mobile networks interfere 2.4 GHz band WLAN’s through 3rd harmonic distortion

7. Support for legacy devices (802.11b/a) seriously degrades benefits of new standards

8. Lacking interoperability may take down whole network performance

9. Modest access point antenna solutions

10. Performance Management is completely missing

Veli-Pekka Ketonen (7signal)

doc.: IEEE 802.11-13/0545r1

Submission

References

[1] Nokia Networks/Jussi Nervola: Optimization of EGPRS Link Adaptation, 2007/01/16 – M.Sc. Thesis seminar presentation

– http://www.netlab.tkk.fi/opetus/s38310/06-07/Kalvot%2006-07/nervola_160107.ppt

Network statistics from 7signal network optimization and performance assurance reports

May 2013


http://www.netlab.tkk.fi/opetus/s38310/06-07/Kalvot 06-07/nervola_160107.ppt





doc.: IEEE 802.11-13/0545r1

Submission

ADDITIONAL SUGGESTIONS

May 2013


doc.: IEEE 802.11-13/0545r1

Submission

Other input for SG work

May 2013


Topic Description

Client power control In dense networks AP’s have often lower power levels than clients. High amount of high power clients with a lot of traffic (data, control or

management) take a lot of air time and cause unnecessary interference.

Prevent hiding SSID’s Hidings SSID’s increases utilization. All beacons are anyway sent, just without SSID name. Without SSID names in beacons, Clients need to

probe continuously. Remote possibility of hiding SSID names as it provides so little value. Alternatively implement so that beacons are not sent at

all is SSID is hidden.

Improve DFS implementation DFS operation is commonly reported to be overly sensitive and prevents using DFS channels in many areas. This needs to change with .ac and

.hew to allow efficient use of 5 GHz band.

Improve client roaming behavior Some clients use excessive off channel scanning. This sometimes results as QoS Null frame flood that takes air time and increase congestion.

Use adaptive beaconing When there are no relevant clients nearby for a longer time, transmit beacons less often. This reduces overall spectrum load in the surrounding

areas remarkably. Currently APs beaconing (usually 1 Mbit/rate & 100ms interval) consume a lot of spectrum day and night for no good purpose.

Consider ways to work around the power save mode operation.

Use dynamic fragmentation Client traffic could start with a smaller packets (with fragmentation) at higher data rate (less airtime, less interference). Once rate control has a

good grip of proper rates for that client packet flow, fragmentation could be gradually removed. Rate control is slow and needs some time to

adapt. In addition to lowering retries, utilization and interference, this would allow some time for rate control to work better.

Beacons and probes should use

higher data rates

Beacons (and probes/probe responses) should not be transmitted with the low data rates. By using higher data rate there, the nearby clients (the

only ones relevant to beaconing process) can receive them and the devices further away not. Rate control still should be able to move to lower

data rates when really needed. This would be easy way to reduce utilization further away from AP.

Cloud control:

Radio Link Test and Radio Link

Control interfaces to APs

For automated central coordination of a large group of individual APs, there should be two new functionalities in APs. Radio Link Test

interface: Without authenticating to AP/network, an authorized (password) wireless device should be able to run some basic active measurements

against the AP. These include at least FTP, UDP and ICMP traffic flows. Radio Link Control interface: Without authenticating to AP/network,

an authorized (password) wireless device should be able to control basic Radio settings in AP. These include at least radio channel and power

level. Cloud control: With these interfaces, especially dense consumer AP installations (& SMB) could be centrally controlled and managed to

provide optimum quality for everyone.

Improved radio MAC based device

type classification

Current MAC address based device identification should be expanded. Currently only manufacturer names are recorded. This would allow

developing better automated/by-default-on QoS control algorithms to infrastructure.

Automated “closed loop” radio

network control, adaptive/SON

Optimally, wireless network should reconfigure automatically (SON, Self Organizing Networks). So far in WLAN results are modest. Channel

change algorithms degrade performance, rather than improve it. Networks have to make decisions and learn from impact of changes continuously.

Accurate data of end user experience is needed for this to work properly. Comprehensive data collection and analytics should drive this process.

doc.: IEEE 802.11-13/0545r1

Submission

DATA COLLECTION

BACKGROUND

May 2013


doc.: IEEE 802.11-13/0545r1

Submission

Background

• 7signal utilizes its products to optimize and operate critical

WLANs (hospitals, universities, enterprises, manufacturing)

• This process includes continuous collection and analysis of

large amount of performance data, consisting of over 600

different metrics. Optimization takes place by reconfiguration

and pre-emptive changes on network based on the data.

