1. “Support for Radio Resource Management (RRM) in 802.11”
Month 2000
doc.: IEEE /xxx
July 2001
“Support for Radio Resource Management (RRM) in ”
Byoung-Jo “J” Kim, Zoran Kostic, Mathew Sherman
AT&T Labs - Research
Middletown, NJ USA
Date: July 11, 2001
”J” Kim, AT&T Labs - Research
John Doe, His Company

2. Motivation for Pursuing Support for RRM in 802.11
Month 2000
doc.: IEEE /xxx
July 2001
Motivation for Pursuing Support for RRM in
Importance of Radio Resource Management
Simple versions are the de-facto need in today’s products
Higher density, bigger coverage WLAN deployments are coming (Hong Kong, Singapore:Concerned about rapid deployment, interference management. Public WLAN in US, Europe)
Better Mobility/Handover in WLANs
Existence of unpredictable interference in unlicensed bands
RRM as an effective mean of managing QoS
Simple proprietary solutions exist, but opening the interfaces, allowing the interoperability and third party RRM solutions are beneficial to customers
Progress in h: A good Starting point for RRM
Consolidated proposal for Dynamic Frequency Selection (DFS) and Transmit Power Control (TPC) is emerging
”J” Kim, AT&T Labs - Research
John Doe, His Company

3. July 2001
Background
We are Deeply involved with 2G, 3G, 4G Cellular system development with service providers, standards and vendors: Don’t blame us for what you think of 3G!
Cellular Systems are Interference-Limited
Large deployments of WLAN will face similar problems (Some potential operators ask the same questions)
RRM in frequency, time, space, code, power, antenna, tones, etc. are used in Cellular systems to address some of the problems
WLAN may benefit from some of the techniques and new RRM techniques for WLAN are needed
“Now” seems to be the time to start considering RRM for WLAN
”J” Kim, AT&T Labs - Research

4. Approach to Providing RRM Support in 802.11
Month 2000
doc.: IEEE /xxx
July 2001
Approach to Providing RRM Support in
Use open “interfaces” and “protocols” for RRM-relevant “Information Sharing and Configuration” between APs, as well as with “external” world
Particular RRM techniques need not be standard
Leave details of RRM to be implementation-specific
Start with Quasi-Static RRM to Dynamic RRM
Distributed management among AP’s can use extended IAPP, avoiding SNMP managers in AP’s
Management by external entities can use SNMP with extended MIB
Some of needed MIB objects are already present in private MIB’s of many vendors.
Consider wireline and over-the-air means of RRM Support
Consider 11a and 11b differences
”J” Kim, AT&T Labs - Research
John Doe, His Company

5. Generic RRM would need…
July 2001
Generic RRM would need…
Current channel allocations and means to change them
Current load information and means to redistribute them(e.g., MAC list of assoicated STA’s, sleep status)
Current channel conditions per STA (e.g., available maybe via DCS for 11a)
Running statistics of frame error rate, SNR, etc., per STA
Scheduling information if any and means to change them ( txopportunity for PCF via MIB Get/Set or IAPP? )
Current Interference situation per STA and AP
Radio Distance between AP’s (e.g., received beacon strength from other AP’s via DCS, addtionally the transmit power of beacons, antenna gains on tx/rx)
”J” Kim, AT&T Labs - Research

6. e.g., Extending the Published MIB
Month 2000
doc.: IEEE /xxx
July 2001
e.g., Extending the Published MIB
AP ID with (IP, name, MAC address)
dot11CurrentChannel, dot11EDThreshold
loading (number of STA’s associated, number of STA’s, frames transmit/received during last second/min, etc.)
Per STA statistics seen at AP’s
Beacon transmit power(extend dot11CurrentTxPowerLevel per STA & beacon)
Other AP’s beacons that can be heard and their ID’s
Measured noise in available channels
Mode of operation status (PCF,DCF, HCF)
Extend Counter objects to include /sec or /min averages, average number of retransmissions, etc., to reduce number of polling
Traps to detect abnormal radio conditions (New beacon heard, high load, etc.)
”J” Kim, AT&T Labs - Research
John Doe, His Company

7. Continued on Extending the MIB
Month 2000
doc.: IEEE /xxx
July 2001
Continued on Extending the MIB
Accessible from AP’s for associated STA’s
User IDs (MAC or IP address) with
Associated AP ID
SIR, noise power measurement (upstream from AP, downstream from STA, or if AP knows downstream for STA, all available from AP’s)
Current antenna capabilities(extend dot11AntennasList)
Who is heard by STA’s during the last minute upon request (Distinguish beacon and traffic)
Extend Counter objects for “Average” number of retransmissions per STA, Average number of time out, etc.
”J” Kim, AT&T Labs - Research
John Doe, His Company

8. Communication Means for RRM
July 2001
Communication Means for RRM
Distributed RRM among AP’s
Extend IAPP to support Resource management information (subset what’d be available in MIB) exchange among AP’s
Local decision making
Light-weight implementation
Centralized or Distributed RRM
SNMP managers accessing MIB’s at AP’s
Limited Coordination among nearby WLAN’s owned by different entities
Wired access is not assured.
Some limited capabilities coordinated over-the-air
E.g., Can you move to a different channel? Yes or No
”J” Kim, AT&T Labs - Research

9. July 2001
Over-the-air RRM
Basic Coordination between AP’s controlled by different administrative entities for limited RRM.
Only between AP’s that can hear each other. No connectivity over wired network assumed.
Over-the-air Request/Confirm mechanisms for changing channels, power control and optional compliance between AP’s
Load balancing: request STA’s to disassociate and move to another AP.
Over-the-air mechanisms for coordinating PCF. (e.g., multiple AP’s taking turns for CF period.)
”J” Kim, AT&T Labs - Research

10. e.g., Input to 802.11h related to RRM
July 2001
e.g., Input to h related to RRM
r1a-H-TPC and DFS Joint Proposal
For DFS:
Channel Monitoring
AP Channel Measurement Requests
Channel Measurement Process in STAs
Measurement reports from STAs to AP
MODIFICATION: Collecting inputs (via SNMP or IAPP) from other APs and/or central radio resource manager (Need standard Mapping of measurement report to IAPP, or MIB )
AP decision making
AP Channel Switch Announcement
The new channel switch !
Power control
Mobile decides everything, but AP can still provide SNR or Signal Strength to aid mobile to make better decisions.
SNR is asymmetric due to interference.
”J” Kim, AT&T Labs - Research

11. Benefits of RRM Simple deployment and expansion
July 2001
Benefits of RRM
Simple deployment and expansion
Large-scale coverage (airports, downtown, etc), via frequency reuse, timing coordination, etc…
Better QoS
Better co-existance of independent WLAN’s
Higher Capacity
Load balancing
Robustness to interference
”J” Kim, AT&T Labs - Research

12. What to do now? Let’s brainstorm on..
July 2001
What to do now?
Let’s brainstorm on..
What can enable large-scale deployment for ?
What are the benefits of RRM?
What are the cost of RRM?
What are the basic mechanisms that need to be in standards?
What can be done within existing TG’s to accommodate RRM? (MIB, Tge, TGf, TGh.)
What further can we do about RRM?
”J” Kim, AT&T Labs - Research