今日，手機、PDA等無線裝置已經成為每個人很容易擁有的裝置。擁有這些無線裝置會使生活更便利。由無線裝置所構成的點對點網路，不需中央伺服器即可進行溝通。不但對個人隱私有第一層防護，而且又增加了使用上的便利性。因為隨身攜帶的裝置具有可攜性，可以隨時取得最新的資訊。
現在的一些點對點軟體，大部分著重於檔案的分享。把檔案拆成數個節點，由環境內裝有點對點軟體的節點進行分享。每個節點分享自己擁有的部分，檔案很快就能共享完。環境內當然會發生一些自私的節點，不願意分享檔案或是分享一些錯誤的檔案。但各式各樣的軟體透過一些機制，來解決這個問題。並研發出一些誘因機制，促進環境內的活動能熱絡地持續下去。
由於這些無線裝置具有可攜性，利用這些裝置可以交換一些即時的資訊。檔案分享的動作非常類似於我們所需要的交換行為。交換資訊的雙方只要覺得對方是值得相信的，就直接由系統判定可信而進行交換。因此，本研究設計了一套信用評等機制，利用使用者自動進行信用評等的動作，達到自動化地交換資訊。透過此機制，讓系統能持續地進行交換的動作。達到讓環境中的使用者能自動進行交換資訊的目的。

Nowadays, we can get the wireless devices easily, such as cell phone, PDA, etc. It can make the life convenient. The P2P network which has been constructed by the wireless devices does not need the central server. They can communicate by themselves. Not only have protected in the privacy, but also add the convenience. The reason is that the devices are portable, we can get the newest information.
Some P2P software focuses on the sharing. They can share files with other peer. The file can separate into several modes. The software will share these nodes. Every peer shares his own node, and it will speed up the rate of sharing. There are some selfish peers in this environment, and they will not want to share their own node. Moreover, some of them share the incorrect file. The software will solve this kind of problem by some mechanism. And it set some incentive mechanism to make the sharing to go on.
Because the wireless devices are portable, we can use these devices for exchanging immediate information. Sharing the files is similar to the exchanging. Both of the users trust each other. They can exchange automatically. So, our research has designed a reputation based mechanism for exchanging. The users can evaluate each other to exchanging the information automatically. By this mechanism, the user in our system will exchange continuously. We can reach our purpose which makes the user in our environment can exchange automatically.

Table of Contents
LIST OF FIGURES V
LIST OF TABLES VI
CHAPTER 1 INTRODUCTION 1
1.1 RESEARCH BACKGROUND 1
1.2 RESEARCH MOTIVATION 5
1.3 THESIS ORGANIZATION 6
CHAPTER 2 RELATED WORK 7
2.1 FLOODING AND NON-FLOODING 7
2.2 RANK-BASED BROADCAST ALGORITHM 7
2.3 CHORD 8
2.4 XREP PROTOCOL 10
2.5 PEERTRUST 10
2.6 KAZAA 11
2.7 EMULE 12
2.8 FREE-RIDER 13
2.9 BAYESIAN NETWORK-BASED TRUST MODEL 14
2.10 ICLOUDS 16
CHAPTER 3 THE PROPOSED APPROACH 20
3.1 SYSTEM MODEL 20
3.2 THE CONTENTS OF LIST 24
3.3 THE WAY OF CALCULATING THE VALUE K 25
3.4 THE WAY OF CHANGING THE REPUTATION 27
CHAPTER 4 SYSTEM DESIGN AND VERIFICATION 29
4.1 ENVIRONMENT SETTING 29
4.2 EXPERIMENT 31
CHAPTER 5 THE ANALYSIS OF THE EXPERIMENT RESULT 34
5.1 THE SUCCESS RATE 34
5.2 THE RATE OF THE GOOD OR BAD INTELLIGENCE 35
5.3 THE DIFFUSIBILITY OF THE GOOD OR BAD INTELLIGENCE 37
CHAPTER 6 CONCLUSION AND FUTURE WORK 39
6.1 CONCLUSION 39
6.2 THE FUTURE WORK 39
BIBLIOGRAPHY 41

