To compare MIMOs gains in throughput and range with standard 802.11g implementations, eWEEK Labs recently tested the Airgo MIMO implementation in the Linksys WRT54GX and compared the findings with numbers culled from a pair of popular 802.11g access pointsthe business-class Cisco Aironet 1200 and the consumer-grade Linksys WRT54G. Using Ixias IxChariot 5.4 in conjunction with Ixias 1600T hardware chassis, we measured each products performance at several distances. Using the WRT54GX with Linksys MIMO-enabled CardBus client adapter (WPC54GX) provided excellent throughput performance at short and medium distancesalmost twice the bandwidth we saw from the other access points. However, eliciting this performance required tweaking of default access point settings that could hamper backward compatibility with 802.11b clients. Without these tweaks, we could not squeeze more than 17M-bps throughput from the WRT54GX at close distances, and we could not attach to the network at all at the longest distance.Large organizations will likely want to leverage embedded wireless client devices rather than install and manage new CardBus adapters, so we also performed tests against each access point using Intel Corp.s Pro/Wireless 2200BG adapter that came with our Dell Inc. Latitude 610 laptop. With this client device, the WRT54GXs antenna design added a small performance boost at all distances. These results, however, were significantly inferior to our end-to-end MIMO results. During tests, we monitored the RF environment with AirMagnet Inc.s Laptop Analyzer 4.0 and the AirMagnet Trio wireless adapter. We performed each set of tests on Channel 6 of the 2.4GHz band, which in our labs environment showed the least amount of ambient noise and interference during the late-evening hours when we performed our tests. Like the Aironet 1200 and the WRT54G, the Airgo chip set in the WRT54GX uses only a 20MHz band for transmission. We did not notice any appreciable differences in the levels of interference or noise due to the MIMO implementation compared with that from the other devices. Next page: Dueling proposals.
With tweaks in place and MIMO at the access point and client, we also saw improved performance at the longest distance, but not as great as seen at shorter lengths. At the maximum tested distance of 140 feet, WRT54GX performance dropped to just above 10M bps, about 3M bps greater than that of the other standard 802.11g devices. (It should be noted that, at this distance, our testing grounds included several walls and an elevator shaft between the access point and client.)