1. September 2002 Steve Pope, TISlide 1 doc.: IEEE 802.11-02/520r0 Submission Issues Related to RSSI Measurement Steve Pope Texas Instruments spp@ti.com September 4, 2002

2. September 2002 Steve Pope, TISlide 2 doc.: IEEE 802.11-02/520r0 Submission RSSI Measurement and Reporting -- Topics * Uses of RSSI in existing systems and standards * Measuring RSSI in the Receiver/Baseband Chain * Relationship of RSSI to other signal metrics

3. September 2002 Steve Pope, TISlide 3 doc.: IEEE 802.11-02/520r0 Submission Current Usage of RSSI Measurements * Channel Selection * AGC algorithms * Rate-Fallback algorithms * Optimizing equalizers/decoders * Reporting per existing standards * Proprietary Reporting

4. September 2002 Steve Pope, TISlide 4 doc.: IEEE 802.11-02/520r0 Submission Existing Standards Microsoft NDIS "The RSSI is measured in dBm... Normal values for the RSSI value are between -10 and -200". 802.11-1997 14.2.3.2 "RSSI shall be measured between the beginning of the start frame delimiter (SFD) and the end of the PLCP header error check (HEC)." "RSSI is intended to be used in a relative manner. Absolute accuracy of the RSSI reading is not specified." 15.4.5.10.2 "RSSI indications up to 8 bits (256 levels) are supported." 15.4.8.4 Describes usage of energy detection in forming CCA

5. September 2002 Steve Pope, TISlide 5 doc.: IEEE 802.11-02/520r0 Submission

6. September 2002 Steve Pope, TISlide 6 doc.: IEEE 802.11-02/520r0 Submission Receive Chain RSSI Measurements -- Issues * Radios develop RSSI signals that are useful for AGC operation, but which may not be useful or optimal for signal- strength reporting * An RSSI measurement may (either deliberately or incidentally) include adjacent channel energy * RSSI measurement will be affected by antenna switching * RSSI calculation depends on "backing out" gain ahead of the measurement, which introduces inaccuracy

7. September 2002 Steve Pope, TISlide 7 doc.: IEEE 802.11-02/520r0 Submission

8. September 2002 Steve Pope, TISlide 8 doc.: IEEE 802.11-02/520r0 Submission Possible Values to Report RSSI in dBm, referred to antenna port, and reported for: Each Identified Remote Transmitter Unidentified Transmitters / Interferers Idle Channel Condition Field Strength Excludes effect of receive antenna gain May be useful for mapping coverage area of a transmitter Observed SNR Operating Margin (rate and implementation dependent) Usable Data Rates Measurement Accuracy