InnerWireless, a provider of passive DAS, is strong in the health-care community. With its Horizon system, instead of each AP serving a discrete area with one channel, each location, or segment, can be served by as many as three 802.11b/g APs operating on the three nonoverlapping channels found in the 2.4-GHz range (see "Is DAS the Answer?" in the image gallery).
This solves the coverage concern, but if more capacity than what three APs can offer is required, segments must be subdivided.
LGC Wireless has an active DAS that it sells primarily through carriers, but it doesn't tie a WLAN product inside its DAS. Instead, it offers RF engineering, consulting and installation services, working closely with Cisco. Another vendor, MobileAccess Networks, offers systems across both active and hybrid categories. In its architecture, a central closet aggregates cellular, PCS and paging signals, and transports traffic over fiber to each floor's IDF (intermediary distribution frame) or telecom closet, where Wi-Fi is added. At that point, signal is taken off fiber and shuttled onto RF. Discrete broadband antennas radiate the signal, rather than leaky coax. This vendor has a tighter relationship with Cisco than most--its MA-850 WLAN Module has been officially tested and listed as compatible with Cisco's Unified Wireless LAN.
Finally, Powerwave Technologies is an active-DAS vendor that prides itself on large, complex deployments. Very similar to MobileAccess Networks, it also inserts Wi-Fi at the wiring closet just after the hub converts the RF signal from optical to copper. Powerwave has not announced deals with any Wi-Fi vendors.
If it sounds like DAS vendors are late to the Wi-Fi game, you're right--these guys are definitely more focused on cellular/PCS/paging/public safety. But they understand Wi-Fi and are motivated. What enterprise wants to hear a pitch from a DAS vendor promising to solve all the customer's wireless problems, but oh, wait, I can't help you with Wi-Fi?
