Loss Recovery Method for Content Pre-distribution in VoD Service

In Video on Demand (VoD) services, the demand for content items greatly changes on a daily basis, so reducing the server load at peak time is an important issue for ISPs in reducing server costs. To achieve this goal, we previously proposed to reduce server load by multicasting popular content items to all users independently of actual requests as well as providing ondemand unicast delivery. However, a recovery method for lost packets in this multicast pre-distribution (MPD) has not been investigated. We propose a loss-recovery method suited for the MPD. Because a large number of content items pre-distributed to set-top boxes are not viewed by users, we propose to deliver only lost packets in the requested content item on demand at the time of each user request. Using the access log data of an actual VoD system, we clarify the superiority of the proposed loss recovery method by comparing it with existing loss recovery methods for multicast delivery systems.