網路技術的快速進步與電腦設備的高度普及使一般大眾得以藉由網際網路享受方便的資訊與通訊服務。人們活動在網路上的聚集現象創造出一個極具吸引力的虛擬空間。在其中，人們開始改變他們的生活方式與思考模式。這樣的改變對於人類文明的影響是既深且遠的。我們把前述的虛擬空間稱為數位社區，在本文中，我們將研究並發展一個以有線電視網路為核心，連接多個異質性接取網路如無線網路與有線網路的智慧型寬頻數位社區，以提供高效能、安全與有效的網路服務。其間我們將會探討的關鍵技術包括：網路品質保證技術、群體通訊安全技術以及智慧型資訊擷取技術。
就網路品質保證技術部份，我們先提出一個以差異式服務為基礎的數位社區網路模型。在此模型中，數位社區網路是一個異質性網路並由多個不同的網路領域所連結而成，每一個網路領域均自有其品質保證政策。在此模型下，我們針對有/無線的網路環境設計一個適應性封包排程器決定如何在不同的服務等級間作頻寬分配，以便這些服務等級的品質是可確保的。我們提出的排程器具有下列特性：(1) 使佇列長度作為頻寬控制用的回授信號 (2) 提供封包延遲控制能力 (3) 控制分配頻寬可以敏銳地追蹤流量變動 (4) 控制良好的佇列動態可簡化佇列管理。利用前項排程器我們可以在每一個網路領域保證邊對邊的延遲，甚至點對點的延遲這對於社區內的多媒體通訊服務品質具有重大意義。
其次，為了提供數位社區內有安全的群體通訊，我們提出一個以群體為導向的密鑰管理法則可以允許數位社區內的使用者建立私密性的通訊群組，我們稱這樣私密通訊群組為虛擬俱樂部。密鑰樹是我們所採用以存放密鑰的資料結構，我們研究當群組成員新增、離開或群組合併、切割時，密鑰更新的方法與步驟以確保密鑰安全與通訊私密。 此一密鑰管理法則具有(1) 動態密鑰更新 (2) 分散式密鑰管理 (3) 低計算成本 的特性。這對於大尺度的數位社區而言是十分適用的。
最後，我們提出一個個人化的服務代理器可以提供模糊語意的查詢介面來查詢網際網路上網站的服務內容。我們利用模糊聚類技術來建立此一服務代理器，這將可以協助數社區中的使用者能方便及有效率地取用網路服務。在龐大的網際網路資源中快速地接取所需的服務資料。有效地體現數位社區的新風貌。

The rapid progress of network technology and the high popularity of personal computers make people enjoy various information and communication services through the Internet. The gathering of people activities creates an attractive cyber space, in which people start to gradually change their thinking and living style. Such changing will have a long and deep influence on the human civilization. The gathering of people and their interaction are called as cyber community. In this dissertation, we investigate the development of an Intelligent Broadband Cyber Community (IBCC) and realize it on a Cable TeleVision (CATV) network in which wired and wireless access networks are emerged to offer high-performance, secure and effective network services the network service of high performance, security and effectiveness. The involved technologies including QoS-enabled networking, group security and intelligent information retrieval are the key issues discussed in this dissertation.
First, we adopt the DiffServ model to decouple a community network as a set of interconnected DiffServ domains and design an adaptive packet scheduler to allocate bandwidth for various service classes in a DiffServ router. The proposed packet scheduler has the features: (1) using queue-occupancy as feedback signal, (2) offering delay controllability of packets, (3) tracking sensitively the traffic variation, and (4) alleviating the queue management due to well-controlled queue dynamics. Using the proposed packet scheduler, each DiffServ domain guarantees edge-to-edge delay, and even end-to-end delay of packet crossing several DiffServ domains.
Second, to secure the group communication of community, a group-oriented key management is proposed to allow users having the activity of private group, called as virtual club. The dynamic rekeying mechanism of the proposed scheme enables each virtual club to have secure and private space.
Finally, an intelligent service navigator called as PICA is developed to offer personal and fuzzy-linguistic information retrieval on Internet. The PICA agent is a novel scheme of service-retrieval interface. It changes a content-centered retrieval into a user-centered retrieval.
The detailed modeling and performance analyses of the proposed packet scheduler, secure key management and intelligent service navigator are illustrated in mathematics. Experimental and simulation results show that the developed cyber community effectively utilizes the diverse network technologies to create a widespread cyber space for people activities with the guarantee of high-performance transportation in both wire and wireless networks. The rekeying scheme has less cost and higher flexibility than the past approaches such as TGDH. Certainly, the exhausted content searching is improved by the introduction of personalized intelligent service navigator.