• Data includes

– Automated client device tests, providing L1-L7 data

– Passive L1-L2 packet statistics of all 802.11 air traffic

– RF environment data

– Spectrum analysis data

May 2013


doc.: IEEE 802.11-13/0545r1

Submission

7signal Sapphire consists of three elements

• Monitor

• Measure

• Record

• Report

• Alarm

• Analyze

• Troubleshoot

• Verify

Sonar test servers are located in

in close proximity to application

servers

Centrally located Carat manages

Eyes, provides reports and alarms.

Includes Analyzer software

One Eye unit manages 4-7access

points (indoors)

Radio analysis, radio packet

capture and end-to-end application

measurement

Slide 24

doc.: IEEE 802.11-13/0545r1

Submission

7signal Sapphire data covers all layers 1-7

Synthetic tests (L1-L7) • FTP, PING, HTTP, DHCP, SIP, VOIP

• Association/authentication/IP address/test

success rates, delays, throughput, latency, jitter,

packet loss, MOS, data rates, failure codes

• 60 performance indicators, separately for each

AP/SSID/Sonar pair

RF analysis (L1-L2) • Access point settings and capabilities, signal

levels, channels, noise levels


AP, channel, antenna beam

Traffic analysis (L2) • Radio frame header analysis for traffic flow

between clients and access points

• Data rates, retry rates, air congestion, roaming,

frame size, device vendor, statistics for all 802.11

frame types, reason codes and status codes


client, SSID, AP, band, antenna beam

Spectrum analysis (L1) • High resolution (280kHz) spectrum analysis for

ISM band

• Historical data over months, interference source

analysis with beam steering, compass direction

data on beams

Troubleshooting tests (L1-L7) • Remote, manual process for troubleshooting

purposes

• Full array of tests may be scheduled manually to

each Eye

• Eyes may be assigned to perform the additional

tests without interrupting automated monitoring

process

Full packet capture (L1-L2) • Remote, manual process for troubleshooting

• Full blown remote packet capture and easy export

to packet level analyzer like Wireshark, in case

individual radio packet header content information

is needed

• Eyes may be assigned to perform the test without

interrupting automated monitoring process

Slide 25

doc.: IEEE 802.11-13/0545r1

Submission

7signal Sapphire Eye, the data collection device

• A “turbo charged” client device

• At times active like end users, at times fully passive

• Beam steering technology with low noise amplifiers

• Integrated compass

• 802.11 a/b/g/n support

• High resolution ISM band spectrum analyzer

• High RF performance design; maximized coverage,

minimized quantity, typically 4-7 AP’s per unit

• Standard PoE

• Neutral design and white color

• Attaches easily to ceiling grid, alternatively wall or pole

• Indoor and outdoor versions

• Data analyzed at device, only key results to database

• Minimal load to network, small test packets at

determined intervals

Slide 26

doc.: IEEE 802.11-13/0545r1

Submission

7signal view on QoS, similar to end users

300x

200x

200x

100x

100x

WLAN

radio

Network

900x

5x

Access Point

WLAN controller

LAN

wired

network

Core

switching

network

100x

Core Router 100x

Application

servers

Site

broadband

connection

LAN switch

2x

8x

Core switch Server racks

Servers

10x

End user

terminals

7signal

Sonar

software

7signal

Eyes

Active end-to-end

quality of service

assessment from end

user perspective

End user device

quality of service in

radio network

Radio network and

spectrum analysis

Slide 27

doc.: IEEE 802.11-13/0545r1

Submission

Network Optimization Flow

• Utilize especially “Active/Synthetic” Eye measurements (“automated end user”)

• Optimize until target levels have been achieved

1. Ensure that WLAN/LAN/WAN is

capable providing high quality service

• “Passive”, client and AP level measurements

• Optimize network and configure clients to achieve this

2. Make sure that all clients can utilize the

network properly

• Follow Key Performance Indicators (KPIs) and SLA tables and take actions

• Proactive corrections are needed when metrics degrade

3. Maintain performance at the target level over the

time

Slide 28

top 10 ways for next gen wlan to improve user experience

Technology

signal suggestions

week timevelipekka ketonen

aggressive rate control

rate control dynamic

signal solutions

control regulation

n suggestions

proper rate controlschemes