隨著數位家電技術的進步，近年來，人們己經逐漸習慣應用一些用戶端的設備來擴充電視廣播的服務，例如：數位電視機上盒和數位視訊錄影機。在這篇論文中，我們提出了一個虛擬頻道的平台，透過組織這些用戶端的設備，依據各使用者的要求，為他們量身訂做一個只包含他們喜好節目的虛擬頻道。在這個虛擬頻道的平台裡，其核心部份是一個點對點的影片傳輸架構，透過分享這些用戶端設備的儲存空間及網路頻寬來提高各影片的可得性。除此之外，因為各部影片中的各個小片段可能有著不一樣的熱門度，為了要有效率的分享這些影片，應該要將這些影片先切成一個個的小片段，再將這些小片段分享到點對點的影片傳輸平台上。基於上述的設計，一個虛擬的頻道可視為由一連串的小片段所組成，但是，在一個大規模的點對點網路上要取得這些小片段，可能會需要付出相當可觀的系統負載來查詢這些片段的所在。為了減少這些額外的負載，我們提出了一個虛擬資料流的機制，將一些熱門且相鄰的影片片段在邏輯上視為一個大的影片，以減少在虛擬頻道中的影片的個數，也就代表著查詢的次數會隨之減少。透過一些實驗數據顯示，我們提出的這個虛擬頻道平台確實能改善服務的效能。

With the rapid advances on information appliance technologies, some powerful client devices, e.g., set top box and digital video recorder, are commonly used to enhance digital TV broadcasting services nowadays. In this thesis, we propose a virtual channel platform by organizing these client devices to virtually support each user a dedicated channel according to her/his demand. In the proposed platform, a peer-to-peer video delivery architecture is introduced to improve the availability of each video by means of sharing the cache buffers and network bandwidth of these client devices. In addition, each video is partitioned into many small segments before it is shared in this peer-to-peer network, because different parts of the video could have different popularities. Therefore, a virtual channel can be constructed by retrieving these video segments and composing them into a long video playout sequence. However, to retrieve these small segments over a large scale peer-to-peer overlay network could cause relatively large query overhead. To reduce the query overhead, we propose a virtual stream mechanism by aggregating popular adjacent video segments to logically form a long video object. Thus, the number of video objects in a virtual channel can be decreased, implying that the total number of queries is also reduced. Through some simulation results, the proposed virtual channel platform exhibits that it can improve the service performance.

[1] Digital Video Broadcasting Project (DVB), http://www.dvb.org
[2] A. Rowstron and P. Druschel, “Pastry: Scalable, distributed object location and routing for large-scale peer-to-peer systems,” in Proc. IFIP/ACM Int. Conf. Distributed Systems Platforms (Middleware 2001), Nov. 2001.
[3] I. Stoica, R. Morris, M. Kaashoek, and H. Balakrishnan, “Chord: A scalable peer-to-peer lookup service for Internet applications,” in Proc. ACM SIGCOMM’01, Aug. 2001.
[4] S. Ratnasamy, P. Francis, M. Handley, R. Karp, and S. Shenker, “A scalable content-addressable network,” in Proc. ACM SIGCOMM’01, Aug. 2001.
[5] V. N. Padmanabhan, H. J. Wang, P. A. Chou, and K. Sripanidkulchai, “Distributing streaming media content using cooperative networking,” in Proc. ACM NOSSDAV, May 2002.
[6] Gnutella, http://www.gnutella.com/
[7] Napster, http://www.napster.com
[8] KaZaA, http://www.kazaa.com
[9] eDonkey, http://www.edonkey2000.com
[10] Morpheus, http://www.musiccity.com
[11] X. Zhang, J.C. Liu, B. Li, and T.-S. Peter Yum, “CoolStreaming/DONet: A data-driven overlay network for efficient live media streaming,” in Proc. IEEE INFOCOM, Mar. 2005.
[12] R. Matei, A. Iamnitchi, and P. Foster, “Mapping the Gnutella Network,” IEEE Internet Computing, vol. 6, Jan.–Feb. 2002, pp. 50–57.
[13] S. Ratnasamy, P. Francis, M. Handley, R. Karp, and S. Shenker, “A Scalable Content-Addressable Network,” in Proc. ACM SIGCOMM, Aug. 2001, pp. 161–172.
[14] I. Stoica, R. Morris, D. Liben-Nowell, D.R. Karger, M.F. Kaashoek, F. Dabek, and H. Balakrishnan, “Chord: A Scalable Peer-to-Peer Lookup Protocol for Internet Applications,” IEEE/ACM Trans. Networking, vol. 11, Feb. 2003, pp. 17–32.
[15] B.Y. Zhao, L. Huang, J. Stribling, S.C. Rhea, A.D. Joseph, and J.D. Kubiatowicz, “Tapestry: A Resilient Global-Scale Overlay for Service Deployment,” IEEE J. Selected Areas in Communications, vol. 22, Jan. 2004, pp. 41–53.
[16] S. Jin and A. Bestavros, “Cache and Relay Streaming Media Delivery for Asynchronous Clients,” in Proc. Int. Wor. Networked Group Communication, Oct. 2002.
[17] D. Xu, M. Hefeeda, S. Hambrusch, and B. Bhargava, “On Peer-to-Peer Media Streaming,” in Proc. IEEE ICDCS’02, Jul. 2002.
[18] Y. Cui, B. Li, and K.Nahrstedt, ”oStream: asynchronous streaming multicast in application-layer overlay networks,” IEEE J. Selected Areas in Communications, vol. 22, Jan. 2004, pp. 91–106.
[19] Y. Cui and K. Nahrstedt, “Layered peer-to-peer streaming,” in Proc. NOSSDAV, 2003.
[20] M. Hefeeda, A. Habib, B. Botev, D. Xu, and B. Bhargava, “PROMISE: Peer-to-Peer Media Streaming Using CollectCast,” in Proc. ACM Multimedia, pp 45–54, Nov. 2003.
[21] S. Viswanathan and T. Imielinski, “Metropolitan area video-on-demand service using pyramid broadcasting,” Multimedia Systems, vol. 3, May 1996, pp. 197–208.
[22] K. A, Hua and S. Sheu, “Skyscraper broadcasting: a new broadcasting scheme for metropolitan video-on-demand systems,” in Proc. ACM SIGCOMM’ 97, 1997.
[23] L. Gao, J. Kurose, and D. Towsley, “Efficient schemes for broadcasting popular videos,” in Proc. NOSSDAV’98, 1998.
[24] L.-S. Juhn and L.-M. Tseng, “Harmonic broadcasting for video-on-demand dervice,” IEEE Trans. Broadcasting, vol. 43, no. 3, Sep. 1997, pp. 268–271.