doc.: ieee 802.11-13/1386r2 submission november 2013 veli-pekka ketonen (7signal solutions)slide 1...

doc.: IEEE 802.11-13/1386r2

Submission

November 2013

Veli-Pekka Ketonen (7signal Solutions)Slide 1

Improving WLAN Efficiency and QoE – A Top Down Approach

Date: 2013-11-10

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 802.11-13/1386r2

Submission

November 2013

Slide 2 Veli-Pekka Ketonen (7signal Solutions)

Abstract

This is a submission for 802.11HEW SG in Dallas November 10th-15th

A potential system level approach is suggested for HEW SG consideration

doc.: IEEE 802.11-13/1386r2

Submission

The key message

• WLAN needs to regain the capacity and performance advantage in wireless market

• Ample of potential – Need to be utilized much better• 10X improvements already available by manually

optimizing networks• No need to re-define everything, lose compatibility and

still be unsure if the gains will ever be realized• Reuse/refine existing standards - address bottlenecks• Make this available with smaller steps

November 2013


doc.: IEEE 802.11-13/1386r2

Submission

The Problem• No single problem causes lack of efficiency and QoE, but

many factors accumulate• No single change will radically change this either• General RF configuration must improve. No

MAC/PHY protocol can deliver utmost user experience and capacity in current uncoordinated RF build ups as they stand today in many public areas

• WLAN are widely deployed by non-wireless experts. Addressing practical aspects becomes very important. Preventing harmful configurations and making the optimal Fit-for-Purpose product selection easy

November 2013


doc.: IEEE 802.11-13/1386r2

Submission

Suggested elements for HEW concept1. TRI-BAND WLAN 2.4 (n) - 5 (n/ac) - 60 (ad) – Use all spectrum already available

– “Un-limited” future dense area scalability with 60 GHz band – Overlapping BSS with 802.11ad

2. SIMULTANEOUS DUAL BAND – Seamless coverage and capacity evolution– Simultaneously use two-of-three bands – APs reconfigure based on environment

3. CSMA/CA ACCESS REMAINS – Defines Wi-Fi, innovation in flexibility– CSMA/CS remains but is improved - dynamically adjusting to conditions

4. MAC “SERVICE PACK” – Room to improve, in several areas– A number of MAC protocol improvements, possibly on the current HW platforms

– Introduction of Radio Profiles and Dynamic Protocol Reconfiguration

• PHY IMPROVEMENT – Non-RF experts & general purpose prod., prevent errors…– No new PHY standard. Instead introduce Efficiency Classes and Fit-for-Purpose products

– Minimize/remove opportunities for major mistakes in RF deployments by non-experts

– Utilize better RF and antenna technology. Prevent RF pollution and increase radio link budgets several dBs

1. SELF-ORGANIZING & OPTIMIZING – No fixed set can handle all the conditions– Dynamic control and reconfiguration of MAC/PHY operation against continuously validated SLA targets

– Define an open API for selected MAC/PHY settings. This would speed up ecosystem development

November 2013


doc.: IEEE 802.11-13/1386r2

Submission

1. TRI-BAND WLAN2.4 GHz (n) – 5 GHz (n/ac) - 60 GHz (ad)

• Adding 60 GHz does not solve existing QoE and inefficiency issues at the 2.4 GHz and 5 GHz bands that HEW in about

• However, WLAN competes also against other technologies, like LTE evolution

• A clear tri-band vision would put WLAN back to significant lead as preferred future solution for highest wireless capacity

• Personal empirical study: 95% of consumer/SME laptop models still sold with 2.4 GHz only with sales argument that it supports 802.11n. Sales personnel does not know what is 5 GHz band.