[1] C. S. Skrzypczak, “The Intelligent Home 0f 2010,” IEEE Communication Magazine, vol. 25, No. 12, pp. 81-84, Dec. 1987.
[2] M. H. Sherif, “Intelligent Homes: A New Challenge in Telecommunications Standardization,” pp. 8, IEEE Comm. Magazine, Jan. 2002.
[3] W. Y. Chen, “Emerging Home Digital Networking Needs,”, Proc. of the 4th Int'l Workshop on Community Networking,” pp.7-12, Spet. 1997.
[4] J. E. Cabral Jr. And Yongmin Kim, “Multimedia Systems for Telemedicineb and Their Communications Requirements, “ IEEE Commun. Magazine, pp. 20-27, Jul. 1996.
[5] D. Deloddere, W. Verbiest, and H. Verhille, “Interactive Video on Demand,” IEEE Commun. Mag., pp. 155-162, May 1994.
[6] V. O. K. Li, W. Liao, X. Qiu, and E. W. M. Wong, “Performance Model of Interactive Video-on-Demand System,” IEEE Journal on Selected Areas in Communications”, Vol. 14, No. 6, pp. 1099-1109, Aug. 1996.
[7] Y. D. Lin, C. J. Wu, and W. M. Yin, “PCUP: Pipelined Cyclic Upstream Protocol over HFC,” IEEE Networks Magazine, Vol. 11, No. 1, pp. 24-35, Jan. 1997.
[8] M. H. Willebeek-LeMair and Z. Y. Shae, “Videoconferencing over Packet-based Networks,” IEEE Journal on Selected Areas in Communication, Vol. 15, No. 6, pp. 1101-1114, Aug. 1997.
[9] J. Sutherland and L. Litteral, “Residential Video Service,” IEEE Commun. Mag., pp. 36-41, Jul. 1992.
[10] T. D. C. Little and D. Venkatesh, “Prospects for interactive video on demand,” IEEE Multimedia, pp.14-24, Fall 1994.
[11] James E. Dail et al. “Adaptive Digital Access Protocol: A Mac Protocol for Multiservice Broadband Access Networks,” IEEE Communication Magazine, pp. 104-112, Mar. 1996.
[12] T. C. Kwok, “Residential Broadband Internet Services and Applications Requirements,” IEEE Commun. Magazine, pp. 76-83, Jun. 1997.
[13] Y. H. Kuo et. al “An Intelligent Virtual Club Service system in Interactive CATV networks,” Proceedings of the third Workshop on Real-Time and Media Systems, pp. 375- 384, 1997.
[14] E. J. Hernandez-Valencia, “Architecture for Broadband Residential IP Service over CATV Networks,” IEEE Networks Magazine, Jan./Feb., Vol. 11, No. 1, pp. 36-43, 1997.
[15] E. R. Bartlett, Cable Television Technology and Operations, New York: McGraw-Hill, 1990.
[16] J. W. Eng and J. F. Mollenaur, “ IEEE Project 802.14: Standard for digital Convergence,” IEEE Commun. Mag., pp. 20-23, May 1995.
[17] R. Dukes, “Next Generation Cable Network Architecture,” 1993 NCTA Technical paper. 8-29, 1993
[18] Andrew Paff, “Hybrid Fiber/Coax in the public Telecommunications Infrastructure, “IEEE Commun. Magazine, Apr. 1995, pp.40-45.
[19] C. Bisdikian and B. McNeil, “MLAP: A Mac Level Access Protocol for the HFC 802.14 Network,” IEEE Communication Magazine, pp. 114-121, Mar. 1996.
[20] R. Braden, D. Clark and S. Shenker, “Integrated Services in the Internet Architecture: an Overview”, RFC 1633, June 1994.
[21] R. Braden, L. Zhang, S. Berson, S. Herzog and S. Jamin, “Resource Reservation Protocol (RSVP) Version 1 Functional Specification”, RFC 2205, September 1997.
[22] S. Blake, D. Black, M. Carlson, E. Davies, Z. Wang, and W. Weiss, “An Architecture for Differentiated Services”, RFC 2475, December 1998.
[23] E. Viswanathan and R. Callon, “Multiprotocol Label Switching Architecture”, RFC 3031, January 2001.
[24] D. Stiliadis and A. Varma, “Design and Analysis of Frame-based Fair Queueing: A New Traffic Scheduling Algorithm for Packet-Switched Networks”, Proc. of ACM SIGMETRICS '96, pp. 104-115, May 1996.
