Agent and SIP based Mobile Peer to Peer J. Čakmak, I. Vučak and M. Kušek University of Zagreb, Faculty of Electrical Engineering and Computing, Zagreb, Croatia e-mail: jagor.cakmak@fer.hr, ivan.vucak@fer.hr, mario.kusek@fer.hr. Abstract— Peer-to-Peer systems (P2P) are getting increasingly popular as an efficient way of sharing any kind of data, and they are wide accepted in world of computing. In world of small devices (e.g. Smartphones, PDAs) P2P systems are not widespread yet, due to limitation when considering mobile device connection requirements. However, P2P system could decrease usage of bandwidth for group of users who are in close proximity. In this paper we discuss centralized P2P system for mobile devices based on JADE agent platform and SIP protocol for communication with client devices, and group data sharing over Bluetooth network. I. INTRODUCTION Peer-to-Peer systems are becoming popular in last couple of years. Much of communication on the Internet is transferring from classical client-server relation to P2P. Since mobile devices are getting more powerful in last year’s delivering content to mobile devices [1] and creating P2P system for mobile devices seems like logical progression. When comparing a P2P software on PCs, and on mobile devices, implementation of P2P on mobile devices has a lot of limitations and problems which are to be considered in design of such system. Key issue that was addressed in this paper is decreasing use of mobile network bandwidth (e.g. 3G, EDGE or GPRS) among group of users while downloading a large file, such as a movie trailer, since most users are still paying mobile service dues depending how much data is transferred on monthly bases. Each user will download a part of a file from server over mobile network and share that downloaded part with others in a group. Sharing data in a group of mobile user without some external infrastructure could be accomplished via Bluetooth. Bluetooth is chosen since it is currently only technology that can create ad- hoc network from mobile devices without any infrastructure (usage of wireless LAN would require router or PS with ad-hoc WLAN network near mobile users). This concept could reduce the use of mobile network and increase speed to download file. To increase efficiency of such system there is centralized control, which will direct communication in most efficient way. Users should have all possibilities for registration, file management, etc., as they have on classical P2P system. For these reasons we chose to build P2P system based on SIP protocol for communication with mobile devices and Agent based system for all internal communication and user representation. In the section 2 is related work. Section 3 explains mobile P2P model and architecture and implementation is in Section 4. Section 5 explains the experiment and the results while section 5 concludes the paper. II. RELATED WORK There aren't yet many implementations of P2P systems for mobile devices. Work which is done so far can be divided into two groups: Adaptation of existing PC P2P for mobile devices, and custom made P2P systems for mobile devices. Problem with first group is that existing PC P2P system such as eMule [1], and Gnutella [3] assume free broadband connection to Internet, as user have in their homes. Implementation of these clients for mobile devices cannot remove this problem, and it will show on users’ traffic on the end of the month [4]. Second group are P2P system specially designed for mobile devices, and as such they can take into consideration special requirements considering amount of data transmitted, saving battery power, availability of user etc. For this kind of system a new kind of communication protocol should be made, with efficient transfer of control messages and data, one way of sending control messages is via SIP protocol [5]. However matter of greatly reducing traffic over mobile network stays open. Most of today mobile devices are equipped with ability to communicate over Bluetooth. If users are in close proximity of each other then we can make part of file transfer over Bluetooth, and automatically reduce amount of used bandwidth over mobile network [6], downside to that approach is currently slow speed of Bluetooth compared to mobile network, but this may change in the future. Combination of these approaches could be the key for successful and efficient mobile P2P system. III. MOBILE P2P MODEL While designing this P2P system, one of our main goals was to create a system that can provide services for location based groups. P2P group consists of source node which is somewhere on the Internet and users (peers) which are in range of Bluetooth. In this approach users in Bluetooth range use only piconet and piconet supports only 8 nodes so this is the limit for number of peers on the same location. The source node splits content in fixed number of parts as it is used in [7] and distributes them to the peers. Each part is assigned to a single peer for redistribution. Resourceful peers may redistribute more parts, and less resourceful peers may redistribute less parts (e.g. regarding its battery status). The source node is responsible for distributing information about which peer has which parts. After that each peer can share parts with other peers by sending it to each peer individualy. IV. MOBILE P2P ARCHITECTURE The central part of system (source node) has to be scalable and has ability to distribute its control elements