Wireless WANs include cellular towers, parabolic antennae, satellites, and telecommunications infrastructure. Most wireless WAN applications make use of outdoor connections, but some indoor facilities, such as airports and convention centers, deploy wireless WANs when large numbers of subscribers are present. Wireless WAN infrastructure is expensive compared to other types of wireless networks, but wireless WANs are the most feasible for covering countries and continents. Cellular and satellite systems are the most common forms of wireless WANs capable of providing moderate performance. Meteor burst communications is less expensive, but offers only low performance.