[25] A. Demers, S. Keshav and S. Shenker, “Analysis and Simulation of a Fair Queueing Algorithm”, Proc. of ACM SIGCOMM'89, pp. 3-12, Septemper 1989.
[26] S. S. Kanhere, H. Sethu and A. B. Parekh, “Fair and Efficient Packet scheduling using elastic round robin”, IEEE Trans on Parallel and Distributed Systems, vol. 13, issue 3, pp. 324 -336, March 2002
[27] A. Parekh and R. Gallager, “A generalized processor sharing approach to flow control in integrated services networks: the single-node case”, IEEE/ACM Trans on Networking, vol. 1, no. 3, pp. 344-357,
[28] I. Stoica, H. Zhang, and T. S. Eugene. Ng, “A hierarchical fair service curve algorithm for link-sharing, real-time and priority services”, Proc. ACM SIGCOMM '97, pp. 249-262, September 1997.
[29] P. Goyal and H. M. Vin, “Fair airport scheduling algorithms”, Proc. NOSSDAV '97, pp. 273-282, May 1997.
[30] C. G. Park, D. H. Han and Y. Lee, “ Performance analysis of threshold based bandwidth allocation scheme for IP traffic on ATM networks,” IEE Proc. Commun., vol. 149, pp. 29-33, Feb. 2002.
[31] H. H. Yoon, H. Kim, C. Oh and K. Kim, “A queue length-based scheduling scheme in ATM networks”, Proc. IEEE Region 10 Conference, vol. 1, pp. 234 -237, Septemper 1999.
[32] Y. Ohba, “QLWFQ: a queue length based weighted fair queueing algorithm in ATM networks”, Proc. INFOCOM '97, vol. 2, pp. 566 -575, April 1997.
[33] A. Francini and F. M. Chiussi, “Minimum-latency dual-leaky-bucket shapers for packet multiplexers: theory and implementation”, Proc. Workshop on Quality of Service (IWQoS 2000), pp. 19-28, Pittsbur
[34] H. Ohsaki and M. Murata, “Steady state analysis of the RED gateway: stability, transient behavior and parameter setting”, IEICE Trans. on Comm., vol. E85-B, no. 1, pp. 107-115, January 2002.
[35] R, Johari and D.K.H. Tan, “End-to-end congestion control for the Internet: delays and stability”, IEEE/ACM Trans. on Networking, vol. 9, issue 6, pp. 818-832, December 2001.
[36] S. Bohacek, “Stability of hop-by-hop congestion control “, Proc. 39th IEEE Conference on Decision and Control, vol. 1, pp. 67 -72, 2000.
[37] D. Bertsimas and D. Gamarnik and J.N. Tsitsiklis, “Stability conditions for multiclass fluid queueing networks”, IEEE Trans on Automatic Control, vol. 41, issue 11, pp. 1618 -1631, November 1996.
[38] T. Kailath, ed., Linear Systems, Prentice-Hall, New Jersey, 1980.
[39] L. Kleinrock, ed., Queueing System, Wiley, New York, 1975.
[40] E. L. Hahne and A. K. Choudhury ,”Dynamic queue length thresholds for multiple loss priorities,” IEEE/ACM Trans. on Networking, 368-380, Jun. 2002
[41] M. Andrews et al., “CDMA Data QoS Scheduling on the Forward link with Variable Channel Condition,” Bell Labs Tech. Memo., Apr. 2000.
[42] M. Andrews et al., “Providing Quality of Service over a Shared Wireless Link,” IEEE Communication Magazine, pp. 150-154, Feb. 2001.
[43] C. Dovrolis, D. Stiliadis and P. Ramanathan, “ Proportional Differentiated Services: Delay Differentiation and Packet Scheduling,” IEEE/ACM Trans. on Networking, Vol. 10, No. 1, pp. 12-26, 2002.
[44] T. Nandagopal, N. Venkitaraman, R. Sivakumar and V. Bharghavan, “Delay Differentiation and Adaptation in Core Stateless Networks,”in Proc of IEEE INFOCOM, Mar. 2000.
[45] E. L. Hahne and A. K. Choudhury ,”Dynamic queue length thresholds for multiple loss priorities,” IEEE/ACM Trans. on Networking, 368-380, Jun. 2002.
[46] W. Turin, R. Jana, C. Martin and J. Winters, “Modeling wireless channel fading,” in Proc. of Int'l Conf. Vehicular Technology. VTC'2001, Vol. 3, pp. 1740-1744, Oct. 2001.
