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: "multiuser mimo wireless energy transfer with coexisting opportunistic communication"
  Abstract: This letter considers spectrum sharing between a primary multiuser multiple-input multiple-output (MIMO) wireless energy transfer (WET) system and a coexisting secondary point-to-point MIMO wireless information transmission (WIT) system, where WET generates interference to WIT and degrades its throughput performance. We show that due to the interference, the WIT system suffers from a loss of the degrees of freedom (DoF) proportional to the number of energy beams sent by the energy transmitter (ET), which, in general, needs to be larger than one in order to optimize the multiuser WET with user fairness consideration. To minimize the DoF loss in WIT, we further propose a new single-beam energy transmission scheme based on the principle of time sharing, where the ET transmits one of the optimal energy beams at each time. This new scheme achieves the same optimal performance for the WET system, and minimizes the impact of its interference to the WIT system.

Connected through hyperedge HE-1 (induced by source paper "cognitive wireless power transfer in the presence of reactive primary communication user"):
  with members:
    - "fundamentals of wireless information and power transfer from rf energy harvester models to signal and system designs"
    - "large scale multiantenna multisine wireless power transfer"
    - "distributed wireless power transfer with energy feedback"
    - "joint offloading and computing optimization in wireless powered mobile edge computing systems"
    - "waveform optimization for radio frequency wireless power transfer"
    - "waveform design for wireless power transfer"
    - "surveillance and intervention of infrastructure free mobile communications a new wireless security paradigm"
    - "a general design framework for mimo wireless energy transfer with limited feedback"

Connected through hyperedge HE-2 (induced by source paper "robust transmissions in wireless powered multi relay networks with chance interference constraints"):
  with members:
    - "optimization of a power splitting protocol for two way multiple energy harvesting relay system"
    - "from d2d to ds2d prolonging the battery life of mobile devices via ds2d communications"
    - "an overview of sustainable green 5g networks"
    - "separation framework an enabler for cooperative and d2d communication for future 5g networks"
    - "practical non linear energy harvesting model and resource allocation for swipt systems"
    - "wireless networks with rf energy harvesting a contemporary survey"
    - "distributed resource allocation for relay aided device to device communication a message passing approach"
    - "physical layer multicasting by stochastic transmit beamforming and alamouti space time coding"

Connected through hyperedge HE-3 (induced by source paper "wireless energy beamforming using received signal strength indicator feedback"):
  with members:
    - "a general design framework for mimo wireless energy transfer with limited feedback"
    - "wireless powered communication opportunities and challenges"
    - "throughput optimization for massive mimo systems powered by wireless energy transfer"
    - "enhancing wireless information and power transfer by exploiting multi antenna techniques"
    - "optimized training for net energy maximization in multi antenna wireless energy transfer over frequency selective channel"
    - "energy beamforming with one bit feedback"
    - "optimized training design for wireless energy transfer"
    - "dynamic resource allocation for multiple antenna wireless 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"
    - "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"
    - "energy efficient optimization for wireless information and power transfer in large scale mimo systems employing energy beamforming"
    - "mimo broadcasting for simultaneous wireless information and power transfer"

Connected through hyperedge HE-5 (induced by source paper "optimal energy beamforming under per antenna power constraint"):
  with members:
    - "wireless energy beamforming using received signal strength indicator feedback"
    - "distributed wireless power transfer with energy feedback"
    - "retrodirective multi user wireless power transfer with massive mimo"
    - "communications and signals design for wireless power transmission"
    - "wireless powered communication opportunities and challenges"
    - "collaborative wireless energy and information transfer in interference channel"
    - "enhancing wireless information and power transfer by exploiting multi antenna techniques"
    - "energy beamforming with one bit feedback"

Connected through hyperedge HE-6 (induced by source paper "uav enabled wireless power transfer trajectory design and energy region characterization"):
  with members:
    - "waveform design for wireless power transfer"
    - "a general design framework for mimo wireless energy transfer with limited feedback"
    - "wireless communications with unmanned aerial vehicles opportunities and challenges"
    - "communications and signals design for wireless power transmission"
    - "wireless powered communication opportunities and challenges"
    - "energy beamforming with one bit feedback"
    - "optimized training design for wireless energy transfer"
    - "multiuser miso beamforming for simultaneous wireless information and power transfer"

Connected through hyperedge HE-7 (induced by source paper "theory and experiment for wireless powered sensor networks how to keep sensors alive"):
  with members:
    - "experiment modeling and analysis of wireless powered sensor network for energy neutral power management"
    - "distributed charging control in broadband wireless power transfer networks"
    - "adaptively directional wireless power transfer for large scale sensor networks"
    - "communications and signals design for wireless power transmission"
    - "joint beamforming design for multi user wireless information and power transfer"
    - "joint transmit beamforming and receive power splitting for miso swipt systems"
    - "application of smart antenna technologies in simultaneous wireless information and power transfer"
    - "multi antenna wireless powered communication with energy beamforming"

Connected through hyperedge HE-8 (induced by source paper "user cooperation for enhanced throughput fairness in wireless powered communication networks"):
  with members:
    - "distributed charging control in broadband wireless power transfer networks"
    - "wireless powered communication networks an overview"
    - "wireless powered communication opportunities and challenges"
    - "wireless powered relays in cooperative communications time switching relaying protocols and throughput analysis"
    - "placement optimization of energy and information access points in wireless powered communication networks"
    - "spatial throughput maximization of wireless powered communication networks"
    - "harvest then cooperate wireless powered cooperative communications"
    - "user cooperation in wireless powered communication 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)