CACHE SYSTEM AND CACHE ALLOCATION METHOD FOR CONTENT ON DEMAND SERVICE USING MULTICAST

摘要

PURPOSE: A cache system and a cache allocation method for a content-on-demand service using a multicast is provided to store the front part of the popular content having a high content exposure rate, transmit the front part of the content from the cache server to a unicast, and transmit the other part from a server to a multicast. CONSTITUTION: A content providing system determines data length of near content-on-demand content to be stored in a cache server(610). If a multicast transmission cost is less than a unicast transmission cost, the system orders to store data as long as the cache length of corresponding content in the cache server(630,640). The system generates a transmission schedule mixing the cache server and a source server(650). According to the transmission schedule, the system transmits a partial stream corresponding to the first part of the content in the unicast mode. The system transmits the stream in a multicast mode(680). [Reference numerals] (610) Calculating a cache length(l) by using related information of contents; (620) Calculating a multicast transmission cost(Cm) and a unicast transmission cost(Cu) according to the cache length(l); (640) Ordering to store the initial part of the contents as long as the cache length(l) in a server; (650) Generating a transmission schedule mixing an original server and a cache server; (660) Deleting an existing cache stored in the cache server; (670) Generating a transmission schedule using the original server; (680) Controlling to transmit corresponding contents according to the transmission schedule; (AA) Start; (BB) No; (CC) Yes; (DD) End