Residents and visitors in some areas of San Francisco won't have to wait for the controversial proposed citywide Wi-Fi service to get free wireless Internet access.MetroFi, a maker of wireless mesh network gear, has set up three "hot zones" in the city that are available now, the Mountain View, Calif., company said Tuesday. The city awarded MetroFi the right to set up the zones through an RFP process that began in April, according to MetroFi President and CEO\u00a0Chuck Haas.San Francisco also is preparing an RFP for a free, citywide wireless Internet service. That project has been one of the most well-publicized plans for municipal wireless service in the U.S., partly because Google has proposed giving such a network to the city free of charge and supporting it via location-based advertising. The idea of governments authorizing or subsidizing Internet access services has drawn fire from some carriers and lawmakers as unfair and an unwise use of public resources.MetroFi is one of the entities that wants to provide that citywide network, and the backbone that supports the three new hot zones would also be used for the citywide service, Haas said. A key difference is that today's hot zones are free and open, whereas a MetroFi citywide network would be supported by advertising and secured via\u00a0Wi-Fi Protected Access (WPA), he said.The three hot zones are located in the Civic Center area, around the Ferry Building on San Francisco Bay, and in Portsmouth Square in the city's financial district. Anyone in range of the networks will be able to use them by picking the "SF TechConnect"\u00a0Service Set Identifier (SSID), looking at a splash screen with an acceptable use policy and clicking to indicate they've read it, Haas said. The use policy is a basic one covering rules such as not using the network for illegal purposes, he said.The MetroFi access points in those hot zones, which are located primarily on city light poles, aren't plugged directly into phone lines. They form a mesh, with each access point having both an IEEE 802.11b\/g radio for user Wi-Fi access and a modified IEEE 802.11a radio to link up with other access points. The backhaul for this whole mesh is a 36M\u00a0bit\/sec wireless line-of-site connection to an antenna on a hill about two miles from the Civic Center. That antenna, in turn, feeds into city-owned fiber that goes to an Internet point of presence in the city, Haas said.In a citywide network, a leased data line to every access point would be too expensive and complex, he said."This is the architecture we would deploy for close to 1,500 access points in the city. ... Trying to manage 1,500 T-1s is a daunting challenge," Haas said.Recognizing interference in the 2.4 GHz band in which IEEE 802.11b\/g operates, MetroFi won't promise more than 1M bit\/sec to end users, he said.In an advertising-supported citywide network, MetroFi would sell ads that would take up part of the user's screen whenever they were using the service, as with free dial-up Internet services. The city has said it will produce an RFP for the citywide service by the end of this month.MetroFi already operates citywide wireless networks in the Silicon Valley cities of Sunnyvale and Cupertino, on what Haas said are strictly commercial deals in which MetroFi pays for rights of way just like any carrier. But he defended the concept of city-backed wireless as a resource for municipal employees. Even at 1M bit\/sec or less, the network would be faster than legacy wireless systems used by government, such as\u00a0cellular digital packet data (CDPD), he said."The real value in these networks is to have them be mixed use. It does make sense for the city to barter its assets in return for city services," Haas said.