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: "a survey of energy efficient techniques for 5g networks and challenges ahead"
  Abstract: After about a decade of intense research, spurred by both economic and operational considerations, and by environmental concerns, energy efficiency has now become a key pillar in the design of communication networks. With the advent of the fifth generation of wireless networks, with millions more base stations and billions of connected devices, the need for energy-efficient system design and operation will be even more compelling. This survey provides an overview of energy-efficient wireless communications, reviews seminal and recent contribution to the state-of-the-art, including the papers published in this special issue, and discusses the most relevant research challenges to be addressed in the future.

Connected through hyperedge HE-1 (induced by source paper "5g network slicing using sdn and nfv a survey of taxonomy architectures and future challenges"):
  with members:
    - "a novel qoe aware sdn enabled nfv based management architecture for future multimedia applications on 5g systems"
    - "securing fog to things environment using intrusion detection system based on ensemble learning"
    - "wireless network slicing generalized kelly mechanism based resource allocation"
    - "resource orchestration of 5g transport networks for vertical industries"
    - "slice as an evolutionary service genetic optimization for inter slice resource management in 5g networks"
    - "network slicing based 5g and future mobile networks mobility resource management and challenges"
    - "network slicing for 5g with sdn nfv concepts architectures and challenges"
    - "a survey on mobile edge computing the communication perspective"

Connected through hyperedge HE-2 (induced by source paper "joint active and passive beamforming for intelligent reflecting surface assisted massive mimo systems"):
  with members:
    - "joint active and passive beamforming optimization for intelligent reflecting surface assisted swipt under qos constraints"
    - "large intelligent surface antennas lisa making reflective radios smart"
    - "secure wireless communication via intelligent reflecting surface"
    - "cascaded channel estimation for large intelligent metasurface assisted massive mimo"
    - "enabling secure wireless communications via intelligent reflecting surfaces"
    - "secrecy rate maximization for intelligent reflecting surface assisted multi antenna communications"
    - "intelligent reflecting surface assisted secrecy communication via joint beamforming and jamming"
    - "towards smart and reconfigurable environment intelligent reflecting surface aided wireless network"

Connected through hyperedge HE-3 (induced by source paper "the potential short and long term disruptions and transformative impacts of 5g and beyond wireless networks lessons learnt from the development of a 5g testbed environment"):
  with members:
    - "the current state of affairs in 5g security and the main remaining security challenges"
    - "blockchain for internet of things a survey"
    - "a vision of 6g wireless systems applications trends technologies and open research problems"
    - "a speculative study on 6g"
    - "5g nr jamming spoofing and sniffing threat assessment and mitigation"
    - "a concise review of 5g new radio capabilities for directional access at mmwave frequencies"
    - "mutual heterogeneous signcryption schemes for 5g network slicings"
    - "ultra reliable and low latency communications in 5g downlink physical layer aspects"

Connected through hyperedge HE-4 (induced by source paper "distributed power control with partial channel state information performance characterization and design"):
  with members:
    - "interference coordination via power domain channel estimation"
    - "ultra dense small cell networks turning density into energy efficiency"
    - "coordination in distributed networks via coded actions with application to power control"
    - "coded power control performance analysis"
    - "robust precoding for network mimo with hierarchical csit"
    - "a game theoretic analysis for energy efficient heterogeneous networks"
    - "mac with action dependent state information at one encoder"
    - "framework for link level energy efficiency optimization with informed transmitter"

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"
    - "index modulation techniques for 5g wireless networks"
    - "energy efficiency in massive mimo based 5g networks opportunities and challenges"

Connected through hyperedge HE-6 (induced by source paper "delay optimal and energy efficient communications with markovian arrivals"):
  with members:
    - "joint queue aware and channel aware delay optimal scheduling of arbitrarily bursty traffic over multi state time varying channels"
    - "accelerated structure aware reinforcement learning for delay sensitive energy harvesting wireless sensors"
    - "delay optimal probabilistic scheduling in green communications with arbitrary arrival and adaptive transmission"
    - "delay optimal buffer aware scheduling with adaptive transmission"

Connected through hyperedge HE-7 (induced by source paper "cloud based management of energy efficient dense ieee 802 11ax networks"):
  with members:
    - "joint power control and time division to improve spectral efficiency in dense wi fi networks"
    - "energy efficient scheduling and power allocation in downlink ofdma networks with base station coordination"

Connected through hyperedge HE-8 (induced by source paper "energy sustainable paradigms and methods for future mobile networks a survey"):
  with members:
    - "information exchange in randomly deployed dense wsns with wireless energy harvesting capabilities"
    - "a stochastic geometry based demand response management framework for cellular networks powered by smart grid"
    - "fog computing based radio access networks issues and challenges"
    - "a hybrid energy sharing framework for green cellular networks"
    - "recent advances in cloud radio access networks system architectures key techniques and open issues"
    - "green networking in cellular hetnets a unified radio resource management framework with base station on off switching"
    - "online ski rental for on off scheduling of energy harvesting base stations"
    - "dynamic clustering and on off strategies for wireless small cell 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)