Mobile Network Objects

Computer networks are collections of computing nodes interconnected by communication channels. They have experienced explosive growth recently, primarily due to the steadily decreasing costs of hardware, and have become an integral part of daily life for most businesses, government institutions, and individuals. One of the main objectives of interconnecting individual computers into networks is to permit them to exchange information or to share resources. This can take on a number of diierent forms, including electronic mail messages exchanged among individuals, down-or uploading of les, access to databases and other information sources, or the use of a variety of services. It also permits the utilization of remote computational resources, such as specialized processors or supercomputers necessary to accomplish a certain task, the utilization of multiple interconnected computers to solve a problem through parallel processing, or simply the utilization of unused processing or storage capacity available on remote network nodes. The recent explosion in the use of portable devices, such as laptop computers or various communication devices used by \nomadic" users, has opened new opportunities but has also created new technological challenges. The main problem is that such devices are connected to the network intermittently and typically for only brief periods of time, they use low