15. Mixed Mode - True MIMO

• WPN824 RangeMax...
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• • NextWarehouse.com
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• • Directron
  • $59.99
• • Mwave.com
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• • TECH ON WEB
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My mix of a Linksys WPC54GX True MIMO card with the RangeMax produced the most interesting results. Figure 28 shows very low and erratic throughput for both the RangeMax and True MIMO clients when the True MIMO client is on the air and both are running uplink.

Figure 28: Mixed RangeMax and True MIMO uplink - RangeMax first
(click on image to enlarge)

Although it's hard to see, Figure 29 - which is also an uplink test but with the True MIMO card starting first - shows that the True MIMO client's throughput is very erratic, even when it runs by itself at the beginning and end of the tests. This erratic behavior was also observed when I completely shut off the RangeMax client and ran only the Linksys SRX client by itself.

Figure 29: Mixed RangeMax and True MIMO uplink - True MIMO first
(click on image to enlarge)

Things definitely improved, however, when I ran my downlink tests. The results in Figure 30 are so different, it looks like I'm testing an entirely different product! This combination produces a very equitable sharing of bandwidth between two "MIMO" products, which is how it should be!

Figure 30: Mixed RangeMax and True MIMO downlink - RangeMax first
(click on image to enlarge)

Figure 31 shows that the equitable bandwidth-sharing also occurs when the True MIMO client starts first. Comparing both plots also shows noticeably lower throughput variation from the True MIMO client - even when running off a RangeMax AP!

Figure 31: Mixed RangeMax and True MIMO downlink - True MIMO first
(click on image to enlarge)

I remembered a comment in one of the recent MIMO print reviews about poor True MIMO close-range performance being caused by signal overloading. So I moved the notebook with True MIMO client to my Location 2 (approximately 30 feet away and two sheetrock walls between AP and client) and re-ran the tests.

Figure 32: Mixed RangeMax and True MIMO uplink - True MIMO first & in Location 2
(click on image to enlarge)

Figure 32 shows that while the True MIMO client's throughput variation isn't as low as in the downlink case, variation is much better, and more importantly, throughput sharing is much more equitable.