延迟容忍网络中能量有效的接触探测研究

在延迟容忍网络中，为了发现在其通信范围内的邻居节点，网络中的节点必须不断地探测周围的环境。这个接触探测过程极其耗费能量。如果网络中的节点探测太过频繁，会耗费很多能量，且使得网络能量的使用效率降低。另一方面，稀疏的探测可能导致节点失去和其它节点的接触，从而错失交换数据的机会。因此，在延迟容忍网络中能量效率和接触机会之间存在着一种折中的关系。为了研究这种折中关系，该文首先对基于随机路点模型(Random Way-Point model, RWP)的接触探测过程进行建模，得到恒定探测间隔下接触探测概率的表达式，并且证明在所有平均探测间隔相同的策略中，以恒定间隔探测的策略是最优的。其次，基于提出的理论模型，分析不同情况下能量效率和接触探测概率之间的折中。最后，通过仿真实验验证该理论模型的正确性。

Research on Energy-efficient Contact Probing in Delay Tolerant Networks

In the Delay Tolerant Networks (DTNs), in order to discover the neighbors, the nodes in the network have to probe the surrounding environment continually. This can be an extremely energy-consuming process. If the nodes probe very frequently, they consume a lot of energy, and may be energy inefficient. On the other hand, infrequent contact probing might cause loss of many contacts, and thus missing the opportunities to exchange data. Therefore, there exists a trade-off between the energy efficiency and contact opportunities in the DTNs. In order to investigate this trade-off, this study first proposes a model to quantify the contact detecting probability when the contact probing interval is constant based on the Random Way-Point (RWP) model. Moreover, this study also demonstrates that the strategy which probes at a constant interval performs the best performance, among all contact probing strategies with the same average contact probing interval. Then, based on the proposed model, this study analyzes the trade-off between the energy efficiency and contact detecting probability under different situations. Finally, extensive simulations are conducted to validate the correctness of the proposed model.