A look at IEEE 802.11ah: Wi-Fi below 1 GHz: Page 4 of 4

August 26, 2015 //By Kevin Qian and Mingyan Wang
Kevin Qian and Mingyan Wang examine the key issues of the IEEE 802.11ah standard

Measurement Challenges

As shown in Table 1, the 802.11ah standard covers a wide range of data rates, modulation complexities, and multi-stream configurations, although the most common use cases are for single channel and low data rates. The test challenges for higher modulation schemes, higher MIMO order (up to 4x4), beamforming and multi-user MIMO are also optional to 802.11ah. For these applications that take advantage of more complex modulation schemes, test equipment with the necessary performance is required. For example, considering modulation accuracy, transmitter testing with a low enough EVM floor will be required for measuring 256QAM modulations. Knowing the limitation of the test equipment performance, including factors such as phase noise, is necessary and important. Also, the test instrument needs to support generating and analyzing much narrower bandwidth signals for 802.11ah RF test, as well as meet the standard requirements for narrow bandwidth uses.

Transmitter and receiver test items are defined in the 802.11ah draft standard (Table 2). These items are similar to the other WLAN standards, except scaled down according to the bandwidth and timing per packet. For example, receiver minimum input level sensitivity test needs to be 10 dB lower because 1/10 bandwidth is required compared with 802.11ac standards.

Table 2: IEEE 802.11ah transmitter and receiver test items.

Design category: