802.11ac promises data rates up to 10 times higher than those offered by the current 802.11nstandard. The 802.11ac standard defines three wide bandwidth variants: a mandatory 80 MHz bandwidth; a non-contiguous 80+80 MHz option; and an optional 160 MHz contiguous bandwidth. It also introduces high-density modulation, optionally up to 256QAM, and higher order Multiple-Input, Multiple-Output with the option of up to eight spatial streams.
In addition to wider bandwidth measurements, the new test system offers best-in-class phase noise performance and a simplified programming API. Frequency and levelling switching are also faster than has previously been available. The WLAN 802.11ac test system comprises the Aeroflex 3070 high performance vector signal analyzer and the 3050/3320 high performance vector signal generator, and is housed in the new PXI 3005 Smart PXI Chassis with universal AC power supply. When used with the WLAN 802.11ac Measurement Suite and IQCreator, the test system provides complete waveform generation and analysis capability for high bandwidth 802.11ac WLAN devices. Both these software suites have been upgraded to handle measurements over a 160 MHz bandwidth.
IEEE 802.11ac is forecast to replace 802.11n as the most popular WLAN standard by 2014, due to the much higher data rate enabled by the wider bandwidth and higher order modulation, as well as the option of up to 8x8 MIMO streams, said Pi Huang, Product Manager at Aeroflex. In order to test these new features, a new generation of test equipment is needed. The PXI 3000 Series provides the ideal platform for these high bandwidth measurements in both R&D and manufacturing environments.
PXI 3000 Series WLAN 802.11ac Test System Performance
The 3070 high performance vector signal analyzer operates over a frequency range of 250 MHz to 6 GHz with a 160 MHz bandwidth. Typical noise floor is -160 dBm/Hz.
The 3050/3320 high performance vector signal generator operates over 100 kHz to 6 GHz with a 200 MHz bandwidth and up to +20 dBm output power. Typical noise floor is -150 dBm/Hz.
Both 3070 and 3050 have class leading phase noise of -135 dBc/Hz at 1 GHz with 20 kHz offset and have a build-in oven controlled crystal oscillator frequency reference.
Measuring Error Vector Magnitude requires the residual EVM of the test equipment to be at least 5 dB below the EVM specification of the device under test, which for 256QAM is -32 dB maximum. The PXI 3000 Series test system comfortably achieves this, with typical residual EVM of -42 dB for 80 MHz and -38 dB for 160 MHz for both signal analysis and generation.