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: "waveform optimization for radio frequency wireless power transfer"
  Abstract: In this paper, we study the waveform design problem for a single-input single-output (SISO) radio-frequency (RF) wireless power transfer (WPT) system in frequency-selective channels. First, based on the actual non-linear current-voltage model of the diode at the energy receiver, we derive a semi-closed-form expression for the deliverable DC voltage in terms of the incident RF signal and hence obtain the average harvested power. Next, by adopting a multisine waveform structure for the transmit signal of the energy transmitter, we jointly design the multisine signal amplitudes and phases overall frequency tones according to the channel state information (CSI) to maximize the deliverable DC voltage or harvested power. Although our formulated problem is non-convex and difficult to solve, we propose two suboptimal solutions to it, based on the frequency-domain maximal ratio transmission (MRT) principle and the sequential convex optimization (SCP) technique, respectively. Using various simulations, the performance gain of our solutions over the existing waveform designs is shown.

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 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"
    - "wireless powered communication networks an overview"

Connected through hyperedge HE-2 (induced by source paper "multi tone signal optimization for wireless power transfer in the presence of wireless communication links"):
  with members:
    - "retrodirective multi user wireless power transfer with massive mimo"
    - "low complexity adaptive multisine waveform design for wireless power transfer"
    - "waveform design for wireless power transfer"
    - "waveform optimization for swipt with nonlinear energy harvester modeling"
    - "wireless powered communication opportunities and challenges"
    - "practical non linear energy harvesting model and resource allocation for swipt systems"
    - "multi antenna wireless energy transfer for backscatter communication systems"
    - "simultaneous wireless information and power transfer in a two user ofdm interference channel"

Connected through hyperedge HE-3 (induced by source paper "conditional capacity and transmit signal design for swipt systems with multiple nonlinear energy harvesting receivers"):
  with members:
    - "fundamentals of wireless information and power transfer from rf energy harvester models to signal and system designs"
    - "on the capacity of swipt systems with a nonlinear energy harvesting circuit"
    - "on capacity achieving distributions over complex awgn channels under nonlinear power constraints and their applications to swipt"
    - "wireless information and power transfer over an awgn channel nonlinearity and asymmetric gaussian signaling"
    - "waveform design for wireless power transfer"
    - "wireless information and power transfer nonlinearity waveform design and rate energy tradeoff"
    - "practical non linear energy harvesting model and resource allocation for swipt systems"
    - "capacity of the gaussian two hop full duplex relay channel with residual self interference"

Connected through hyperedge HE-4 (induced by source paper "on the beneficial roles of fading and transmit diversity in wireless power transfer with nonlinear energy harvesting"):
  with members:
    - "fundamentals of wireless information and power transfer from rf energy harvester models to signal and system designs"
    - "sensitive and nonlinear far field rf energy harvesting in wireless communications"
    - "waveform design for wireless power transfer with limited feedback"
    - "large scale multiantenna multisine wireless power transfer"
    - "on capacity achieving distributions over complex awgn channels under nonlinear power constraints and their applications to swipt"
    - "wireless information and power transfer over an awgn channel nonlinearity and asymmetric gaussian signaling"
    - "low complexity adaptive multisine waveform design for wireless power transfer"
    - "waveform design for wireless power transfer"

Connected through hyperedge HE-5 (induced by source paper "wireless powered cooperative jamming for secure ofdm system"):
  with members:
    - "waveform design for wireless power transfer"
    - "secrecy wireless information and power transfer in fading wiretap channel"
    - "a general design framework for mimo wireless energy transfer with limited feedback"
    - "wireless power transfer in massive mimo aided hetnets with user association"
    - "accumulate and jam towards secure communication via a wireless powered full duplex jammer"
    - "communications and signals design for wireless power transmission"
    - "to harvest and jam a paradigm of self sustaining friendly jammers for secure af relaying"
    - "wireless powered communication opportunities and challenges"

Connected through hyperedge HE-6 (induced by source paper "uav enabled wireless power transfer trajectory design and energy optimization"):
  with members:
    - "uav enabled wireless power transfer trajectory design and energy region characterization"
    - "energy efficient uav communication with trajectory optimization"
    - "waveform design for wireless power transfer"
    - "robust beamforming for swipt systems with non linear energy harvesting model"
    - "distributed charging control in broadband wireless power transfer networks"
    - "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"

Connected through hyperedge HE-7 (induced by source paper "waveform design for wireless power transfer with limited feedback"):
  with members:
    - "large scale multiantenna multisine wireless power transfer"
    - "prototyping and experimentation of a closed loop wireless power transmission with channel acquisition and waveform optimization"
    - "low complexity adaptive multisine waveform design for wireless power transfer"
    - "waveform design for wireless power transfer"
    - "a general design framework for mimo wireless energy transfer with limited feedback"
    - "waveform optimization for large scale multi antenna multi sine wireless power transfer"
    - "communications and signals design for wireless power transmission"
    - "optimized training for net energy maximization in multi antenna wireless energy transfer over frequency selective channel"

Connected through hyperedge HE-8 (induced by source paper "on the capacity of swipt systems with a nonlinear energy harvesting circuit"):
  with members:
    - "wireless information and power transfer over an awgn channel nonlinearity and asymmetric gaussian signaling"
    - "waveform design for wireless power transfer"
    - "wireless information and power transfer nonlinearity waveform design and rate energy tradeoff"
    - "capacity of the gaussian two hop full duplex relay channel with residual self interference"
    - "mimo broadcasting for simultaneous wireless information and power transfer"

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)