“WLAN Testing and Associated Challenges”

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Benchtop instruments are also making their appearance in a big way, replacing the traditional table-top variants in most applications.

Baldua: Today, we see a lot of test instruments with automatic test capability, which are also capable of displaying the results in a variety of different units to make comprehensibility a whole easier. Also, the whole test and measurement environment is now starting to adjust to the presence of 802.11ac standard and trying to make products that can serve the new-generation chips so that it is not left behind the competition.

Narasimhan: Today, RF needs to be understood as a dynamic phenomenon. Current communication systems operate in burst mode, which requires understanding of this burst behaviour. There is also a lot of spectral reuse, which can lead to interference. In satellite domain there is a lot of malicious transmission hidden within a signal to disrupt the signal quality. Using a conventional test method, the system might pass all tests and work perfectly in the lab. But to work in the market, a device needs robust testing with the aid of real-time spectrum analysers.

Kumar: Recently, the demands for even higher data rates on WLAN technologies have expanded applications to wireless HD video streaming among TV sets, multimedia players, video cameras, PCs, smartphones and tablets. IEEE 802.11ac aims for a minimum 500Mbps data rate and up to around 6.93 Gbps with various advanced technologies including wider channel bandwidth up to 160 MHz, and higher modulation up to 256 QAM.

Q. How is the industry moving towards increasing the throughput of WLAN?
Samant: One way is higher modulation schemes like 256 QAM and MIMO. So the trend that I am seeing is a cross-layer collaboration between mac and physical layers so that more information is shared between these two rather than increasing the complexity of the chip.

Tripathi: The industry is moving towards achieving higher data rates for WLAN devices. End users want faster delivery of content and a higher data rate is the most demanding expectation.
Now that 802.11 a, b, g and n standards have matured, work is underway for 802.11ac and 802.11ad, which are targeted to provide 7000Mbps per stream data rates.

Baldua: The throughput of WLAN completely depends on the configuration and the design associated with it. It is a built-in system with its own properties and tendencies. As time passes, newer configurations will enable designers to radically improve the existing throughput values and move towards a higher level for them.

Narasimhan: With 802.11ac already being implemented, MIMO is now the latest way to increase your throughput. The industry is now moving towards 4×4 and 8×8 MIMO to adjust to the new standards. Once you have a 2×2 MIMO system, you are basically pumping twice the data in the same bandwidth, and this doubles your throughput.

Kumar: The latest WLAN technology, 802.11ac, builds on 802.11n with a wider RF bandwidth (up to 160 MHz), MIMO and high-density 256QAM modulation promises to take the throughput of WLAN to newer places. As a result of the advanced technology, WLAN 802.11ac will provide a high throughput of 1 Gbps below 6 GHz, for multiple stations.


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