human: Given a node-centered hypergraph: <hypergraph>, where nodes represent papers and hyperedges represent sets of papers co-cited by a source paper.

Details of the hypergraph:
Center node: "optical communication in space challenges and mitigation techniques"
  Abstract: In recent years, free space optical (FSO) communication has gained significant importance owing to its unique features: large bandwidth, license free spectrum, high data rate, easy and quick deployability, less power, and low mass requirements. FSO communication uses optical carrier in the near infrared band to establish either terrestrial links within the Earth’s atmosphere or inter-satellite/deep space links or ground-to-satellite/satellite-to-ground links. It also finds its applications in remote sensing, radio astronomy, military, disaster recovery, last mile access, backhaul for wireless cellular networks, and many more. However, despite of great potential of FSO communication, its performance is limited by the adverse effects (viz., absorption, scattering, and turbulence) of the atmospheric channel. Out of these three effects, the atmospheric turbulence is a major challenge that may lead to serious degradation in the bit error rate performance of the system and make the communication link infeasible. This paper presents a comprehensive survey on various challenges faced by FSO communication system for ground-to-satellite/satellite-to-ground and inter-satellite links. It also provides details of various performance mitigation techniques in order to have high link availability and reliability. The first part of this paper will focus on various types of impairments that pose a serious challenge to the performance of optical communication system for ground-to-satellite/satellite-to-ground and inter-satellite links. The latter part of this paper will provide the reader with an exhaustive review of various techniques both at physical layer as well as at the other layers (link, network, or transport layer) to combat the adverse effects of the atmosphere. It also uniquely presents a recently developed technique using orbital angular momentum for utilizing the high capacity advantage of optical carrier in case of space-based and near-Earth optical communication links. This survey provides the reader with comprehensive details on the use of space-based optical backhaul links in order to provide high capacity and low cost backhaul solutions.

Connected through hyperedge HE-1 (induced by source paper "unmanned aerial vehicles uavs a survey on civil applications and key research challenges"):
  with members:
    - "resource allocation for solar powered uav communication systems"
    - "3 d placement of an unmanned aerial vehicle base station for maximum coverage of users with different qos requirements"
    - "indoor mobile coverage problem using uavs"
    - "the sky is not the limit lte for unmanned aerial vehicles"
    - "a tutorial on uavs for wireless networks applications challenges and open problems"
    - "wireless communication using unmanned aerial vehicles uavs optimal transport theory for hover time optimization"
    - "efficient 3d placement of a uav using particle swarm optimization"
    - "placement optimization of uav mounted mobile base stations"

Connected through hyperedge HE-2 (induced by source paper "a key 6g challenge and opportunity connecting the remaining 4 billions a survey on rural connectivity"):
  with members:
    - "connecting the unconnected towards frugal 5g network architecture and standardization"
    - "5g new radio evolution meets satellite communications opportunities challenges and solutions"
    - "aeronautical ad hoc networking for the internet above the clouds"
    - "percolation for d2d networks on street systems"
    - "information and communications technologies for sustainable development goals state of the art needs and perspectives"
    - "sum rate analysis for high altitude platform hap drones with tethered balloon relay"
    - "feasibility architecture and cost considerations of using tvws for rural internet access in 5g"
    - "fso based vertical backhaul fronthaul framework for 5g wireless networks"

Connected through hyperedge HE-3 (induced by source paper "aeronautical ad hoc networking for the internet above the clouds"):
  with members:
    - "optimizing space air ground integrated networks by artificial intelligence"
    - "regularized zero forcing precoding aided adaptive coding and modulation for large scale antenna array based air to air communications"
    - "a survey of multi objective optimization in wireless sensor networks metrics algorithms and open problems"
    - "adaptive coding and modulation for large scale antenna array based aeronautical communications in the presence of co channel interference"
    - "survey of important issues in uav communication networks"
    - "on the security of the automatic dependent surveillance broadcast protocol"
    - "security challenges in mobile ad hoc networks a survey"
    - "massive mimo for next generation wireless systems"

Connected through hyperedge HE-4 (induced by source paper "leo small satellite constellations for 5g and beyond 5g communications"):
  with members:
    - "architectures and key technical challenges for 5g systems incorporating satellites"
    - "integration of satellites in 5g through leo constellations"
    - "survey of inter satellite communication for small satellite systems physical layer to network layer view"

Connected through hyperedge HE-5 (induced by source paper "non terrestrial communication in the 6g era challenges and opportunities"):
  with members:
    - "towards 6g networks use cases and technologies"
    - "integrated access and backhaul in 5g mmwave networks potentials and challenges"
    - "beyond 5g with uavs foundations of a 3d wireless cellular network"

Connected through hyperedge HE-6 (induced by source paper "rf assisted free space optics for 5g vehicle to vehicle communications"):
  with members:
    - "millimeter wave v2v communications distributed association and beam alignment"
    - "millimeter wave vehicular communication to support massive automotive sensing"

Connected through hyperedge HE-7 (induced by source paper "a comparative survey of optical wireless technologies architectures and applications"):
  with members:
    - "separation framework an enabler for cooperative and d2d communication for future 5g networks"
    - "on the performance of mimo fso communications over double generalized gamma fading channels"
    - "dynamic channel allocation for class based qos provisioning and call admission in visible light communication"
    - "what will 5g be"

Connected through hyperedge HE-8 (induced by source paper "communicating using spatial mode multiplexing potentials challenges and perspectives"):
  with members:
    - "spatial mode diversity and multiplexing for fso communication with direct detection"
    - "millimeter wave communications with oam sm scheme for future mobile networks"

Question: Please tell me which class the center node belongs to. The 40 classes are: cs.NA(Numerical Analysis), cs.MM(Multimedia), cs.LO(Logic in Computer Science), cs.CY(Computers and Society), cs.CR(Cryptography and Security), cs.DC(Distributed, Parallel, and Cluster Computing), cs.HC(Human-Computer Interaction), cs.CE(Computational Engineering, Finance, and Science), cs.NI(Networking and Internet Architecture), cs.CC(Computational Complexity), cs.AI(Artificial Intelligence), cs.MA(Multiagent Systems), cs.GL(General Literature), cs.NE(Neural and Evolutionary Computing), cs.SC(Symbolic Computation), cs.AR(Hardware Architecture), cs.CV(Computer Vision and Pattern Recognition), cs.GR(Graphics), cs.ET(Emerging Technologies), cs.SY(Systems and Control), cs.CG(Computational Geometry), cs.OH(Other Computer Science), cs.PL(Programming Languages), cs.SE(Software Engineering), cs.LG(Machine Learning), cs.SD(Sound), cs.SI(Social and Information Networks), cs.RO(Robotics), cs.IT(Information Theory), cs.PF(Performance), cs.CL(Computation and Language), cs.IR(Information Retrieval), cs.MS(Mathematical Software), cs.FL(Formal Languages and Automata Theory), cs.DS(Data Structures and Algorithms), cs.OS(Operating Systems), cs.GT(Computer Science and Game Theory), cs.DB(Databases), cs.DL(Digital Libraries), cs.DM(Discrete Mathematics). Directly output the class name.

gpt: cs.IT(Information Theory)