preliminary coexistence tests

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Preliminary Coexistence Tests. The same 802.11 wireless signal was used as the victim: Power Level = 0 dBm BW = 20 MHz Center Frequency = 2.412 GHz Orthogonal frequency-division multiplexing (OFDM) Data Rate = 6 Mbps BPSK. OFDM concept. - PowerPoint PPT Presentation

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PowerPoint Presentation

Preliminary Coexistence TestsThe same 802.11 wireless signal was used as the victim:Power Level = 0 dBmBW = 20 MHzCenter Frequency = 2.412 GHzOrthogonal frequency-division multiplexing (OFDM) Data Rate = 6 MbpsBPSKOFDM concept

Transmit data is spread over a number of orthogonal subcarriers in the frequency domainError vector magnitude (EVM) measurement of the receive signal constellation

Comparing Impacts of Different Interference Modulation/TechnologiesSetupCurrently conductive Eventually move to radiatedTarget protocol WLANInterfering Modulation/Technologies CW AM SignalBluetooth (BT)LTEWLANPeak Spectrum of 802.11 WLAN Test Signal Recieved WLAN Constellation, no interference.

Recieved WLAN EVM Spectrum with no Interfering signal

Interfering signal spectrums (with 20 MHz WLAN at center frequency = 2.417 GHz)Interfering Signal 1: CW AM SignalParameters:Center Frequency = 2.41 GHz (within, but off center, of WLAN band)AM Modulation: 1 kHz and 80% (as in IEC 61000-4-3, Annex A) Power level = -10 dBmWLAN does not failRMS EVM of approx. -23 dBm (by inspection) as an instant average over all subcarriersRecieved WLAN Constellation from Interfering Signal 1

Recieved WLAN EVM spectrum from Interfering Signal 1

Interfering Signal 2: BluetoothParametersPower Level = -10 dBmCenter Frequency = 2.41 GHz (same as Signal 1)Max Payload length, Carrier BurstWLAN intermittently fails as a result of the BT signalRMS EVM of WLAN is regularly about -50 dBm (by inspection), with short periods of Higher EVM (at failure)Consistently much lower EVM from signal 1 Received WLAN Constellation with Interfering Signal 2, WLAN Failure

Recieved WLAN EVM Spectrum with Interfering Signal 2, WLAN Failure

Interfering Signal 3: LTEParametersPower Level = -10 dBmCenter Frequency = 2.41 GHzBW = 10 MHzWith these Parameters the WLAN Receiver was never able to establish a link

Interfering Signal 3: LTE Cont.Highest 10 MHz LTE power that allowed the WLAN system to make a connection was -27 dBmConsistent EVM of about -25 dBm (by inspection)Large number of subcarriers are affected (see following EVM plot) by this signalThis is due to the wider bandwidth of LTE compared to Bluetooth or the CW AM signalReceived WLAN Constellation with Interfering Signal 3 (-27 dBm Power)

Recieved WLAN EVM Spectrum with Interfering Signal 3 (-27 dBm Power)

Interfering Signal 4: 802.11 WLANThe interfering WLAN is on the 802.11 band nearest the victim:Power = -30 dBmCenter Frequency = 2.417 GHzBW = 20 MHz-30 dBm interference power setting was the highest that allowed consistent victim connectionConsistent average RMS EVM of about 29 dBm (from inspection)Recieved WLAN Constellation from Interfering Signal 4

Recieved WLAN EVM spectrum from Interfering Signal 4

Backup SlidesReceived WLAN Constellation with Interfering Signal 2, No WLAN Failure

Recieved WLAN EVM Spectrum with Interfering Signal 2, no WLAN Failure

Peak Spectrum Comparison of CW AM, Bluetooth , and LTE from Tests

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