 a few were actually launched, and these have working (WLAN) technologies. These technologies had trouble maintaining financial viability in the face (mostly based on the IEEE 802.11 family of standards of ever-increasing terrestrial cellular coverage. Two sys- and marketed under the Wi-Fi banner) operate in un- tems provide cellular-like service: Globalstar and Iridium. licensed spectrum, and provide wired LAN extension or Others (e.g., Orbcomm) provide two-way paging-like replacement. The Wi-Fi family, also known as Wireless services (though with increased latency, as its LEO satel- Ethernet, allows generic applications to operate seam- lites are not always overhead). More ambitious systems lessly over a transparent layer 1 and 2. such as Teledesic await the day when the investment Initially deployed as corporate LAN extensions, their climate may be more propitious. low price, high performance (to tens of Mbps), and lease of Successful service providers leverage mobile satellite operation have made them popular in the home office technology to benefit niche markets. Inmarsat uses environment and to a lesser degree as a substitute for a GEO satellite constellation to provide connectivity to traditional point-to-point microwave systems. Additional maritime and other high-value assets. Omni-Tracs pro- vertical applications are starting to appear. Some vehicular vides vehicular tracking and communications via satellite toll collection systems employ 802.11, and commercial to the long-haul trucking industry. airlines have announced installation of WLANs in their aircraft for in-flight passenger use. Free access community Specialized private systems networks are sprouting in numerous high-tech locales, potentially challenging the business model of established Most wide area radio communications-like cellular and wireless carriers. Wi-Fi's well-publicized security limita- paging-are provided as services offered by carriers to tions are expected to be solved before they significantly the public. A notable exception is 