We consider the problem of minimizing age of information in multihop wireless networks and propose three classes of policies to solve the problem - stationary randomized, age difference, and age debt. For the unicast setting with fixed routes between each source-destination pair, we first develop a procedure to find age optimal Stationary Randomized policies. These policies are easy to implement and allow us to derive closed-form expression for average AoI. Next, for the same unicast setting, we develop a class of heuristic policies, called Age Difference, based on the idea that if neighboring nodes try to reduce their age differential then all nodes will have fresher updates. This approach is useful in practice since it relies only on the local age differential between nodes to make scheduling decisions. Finally, we propose the class of policies called Age Debt, which can handle 1) non-linear AoI cost functions; 2) unicast, multicast and broadcast flows; and 3) no fixed routes specified per flow beforehand. Here, we convert AoI optimization problems into equivalent network stability problems and use Lyapunov drift to find scheduling and routing schemes that stabilize the network. We also provide numerical results comparing our proposed classes of policies with the best known scheduling and routing schemes available in the literature for a wide variety of network settings.
翻译:我们考虑如何在多点无线网络中尽量减少信息年龄的问题,并提出解决该问题的三类政策 -- -- 固定随机化、年龄差异和年龄债务。对于每个源端-目的地配对之间固定路线的单人设置,我们首先制定程序,寻找最适合年龄的定点随机化政策。这些政策易于实施,并允许我们为普通AoI产生封闭式的表达方式。接着,对于同一个单人设置,我们制定了一种叫“年龄差异”的休养政策,其基础是,如果邻近节点试图减少年龄差异,那么所有节点都会有更新的更新。这个方法在实践中有用,因为它只依靠每个源端之间的本地年龄差异来做出时间安排决定。最后,我们提出了称为“年龄债务”的政策类别,它能够处理:(1) 非线性AoI的成本功能;(2) 单人、多播报和广播流;以及(3) 事先没有指定固定的路线。在这里,我们把AoI优化问题转换成同等的网络稳定性问题,并利用Lyapunov流来寻找最新的更新。这个方法在实践上是有用的,因为它仅仅依靠本地的节点之间的当地年龄差差差差,以便比较现有的网络的网络。我们提供数字结果,以比较现有的网络。我们还提供最清楚的网络设置。