Method and system for downloading in ubiquitous network by means of multicast

A method for downloading in a ubiquitous network by multicast, comprising:

• after requesting to download a media service, acquiring, by a terminal from a tracing server, an address of a cache server corresponding to the media service, and requesting the cache server to transmit the media service;
• after receiving the request, triggering, by the cache server, a context server to determine, according to a preset multicast terminal threshold value, whether a condition for triggering multicast is met;
• when the condition for triggering multicast is met, cooperating, by the cache server, with the context server and a joint radio resource management server to determine a plurality of terminals participating in multicast and a multicast channel;
• and
• sending, by the cache server, data of the media service to each terminal on the multicast channel via a resource control node,
• wherein the triggering of the context server to determine, according to the preset multicast terminal threshold value, whether the condition for triggering multicast is met comprises:
• after receiving the request, sending, by the cache server, a signalling for inquiring a multicast condition to the context server, and
• determining, according to working conditions of surrounding terminals of the terminal returned by the context server and the preset multicast terminal threshold value, whether the condition for triggering multicast is met,
• wherein the preset multicast terminal threshold value comprises:
• a preset index evaluated according to the number of terminals participating in multicast, multicast service transmission progress and quality of the multicast channel.