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: "relaying strategies for wireless powered mimo relay networks"
  Abstract: This paper investigates relaying schemes in an amplify-and-forward multiple-input multiple-output relay network, where an energy-constrained relay harvests wireless power from the source information flow and can be further aided by an energy flow (EF) in the form of a wireless power transfer at the destination. However, the joint optimization of the relay matrix and the source precoder for the energy-flow-assisted (EFA) and the non-EFA (NEFA) schemes is intractable. The original rate maximization problem is transformed into an equivalent weighted mean square error minimization problem and optimized iteratively, where the global optimum of the nonconvex source precoder subproblem is achieved by semidefinite relaxation and rank reduction. The iterative algorithm finally converges. Then, the simplified EFA and NEFA schemes are proposed based on channel diagonalization, such that the matrices optimizations can be simplified to power optimizations. Closed-form solutions can be achieved. Simulation results reveal that the EFA schemes can outperform the NEFA schemes. Additionally, deploying more antennas at the relay increases the dimension of the signal space at the relay. Exploiting the additional dimension, the EF leakage in the information detecting block can be nearly separated from the information signal, such that the EF leakage can be amplified with a small coefficient.

Connected through hyperedge HE-1 (induced by source paper "energy efficiency fairness for multi pair wireless powered relaying systems"):
  with members:
    - "joint power allocation and beamforming for energy efficient two way multi relay communications"
    - "energy efficiency maximization of full duplex two way relay with non ideal power amplifiers and non negligible circuit power"
    - "energy efficient beam coordination strategies with rate dependent processing power"
    - "wireless powered relays in cooperative communications time switching relaying protocols and throughput analysis"
    - "practical non linear energy harvesting model and resource allocation for swipt systems"
    - "wireless networks with rf energy harvesting a contemporary survey"
    - "energy efficiency optimization in relay assisted mimo systems with perfect and statistical csi"
    - "power allocation strategies in energy harvesting wireless cooperative networks"

Connected through hyperedge HE-2 (induced by source paper "secure swipt for directional modulation aided af relaying networks"):
  with members:
    - "spectral and energy efficient wireless powered iot networks noma or tdma"
    - "an overview of sustainable green 5g networks"
    - "a survey on wireless security technical challenges recent advances and future trends"
    - "secrecy wireless information and power transfer challenges and opportunities"
    - "to harvest and jam a paradigm of self sustaining friendly jammers for secure af relaying"
    - "relay selection improves the security reliability trade off in cognitive radio systems"
    - "noncoherent relaying in energy harvesting communication systems"
    - "robust beamforming for secure communication in systems with wireless information and power transfer"

Connected through hyperedge HE-3 (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"
    - "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"
    - "harvest then cooperate wireless powered cooperative communications"

Connected through hyperedge HE-4 (induced by source paper "joint resource allocation in swipt based multi antenna decode and forward relay networks"):
  with members:
    - "power allocation for secure swipt systems with wireless powered cooperative jamming"
    - "distributed power splitting for swipt in relay interference channels using game theory"
    - "joint wireless information and power transfer for an autonomous multiple antenna relay system"
    - "information and energy cooperation in ofdm relaying protocols and optimization"
    - "joint power splitting and antenna selection in energy harvesting relay channels"
    - "energy harvesting for physical layer security in ofdma networks"
    - "enhancing wireless information and power transfer by exploiting multi antenna techniques"
    - "wireless information and energy transfer for two hop non regenerative mimo ofdm relay networks"

Connected through hyperedge HE-5 (induced by source paper "large scale multiantenna multisine wireless power transfer"):
  with members:
    - "low complexity adaptive multisine waveform design for wireless power transfer"
    - "waveform design for wireless power transfer"
    - "waveform optimization for large scale multi antenna multi sine wireless power transfer"
    - "communications and signals design for wireless power transmission"
    - "massive mimo multicasting in noncooperative cellular networks"
    - "energy beamforming with one bit feedback"
    - "optimized training design for wireless energy transfer"
    - "wireless information and power transfer architecture design and rate energy tradeoff"

Connected through hyperedge HE-6 (induced by source paper "wireless information and power transfer over an awgn channel nonlinearity and asymmetric gaussian signaling"):
  with members:
    - "waveform design for wireless power transfer"
    - "waveform optimization for swipt with nonlinear energy harvester modeling"
    - "waveform and transceiver design for simultaneous wireless information and power transfer"
    - "relaying protocols for wireless energy harvesting and information processing"
    - "mimo broadcasting for simultaneous wireless information and power transfer"

Connected through hyperedge HE-7 (induced by source paper "wireless information and power transfer nonlinearity waveform design and rate energy tradeoff"):
  with members:
    - "waveform design for wireless power transfer with limited feedback"
    - "wirelessly powered backscatter communications waveform design and snr energy tradeoff"
    - "large scale multiantenna multisine wireless power transfer"
    - "wireless information and power transfer over an awgn channel nonlinearity and asymmetric gaussian signaling"
    - "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 optimization for radio frequency wireless power transfer"
    - "waveform design for wireless 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)