Abstract: In this paper we try to identify the limitations of the traditional BitTorrent protocol in providing spatial image streaming services and describe the mechanism which support spatial image streaming in BitTorrent. A spatial image streaming model base on BitTorrent is also proposed. The model makes use of tracker in locating resources. Further, dynamic image tiles downloading queue which optimize image transmission is adopted in our model. Considering that the piece selection algorithms of the traditional BitTorrent protocol have many limitations in supporting image streaming, our approach gives image tiles different priorities firstly before they're requested. Then we use a parameter K to strike the balance between high priority tiles and low priority image tiles. Experimental results show that the model has the best performance when parameter K equals to 0.8 and maintains stable in the scenario of flash crowd. Also, the model gets improvement in controlling the workload balance of the network.

Key words: BitTorrent, streaming, spatial image, peer-to-peer