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Analysis: Alternative WLAN Technologies: Page 9 of 16

The evolution of the modern enterprise WLAN infrastructure has marginalized standalone APs in favor of those managed through a switch or controller. This coordination allows for controlled access to the downlink across multiple APs. Considering that most traffic is headed downstream, this has led to some unique offerings from Meru and Extricom.

Meru was the first to suggest that both AP and client access could be more deterministic. Although actual methods to accomplish this have been hotly debated in these pages (see Wireless Network Head-to-Head: Cisco Vs. Meru and Cisco Vs. Meru: The Vendors Speak ), test results do show more time-based evenness to clients, higher aggregate throughput rates and better Vo-Fi quality scores.

Meru uses a single channel and BSSID (Basic Service Set Identifier, or AP MAC address) across the entire WLAN coverage area, which means clients don't roam--the infrastructure decides which AP communicates with which client. This also means, however, that when a client does transmit, all nearby clients and APs will hear, and therefore wait before transmitting, because they're all on the same channel. Meru claims to have algorithms that minimize potential deadlock, and of course, it's fair to ask if a conventional WLAN infrastructure operating at 10 mW to create microcells, with associated clients operating at 100 mW, will be any better at mitigating the interference with neighboring microcells operating on the same channel.

But the most obvious criticism to Meru's technology is that because a single channel is used, aggregate capacity is capped. Meru's answer is to overlay the area with additional APs on other, nonoverlapping channels, or to use the Radio Switch. It's not clear how Meru prevents clients from roaming between different networks, but that can presumably be minimized if APs are deployed densely enough to maintain a strong signal level.

Meru also does well with client capacity. In an article on technology in universities (see Tech U: Compressed Air), Meru was the only vendor to drum up several production wireless networks with more than 50 good-performing clients per AP.