A Brief Introduction to the IEEE802.11h Draft January 2003 A Brief Introduction to the IEEE802.11h Draft TGk Radio Resource Measurement January 2003 Simon Black simon.black@qosine.co.uk Simon BlackSimon Black, Qosine

January 2003 What is IEEE802.11h? A draft supplement to the IEEE802.11 WLAN Standard ‘Spectrum management in the 5GHz band in Europe’ ‘Defines mechanisms for dynamic frequency selection (DFS) and transmit power control (TPC) that may be used to satisfy regulatory requirements for operation in the 5GHz band in Europe.’ A protocol tool-kit for Transmit Power Control (TPC) and Dynamic Frequency Selection (DFS) Simon BlackSimon Black, Qosine

Why is IEEE802.11h interesting for Radio Resource Measurement? January 2003 Why is IEEE802.11h interesting for Radio Resource Measurement? TPC and DFS involve radio resource measurement! The management model is relevant Where are the decisions made? What supporting protocol is required? Some of the management frames & elements may be usable A complete and stable draft exists and is currently undergoing the sponsor ballot process Simon BlackSimon Black, Qosine

TPC Service The TPC service provides for the: January 2003 TPC Service The TPC service provides for the: Association of STAs with an AP in a BSS based on the STAs power capability Specification of regulatory and local maximum transmit power levels for the current channel Selection of a transmit power for each transmission in a channel within constraints imposed by regulatory requirements Adaptation of transmit power based on a range of information, including path loss and link margin estimates Simon BlackSimon Black, Qosine

DFS Service The DFS service provides for: January 2003 DFS Service The DFS service provides for: Association of STAs with an AP in a BSS based on the STAs’ supported channels Quieting the current channel so it can be tested for the presence of radar with less interference from other STAs Testing channels for radar before using a channel and while operating in a channel Discontinuing operations after detecting radar in the current channel to avoid interference with radar Detecting radar in the current and other channels based on regulatory requirements Requesting and reporting of measurements in the current and other channels Selecting and advertising a new channel to assist the migration of a BSS or IBSS after radar is detected Simon BlackSimon Black, Qosine

IEEE802.11h Layer Model SME MLME January 2003 MAC Timing Measurement Protocol Policy Channel Switch Decision Frames SME MLME Timing PLME MEASURE CHANNEL SWITCH MREQUEST& MREPORT MLME Frames Simon BlackSimon Black, Qosine

IEEE802.11h Management Frames Extensions to existing frames January 2003 IEEE802.11h Management Frames Extensions to existing frames Element based, building on existing IEEE802.11 management protocol Beacon/Probe Response extensions Country Power Constraint Channel Switch Announcement Quiet IBSS DFS TPC Report Association/Reassociation Request extensions Supported Channels Power Capability Simon BlackSimon Black, Qosine

IEEE802.11h Management Frames Action frames January 2003 IEEE802.11h Management Frames Action frames Action management frame defined to minimise the number of management frame subtypes used The IEEE802.11e draft shares this mechanism Defined spectrum management action frames Measurement Request Measurement Report TPC Request TPC Report Channel Switch Announcement Simon BlackSimon Black, Qosine

Requesting Measurements January 2003 Requesting Measurements Requested using Measurement Request Action frame Dialog Token identifies measurement Timing can overlap, or be separate from other measurements Duration of measurement defined in the request Three measurement types defined Basic CCA (Clear Channel Assessment) RPI (Receive Power Indication) Histogram Only Basic measurement is mandatory STA can refuse to perform a measurement even though it may be capable Measurement results returned in a Measurement Report Action frame Simon BlackSimon Black, Qosine

Example of Measurement Request Frame Body Format – Basic Request January 2003 Example of Measurement Request Frame Body Format – Basic Request Category = 0 (Spectrum Management) Action = 0 (Measurement Request) Dialog Token Activation Delay (Beacon intervals) Measurement Offset (TU) Measurement Request Element Measurement Request Element Measurement Request Element Element ID = 38 (Measurement Request) Length = 6 Measurement Token Measurement Request Mode Measurement Type = 0 (Basic Request) Channel Number Measurement Duration (TU) Simon BlackSimon Black, Qosine

Example of Measurement Report Frame Body Format – Basic Report January 2003 Example of Measurement Report Frame Body Format – Basic Report Category = 0 (Spectrum Management) Action = 1 (Measurement Report) Dialog Token Measurement Report Element Measurement Request Element Element ID = 39 (Measurement Request) Length = 7 Measurement Token Measurement Report Mode Measurement Type = 0 (Basic Report) Channel Number Measurement Duration (TU) Map Simon BlackSimon Black, Qosine

