Mobile awareness in a wide area wireless network of info-stations

Wireless networking is becoming an increasingly important com-munication means, yet high wide-area wireless data connectivity is difficult to achieve due to technological and physical limitations. To alleviate these problems we experiment with an alternative by placing many high bandwidth local "islands"of info-stations dispersed throughout the low bandwidth wide-area wireless net-work. The location and distribution of the individual stations is crucial for the network's overall effectiveness, as demonstrated by our investigations. The info-stations are deployed in a transparent manner, often not geographically visible to the user. Applications must be designed to be mobile-aware and able to account for changing network characteristics by optimally utilizing the available network resources. We simulate alternative network layouts and determine their effectiveness by experimenting with an incremental map downloading application for road travelers that uses intelligent prefetching to take advantage of the info-stations. The prefetching algorithm uses location, route, and speed information to predict future data access. Our experiments show substantial performance improvement of the mobile-aware application in the info-station network over a mobile-unaware application in a conventional wide-area wireless network. The prefetching algorithm proves to hide latency from the user better than a naive prefetching algorithm. We have achieved between 16% to 50% improvements, depending on the prefetched amount. The results also suggest that a network design with frequent short range info-stations is better than one with fewer, longer range stations.