[47] M. Mirhakkak, N. Schult and D. Thomson, “ Dynamic Bandwidth Management and Adaptive Application for a Variable Bandwidth Wireless Environment,” IEEE J. on Select. Areas Commun., vol. 19, no. 10, pp. 1984-1997, Aug. 2001.
[48] Z. Sahinoglu and S. Tekinay, “On multimedia networks: self-similar traffic and network performance,” IEEE Communications Magazine, Vol. 37, pp. 48-52, 1999.
[49] W.E. Leland, M.S. Taqqu, W. Taqqu and D.V. Wilson, “On the self-similar nature of Ethernet traffic,” IEEE/ACM Trans. on Networking, Vol. 2 issue 1, pp.1-15, 1994.
[50] B. Tsybakov and N.D. Georganas, “Self-similar processes in communications networks,” IEEE Trnas. on Infor. Theory, Vol. 44, Issue 5, pp.1713-1725, 1998.
[51] A. A. Tarraf, I. W. Habib, T. N. Saadawi, and S. A. Ahmed, “ATM multimedia traffic prediction using neural networks,” Proc. of Global Data Networking, pp. 77-84, 1993.
[52] A. Kolarov, A. Atai and J. Hui, “Applications of Kalman filter in high-speed networks,” Proc. of Global Telecommunications Conference, Vol. 1, Globalcom, pp. 624-628, 1994.
[53] B. E. Shaneyfelt and T. H. Wu, “Statistical analysis of network traffic for class of service in packet-switched networks,” IEEE Journal on Selected Areas in Communications, Vol. 64, pp. 766 -777, May 1988.
[54] K. Tutschku and P. Tran-Gia, “Spatial traffic estimation and characterization for mobile communication network design,” IEEE. Journal on Selected Areas in Communications, Vol. 16, Issue 5, pp. 804-811, Jun. 1998.
[55] N. Qiu, “A predictive fuzzy logic congestion avoidance scheme,” Proc. of Global Telecommunications Conference, Vol. 2, pp. 967-971, 1997.
[56] W. Lobejko, “Traffic prediction by neural network,” Proc. of Military Communication Conference, Vol. 2, pp. 571-575, 1996.
[57] Lin Hsiou-Ping and Ouyang Yen-Chieh, “Neural networks based traffic prediction for cell discarding policy,” Proc. of Int'l Conf. on Neural Networks, pp. 2051-2056, 1997.
[58] Z. Fan and P. Mars, “Access flow control scheme for ATM networks using neural-network-based traffic prediction,” Communications, IEE Proceedings Vol. 1445, pp. 295 –300, Oct. 1997.
[59] Qixiang Pang, Shiduan Cheng, and Peng Zhang, “Adaptive fuzzy traffic predictor and its applications in ATM networks,” Proc. of Int'l Communication Conference, Vol. 3, pp. 1759-1763, 1998.
[60] M. F. Scheffer, J. J. P. Beneke and J. S. Kunicki, “Fuzzy modeling and prediction of network traffic fluctuations,” Proc. of IEEE COMSIG, pp. 41-45, 1995.
[61] J. Hall and P. Mars, “The limitations of artificial neural networks for traffic prediction,” Proc. of Computers and Communications, pp.8-12, 1998.
[62] J. C. Bezdek, Pattern Recognition with Fuzzy Objective Function Algorithms, New York: Plenum, 1981.
[63] Y. Kim, A. Perring, and G. Tsudik, Simple and Fault-tolerant Key Agreement for Dynamic Collaborative Groups, Proceedings 7th ACM Conference on Computer and Communications Security, ACM Press, November 2000, pages 235-244.
[64] D. Wallner, E. Harder, and R. Agee, Key Management for Multicast: Issues and Architectures, Internet Engineering Task Force, RFC 2627, June 1999.
[65] C. Wong, M. Gouda, and S. Lam, “Secure Croup Communication Using Key Graphs,” IEEE/ACM Transactions on Networking, Vol. 8 Issue: 1, pp. 16-30, Feb. 2000.
[66] W. Diffie and M.E. Hellman, “New Directions in Cryptography,” IEEE Transactions on Information Theory, Vol. IT-22, No.6, pp. 644-654, November, 1976.
[67] A. Perrig, “Efficient Collaborative Key Management Protocols for Secure Autonomous Group Communication,” In International Workshop on Cryptographic Techniques and E-Commerce (CrypTEC '99), pp. 192-202, 1999.
[68] M. Steiner, G. Tsudik, and M. Waidner, Key Agreement in Dynamic Peer Groups, IEEE Transactions on Parallel and Distributed Systems, August 2000.