• => Vendors need to reassess strategy here. Current situation is not beneficial for industry or end users

November 2013


doc.: IEEE 802.11-13/1386r2

Submission

2. SIMULTANEOUS DUAL BAND,OVERLAPPING BSS

• Dynamically alternating connection to one physical AP– Dynamically alternating the best connection, both connected, one transmitting at a time

• Parallel connection to one physical AP – Single path TCP over one AP. Processing within client and AP radios

• Parallel Multipath TCP (MPTCP) to two physical APs– A natural extension as IP/TCP technology evolves (Ref. Siri MPTCP, [1])

Why would this matter in HEW?• Additional redundancy and capacity with parallel 2.4 & 5 GHz connection

• 60 GHz signal attenuate very rapidly with a person leaving the room. Without instant seamless roaming, 802.11ad may not serve Enterprise WLAN needs

November 2013


2.4 5 60

Access point

2.4 5

Access point

2.4 5 60

Access point

STA

STA

STA

STA STA

STA STA

doc.: IEEE 802.11-13/1386r2

Submission

3. CHANNEL ACCESS

• CSMA/CS remains but improved– Asymmetric priority control. Promising research results available on this

topic [2] [3]

– Dynamic Sensitivity Control [4]

– Other optimizations

• 802.11 remains backwards compatible

• Full duplex APs with interference cancellation (“Wave 2”)– Once interference cancellation is sufficiently mature [5]

– APs would benefit more from full duplex than STAs

November 2013


doc.: IEEE 802.11-13/1386r2

Submission

4. MAC “SERVICE PACK”

November 2013


MAC improvement candidatesItem DescriptionEnvironment Optimized Radio Profiles with more efficient MAC behavior

Define a sufficiently many standardized Radio Profiles that include settings optimized for different use cases. For example public place, hospital, outdoor, campus,... These include all key settings, for example: AP power control operation, channel selection, channel access priority (CW, TXOP, backoff...), beacon interval, probing/respose behavior, enabled MCSs, MCS selection algorith, fragmentation, carriers sense limit, others tbd.

High Efficiency Certification program and Efficiency Classes for MAC/PHY operation

Introduce Efficiency Classes and granting an Efficiency Class for all High Efficiency devices. High efficiency approved product will need to pass radio efficiency tests and meet certain class requirements. These include a number of AP and client behavior efficiency related aspects. As well, these include device RF characterisctics.

HARQ with incremental redundancy Stronger coding in poor conditions and soft combining of consecutive transmissions. Currently a clean packet thru needed. All retries are similar (data rate may vary).

Combine all SSIDs to one beacon Create a MAC feature that combines all beacons to one common message in each AP radio.

MAC mode preventing non-supported STAs probing

A new capability would allow limiting non-supported STA probing interference to other traffic. Currently legacy STA continues to probe and this creates interference to desired traffic. Now this is relevant to -b but in the future to the future stadards

Dynamic header coding Consider making training field coding variable according to rate control with 2-3 rate steps and by still retaining it clearly more robust coding that data field. Training and L-SIG fields coding use always 6 Mbit/s. Required SNR difference between MCS0 and higest rates is 25 dB. Far away devices capture header and must avoid using the channel at very large distance where the actual high rate data symbols are totally undetectable and ignored

Legacy impact reduction Remove 802.11b from new products, set new consumer product beacon interval to 300ms, define a MAC feature that prevents non-supported legacy devices probing, remove possibility to hide SSIDs

Other suggestions to be agreed

doc.: IEEE 802.11-13/1386r2

Submission

5. PHY ENHANCEMENTS

November 2013


PHY improvement candidatesItem DescriptionForce everyone to a valid channel grid. Completely remove unnecessary channels from APs and STAs

Usage of channels is often almost random public places. Plenty of APs and Ad hoc’s with 1, 2, 3 channel offset’s from "the grid". HT bonding may vary randomly. All this is worse than having them all on one channel and allowing CSMA/CS operate. Remove support for unnecessary channels and freeze the channel plans. I.e. in U.S. remove ch 2, 3, 4, 5, 7, 8, 9, 10. Fix HT bonding schemes.

AP transmit power control (improved, still slow and non-client specific for simplicity)

Add at least a slow power control for APs. A common configuration in WLAN is that AP power is +7 dBm and client power +14 dBm. From overall system capacity point of view, this is not a desirable situation.

