Open Access
Zhao, Bo
Graduate Program:
Computer Science and Engineering
Doctor of Philosophy
Document Type:
Date of Defense:
October 05, 2011
Committee Members:
  • Guohong Cao, Dissertation Advisor
  • Guohong Cao, Committee Chair
  • Thomas F Laporta, Committee Member
  • Sencun Zhu, Committee Member
  • Heng Xu, Committee Member
  • Web Browsing
  • 3G Networks
  • Energy
  • Smartphone
  • Power
  • Security
  • Service
  • Cloud Computing
Because of improved smartphones and 3G networks, a lot of new services, which are used to be only on PCs, have been developed and running on smartphones. These applications extend the functionalities of smartphones and make them more convenient for users to be connected. However, these processes generate heavy workload and traffic which negatively affect both smartphones and 3G networks. For smartphones, heavy workload and traffic quickly drain the battery. For 3G networks, traffic increase demands more investment on networks for bandwidth expansion. An additional problem is that the security of 3G networks and their new services have not been fully examined. This dissertation contributes to comprehensive solutions that attempt to improve the power efficiency and provide security support for new services in 3G networks. We find that the key reason for the long delay and high power consumption in web browsing is not due to bandwidth limitation in 3G networks. Instead, the local computation limitation and the wireless protocol of the smartphone are the actual limitations which hamper webpage loading rates. To address this issue we design and evaluate an architecture called Virtual-Machine based Proxy (VMP). The argument is that if we can shift the computing from smartphones to the VMP we can enhance speed of access to complex webpages. Second, we design and evaluate an energy-aware approach for web browsing in 3G based smartphones without a remote proxy. When loading a webpage, we reorganize the computation sequence of the web browser so that the web browser can first run the computations that will generate new data transmissions and retrieve these data from the web server. The web browser can then put the 3G radio interface into low power state, release the radio resource and run the remaining computations. After a webpage is downloaded, we introduce a practical data mining based method to predict the user reading time of webpages. This information is used by the smartphone to switch to a low power state when reading time is longer than a threshold. Third, we design and evaluate a new framework which uses Cloud Computing and VM techniques to shift the workload of various services from smartphones to a computational infrastructure in telecom networks. This shift can greatly reduce the workload and expand the resources of smartphones. Finally, we present a novel DoS attack against the IP Multimedia Subsystem (IMS). By congesting the presence service, a core service of IMS, a malicious attack can cause chained automatic reaction of the system, thus blocking all the services of IMS. Because of the low-volume nature of this attack, an attacker only needs to control several clients to paralyze an IMS network supporting one million users. To address this DoS attack, we propose an online early defense mechanism, which aims to first detect the attack, then identify the malicious clients, and finally block them.