Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2008.Page 155 blank.Includes bibliographical references (p. 149-154).This thesis describes the design and development of a system that is aimed for personalized and group-wise broadcasts to collaboratively distribute information and to coordinate locally created events in infrastructure-free milieu. This system, called XCast, has two targets: One is to permit people to create personalized communicators, "broadcast stations" over mobile devices, for extemporaneous events or individually motivated presentations. The other is to provide people with a cognitive platform for social event awareness that informs what is happening around them and then timely coordinates the events. This system applies wireless/mobile peer-to-peer networking technologies, such as 802.11 ad-hoc and mesh networking. To achieve the targets, in the thesis, we focus on newly designing architecture of the cognitive platform and then developing a robust and agile protocol which makes it possible for the platform to reliably work in wireless ad-hoc/mesh networks. The former work is to build a group of broadcast stations into a distributed crystal-gazing system to be aware seasonably of what is going on in our surroundings. With respect to the latter, we propose a distributed protocol, dubbed "Broadcast Resource Schedule Protocol (BRSP)." It has broadcast operations more reliable and scalable in wireless ad-hoc/mesh networks via synchronization and neighbor knowledge schemes. In the end, the BRSP evolves a wireless peer-to-peer network into a cognitive network to support the platform. This system offers a riper breeding ground for creation of a platform for social event networking and of cooperative media for a local community. The value of this is in considering community networks that are matrices of social collaboration, rather than point connections, as well as sources of novel civic media initiated by grassroots.by Sung-Hyuck Lee.S.M