Simple, mandatory client transmit power control (slow, for simplicity)

In strong RF and several neighbor APs available, clients need to reduce their power level by themselves. Simple algorithm, no feedback loop. Clients transmit with full power always, even higher power than APs. Very few have TPC and these are vendor specific implementations. AP to have a control bit for using this is disabling

High Efficiency Antenna Approval Program

Introduce high efficiency AP antennas with a specific performance characteristics (gain/tilt towards users, null towards other APs) and approved for certain use cases. Gain of Enterprise Grade AP antennas is often not pointing towards end users where they would need to gain to enhance uplink. Antenna lobes often overshoot or point straight down toward very near clients. Enterprise grade APs often have their max gain towards neighbor AP.

doc.: IEEE 802.11-13/1386r2

Submission

6. SELF-ORGANIZING AND OPTIMIZING, OPEN API

• Network performance management, self-organizing and self-optimizing networks are a major research, development and operational focus area in mobile networks

• Current state of performance management and radio automation is WLAN is very modest and performance significantly lacking (= one key reason for HEW)

• Carefully done manual optimization provides already now even order of 10x improvements to throughputs under load compared to current automation

• Networks are often operated by non-specialists and conditions vary constantly • No single configuration can service optimally different environments• WLAN has to become truly automatically reconfiguring and optimizing

towards a target performance • Standardizing an open API for network radio control as an alternative to vendor

internal implementation would likely increase speed of evolution and innovation towards seamless HetNets

November 2013


doc.: IEEE 802.11-13/1386r2

Submission

Suggested High Efficiency Initiative Scope

November 2013


2.4 GHz clean up and legacy impact reduction w/ better settings

High Efficiency Certification programs with Efficiency Classes

Bring 5 GHz (n/ac) support to end users devices

Self-optimizing and reconfiguring

Full duplex APs with interference cancellation

Tri-band WLAN products

Simultaneous Dual Band with overlapping BSS to single AP

Simultaneous dual band Multipath TCP over two APs/other radios

Fit-to-Purpose products with predefined std. Radio Profiles

Optimize networks with addition of Performance Management

Open Radio Control API definition

MAC “Service Pack” Dynamic sensitivity controlAsymmetric ch. access priorityMaster beaconBasic power control Feature to prevent legacy probingOthers to be agreed

Industry/WFA (2013-2015)

HEW “WAVE 1” SW/FW (2016-2017)

HEW “WAVE 2” HW (2018-)

“10X” “10X” “10X”

Open Radio API Self-Optimizing and Reconfiguring products

802.11ac Wave 1 & Wave 2

Implementation improvements: ch selection, rate control, power cntrl, antennas,...

[6]

HARQ with incremental redundancy

doc.: IEEE 802.11-13/1386r2

Submission

Suggested High Efficiency Initiative Scope

November 2013


2.4 GHz clean up and legacy impact reduction w/ better settings

High Efficiency Certification programs with Efficiency Classes

Bring 5 GHz (n/ac) support to end users devices

Self-optimizing and reconfiguring

Full duplex APs with interference cancellation

Tri-band WLAN products

Simultaneous Dual Band with overlapping BSS to single AP

Simultaneous dual band Multipath TCP over two APs/other radios

Fit-to-Purpose products with predefined std. Radio Profiles

Optimize networks with addition of Performance Management

Open Radio Control API definition

MAC “Service Pack” Dynamic sensitivity controlAsymmetric ch. access priorityMaster beaconBasic power control Feature to prevent legacy probingOthers to be agreed

Industry/WFA (2013-2015)

HEW “WAVE 1” SW/FW (2016-2017)

HEW “WAVE 2” HW (2018-)

“10X” “10X” “10X”

Open Radio API Self-Optimizing and Reconfiguring products

802.11ac Wave 1 & Wave 2

Implementation improvements: ch selection, rate control, power cntrl, antennas,...

[6]

HARQ with incremental redundancy

Fully utilize the obvious and easy

opportunities

Reduce non-intentional “damage”

Standardize Wave 1

QUICK GAINSHelp non-RF experts implement correctlyImprove robustnessImprove efficiencyAuto-reconfigure

Accelerate innovationStandardize Wave 2

VERY HIGH CAPAEnable seamless use of

all three bands

Benefit from open interface innovations

Seamless HetNets

doc.: IEEE 802.11-13/1386r2

Submission

References• [1] Multipath TCP lets Siri seamlessly switch between WiFi and 3gLTE

– http://arstechnica.com/apple/2013/09/multipath-tcp-lets-siri-seamlessly-switch-between-wi-fi-and-3glte/

• [2] WiFox: Scaling WiFi Performance for Large Audience Environments– http://conferences.sigcomm.org/co-next/2012/eproceedings/conext/p217.pdf

