The unprecedented increase in the demand for mobile data, fuelled by new emerging applications such as HD video streaming and heightened online activities has caused massive strain on the existing cellular networks. As a solution, the 5G technology has been introduced to improve network performance through various innovative features such as mmWave spectrum and HetNets. In essence, HetNets include several small cells underlaid within macro-cell to serve densely populated regions. Recently, a mobile layer of HetNet has been under consideration by the researchers and is often referred to as moving networks. Moving networks comprise of mobile cells that are primarily introduced to improve QoS for commuting users inside public transport because the QoS is deteriorated due to vehicular penetration losses. Furthermore, the users inside fast moving public transport also exert excessive load on the core network due to large group handovers. To this end, mobile cells will play a crucial role in reducing overall handover count and will help in alleviating these problems by decoupling in-vehicle users from the core network. To date, remarkable research results have been achieved by the research community in addressing challenges linked to moving networks. However, to the best of our knowledge, a discussion on moving networks in a holistic way is missing in the current literature. To fill the gap, in this paper, we comprehensively survey moving networks. We cover the technological aspects and their applications in the futuristic applications. We also discuss the use-cases and value additions that moving networks may bring to future cellular architecture and identify the challenges associated with them. Based on the identified challenges we discuss the future research directions.

中文翻译：

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移动网络综合调查

在高清视频流和在线活动增加等新兴应用的推动下，对移动数据的需求空前增长，给现有的蜂窝网络造成了巨大压力。作为解决方案，引入了 5G 技术，通过毫米波频谱和 HetNets 等各种创新功能来提高网络性能。本质上，HetNet 包括位于宏小区内的几个小小区，以服务于人口稠密的地区。最近，研究人员正在考虑 HetNet 的移动层，通常将其称为移动网络。移动网络由移动小区组成，主要是为了提高公共交通内通勤用户的 QoS，因为 QoS 由于车辆穿透损失而恶化。此外，快速移动的公共交通中的用户也由于大量的群体切换而对核心网络施加了过多的负载。为此，移动小区将在减少整体切换次数方面发挥关键作用，并将通过将车载用户与核心网络解耦来帮助缓解这些问题。迄今为止，研究界在解决与移动网络相关的挑战方面取得了显着的研究成果。然而，据我们所知，当前文献中缺少关于以整体方式移动网络的讨论。为了填补这一空白，在本文中，我们全面调查了移动网络。我们涵盖了技术方面及其在未来应用中的应用。我们还讨论了移动网络可能为未来蜂窝架构带来的用例和增值，并确定了与之相关的挑战。基于已确定的挑战，我们讨论了未来的研究方向。