Communication modes of cluster heads and base station in sensor networks can be categorized into two types:multi-hop and single-hop.If the previous is adopted

cluster heads closer to the base station tend to die earlier because more data packets are needed to transmit.Alternatively

if all cluster heads transmit data packets directly to the base station

nodes further from the base station will die much more quickly than those closer to the base station.Aimed at the problems

an algorithm of data gathering based on unequal clustering is proposed.The algorithm enables that clusters closer to the base station have smaller size.Experament results show that the proposed algorithm is effective for prolonging the network lifetime.