“Support for Radio Resource Management (RRM) in 802.11” Month 2000 doc.: IEEE 802.11-00/xxx July 2001 “Support for Radio Resource Management (RRM) in 802.11” Byoung-Jo “J” Kim, Zoran Kostic, Mathew Sherman AT&T Labs - Research Middletown, NJ USA Macsbug@research.att.com 732-420-9028 Date: July 11, 2001 ”J” Kim, AT&T Labs - Research John Doe, His Company

Motivation for Pursuing Support for RRM in 802.11 Month 2000 doc.: IEEE 802.11-00/xxx July 2001 Motivation for Pursuing Support for RRM in 802.11 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 802.11h: 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

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

Approach to Providing RRM Support in 802.11 Month 2000 doc.: IEEE 802.11-00/xxx July 2001 Approach to Providing RRM Support in 802.11 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

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

e.g., Extending the Published MIB Month 2000 doc.: IEEE 802.11-00/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

Continued on Extending the MIB Month 2000 doc.: IEEE 802.11-00/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

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

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

e.g., Input to 802.11h related to RRM July 2001 e.g., Input to 802.11h related to RRM 11-01-169r1a-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

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

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 802.11? What are the benefits of RRM? What are the cost of RRM? What are the basic mechanisms that need to be in 802.11 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