VeriWave Demonstrates 300Mbps Data Rate with 802.11n 3x3 MIMO Technology

(Top News, 18 Mar 2008)

In launching the Release 3.2 of its WaveTest software, which is said to be the first test solution for full-rate 802.11n 3x3 MIMO, VeriWave demonstrated that sustained data rates of over 300Mbps are achievable and benchmarked the impact of design options currently facing vendors as they develop the next generation of higher-speed access points.

"VeriWave has the only test solution on the market that can transmit and receive at true MIMO 3x3 speeds," says Eran Karoly, VeriWave's Vice President of Marketing. "To prove high-speed, error-free, data transfer of new 802.11n 3x3 MIMO devices, an objective test tool needs to be available. With our new version 3.2, we make this test tool a reality. It is the only way 802.11n manufacturers can verify the performance of their devices."

VeriWave's WaveTest platform lets testers generate client traffic while varying traffic conditions, thus measuring the functionality and performance of their designs, and qualifying how these designs will perform in real world conditions. As no APs supporting 3x3 MIMO operation were commercially available at the time of testing, the data rates of 300Mbps were achieved by using the VeriWave system in back-to-back mode—the VeriWave system was used to generate the client traffic as well as the server traffic.


As part of its ongoing industry updates on the progress of 802.11n-compliant products, VeriWave performed extensive tests on existing APs that analyzed the impact of various design options currently available to vendors as they develop the next generation of higher-speed access points.

Detailed results are available at: http://www.veriwave.com/gurus/release_3.2_results.asp.

"Our tests show that achieving sustained data rates greater than 150Mbps using the 802.11n technology is in fact achievable," says Tom Alexander, VeriWave's Chief Technology Officer. "Our results also show that the current generation of APs shipping has a ways to go in achieving the theoretical maximum promised by this standard, which stands at over 350Mbps. To that end, we explored some of the implementation choices available to vendors today, and believe this sort of testing can speed the introduction of new equipment that takes full advantage of the standard."

Tests on existing Access Points conducted using Release 3.2 highlighted critical performance issues:

- Co-existence remains an issue
The co-existence of various types of equipment has tremendous effect on the overall quality and capacity of the deployed network. Adding 802.11a/g clients to an 802.11n network severely challenges today's APs with theoretical performance dropping 50 percent, from approximately 225Mbps to roughly 125Mbps and actual performance dropping as much as 75 percent. Similarly, issues remain for 20MHz / 40MHz coexistence also leading to 50 percent performance drops;

- 3 x 3 MIMO significantly improves performance
Sustained data rates of over 300Mbps are possible as measured by the VeriWave test equipment in back-to-back operation. However, as no commercially available enterprise-class and consumer-class APs support true 3x3 MIMO operation, measured data rates of these APs tops off at just over 160Mbps;

- All enhancements specified by the IEEE standard must be implemented
In particular, VeriWave's testing determined that AMPDU aggregation, 40MHz channels and Short Guard Intervals must be implemented to keep frame overhead from limiting performance. Without these enhancements, one of two enterprise-class 802.11n APs tested was not even able to sustain legacy 802.11g rates;

- As expected, 40MHz channels double capacity over 20MHz channels enabling sustained MAC data rates of approximately 250Mbps. To date, enterprise-class APs have not yet fully realized this benefit;

- Using Long Guard Interval in Short Guard Interval networks has little effect:
Mixing long and short guard intervals results in "in-between" aggregate throughput, but current enterprise-class APs cannot take full advantage of this yet.

VeriWave shared these and other results during a recent Webinar, the third in an ongoing series on the evolution of 802.11n. The Webinar content can be viewed at http://www.veriwave.com/gurus/webinararchive.asp.

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