| dc.description.abstract | With the advancement of broadband networking technology, and the growth of processor speed and storage capacity, Video-on-Demand (VoD) service is getting increasingly popular among users. However, there are still many challenges towards building cost-effective, robust and scalable VoD streaming systems due to the huge size, high bandwidth and delay requirements for video streaming. Hence, segment based broadcasting schemes are proposed to solve the problems. Many significant broadcasting schemes are proposed to reduce the client waiting time. However, these schemes usually require clients to receive video segments altogether from all channels. This disregard not only needs a lot of client bandwidth, but also incurs more client buffer space.
To escape from these constraints, in this dissertation, we first propose the basic staircase-harmonic broadcasting (SHB) scheme, which integrates harmonic broadcasting (HB) and staircase broadcasting (SB) schemes to obtain the strengths of small client waiting time and low client buffer space. Furthermore, this dissertation proposes adaptive staircase-harmonic broadcasting (ASHB) scheme, which goal is to guarantee a maximum client waiting time and effectively utilize other three resources: the number of dedicated server bandwidth, the client buffer space and the client bandwidth. When client buffer space and bandwidth are not constrained, the scheme requires a client to buffer only 25% of a playing video and the maximum waiting time is slightly higher than that of HB scheme, which provides a theoretical lower bound. In comparison with fast broadcasting (FB), recursive frequency splitting (RFS), and HB schemes, ASHB scheme saves the buffer space by 50%, 33%, and 33%. If client buffer space and bandwidth are constrained, ASHB scheme has the smallest client waiting time than client-centric approach (CCA), greedy disk-conserving broadcasting (GDB) and SB schemes. For example, at a server bandwidth of ten times the video playback rate, a client bandwidth of triple the playback rate, and a client buffer of 25% of the video size, ASHB has 87%, 87%, and 20% lower waiting time than CCA, GDB, and SB.
Furthermore, this dissertation propose a broadcasting scheme, called adaptive efficient harmonic broadcasting (AEHB) scheme, to show how to adjust the division and assignment of segments for HB scheme to meet the constraints of client bandwidth and client buffer space. AEHB scheme can effectively offers a tradeoff among three resources: the number of dedicated server bandwidth, the client buffer space and the client bandwidth, and further gives a smaller maximum client waiting time. Since the maximum client waiting time is equal to the access time of a segment, the larger number of segments a video program can divide can lead to a smaller client waiting time. Given server bandwidth of ten times the video playback rate, client bandwidth of triple the video playback rate, and a client buffer 25% of the video size, AEHB scheme can divide the video program into 6485 segments, while ASHB, limited client capability broadcasting (LCCB), CCA and GDB schemes can divide the video program into 1151, 364, 169 and 161 segments respectively. AEHB scheme can great outperforms than other schemes.
The difference between ASHB and AEHB schemes is: AEHB scheme has better performance than ASHB scheme, but ASHB scheme is much simpler to compute, so that it can easily get the broadcast schedule. | en_US |