Introduction to WIFI-OTA Test Specification (Part 3)

1. Transmit Power Test:
    The test procedure for radiated power is the same as that for conducted transmit power. The AP and RX attenuator settings are different due to the loss in the radiation path. Here we assume that the path loss and gain of the test antenna are known.

Test Procedure:
    Recommended Procedure:
        1) Set the AP attenuator so that the received signal level at the antenna connection of the DUT is 10dB higher than the initial receive sensitivity.
        2) Set the RX attenuator so that the received signal level of the DUT at the output of the WLAN receiver is 10dB higher than the initial receive sensitivity.
        3) Set the AP tester to transmit the required signal at the specified channel, modulation mode and data rate.
        4) The DUT is connected to the AP tester.
        5) The AP tester transmits continuous unicast test packets to the DUT.
        6) The DUT reports the received unicast test packets with ACK control frames.
        7) The WLAN receiver reports the received ACK control frames, data rate and RSSI value read by the control computer. Calculate and record the average RSSI value for about 10 seconds.
        8) Repeat steps 3 to 7 for each desired channel and data rate.
        9) Create a table with the channel, modulation, data rate, and RSSI average for each test.
RSSI reading:
        10) Remove the test antenna and connect to a vector signal generator capable of generating the WLAN IEEE 802.11a/b/g signal.
        11) Set the RX attenuator to a value equal to the path loss minus the test antenna gain
        12) Set the signal generator to the specified center frequency, modulation, and data rate as in the table for the initial test in step 9 and send a WLAN ACK control frame.
        13) Set the WLAN receiver to the same channel as the signal generator.
        14) Monitor the RSSI reported by the WLAN receiver.
        15) Adjust the signal output level to record the RSSI reported by the WLAN receiver in the corresponding receive sensitivity test and record the signal output level.
        16) Repeat steps 12-15 for all data rates and channels as shown in the table.

2. Receiver sensitivity test:
Test steps:

    Recommended steps:
        1) Set the AP attenuator to ensure that the received signal at the antenna connection of the UUT is at least 10 dB higher than the initial receive sensitivity.
        2) Set the RX attenuator to ensure that the received signal level of the UUT at the output of the WLAN receiver is at least 10 dB higher than the initial receive sensitivity, but not more than 50 dB.
        3) Set the AP tester to transmit the required signal at the specified channel, modulation mode and data rate.
        4) The UUT is connected to the AP.
        5) The AP tester transmits continuous unicast test packets to the UUT.
        6) The UUT feeds back the received unicast test packets with ACK control frames.
        7) The WLAN receiver reports the received ACK control frames to the control computer.
        8) The control computer counts the number of 100 (TBF) data frames received and the number of ACK control frames with corresponding ACKs in a period of time. The frame reception rate (FRR) is calculated as follows: ACK received/data frames sent.
        9) Increase the attenuation of the AP attenuator until the FRR decreases by less than 90% for each 1dB increase in attenuation.
        10) Record this value as "A" for each 1dB decrease in the AP attenuator.
        11) Repeat steps 3 to 10 to test each required channel and data rate.
        12) Make a table to fill in the channel, modulation, data rate and AP attenuator settings for each test.
Settings of the AP tester and AP attenuator:
        13) Measure the power level and record it to the nearest 0.5dBm as "P".
        14) Increase the power level measured in step 13 by 10dB and reduce it to the AP attenuator value recorded in step 10: P+10-A. The final value is the receive sensitivity and is accurate to 1dBm.
        15) Repeat steps 13-14 to test all channels, modulations, data rates and other test modes.

    The above is an introduction to the radiation test of WLAN terminals. We will continue to explain the WLAN-OTA test specifications in detail in the next few issues.