Abstract: In Wireless Sensor Networks（WSNs），energy hole problem is a key factor of affecting the lifetime of networks.In a circular multi-hop sensor network（modeled as concentric coronas），the optimal transmission ranges of all coronas can effectively improve system lifetime.We propose an approximate greedy algorithm for searching trees with maximal lifetime，ASGT（Algorithm for Searching Good Trees）.In ASGT the paper use graph scheme to analyzes the problem，and transform it to a problem of generating optimal tree from original graph.ASGT can not only reduce the searching complexity but also get results approximated to the optimal solution.Furthermore，the simulation results indicate that the lifetime got from ASGT approximates to the lifetime from optimal list.Compared with algorithm in other literatures，ASGT can prolong more than 2 times of system lifetime.

摘要： 无线传感器网络中的能量洞问题是影响网络寿命的关键因素之一。在基于环模型的多跳传感器网络中，通过优化所有环的传输距离可以有效地延长网络寿命。提出了一种近似的贪婪算法（ASGT），该算法将最优传输距离序列问题转化为最优生成树问题，在降低搜索（算法）复杂度的同时得到与最优解近似的结果。模拟实验证明了采用ASGT算法的网络寿命逼近于理想最优序列下的网络生命时间，并且与已有的文献算法相比，ASGT可以延长网络寿命两倍以上。