[1] K. C. Laudon and J. P. Laudon, Management Information Systems. Prentice Hall PTR Upper Saddle River, NJ, USA, 1999,
[2] books.com.tw, "books.com.tw," 2007.
[3] C. Law, A. K. Mehta and K. Y. Siu, "A New Bluetooth Scatternet Formation Protocol," Mobile Networks and Applications, vol. 8, pp. 485-498, 2003.
[4] Z. B. Alliance, "Zigbee Specification," Zigbee Alliance Board of Directors, December, 2004.
[5] J. Wojtiuk, "Bluetooth and WiFi integration: Solving co-existence challenges," PRIMEDIA, Oktober, 2004.
[6] J. Easton, Going Wireless: Transform Your Business with Mobile Technology. HarperBusiness, 2002,
[7] H. Cao, O. Wolfson, B. Xu and H. Yin, "MOBI-DIC: MOBIle DIscovery of loCal Resources in Peer-to-Peer Wireless Network," IEEE Data Eng.Bull, vol. 28, pp. 11–18, 2005.
[8] Ta-Cheng Li, "A Reputation Mechanism Based on Collaborative Automated Trust Negotiation in P2P System," Institute of Computer and CommunicationNational Cheng Kung University Thesis for Master of Science, 2005.
[9] M. Ripeanu, "Peer-to-peer architecture case study: Gnutella network," Proceedings of International Conference on Peer-to-Peer Computing, vol. 101, 2001.
[10] N. S. Good and A. Krekelberg, "Usability and privacy: a study of Kazaa P2P file-sharing," Proceedings of the SIGCHI Conference on Human Factors in Computing Systems, pp. 137-144, 2003.
[11] S. Saroiu, K. P. Gummadi and S. D. Gribble, "Measuring and analyzing the characteristics of Napster and Gnutella hosts," Multimedia Systems, vol. 9, pp. 170-184, 2003.
[12] C. Mastroianni, D. Talia and O. Verta, "A super-peer model for resource discovery services in large-scale Grids," Future Generation Comput. Syst., vol. 21, pp. 1235-1248, 2005.
[13] DGT, "Top Mobile Markets," 2001.
[14] A. Heinemann, J. Kangasharju, F. Lyardet and M. Muhlhauser, "iClouds–Peer-to-Peer Information Sharing in Mobile Environments," Proceedings of the 9th International Euro-Par Conference,(Euro-Par 2003), vol. 2790, pp. 1038–1045, 2003.
[15] D. Tsoumakos and N. Roussopoulos, "Analysis and comparison of P2P search methods," Proceedings of the 1st International Conference on Scalable Information Systems, 2006.
[16] O. Wolfson, B. Xu, H. Yin and H. Cao, "Search-and-Discover in Mobile P2P Network Databases," Proceedings of the 26th IEEE International Conference on Distributed Computing Systems, 2006.
[17] S. Lee, L. Quan, K. G. Lee, T. Cho and J. Jang, "A Peer-to-Peer Search Scheme over Mobile Ad hoc Networks," 2004.
[18] I. Stoica, R. Morris, D. Karger, M. F. Kaashoek and H. Balakrishnan, "Chord: A scalable peer-to-peer lookup service for internet applications," Proceedings of the 2001 SIGCOMM Conference, vol. 31, pp. 149-160, 2001.
[19] E. Damiani, S. Paraboschi, P. Samarati and F. Violante, "A reputation-based approach for choosing reliable resources in peer-to-peer networks," Proceedings of the 9th ACM Conference on Computer and Communications Security, pp. 207-216, 2002.
[20] M. Gupta, P. Judge and M. Ammar, "A reputation system for peer-to-peer networks," Proceedings of the 13th International Workshop on Network and Operating Systems Support for Digital Audio and Video, pp. 144-152, 2003.
[21] J. O. Patterson, "A Matter of Trust: Reputation Management in Peer-to-Peer Networks," Computer Science Seminar II Conference, 2003.
[22] L. Xiong and L. Liu, "PeerTrust: supporting reputation-based trust for peer-to-peer electronic communities," IEEE Trans. Knowled. Data Eng., vol. 16, pp. 843-857, 2004.
[23] B. Yu and M. P. Singh, "A social mechanism of reputation management in electronic communities," Cooperative Information Agents, vol. 154165, 2000.
[24] G. ZACHARIA, "TRUST MANAGEMENT THROUGH REPUTATION MECHANISMS," Appl. Artif. Intell., vol. 14, pp. 881-907, 2000.
[25] Kazaa, "Kazaa," vol. 2007, 2007.
[26] O. Heckmann and A. Bock, "The eDonkey 2000 Protocol," The eDonkey 2000 Protocol, 2003.
[27] eMule, "eMule-Project," 2007.
[28] Y. Kulbak and D. Bickson, "The eMule Protocol Specification," EMule Project, Http://sourceforge.Net, January 20. 2005.
[29] Soe-Tsyr Yuan and Tzu-Heng Huang, "A Study on Free-Rider Distributed Impermeability for WP2P Content Sharing," Journal of Information Management, vol. 13, pp. 29-61, 2006.
[30] Y. Wang and J. Vassileva, "Bayesian network-based trust model," Web Intelligence, 2003.WI 2003.Proceedings.IEEE/WIC International Conference on, pp. 372-378, 2003.
[31] Y. Wang and J. Vassileva, "Trust and reputation model in peer-to-peer networks," Peer-to-Peer Computing, 2003.(P2P 2003).Proceedings.Third International Conference on, pp. 150-157, 2003.
[32] S. Buchegger and J. Y. Le Boudec, "The effect of rumor spreading in reputation systems for mobile ad-hoc networks," Proceedings of WiOpt ‘03: Modeling and Optimization in Mobile, Ad Hoc and Wireless Networks, vol. 4, pp. 4.1, 2003.
[33] T. Straub and A. Heinemann, "An anonymous bonus point system for mobile commerce based on word-of-mouth recommendation," Proceedings of the 2004 ACM Symposium on Applied Computing, pp. 766-773, 2004.
[34] Shyh-Rong Fang, The Introduction of the Statistic. Hua-Tie, 1990,
[35] W. Stallings, Cryptography and Network Security: Principles and Practices. Pearson Education Inc, 2003,