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

2. 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

3. March 2003
Background: Worst-case Receiver Sensitivity per the Standards (802.11b ; a )
Examples:
Modulation Mode Sensitivity Condition
CCK dBm % FER, 1024-byte frames
OFDM dBm % FER, 1000-byte frames
OFDM dBm % FER, 1000-byte frames
OFDM dBm % FER, 1000-byte frames
OFDM dBm % FER, 1000-byte frames
OFDM dBm % FER, 1000-byte frames
OFDM dBm % FER, 1000-byte frames
Steve Pope, Texas Instruments

4. 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

5. March 2003
Steve Pope, Texas Instruments

6. (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

7. 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

8. 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

9. 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, , 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

10. * 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