The problem of inefficient and unevenly distributed spectrum usage in industrial wireless networks has led to the emergence of the concept of industrial cognitive radio (CR) networks, which have particularly important applications in automotive industry. Industrial CR networks are planned to function in a wide spectrum range; therefore, they have high energy consumption because of frequency switching while other wireless technologies do not have this problem. A distinctive feature of this switching cost is that it depends on the wideness between the two frequency bands. In this article, we formulate the joint frequency assignment and scheduling problem for multihop industrial CR networks with a single transceiver by considering varying amounts of energy consumption that occurs while CR devices switch to different frequency bands. Our optimization problem, which we formulate as an integer linear program, minimizes the energy cost related to frequency switching while making frequency and time slot allocation to the cognitive devices. We prove that even on star graphs, our formulated problem is inapproximable within any polynomial-time computable function f(n) in addition to being NP-Hard in the strong sense. Therefore, we propose a polynomial-time heuristic algorithm to solve the energy consumption problem due to channel switching. Simulation results demonstrate that the performance of our heuristic algorithm is very close to the results obtained from the integer linear programming implementation by CPLEX optimization software. We also compare our proposed method with the corresponding constant energy consumption for frequency switching case and two state-of-the-art algorithms and demonstrate that taking into account the different energy consumption while switching to different frequency bands is vital for joint frequency assignment and scheduling in multihop industrial CR networks with a single transceiver.

中文翻译：

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工业认知无线电网络的切换成本感知联合频率分配和调度


工业无线网络中频谱使用效率低下且分布不均匀的问题导致了工业认知无线电（CR）网络概念的出现，该网络在汽车行业中有着尤为重要的应用。工业 CR 网络计划在广泛的频谱范围内运行；因此，它们由于频率切换而具有较高的能耗，而其他无线技术则不存在此问题。这种切换成本的一个显着特征是它取决于两个频带之间的宽度。在本文中，我们通过考虑 CR 设备切换到不同频段时发生的不同能量消耗量，制定了具有单个收发器的多跳工业 CR 网络的联合频率分配和调度问题。我们的优化问题被表述为整数线性程序，在为认知设备分配频率和时隙的同时，最大限度地减少与频率切换相关的能源成本。我们证明，即使在星图上，我们提出的问题除了在强意义上是 NP-Hard 之外，在任何多项式时间可计算函数 f(n) 内也是不可逼近的。因此，我们提出了一种多项式时间启发式算法来解决信道切换引起的能耗问题。仿真结果表明，我们的启发式算法的性能非常接近通过 CPLEX 优化软件实现整数线性规划所获得的结果。 我们还将我们提出的方法与频率切换情况下相应的恒定能耗以及两种最先进的算法进行比较，并证明在切换到不同频段时考虑不同的能耗对于联合频率分配和调度至关重要在具有单个收发器的多跳工业 CR 网络中。