Super G Turbo vs. ACE
Since both technologies use 40MHz of bandwidth, i.e. two 802.11b/g channels, comparisons between Atheros’ controversial Super-G channel bonding and Airgo’s ACE technologies are inevitable, so I’ll wade right in. Since I’m not an expert in 802.11n and haven’t yet been able to spend some quality time with those who are, I’ll keep my comments focused on observed behavior of the two technologies.
I used Cognio’s ISMS Mobile 1.0 (reviewed here as AirMagnet’s Spectrum Analyzer) to plot the spectra and a Netgear WGU624 Double 108Mbps router and WG511U CardBus card to produce the Super-G signal.
Figure 26: Super-G in channel bonding mode
(click on image to enlarge)
Figure 26 shows the spectrum produced by Super-G running in channel bonded mode when driven with a continuously looping standard IxChariot throughput script. As you may remember, when Super-G is set to Turbo mode it forces the channel selection to 6 and doesn’t allow it to be changed. Figure 27, on the other hand, shows the spectrum produced by Airgo’s ACE when I forced the channel to 8 (and it automatically set the secondary channel to 4).
Figure 27: RM240 40MHz bandwidth mode, set to Channel 8
(click on image to enlarge)
To my eye, both spectra look very similar with similar maximum power levels and roll-off characteristics into channels 1 and 11. So for all intents and purposes, both Super in channel bonded mode and ACE in 240Mbps mode both occupy similar swaths of the 2.4GHz band.
But one advantage that ACE has over Super-G has is that ACE isn’t locked into occupying the center of the 2.4GHz WLAN spectrum, as illustrated in Figure 28.
Figure 28: RM240 40MHz bandwidth mode, set to Channel 1
(click on image to enlarge)
Figure 28 shows the Airgo ACE spectrum with the primary channel set to 1 and ACE automatically assigning Channel 5 as the secondary channel. You can easily see that the power level in Channel 11 would provide little interference with a WLAN operating there. And similarly, a neighboring WLAN could happily operate in Channel 1 with ACE moving its channels to the other end of the 2.4GHz spectrum.
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