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: "optimization and analysis of wireless powered multi antenna cooperative systems"
  Abstract: In this paper, we consider a three-node cooperative wireless powered communication system consisting of a multi-antenna hybrid access point (H-AP) and a single-antenna relay and a single-antenna user. The energy constrained relay and user first harvest energy in the downlink and then the relay assists the user using the harvested power for information transmission in the uplink. The optimal energy beamforming vector and the time split between harvest and cooperation are investigated. To reduce the computational complexity, suboptimal designs are also studied, where closed-form expressions are derived for the energy beamforming vector and the time split. For comparison purposes, we also present a detailed performance analysis in terms of the achievable outage probability and the average throughput of an intuitive energy beamforming scheme, where the H-AP directs all the energy towards the user. The findings of the paper suggest that implementing multiple antennas at the H-AP can significantly improve the system performance, and the closed-form suboptimal energy beamforming vector and time split yields near optimal performance. Also, for the intuitive beamforming scheme, a diversity order of (N+1)/2 can be achieved, where N is the number of antennas at the H-AP.

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"
    - "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"
    - "wireless powered communication opportunities and challenges"

Connected through hyperedge HE-2 (induced by source paper "optimizing throughput fairness of cluster based cooperation in underlay cognitive wpcns"):
  with members:
    - "throughput maximization for uav enabled wireless powered communication networks"
    - "multi antenna enabled cluster based cooperation in wireless powered communication networks"
    - "user cooperation for enhanced throughput fairness in wireless powered communication networks"
    - "distributed charging control in broadband wireless power transfer networks"
    - "wireless powered communication networks an overview"
    - "wireless powered communication opportunities and challenges"
    - "placement optimization of energy and information access points in wireless powered communication networks"
    - "cognitive wireless powered network spectrum sharing models and throughput maximization"

Connected through hyperedge HE-3 (induced by source paper "multi antenna enabled cluster based cooperation in wireless powered communication networks"):
  with members:
    - "group cooperation with optimal resource allocation in wireless powered communication networks"
    - "user cooperation for enhanced throughput fairness in wireless powered communication networks"
    - "distributed charging control in broadband wireless power transfer networks"
    - "wireless powered communication networks an overview"
    - "wireless powered communication opportunities and challenges"
    - "placement optimization of energy and information access points in wireless powered communication networks"
    - "throughput optimization for massive mimo systems powered by wireless energy transfer"
    - "harvest then cooperate wireless powered cooperative communications"

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)