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: "energy efficient optimization for wireless information and power transfer in large scale mimo systems employing energy beamforming"
  Abstract: In this letter, we consider a large-scale multiple-input multiple-output (MIMO) system where the receiver should harvest energy from the transmitter by wireless power transfer to support its wireless information transmission. The energy beamforming in the large-scale MIMO system is utilized to address the challenging problem of long-distance wireless power transfer. Furthermore, considering the limitation of the power in such a system, this letter focuses on the maximization of the energy efficiency of information transmission (bit per Joule) while satisfying the quality-of-service (QoS) requirement, i.e. delay constraint, by jointly optimizing transfer duration and transmit power. By solving the optimization problem, we derive an energy-efficient resource allocation scheme. Numerical results validate the effectiveness of the proposed scheme.

Connected through hyperedge HE-1 (induced by source paper "transmission delay minimization in wireless powered communication systems"):
  with members:
    - "power allocation and effective capacity of af successive relays"
    - "optimization and analysis of wireless powered multi antenna cooperative systems"
    - "cross layer optimization for ultra reliable and low latency radio access networks"
    - "wireless powered dual hop multi antenna relaying systems impact of csi and antenna correlation"
    - "effective capacity of receive antenna selection mimo ostbc systems in co channel interference"
    - "wireless charging technologies fundamentals standards and network applications"
    - "wireless powered communication networks an overview"
    - "some new research trends in wirelessly powered communications"

Connected through hyperedge HE-2 (induced by source paper "optimization of power transfer efficiency and energy efficiency for wireless powered systems with massive mimo"):
  with members:
    - "robust resource allocation for mimo wireless powered communication networks based on a non linear eh model"
    - "on the feasibility of wireless energy transfer using massive antenna arrays"
    - "communications and signals design for wireless power transmission"
    - "wireless powered communication opportunities and challenges"
    - "practical non linear energy harvesting model and resource allocation for swipt systems"
    - "energy harvesting wireless communications a review of recent advances"
    - "on the efficiency of far field wireless power transfer"
    - "powering the next billion devices with wi fi"

Connected through hyperedge HE-3 (induced by source paper "maximizing ergodic throughput in wireless powered communication networks"):
  with members:
    - "beamforming optimization for full duplex wireless powered mimo systems"
    - "wireless power meets energy harvesting a joint energy allocation approach in ofdm based system"
    - "wireless powered communication networks an overview"
    - "throughput optimization for massive mimo systems powered by wireless energy transfer"
    - "joint beamforming design and time allocation for wireless powered communication networks"
    - "optimized training design for wireless energy transfer"
    - "throughput maximization in wireless powered communication networks"
    - "mimo broadcasting for simultaneous wireless information and power transfer"

Connected through hyperedge HE-4 (induced by source paper "wireless energy transfer to a pair of energy receivers using signal strength feedback"):
  with members:
    - "wireless energy beamforming using received signal strength indicator feedback"
    - "enhancing wireless information and power transfer by exploiting multi antenna techniques"
    - "multiuser mimo wireless energy transfer with coexisting opportunistic communication"
    - "optimized training for net energy maximization in multi antenna wireless energy transfer over frequency selective channel"
    - "energy beamforming with one bit feedback"
    - "wireless networks with rf energy harvesting a contemporary survey"
    - "mimo broadcasting for simultaneous wireless information and power transfer"

Connected through hyperedge HE-5 (induced by source paper "optimization and analysis of wireless powered multi antenna cooperative systems"):
  with members:
    - "on the performance of multi antenna wireless powered communications with energy beamforming"
    - "relaying strategies for wireless powered mimo relay networks"
    - "wireless powered communication opportunities and challenges"
    - "on the efficiency of far field wireless power transfer"
    - "wireless powered communications performance analysis and optimization"
    - "energy efficient resource allocation for wireless powered communication networks"
    - "optimum wirelessly powered relaying"
    - "spatial throughput maximization of wireless powered communication networks"

Connected through hyperedge HE-6 (induced by source paper "secure swipt networks based on a non linear energy harvesting model"):
  with members:
    - "robust layered transmission in secure miso multiuser unicast cognitive radio systems"
    - "secrecy wireless information and power transfer challenges and opportunities"
    - "practical non linear energy harvesting model and resource allocation for swipt systems"
    - "energy efficient resource allocation for wireless powered communication networks"
    - "enhancing wireless information and power transfer by exploiting multi antenna techniques"
    - "multi objective optimization for robust power efficient and secure full duplex wireless communication systems"
    - "robust beamforming for secure communication in systems with wireless information and power transfer"
    - "simultaneous wireless information and power transfer in modern communication systems"

Connected through hyperedge HE-7 (induced by source paper "max min fair beamforming for swipt systems with non linear eh model"):
  with members:
    - "secure swipt networks based on a non linear energy harvesting model"
    - "robust resource allocation for mimo wireless powered communication networks based on a non linear eh model"
    - "practical non linear energy harvesting model and resource allocation for swipt systems"
    - "enhancing wireless information and power transfer by exploiting multi antenna techniques"
    - "robust beamforming for secure communication in systems with wireless information and power transfer"
    - "secure and green swipt in distributed antenna networks with limited backhaul capacity"
    - "max min fair wireless energy transfer for secure multiuser communication systems"
    - "secrecy wireless information and power transfer with miso beamforming"

Connected through hyperedge HE-8 (induced by source paper "wireless power transfer in massive mimo aided hetnets with user association"):
  with members:
    - "user association in massive mimo hetnets"
    - "user association in 5g networks a survey and an outlook"
    - "joint downlink cell association and bandwidth allocation for wireless backhauling in two tier hetnets with large scale antenna arrays"
    - "millimeter wave energy harvesting"
    - "performance analysis of simultaneous wireless information and power transfer with ambient rf energy harvesting"
    - "why to decouple the uplink and downlink in cellular networks and how to do it"
    - "5g cellular key enabling technologies and research challenges"
    - "millimeter wave power transfer and information transmission"

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)