This triggers the user entity to send a SIP INVITE request message to the m-learning server, with a courseware URI such as sip:coursewareA@nbut.cn in its re-quest URI and an IP address o
Trang 1An Optimized Scheme for Mobile Learning on IP-Based Network Using SIP 549
To: <sip:alice@nbut.cn>
Call-ID: fverVterCnrc.PmB9P5OeciLSb@192.168.0.100
Contact: <sip:alice@192.168.0.100:5060>
Authorization: Digest
user-name="alice@nbut.cn",realm="nbut.cn",nonce="dd2de673348 f1d19337082e347115bf1",uri="sip:nbut.cn",response="a487 130029eae4a850da14342dfaf682",algorithm=MD5
SIP/2.0 200 OK
From:
<sip:alice@nbut.cn>;tag=nVfdNPfdu7qq_tnj*t4-U39aC8
To: <sip:alice@nbut.cn>;tag=6101
Call-ID: fverVterCnrc.PmB9P5OeciLSb@192.168.0.100
Contact: <sip:alice@192.168.0.100:5060>;expires=3600
REGISTER sip:nbut.cn SIP/2.0
From:
<sip:alice@nbut.cn>;tag=ImJMioJMu7qq_tnj*t4-V.QmE_
To: <sip:alice@nbut.cn>
Call-ID: xgA5+eA5H+Pdgz4AeznPA.Q_E8@192.168.0.100
Contact: <sip:alice@192.168.0.100:5060>
Authorization: Digest
user-name="alice@nbut.cn",realm="nbut.cn",nonce="dd2de673348 f1d19337082e347115bf1",uri="sip:nbut.cn",response="a487 130029eae4a850da14342dfaf682",algorithm=MD5
SIP/2.0 200 OK
From:
<sip:alice@nbut.cn>;tag=ImJMioJMu7qq_tnj*t4-V.QmE_
To: <sip:alice@nbut.cn>;tag=6792
Call-ID: xgA5+eA5H+Pdgz4AeznPA.Q_E8@192.168.0.100
Contact: <sip:alice@192.168.0.100:5060>;expires=3600
In the flow of playing courseware and updating session as illustrated in figure 6, Alice chooses to play a courseware, which could be retrieved from her courseware list This triggers the user entity to send a SIP INVITE request message to the m-learning server, with a courseware URI such as sip:coursewareA@nbut.cn in its re-quest URI and an IP address of 192.168.0.100 both in contact head field and SDP After receiving this message, the server will prepare for playing this courseware Af-ter it is done, the server will respond with a 200 OK message to Alice, and Alice will send back an ACK message to acknowledge the receiving of 200 OK After the
Trang 2550 S Fan et al
Fig 6 Process of playing courseware and updating session
three-way SIP signal is completed, an RTP media stream will be sent directly to Alice from m-learning server The stream can be either audio or video The user entity of Alice will properly play it for Alice If Alice moves and IP address changes to 192.168.1.200, the user entity will send an UPDATE message with a new address of 192.168.1.200 both in contact head field and SDP to update the SIP session Then the RTP stream could be sent to the new address and the future SIP message in the same session could be sent to Alice correctly
5 Conclusion and Future Work
In this paper we first analyzed the attributes that a general m-learning system should cover, then explored the advantages of applying SIP in m-learning systems An opti-mized scheme for m-learning using SIP is proposed after that We can see that by introducing SIP, we get excellent personal mobility and service mobility that are im-possible to get in traditional m-learning systems using HTTP More interactive and
Trang 3An Optimized Scheme for Mobile Learning on IP-Based Network Using SIP 551
real-time m-learning applications can be implemented based on the optimized archi-tecture Courseware is available to be subscribed and played anytime and anywhere, sessions could be continued and updated seamlessly with the movement of users However, SIP mobility cannot support TCP connections, while there are still many m-learning applications running on TCP, such as HTTP and FTP services This problem can be solved by integrating Mobile IP technology into SIP The integration of SIP and MIP on m-learning is left for future study Moreover, the current m-learning sys-tem only includes basic e-learning functions, more complex applications, like multi-party conference, courseware sharing, and virtual whiteboard, can be added in the future
Acknowledgements
This paper is partially supported by NSCF 2007A610047
References
1 Iva, B., Pierre, V., Murat, K.: Virtual Classroom for Multimedia Teaching on WWW In: 32nd ASEE/IEEE Frontiers in Education Conference (2002)
