Signal Quality Measurements March 2003 Signal Quality Measurements Steve Pope Texas Instruments March 13, 2003 Steve Pope, Texas Instruments

March 2003 Scope of Presentation Define parameters that can be measured and/or reported, and that describe signal quality Not discussed: Mechanisms for requesting or reporting parameters Formatting of parameters into MIB’s or other structures Packet Statistics (e.g. FER) as opposed to signal measurements Steve Pope, Texas Instruments

March 2003 Background: Worst-case Receiver Sensitivity per the Standards (802.11b 18.4.8.1 ; 802.11a 17.3.10.1) Examples: Modulation Mode Sensitivity Condition CCK11 -76 dBm 8% FER, 1024-byte frames OFDM6 -82 dBm 10% FER, 1000-byte frames OFDM12 -79 dBm 10% FER, 1000-byte frames OFDM24 - 74 dBm 10% FER, 1000-byte frames OFDM36 -70 dBm 10% FER, 1000-byte frames OFDM48 -66 dBm 10% FER, 1000-byte frames OFDM54 -65 dBm 10% FER, 1000-byte frames Steve Pope, Texas Instruments

March 2003 Issues: * Individual Radio/BB’s will exceed these specs by varying amounts for the different rates * Shape of FER vs. SNR curve will also vary by Radio/BB * Channel impairments will affect different radios/rates differently Steve Pope, Texas Instruments

March 2003 Steve Pope, Texas Instruments

(1) Static Radio Signal Measurements: March 2003 Proposed Approach Signal Quality is determined by characteristics of both the radio/BB, and by characteristics of the on-air signal itself. Define two broad classes of parameters that can be measured/reported, and that when combined indicate signal quality: (1) Static Radio Signal Measurements: Reported infrequently; describe unchanging performance characteristics of each STA/AP’s radio/BB (2) Radio Signal Information More frequent reports of on-air signal measurements Steve Pope, Texas Instruments

1. Static Radio Measurement Information March 2003 1. Static Radio Measurement Information 1.1 For each supported band and modulation mode, the sensitivity in dBm, as measured at the antenna port, under the conditions of no channel impairments (multipath, interference, etc.) Sensitivity is defined for a TBD packet error rate / packet length. 1.2 For each supported band and modulation mode, the maximum transmit output power available in dBm. 1.3 For each supported band, the antenna type (from a defined enumerated list of types) and the antenna gain (in dBi) at peak lobe. Examples of antenna types: single omni, switched omni, steerable... Steve Pope, Texas Instruments

2. Radio Signal Information March 2003 2. Radio Signal Information Each STA/AP measures this for each channel in use and/or scanned, and for each remote STA/AP on that channel (if the remote MAC address is known, otherwise generic report). 2.1 Received signal power (RSP) in dBm at the antenna port 2.2 Channel Impairment (in dB) -- for each supported modulation mode, the discrepancy in dBm between the ideal sensitivity (from 1.1 above) and the actual RSP needed to achieve the defined FER. "Impairment" takes into account multipath, adjacent-channel interference, co-channel interference, etc. Steve Pope, Texas Instruments

2. Radio Signal Information (continued) March 2003 2. Radio Signal Information (continued) 2.3 Co-channel interference Basic report -- measured noise floor or interferer level (in dBm) Optional -- type of interferer (from a defined list: unknown, 802.11, BT, microwave, cordless phone, other) 2.4 Adjacent channel interference level (dBm and type) Propose that STA’s make this measurement only in response to a request, since it requires changing channels Steve Pope, Texas Instruments

* Conditions for sensitivity measurement are open to debate: March 2003 Additional Issues * All measurements must be accompanied by an accuracy value, and/or must conform to a standard accuracy * Some measurements might have to be made optional depending on radio/baseband capabilities * Conditions for sensitivity measurement are open to debate: FER of 7% - 10% is probably higher than that desired for robust network performance * “Channel Impairment” is a required measurement in this proposal; approaches for performing this must be worked out Steve Pope, Texas Instruments