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: "index modulation techniques for 5g wireless networks"
  Abstract: The ambitious goals set for 5G wireless networks, which are expected to be introduced around 2020, require dramatic changes in the design of different layers for next generation communications systems. Massive MIMO systems, filter bank multi-carrier modulation, relaying technologies, and millimeter-wave communications have been considered as some of the strong candidates for the physical layer design of 5G networks. In this article, we shed light on the potential and implementation of IM techniques for MIMO and multi-carrier communications systems, which are expected to be two of the key technologies for 5G systems. Specifically, we focus on two promising applications of IM: spatial modulation and orthogonal frequency-division multiplexing with IM, and discuss the recent advances and future research directions in IM technologies toward spectrum- and energy-efficient 5G wireless networks.

Connected through hyperedge HE-1 (induced by source paper "a survey on spatial modulation in emerging wireless systems research progresses and applications"):
  with members:
    - "spatial modulation assisted multi antenna non orthogonal multiple access"
    - "adaptive spatial modulation based visible light communications ser analysis and optimization"
    - "two high performance schemes of transmit antenna selection for secure spatial modulation"
    - "receive spatial modulation for massive mimo systems"
    - "polarization shift keying polarsk system scheme and performance analysis"
    - "space time channel modulation"
    - "on the achievable spectral efficiency of spatial modulation aided downlink non orthogonal multiple access"
    - "spectral efficient analog precoding for generalized spatial modulation aided mmwave mimo"

Connected through hyperedge HE-2 (induced by source paper "reconfigurable intelligent surface based index modulation a new beyond mimo paradigm for 6g"):
  with members:
    - "cascaded channel estimation for large intelligent metasurface assisted massive mimo"
    - "enabling secure wireless communications via intelligent reflecting surfaces"
    - "enabling large intelligent surfaces with compressive sensing and deep learning"
    - "towards smart and reconfigurable environment intelligent reflecting surface aided wireless network"
    - "energy efficient multi user miso communication using low resolution large intelligent surfaces"
    - "achievable rate maximization by passive intelligent mirrors"
    - "beamforming optimization for intelligent reflecting surface with discrete phase shifts"
    - "reconfigurable intelligent surfaces for energy efficiency in wireless communication"

Connected through hyperedge HE-3 (induced by source paper "propagation modeling and analysis of reconfigurable intelligent surfaces for indoor and outdoor applications in 6g wireless systems"):
  with members:
    - "a novel communication paradigm for high capacity and security via programmable indoor wireless environments in next generation wireless systems"
    - "secure wireless communication via intelligent reflecting surface"
    - "enabling secure wireless communications via intelligent reflecting surfaces"
    - "secrecy rate maximization for intelligent reflecting surface assisted multi antenna communications"
    - "the roadmap to 6g ai empowered wireless networks"
    - "energy efficient multi user miso communication using low resolution large intelligent surfaces"
    - "intelligent reflecting surface enhanced wireless network via joint active and passive beamforming"
    - "beamforming optimization for intelligent reflecting surface with discrete phase shifts"

Connected through hyperedge HE-4 (induced by source paper "index modulation for molecular communication via diffusion systems"):
  with members:
    - "channel estimation for diffusive mimo molecular communications"
    - "machine learning based channel modeling for molecular mimo communications"
    - "spatial diversity in molecular communications"
    - "modeling and simulation of molecular communication systems with a reversible adsorption receiver"
    - "molecular mimo from theory to prototype"
    - "a comprehensive survey of recent advancements in molecular communication"
    - "molecular mimo communication link"
    - "detection algorithms for molecular mimo"

Connected through hyperedge HE-5 (induced by source paper "discussions on signal uncertainty principle in shannon channel capacity equation and research on breaking shannon limit method"):
  with members:
    - "power domain non orthogonal multiple access noma in 5g systems potentials and challenges"
    - "a survey on low latency towards 5g ran core network and caching solutions"
    - "mixed adc massive mimo"
    - "a survey of energy efficient techniques for 5g networks and challenges ahead"
    - "energy efficiency in massive mimo based 5g networks opportunities and challenges"

Connected through hyperedge HE-6 (induced by source paper "towards higher spectral efficiency spatial path index modulation improves millimeter wave hybrid beamforming"):
  with members:
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "dynamic subarrays for hybrid precoding in wideband mmwave mimo systems"
    - "channel estimation and hybrid precoding for millimeter wave cellular systems"
    - "millimeter wave cellular wireless networks potentials and challenges"
    - "spatially sparse precoding in millimeter wave mimo systems"

Connected through hyperedge HE-7 (induced by source paper "single carrier index modulation for iot uplink"):
  with members:
    - "a variational inference based detection method for repetition coded generalized spatial modulation"
    - "multiple input multiple output ofdm with index modulation"
    - "a tight upper bound on bit error rate of joint ofdm and multi carrier index keying"

Connected through hyperedge HE-8 (induced by source paper "optimum low complexity decoder for spatial modulation"):
  with members:
    - "solutions to integrals involving the marcum q function and applications"
    - "what will 5g be"
    - "generalised sphere decoding for spatial modulation"

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)