Wireless Tests – Throughput vs. Range plots
26 January 2006 Update – Airgo said that they have found the behavior where TCP/IP connection pairs trade off throughput to be a function of IxChariot and the Windows TCP-IP stack and not throughput variation in the product itself. Subsequent additional testing with a single endpoint pair confirmed this.
I also have to say that I’m disappointed in the high downlink throughput variation. You can see the nature of the variation in the selected IxChariot plots shown below.
Figure 6: RangeMax 240 Location 1 downlink throughput
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Figure 6 shows the particularly nasty nature of the throughput variation, with periodic throughput drops down to 4Mbps or so. I tried a few experiments to see if this was related to the use of two clients in the test or to a specific wired client. But the only thing common to the dropouts was that they occured during downlink tests only.
Figure 7 shows no sign of them during uplink tests, with the resulting much lower Relative Precision values.
Figure 7: RangeMax 240 Location 1 uplink throughput
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Figures 6 and 7 are pretty much what the throughput profile looked like for my test Locations 1 through 3. Figures 8 and 9 show what things looked like during the Location 4 test run.
Figure 8: RangeMax 240 Location 4 downlink throughput
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Once again, downlink doesn’t fare as well as uplink, with the dropouts stretching into multiple seconds. The aggregate throughput is still impressive, but downlink variation of this magnitude would definitely break up the picture in streaming video applications.
Figure 9: RangeMax 240 Location 4 uplink throughput
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I was bugged at the RM240′s complete failure to establish a link in Location 5, so broke my “test-with-defaults” rule and changed the Wireless Interference Setting to Maximum Range.
Figure 10: RangeMax 240 Location 5 downlink throughput – with Maximum Range setting
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Figures 10 and 11 show that I was rewarded with about 21Mbps of aggregate throughput.
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