January 2003

Byoung-Jo “J” KimSlide 1

doc.: IEEE 802.11-03/124r0

Submission

RRM Requirements forPublic WLAN Service Provider

Byoung-Jo “J” Kim

AT&T Labs-Research

January 2003

Byoung-Jo “J” KimSlide 2

doc.: IEEE 802.11-03/124r0

Submission

Outline

• The Needs of Public WLAN Service Provider

• Summary of What we achieved so far

January 2003

Byoung-Jo “J” KimSlide 3

doc.: IEEE 802.11-03/124r0

Submission

Caveats with Scenarios

• Scenarios are hard to get right. Even which scenario is important

• A lot of parameters are common– Sometimes, scenarios are created with what is available in mind

• New unexpected scenarios or applications will happen, utilizing RRM “toolkits”

• Our architectural choices are limited– Even if a critical scenario demands a new approach, it may be

outside of the scope of 11k, and 802.• Address clear needs that can be done in a reasonable time to

be useful– consider more advanced features more carefully w.r.t.

standardization feasibility: Controversial? Out of Scope? Implementation difficulty?

January 2003

Byoung-Jo “J” KimSlide 4

doc.: IEEE 802.11-03/124r0

Submission

General Characteristics ofPublic WLAN service

• Many far-flung locations with small to large number of APs• Variety of Backhaul arrangements: DSL, Cable, T1, ATM, IP,

Frame, Fixed Wireless, which may dictate user throughput• Managed at a few large NOCs• Installers with little knowledge on WLAN beyond general

directives• No or little local support• User supports and truck-rolls are costly to the business model• Uncontrolled interference environments: 802.11 and non-

802.11• Due to security, only SNMP read may be enabled: Action

triggered via SNMP write may be impractical• Remotely, Remotely, Automate, Automate, Automate

January 2003

Byoung-Jo “J” KimSlide 5

doc.: IEEE 802.11-03/124r0

Submission

Features needed w.r.t. RRM• Automatic frequency and power adjustment during

AP installation and operation– Instantaneous values need to be aggregated in some way– presence of all .11 AP’s and STAs in the relevant band– RSSI per STA in absolute scale– A signal quality measure per STA, like 03/100r1– non-802.11 energy, and noise power when CCA is

negative– Rates in use: current and averaged over window? or

histogram?– Per STA counters: retry, drops, frames, checksum errors – Anything else?

January 2003

Byoung-Jo “J” KimSlide 6

doc.: IEEE 802.11-03/124r0

Submission

Features (continued)• Performance auto-tune and alarms

– info on the situation• Interference from other 802.11 systems? Non-802.11 sources?

• Nearby BSSs eating up bandwidth

• Large part of CCA negative is due to who?

– Automatic remedies: by adjusting Power, Frequency, Fragmentation, retry limits, etc..• Outside of 11k, but what would you need to know if these are

our tools for remedies?

– Performance Alarms• A significant portion of the users are in poor channel quality

• Overall high retries and drops

January 2003

Byoung-Jo “J” KimSlide 7

doc.: IEEE 802.11-03/124r0

Submission

Features (continued)• Remote diagnosis and user support

– Among many things that can go wrong in user devices, radio link condition is one• Is the user too far, interference, mis-configured….

• Is there any radio related parameter that has not been covered?

• Notifications of significant events (association, authentication, etc, etc., some are available)

• QoS related monitoring• Control of Client parameters (as in “out of scope

of 11k”) is not an immediate requirement

January 2003

Byoung-Jo “J” KimSlide 8

doc.: IEEE 802.11-03/124r0

Submission

General Agreement so far(in the context of Public WLAN)

• Architecture following 11h as outlined in 080r0• Per-STA self-measured MIB variables, available at

APs, for some Passively observable parameters– Initial thoughts in 11-02-676r0-RRM-SG– Requires standard changes only in MIB. No new frame

types, actions, etc.– AP Manufactures need to update their firmware– May increase memory requirement, but most already

have enough– RSSI, retry counters, CCA fractions, lost packet

counters, a signal quality measure, a load measure, etc.

January 2003

Byoung-Jo “J” KimSlide 9

doc.: IEEE 802.11-03/124r0

Submission

Continued

• Several Extensions of 11h frames to include a more measurements– Initial suggestions in 11-03-029r0-K– Beacon Report, Extended CCA report, RSSI

histogram, Frame report

January 2003

Byoung-Jo “J” KimSlide 10

doc.: IEEE 802.11-03/124r0

Submission

Continued

• How to get passively observed parameters from STAs to APs is not clear– What are the parameters? Anything more than 029r0?

• If not, no concern.

– Map some MIB to parameter variables? (dynamic tables?) and use 11h-like frames to transfer

– Leave it to SNMP?– Treat some of them like action requests in 11h?

• Start recording the following. Return results when requested• Not much different from simple requests if the result can be put

in a simple format

January 2003

Byoung-Jo “J” KimSlide 11

doc.: IEEE 802.11-03/124r0

Submission

More to Consider(Critical issues in Red)

• A new signal quality measure. Across PHY and Rate?– Yes we need one, but exactly what

• Refined RSSI definition• Refined measure of loading. Across PHY/Rate?• How to aggregate/trend instantaneous parameters

– Average, windowing, histogram, parameter specific• How higher layers trigger measurement Actions and Other

Interactions (as recommended practice, SNMP for APs)• Neighborhood/Boundary report and other service info dissemination• Some form of Roaming support within 802.11, across PHY, across

3G• Security Implications• Anything else?