אירועים והרצאות בפקולטה למדעי המחשב ע"ש הנרי ומרילין טאוב

Mobile phones and tablets are becoming the main devices to access the Internet, and wireless proximity technology has improved significantly over the last years. This creates the right environment for mobile applications that rely on proximity and close peers to improve their performance. One possible use of this kind of applications applies to Opportunistic Networking, leveraging social contacts to efficiently transfer and store information. This generates the need of understanding the patterns and social characteristics of the wireless connections people usually make over the days, as well as possible new patterns of file storage in current mobile phones. There is also a need for new algorithms and architectures to transfer and store data. We first present an analysis of wireless users’ activity in the Technion campus Wi-Fi network, where users connect through mobile phones, tablets and laptops, over the course of 4 weeks during the semester. The findings shed light on the behavior of users and offer some indications for opportunistic network protocols. Next, we report on the analysis of data from Android mobile phones of 38 users, composed of access traces of the users’ mobile file systems during 30 days. We shed new light on the file usage patterns and present the data in terms of file size distributions, file sessions, file lifetime, file access activity and read / write access patterns. Finally, we use the prior analysis to create an implementation of an opportunistic replication system for mobile phones. It enables backing up files in devices that are encountered on a regular basis. The design of the system includes mechanisms for detecting and identifying regular wireless encounters as well as file accesses. Results show that a vast majority of the nodes are able to replicate and retrieve their files within a reasonable delay.