Heterogeneous Wireless Networks

Heterogeneous wireless networks (HWNs) provide flexible and diversifiedwireless network access (e.g., cellular, IEEE 802.11) by integrating cellular networks,wireless LANs, and ad hoc networks with the Internet. It has beenemerging as a promising solution to offer a variety of exciting applications,anytime and anywhere. The flexibility and benefits of the HWN, for example,is to extend the service coverage of the existing cellular and WLAN infrastructure,to improve the communication throughput, and reduce packettransmission latency, based on availability of different types of radio networkin the roaming area (cellular, WLAN, or others). In the study, we answer somefundamental questions in the design and deployment of a HWN. The first ishow to effectively operate a mobile terminal in ad hoc mode to access theInternet through a cellular network, WLAN or other underlying wireless accessnetworks. The second is how to design ubiquitous seamless mobility supportfor a roaming user, allowing ubiquitous and bi-directional Internet accessibility,connectivity, and mobility. Finally, it answers the questions that whatis the security threats for a mobile terminal that is operating in the ad hocmode, and how to provide information confidentiality for a continuously movingmobile terminal.