A bitmap coding method for P2P streaming protocols

To reduce signal overhead, we present a bitmap coding method which just codes changing bits between two continuous bitmaps sent by the same peer. Our method has a novel characteristic that the smaller the bitmap exchange interval is, the shorter the coded sequence is. The average compression ratio of our method is 13.46:1 for real bitmaps crawled from PPLive. For the same bitmap crawled from UUSee, the average compression ratio of UUSee´s coding method is 6.26:1, but that of our method is 9.96:1. Besides high compression ratio, our method is also very simple for coding and decoding.