由於GPSR（Greedy Perimeter Stateless Routing）最早提出是應用於無線隨意網路（ad hoc network）中的演算法，直接用在WSNs中，因為沒有考慮節點有能力限制的特性，而產生許多問題。例如，不考慮節點所剩下的電量將會導致封包遺失（packet loss），因為節點可能沒有足夠的電力將封包傳遞出去。而不考慮能量的平衡，總是使用某幾條路徑，將會降低網路的生命，無法有效使用能量，導致能量消耗不均，造成部分節點較快死亡，使得死路的問題更加嚴重。。
基於以上原因，研究改良GPSR中貪婪傳遞（greedy forwarding）的步驟，考慮節點的剩餘電量與周圍鄰居的密集度，並估計周期廣播的時間長短，使得WSNs能夠達到能量平均與能量有效率，以延長整個網路的生命。經過模擬結果發現，在總共傳遞的回合數上有4%至27%的成長，而在周圍鄰居較密集的網路環境下則有13%至25%的成長。

WSNs are distributed event-based systems that consist of thousands of tiny and low-cost nodes. A large number of sensor nodes are densely deployed in a random manner. It is difficult to know network topology. We modify a geographic routing protocol-GPSR, which was designed for ad hoc networks without severe restriction of energy. It may suffer dead-end problem when some node dead or disappear. We want to consider residual energy and node density to improve energy balance and dead-end avoidance based on GPSR. We also estimate the time of Broadcast period. We can find out the total rounds of transmission can prolong 4% to 27%. In density network, it can prolong 13% to 25%.

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