Measurement Types Basic CCA RPI Histogram January 2003 Measurement Types Basic Simple flags for BSS, radar, OFDM preamble, unidentified CCA Fraction of measurement duration CCA was busy RPI Histogram Distribution of received power density over measurement duration quantised into eight bins Simon BlackSimon Black, Qosine

Measurement MSC – STA Accepts January 2003 Measurement MSC – STA Accepts Decision to request measurement from peer STA SME MLME IEEE802.11h STA MLME-MREQUEST.req MLME-MREQUEST.ind Decision to accept measurement request from peer STA MLME- MEASURE.req Measurement Process MLME- MEASURE.cfm Compile Measurement Report MLME- MREPORT.req MEASUREMENT REQUEST FRAME MEASUREMENT REPORT FRAME MLME-MREQUEST.cfm MLME- MREPORT.ind MLME- MREPORT.cfm Measurement Request Completed Simon BlackSimon Black, Qosine

Measurement MSC – STA Refuses January 2003 Measurement MSC – STA Refuses IEEE802.11h STA IEEE802.11h STA SME MLME MLME SME Decision to request measurement from peer STA MLME-MREQUEST.req MEASUREMENT REQUEST FRAME MLME-MREQUEST.ind MLME-MREQUEST.cfm Decision to refuse measurement request from peer STA or unsupported request MLME- MREPORT.req MLME- MREPORT.ind MEASUREMENT REPORT FRAME MLME- MREPORT.cfm Measurement Request Completed Simon BlackSimon Black, Qosine

IEEE802.11h Quiet Interval Facility to quieten BSS January 2003 IEEE802.11h Quiet Interval Facility to quieten BSS May be used to assist in making measurements without interference from transmissions by members of the BSS May be included in Beacon and Probe Response Frames Quiet interval scheduling Single, or periodic Starts at a defined offset from the TBTT Duration in units of TU (1024us) Simon BlackSimon Black, Qosine

January 2003 IEEE802.11h TPC STAs signal maximum and minimum transmit power capability in Association Request frames AP determines local transmit power constraint (with regard to regulatory requirements) and communicates this in Beacon frames Adaption of transmit power (optional) TPC request Action frame may be sent to any STA STA responds with the transmit power used to transmit the TPC response and the link margin for the received TPC request Simon BlackSimon Black, Qosine

Decision to adapt transmit power January 2003 TPC Adjust MSC IEEE802.11h STA IEEE802.11h STA SME MLME MLME SME Decision to adapt transmit power MLME- TPCADAPT.req TPC REQUEST FRAME TPC Protocol TPC REPORT FRAME TPC Protocol MLME- TPCADAPT.cfm Simon BlackSimon Black, Qosine

January 2003 Channel Switching May be used to try and move a BSS to a new operating channel if a radar signal is detected Announced by Channel Switch Announcement Action frame Broadcast (unacknowledged) May be transmitted more than once and the information included in Beacon & Probe Response Frames to increase probability of reception Actual channel switch is synchronised to TBTT Facility to quieten BSS until switch occurs Simon BlackSimon Black, Qosine

Channel Switching MSC January 2003 IEEE802.11h STA IEEE802.11h STA SME MLME PLME PLME MLME SME Decision to switch channel MLME-CHANNEL SWITCH.req MLME-CHANNEL SWITCH.ind CHANNEL SWITCH ANNOUNCEMENT CHANNEL SWITCH ANNOUNCEMENT Decision to follow channel switch T T CHANNEL SWITCH ANNOUNCEMENT MLME-CHANNEL SWITCH.resp PLME-SET PLME-SET MLME-CHANNEL SWITCH.cfm MLME-CHANNEL SWITCH.cfm Announcements Repeated in Beacon Frames Channel switch complete Channel switch complete Simon BlackSimon Black, Qosine

January 2003 IBSS DFS There is no AP function for collating measurements, or coordinating a channel switch The lack of an association protocol means No exchange of supported channel information No way to determine membership of the IBSS at a given instant for requesting measurements The IBSS DFS protocol attempts to provide a solution A DFS Owner service provides a central point of coordination for a channel switch. Each STA includes a Channel Map field within the IBSS DFS elements that it transmits. This communicates the STA supported channel set and basic measurement reports for that STA. Best effort due to hidden node issue! Simon BlackSimon Black, Qosine

Basis for Radio Resource Measurement? January 2003 Basis for Radio Resource Measurement? Use the management model Use/adapt/extend some of the MAC Management messages Measurement request/report mechanism Use the simple TPC principles Simon BlackSimon Black, Qosine

A Brief Introduction to the IEEE802.11h Draft January 2003 A Brief Introduction to the IEEE802.11h Draft TGk Radio Resource Measurement January 2003 Simon Black simon.black@qosine.co.uk Simon BlackSimon Black, Qosine