Behavioral analysis, user modeling, and protocol design based on large-scale wireless network traces
Ahmed Helmy, Wei-jen Hsu · 2008
In this dissertation we describe the TRACE framework, which is a five-step procedure for the environment-aware approach towards wireless mobile computer networks. As mobile computer networks become ubiquitous and deeply integrated with the daily lives, it is crucial to understand the network and design its protocols and services with the environment-aware approach: We first collect extensive network Traces that reflect truthfully the detailed behaviors of its users, and Represent the rich data sets in concise representations. Then we Analyze these constructed representations to Characterize the users. While many observed characteristics are interesting in themselves and reveal important differences between the realistic environment and commonly made assumptions in the literature, we further add values to these findings by Employing them in various important tasks, including modeling the network users and designing routing protocols. The dissertation is centered around three major case studies, ranging from the microscopic, individual user behavior in the wireless networks to the macroscopic, global user encounter patterns. Specifically, in the case studies, we (1) observe the individual user mobility from the collected traces, identify skewed preferences and periodical re-appearance at the same location as prominent mobility characteristics, and propose the time-variant community (TVC) mobility model to capture such behaviors. The TVC model is flexible to match with many empirical traces while being mathematically tractable. (2) We construct an efficient way for mobile users to summarize their mobility preferences based on singular value decomposition (SVD) and calculate the distance metric between users. Based on this distance metric, we identify user groups in the population based on their mutual similarities, and design a profile-cast service to deliver messages to these behavioral groups without knowing their identities. (3) We further analyze the global encounter patterns between nodes, observe a fast-emerging Small World encounter pattern, and leverage such a network property to design an efficient message dissemination protocol named CSI, in which Communication relies on the Stable yet Implicit structures in mobile networks.