Lecture Notes in Computer Science- P112:This year, we received about 170 submissions to ICWL 2008. There were a total of 52 full papers, representing an acceptance rate of about 30%, plus one invited paper accepted for inclusion in this LNCS proceedings. The authors of these accepted papers | 544 S. Fan et al. 3 Architecture Design for Mobile Learning The m-learning architecture based on SIP should support the requirements of traditional e-learning processes which include registration message communica-tion courseware subscription and other methods that will fully engage the students in the learning process through an interactive dynamic environment involving the student on-line materials and teacher. As discussed in section the new architecture should also support the unique requirements of m-learning which include enough flexibility and mobility. At the same time it should have high multimedia data exchange capacity 11 . The architecture proposed in this paper is illustrated in figure 1. User Entities Fig. 1. Architecture for m-learning system As illustrated in figure 1 four elements will be included in our system registrar proxy m-learning server and user entity. A registrar is a server that accepts learners and educators registration and provides m-learning server with proper information. A proxy server primarily plays the role of routing. It receives SIP message and decides the next hop. M-learning server is used to provide users with functions such as courseware subscription and play presence subscription and so on. The user entity is a logical entity that can act as both UAC user agent client and U AS user agent server . Installed at user s terminal devices the user entity is implemented as a client software for accessing m-learning services. With the increasing use of SIP in various fields there are already many developed SIP software and applications. We will reuse these resources to implement our m-learning system. For example SER SIP Express Router is a free SIP server licensed under the open-source GNU license. We will use SER as registrar and proxy in our An Optimized Scheme for Mobile Learning on IP-Based Network Using SIP 545 system. The development of m-learning server and user entity will be based on oSIP eXosip and oRTP which are .