• [3] A Measurement Study of WiFi Backoff Protocols– https://mentor.ieee.org/802.11/dcn/13/11-13-0494-00-0wng-ieee-presentation-backoff.ppt

• [4] Dynamic Sensitivity Control• https://mentor.ieee.org/802.11/dcn/13/11-13-1012-04-0wng-dynamic-sensitivity-control.pptx

• [5] Considerations for In-Band Simultaneous Transmit and Receive (STR) feature in HEW

– https://mentor.ieee.org/802.11/dcn/13/11-13-1122-01-0hew-considerations-for-in-band-simultaneous-transmit-and-receive-str-feature-in-hew.pdf

• [6] Possible Vision of HEW-driven Wi-Fi’2020– https://mentor.ieee.org/802.11/dcn/13/11-13-1115-00-0hew-possible-vision-of-the-hew-driven-wi-fi-2020.ppt

November 2013


doc.: IEEE 802.11-13/1386r2

Submission

MAC EFFICIENCY IMPROVEMENTSSUGGESIONS FOR SIMULATIONS

November 2013


MAC improvement candidatesItem Description SuggestionHARQ with incremental redundancy Currently a clean packet thru needed. All retries are similar (data rate may vary). Stronger coding in poor conditions and soft combining of

consecutive transmissions

Combine all SSIDs to one beacon A large amount of SSIDs may be deployed for one network. Create a MAC feature that combines all beacons to one common message in each AP radio

Use case specific Radio Profiles Few radio profiles that include settings optimized for different use cases. Automation may vary used profiles and its settings.

Remove 802.11b from all new products

Overdue supported legacy rates take down the whole network performance through excessive protection leading to high utilization

Expire 802.11b standard at new products. Remove 802.11b standard support from all new devices.

Define a MAC feature that prevents legacy clients probing when std not supported

Legacy devices probe with very low data rates, like 1 Mbit/s even when their support is disabled. This consumes airtime (if supported) or causes packet loss if those rates are not any more supported by APs.

For the future in mind, develop a MAC feature that makes in possible to prevent past legacy standard devices probing in a network

Prevent hiding SSIDs Remove possibility to hide SSID Hiding SSID name does not stop sending beacons or improve security

Default beacon interval 300ms Beacon interval default values in consumer grade WLAN is 100ms. These are widely used in shops etc public places.

Manufacturer default values to be revisited asap. In consumer grade APs, default to be 300ms (quick help).

Dynamic Asymmetric Priority Control Dynamically adjust channel access protocol operation (CW, TXOP, backoff). Allow priority for AP over client. Part of radio Profile.

Dynamic beacon interval Beacons take a lot of airtime when several SSIDs supported and 100ms interval used Beacon interval to be dynamically variable. Discourage vendors assuming in the design that beacon interval does not vary fom 100ms.

Environment specific MCS control Rate control often uses too high rates and this causes high retry rates. Different profiles may help adapt to eqach environment. Dynamic control. Part of Radio Profile.

Add several rate control strategies that fit best the use case. Rate control schemes must be overall improved and tested with WFA approval testing.

Dynamic beacon MCS Beacons are always sent out with the lowest mandatory rate which is usually the lowest supported rate. Default > minimum supported. Part of Radio Profile.

It would be preferable to limit beacon/probe responses to use higher rates and still allow rate control use lower rates when clients really need it. Allow beaconing at higher than lowest mandatory rate.

Dynamic packet 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. Part of Radio Profile

Dynamic carriers sense limit Carrier sense threshold is a fixed value of typically -82 dBm. Even though the noise level increases in network at the time of high utilization, this remains constant. This leads to a situation where high utilization prevents traffic even close to AP. Part of Radio Profile

It may be beneficial to allow this threshold increase somewhat during high WLAN utilization. This limits cell range but increases total capacity

Dynamic header coding Training and L-SIG fields coding use always fixed, very robust codec (6 Mbit/s). Far away devices capture header and must avoid using the channel at very large distance where the actual high rate data symbols are totally undetectable and ignored. Part of Radio Profile

Consider making training field coding variable according to rate control with 2-3 rate steps and by still retaining it clearly more robust coding that data field. Adding capacity needs to push the edge.

Enhanced DFS Redefine DFS operation not to trigger too easily

doc.: ieee 802.11-13/1386r2 submission november 2013 veli-pekka ketonen (7signal solutions)slide 1...

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