[69] M. Burmester and Y. Desmedt, A Secure and Efficient Conference Key Distribution System,” Advances in Cryptology-Eurocrypt’in Lecture Notes of Computer Science, pp. 275-286, 1994.
[70] M. Steiner, G. Tsudik, and M. Waidner, Diffie-Hellman Key Distribution Extended to Group Communication, Proceedings 3rd ACM Conference on Computer and Communications Security, pp. 31-37, 1996.
[71] D. A. McGrew and A. T. Sherman, Key Establishment in Large Dynamic Groups Using One-way Function Tree, Submitted to IEEE Transactions on Software Engineering, May 1998.
[72] Adrian Perrig, Dawn Song, and J. D. Tygar, ELK, “a New Protocol for Efficient Large-Group Key Distribution,” Proc. of IEEE Symposium on Security and Privacy, 2001.
[73] Oded Goldreich, Shafi Goldwasser, and Silvio Micali, How to Construct Random Functions, Journal of the ACM, pp. 792-807, October 1986.
[74] T. Ballardie, Scalable Multicast Key Distribution, RFC 1949, May 1996.
[75] S. Berkovits, How to Broadcast a Secret. In Advances in Cryptology, EUROCRYPT’91, D. W. Davies, Ed. Berlin, Germany: Springer Verlag, vol. 547, Lecture Notes in Computer Science, pp. 535-541, 1991.
[76] T. Ballardie and J. Crowcroft, Multicast-specific Security Threats and Counter-measures, In Proc. Symp. Network and Distributed System Security, 1995.
[77] S. Mittra, Iolus: A Framwork for Scalable Secure Multicast, In Proc. of ACM SIGCOMM’97, pp. 241-250, 1997.
[78] M. Moyer, J. Rao, and P. Rohatgi, Maintaining Balanced Key Trees for Secure Multicast, Internet Research Task Force, draft-irtf-smug-key-tree-balance-00.txt, June 1999.
[79] Ohad Rodeh, Ken Birman, and Danny Dolev, Optimized Group Rekey for Group communication systems, In Proceedings of Network and Distributed System Security Symposium (NDSS'00), San Diego, CA, USA, February 2000.
[80] H. Harney and C. Muckenhirn, Group Key Management Protocol (GKMP) Architecture, Internet Engineering Task Force, RFC 2094, July 1997.
[81] G. Chaddoud, I. Chrisment,and A. Schaff, “Dynamic Group Communication Security,” 2001. Proc. of Sixth IEEE Symposium on Computers and Communications, pages 49-56, 2001.
[82] T. Hardjono and B. Cain, "Secure and Scalable Inter-domain Group Key Management for N-to-N Multicast, Proc. of International Conf. on Parallel and Distributed Systems, pp. 478–485, 1998.
[83] Y. Amir, G. Ateniese, D. Hasse, C. Nita-Rotaru Y. Kim, T. Schlossnagle, J. Schultz, J. Stanton, and G. Tsudik, Secure Group Communication in Asynchronous Networks with Failures: Integration and Experiments. In 20th IEEE International Conference on Distributed Computing Systems (ICDCS), April 2000.
[84] C. F Chen, M. F. Horng and Y. H. Kuo,” Group-oriented Management of Key Trees for Secure Internet,” submitted to Computer Communication, 2003.
[85] V. Tahani, “ A fuzzy model of document retrieval system,” Inf. Process. Manage., vol. 12, pp. 177-187, 1976.
[86] M. Zemankova, “FIIS: A fuzzy intelligent information system,” Data Engineering, vol. 12, no. 2, 1989.
[87] S. Miyamoto, “Information retrieval based on fuzzy association,” Fuzzy sets Systs., vol. 38, pp. 191-205, 1990.
[88] S. M. Chen and Y. J. Horng, “Document retrieval using knowledge-based fuzzy information retrieval techniques,” IEEE Trans. on Syst., Man, Cybern., vol. 25, pp. 793-803, May 1995.
[89] S. M. Chen and Y. J. Horng, “Fuzzy query processing for document retrieval based on extended fuzzy concept networks,” IEEE Trans. on Syst., Man, Cybern., vol. 29, no. 1 Feb., 1999.
[90] Y. H. Kuo et. al., “Intelligent component retrieval with Neuro-fuzzy approach,” Proceedings of the Eighth Workshop on Object-Oriented Technology and Application, pp. 132-138, 1997.
[91] Y. H. Kuo et. al “An Intelligent Virtual Club Service system in Interactive CATV networks,” Proceedings of the third Workshop on Real-Time and Media Systems, pp. 375- 384, 1997.