Analysis: Alternative WLAN Technologies: Page 10 of 16

Extricom has a slightly different angle, taking "thin" to such an extreme that the AP really becomes a radio-on-a-stick. No Layer 2 or Layer 3 connectivity is permitted--APs require a direct physical link to the Extricom WLAN switch. Similar to Meru, there's coordinated access on the downstream transmissions that allows the Extricom switch to decide which AP communicates with a given client. If minimum link rates of 12 Mbps become insufficient, additional radios can be inserted to achieve 24-Mbps throughput without any special RF planning, and capacity concerns are addressed by overlaying the installation with another set of radios operating on a different, nonoverlapping channel.

Extricom also touts channel reuse by allowing nearby APs operating on the same channels to transmit at the same time if the client's carrier-to-interference ratio is calculated to be low enough that the client can clearly receive the signal.

Such claims are difficult to put to the test, but the concept appears reasonable and suggests there's still lots of opportunity for other vendors to tackle the capacity challenge. Extricom makes no specific claims about client capacity or upstream QoS.

The N Factor

The consumer/SOHO Wi-Fi market of the past 12 to 24 months has seen huge growth around pre-802.11n/ MIMO APs. Hey, as 802.11b/g APs became commoditized and fell to sub-$50 prices, Wi-Fi chipset and product vendors had to find ways to prop up profits. Fortunately, work was already under way with 802.11n, and Airgo Networks, now a part of Qualcomm, was on the spot with its MIMO technology (see Changing the Face of Wireless and The New 802.11n Standard).