Resource Cost Balancing with Caching in C-RAN
Resource Cost Balancing with Caching in C-RAN
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DOI：
10.1109/wcnc.2017.7925639
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发表时间：
2017-03
期刊：
影响因子：
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通讯作者：
Alaa Alameer;A. Sezgin
中科院分区：
文献类型：
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作者：
Alaa Alameer;A. Sezgin
云无线电访问网络（C-RAN）有望成为下一代通信网络的骨干。为了降低C-Ran中的瓶颈的回程成本，流行的文件在远程无线电头（RRH）的本地记忆中被缓存，因此与要求它的用户非常接近。在本文中，我们研究了不同的缓存策略，目的是减少回程并传输电源成本。事实证明，共同最大程度地减少发射功率和回程成本的问题构成了混合整数非线性程序（MINLP）。首先，我们介绍了Slack变量，以将问题作为标准混合整数二阶锥体程序（MI-SOCP）提出。通过这种公式，我们可以通过降低计算成本获得全球最佳解决方案。但是，在具有大量用户和RRH的大型网络中，使用MI-SOCP在某些情况下效率低下，甚至是棘手的。因此，我们引入了基于通货膨胀的多项式时间算法。我们通过数值模拟显示，与获得全局最佳所需的时间相比，我们的方法提供了近距离的解决方案。我们还表明，我们的方法比其他最先进的算法更有效，此外，它总是产生整数可行的解决方案，而不是其他放松技术。我们还指出，缓存计划对传输电力和回程成本之间的权衡的基本影响。事实证明，当地缓存的内容冗余使RRH可以合作以降低发电成本，但以增加的回程成本为代价
Cloud radio access networks (C-RAN) are expected to be the backbone of next generation communication networks. In order to reduce the backhaul cost, which is a bottleneck in C-RAN, popular files are cached in local memories at remote radio heads (RRH's) and thus in close proximity to the users demanding it. In this paper we investigate different caching strategies with the objective to reduce backhaul and transmit power cost. It turns out that the problem of jointly minimizing the transmit power and backhaul costs constitutes a mixed integer non linear program (MINLP). First, we introduce slack variables to formulate the problem as a standard mixed integer second order cone program (MI-SOCP). With this formulation we can get the global optimal solution with reduced computational costs. However, in large-scale networks with large number of users and RRH's, using MI-SOCP is either inefficient or even intractable in some cases. Therefore, we introduce an inflation based polynomial time algorithm. We show, with numerical simulations, that our approach provides close-to-optimal solutions with much smaller amount of time compared to that needed for getting the global optimal. We also show that our approach is more efficient than the other state of the art algorithms, besides it always yields an integer feasible solution as opposed to other relaxation techniques. We also point out the essential impact of caching scheme on the trade-off between transmit power and backhaul costs. It turns out that content redundancy at the local caches, enables the RRH's to cooperate for transmit power cost reduction, but at the expense of increased backhaul cost