A permutation-based pyramid broadcasting scheme for video-on-demand systems

Periodic broadcasting can be used to support near video on demand for popular videos. For a given bandwidth allocation, pyramid broadcasting schemes substantially reduce the viewer latency (waiting) time as compared with conventional broadcasting schemes. Nevertheless, such pyramid schemes typically have substantial storage requirements at the client end, and this results in set top boxes needing disks with high transfer rate capabilities. We present a permutation based pyramid scheme in which the storage requirements and disk transfer rates are greatly reduced, and yet the viewer latency is smaller as well. Under the proposed approach, each video is partitioned into contiguous segments of geometrically increasing sizes and each segment is further divided into blocks, where a block is the basic unit of transmission. As in the original pyramid scheme, frequencies of transmission for the different segments of a video vary in a manner inversely proportional to their size. Instead of transmitting the block in each segment in sequential order, the proposed scheme transmits these blocks in a prespecified cyclic permutation to save on storage requirements in the client end. Performance analyses are provided to quantify the benefits of the new scheme.