A multicast transmission schedule for scalable multirate distribution of bulk data using nonscalable erasure-correcting codes

This paper addresses the efficient multicast dissemination of bulk data from a single server to numerous clients. The challenge is complex: a client may commence reception at arbitrary times, should receive as little "extra" data as possible until it can reconstruct the entire content, and should have flexibility in choosing the data rate. From the network perspective, the data rate over any link should be as close as possible to the maximum single-downstream-client subscription rate. Also, the solution should scale to huge files and numerous subscribers, and should withstand changing network conditions and packet loss. Finally, it should be friendly to other traffic. For any base client-subscription rate and integer factors thereof, we jointly achieve all these goals in a near-optimal way while using standard ("any k of N") block erasure-correcting codes. Scalability in file size is attained by breaking the file into equisized groups of equisized blocks and separately encoding each group. The other properties are attained by a unique open-loop layered multicast transmission schedule. Each client merely subscribes to one or more standard multicast groups. The need to use special, nonstandard and possibly proprietary codes that scale well is thus obviated.