Multicast techniques for hybrid RF/FSO DTNs
Multicast techniques for hybrid RF/FSO DTNs
复制标题
DOI：
10.1364/jocn.9.001051
复制
发表时间：
2017-11
期刊：
影响因子：
--
通讯作者：
M. Atakora;H. Chenji
中科院分区：
文献类型：
--
作者：
M. Atakora;H. Chenji
通过多副本路由增加延迟容忍网络 (DTN) 中的联系带宽可以减少数据传输延迟并提高吞吐量。在 DTN 中，节点同时具有射频 (RF) 和自由空间光学 (FSO) PHY 层，可以通过使用 FSO PHY 作为数据通道并执行多播来增加联系带宽。正如我们在本文中所展示的，由于 FSO 的高度定向性（一种幼稚的广播策略，其中波束发散包括广播集中的所有节点），它并不总是导致数据传输延迟的最小化和传输概率的最大化。为此，我们通过模拟移动 DTN 中的静态条件（其中 RF 主要用于控制）来开发混合 RF/FSO DTN 的组播策略。我们证明静态环境中的最优多播问题是最小加权集覆盖问题的抽象，已知该问题是 NP 困难的。为了节省计算时间，我们提出了一种贪婪的局部最优启发式。使用 Epidemic 路由协议在 DTN 模拟器中全面评估各种组播技术的性能。这些评估表明，我们的计算成本低廉的解决方案可产生与最佳结果相同的结果，同时不会影响 DTN 的性能。
Increasing the contact bandwidth in delay tolerant networks (DTNs) via multicopy routing leads to a decrease in data delivery delay and an improvement in throughput. In DTNs, in which nodes have both radio frequency (RF) and free space optical (FSO) PHY layers, contact bandwidth can be increased by using the FSO PHY as the data channel and performing multicasting. As we show in this paper, due to the highly directional nature of FSO, a naïve broadcast strategy where the beam divergence includes all nodes in the broadcast set, it does not always result in the minimization of data delivery delay and the maximization of delivery probability. To this end, we develop multicast strategies for hybrid RF/FSO DTNs via an emulation of static conditions in mobile DTNs in which RF is primarily used for control. We show that the optimal multicast problem in static environments is an abstraction of the minimum weighted set cover problem, which is known to be NP-hard. To save on computation time, we propose a greedy local optimum heuristic. Performance of the various multicast techniques is comprehensively evaluated in a DTN simulator, using the Epidemic routing protocol. These evaluations show that our computationally cheap solution yields results identical to optimal while not compromising the performance of the DTN.