2 Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.R., Peterson, J., Sparks, R., Handley, M., Schooler, E.: SIP: session initiation protocol RFC 3261, IETF (2002)
3 Mikic, F., Anido, L.: M-learning Standardization.: Concepts and New Ideas about Learner Profile Education for the 21st Century - Impact of ICT and Digital Resources (2006)
4 Wagner, E.D.: Enabling Mobile Learning Educause Review 40, 40–53 (2005)
5 Schulzrinne, H., Casner, S., Frederick, R., Jacobson, V.: RTP: A Transport Protocol for Real-Time Applications RFC 3550, IETF (2003)
6 Crocker, D., Overell, P.: Augmented BNF for Syntax Specifications: ABNF RFC 4232, IETF (2005)
7 Handley, M., Jacobson, V., Perkins, C.: SDP:Session Description Protocol RFC 4566, IETF (2006)
8 Johnston, A.B.: SIP: Understanding the Session Initiation Protocol, 2nd edn (2004)
9 Perkins, C.I.: Mobility Support for IPv4 RFC 3344, IETF (2002)
10 Wedlund, E., Schulzrinne, H.: Mobility Support using SIP In: Proc ACM WoWMoM
1999, Seattle (1999)
11 Pozzi, F.: The Impact of m-Learning in School Contexts: An “Inclusive” Perspective Uni-versal Access in Human-Computer Interaction Applications and Services (2007)
12 Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S., Leach, P., Luotonen, A., Stewart, L.: HTTP Authentication: Basic and Digest Access Authentication RFC 2617, IETF (1999)
Trang 4Author Index
Aouag, Sofiane 497
Blumberg, Fran C 477
Cao, Yiwei 253
Chan, Po-Chou 332
Chang, Han-Bin 232
Chang, Hsuan-Pu 529
Chang, Wen-Chih 178, 221, 241, 275
Chang, Yuan-Hou 18, 322
Chao, Louis R 232, 241, 529
Chen, Jianer 285
Chen, Jui-Hung 241
Chen, Kuen-Chi 178
Chen, Ling 187
Chen, Shihong 79
Chen, Tianding 314
Chen, Xi 79
Chen, Yung-Fu 332
Chiu, Yan-Da 275
Choi, Kwansun 196, 208
Chou, Yu-Min 221
Chung, Pei-Yun 87
´
Cukuˇsi´c, Maja 99
de Castro, Juan P 167
Fan, Jianbo 541
Fan, Lei 468
Fan, Shaojing 541
Fang, Fang 468
Fern´andez-Manj´on, Baltasar 253, 486
Fu, Fong-Ling 265
Gao, Jian-Bin 87
Grani´c, Andrina 99
Grigoriadou, Maria 27
Halatsis, Constantine 27
Han, Saeron 196, 208
He, Zhongkun 541
Hong, Min 208
Hornung, Christoph 99
Hsu, Hui-Huang 232
Hu, Zhihui 344
Jeon, Changwan 196, 208 Jeon, Heunggu 196, 208 Jeong, Ok-Ran 1 Kim, Dongsik 196, 208 Kim, Won 1
Klamma, Ralf 253 Koper, Rob 132 Lai, Yen-Shou 18, 322 Laih, Chi-Sung 87 Lee, Chen-Yu 529 Lee, Sunheum 196 Leontidis, Makis 27 Leung, Howard 344
Li, Bin 398
Li, Fei 398
Li, Haifei 145
Li, Kedong 413
Li, Mao-Fan 275
Li, Yong-Na 477
Li, Zhenlong 434 Liang, Wanjie 296 Liao, Hsiu-Li 8 Liao, Ya-Chin 332 Lin, Chi-San 87 Lin, Hsuan-Hung 332 Lin, Suxian 424, 446 Lin, Suxian 521 Linckels, Serge 509 Liu, Guangdong 145 Liu, Qingtang 49, 69
Lu, Hsi-Peng 8 Luo, Nianlong 111 Luo, Qian 59 Mao, Yuxin 457 Mart´ınez-Ortiz, Iv´an 486 Meinel, Christoph 509 Miao, Yongwu 132 Moon, Ilhyun 196, 208 Moreno-Ger, Pablo 253, 486 Mu˜noz, Mar´ıa F 167
Trang 5554 Author Index
Nazemi, Kawa 99
P´erez, Mar´ıa ´A 167
Popescu, Elvira 122
Qi, Li 39
Qiu, Jiangtao 59
Regueras, Luisa M 167
Repp, Stephan 509
Sheng, Yu 285
Shih, Timothy K 529
Sierra, Jos´e Luis 253
Sierra-Rodr´ıguez, Jos´e Luis 486
Sloep, Peter 132
Spaniol, Marc 253
Sun, Zhimei 49
Tan, WenAn 424, 446, 521
Tang, Anqiong 446
Tang, Changjie 59
Tao, Congwu 398
Tian, Wenya 457
Toubekis, Georgios 253
Tsai, Hung-Hsu 18
Verd´u, Elena 167
Verd´u, Mar´ıa J 167
Wang, Chun-Chia 529
Wang, Feng 304
Wang, Jianxin 187, 285
Wang, Kuo-An 332
Wang, Shujuan 69
Wang, Te-Hua 241
Wang, Weiping 285
Wang, Xiaodan 468
Wang, Xin 39
Wang, Yonggu 413 Wang, Zhigang 405 Wang, Zhiwen 390 Wen, Jia-Rong 87 Woo, Sangyeon 208
Wu, Wan-Chi 87
Wu, Xiyuan 145 Xiao, Kun 79
Xu, Kaikuo 59
Xu, Yun 344 Yang, FuJun 446 Yang, Fujun 521 Yang, Heng-Li 157 Yang, Ya-Ting Carolyn 87 Yang, Yun 424, 521 Yao, Yuankun 366 Yeh, Shu-Wei 529 Ying, Ming-Hsiung 157
Yu, Pao-Ta 18, 322
Yu, Sheng-Chin 265 Yuan, Fang 39 Zhang, Xinyu 111, 405 Zhang, Xue 446 Zhang, Xue-Min 477 Zhang, Yongping 541 Zhao, Jianhua 377 Zhao, Jianmin 296 Zhao, Xianhua 424, 521 Zhao, Xiaoming 434 Zheng, Li 111 Zheng, Qinghua 145 Zheng, Xiaoli 304 Zhou, Weiwei 187 Zhu, Chengsong 356 Zhu, Xinzhong 296 Zhu, Yaoting 356