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: "secrecy wireless information and power transfer challenges and opportunities"
  Abstract: Wireless information and power transfer (WIPT) enables more sustainable and resilient communications due to the fact that it avoids frequent battery charging and replacement. However, it also suffers from possible information interception due to the open nature of wireless channels. Compared to traditional secure communications, secrecy wireless information and power transfer (SWIPT) has several distinct characteristic features. Wireless power transfer may increase vulnerability to eavesdropping, since a power receiver as a potential eavesdropper usually has a shorter access distance than an information receiver. On the other hand, wireless power transfer can be exploited to enhance wireless security. This article reviews the security issues in various SWIPT scenarios, with an emphasis on revealing the challenges and opportunities for implementing SWIPT. Furthermore, we provide a survey on a variety of physical layer security techniques to improve secrecy performance. In particular, we propose to use massive MIMO techniques to enhance power transfer efficiency and secure information transmission simultaneously. Finally, we discuss several potential research directions to further enhance the security in SWIPT systems.

Connected through hyperedge HE-1 (induced by source paper "downlink secrecy rate of one bit massive mimo system with active eavesdropping"):
  with members:
    - "robust designs of beamforming and power splitting for distributed antenna systems with wireless energy harvesting"
    - "secure massive mimo communication with low resolution dacs"
    - "on the uplink achievable rate for massive mimo with 1 bit adc and superimposed pilots"
    - "data aided secure massive mimo transmission with active eavesdropping"
    - "secure massive mimo systems with limited rf chains"
    - "secure transmission with large numbers of antennas and finite alphabet inputs"
    - "jamming resistant receivers for the massive mimo uplink"
    - "beamforming and power splitting designs for an aided secure multi user mimo swipt systems"

Connected through hyperedge HE-2 (induced by source paper "covert transmission with a self sustained relay"):
  with members:
    - "achieving covert wireless communications using a full duplex receiver"
    - "multi hop routing in covert wireless networks"
    - "covert communication achieved by a greedy relay in wireless networks"
    - "wireless powered dense cellular networks how many small cells do we need"
    - "covert communication in fading channels under channel uncertainty"
    - "covert communications with a full duplex receiver over wireless fading channels"
    - "covert communication with finite blocklength in awgn channels"
    - "on covert communication with noise uncertainty"

Connected through hyperedge HE-3 (induced by source paper "secrecy outage of swipt in the presence of cooperating eavesdroppers"):
  with members:
    - "energy harvesting for physical layer security in ofdma networks"
    - "secrecy wireless information and power transfer with miso beamforming"
    - "wireless information and power transfer architecture design and rate energy tradeoff"

Connected through hyperedge HE-4 (induced by source paper "an overview of physical layer security with finite alphabet signaling"):
  with members:
    - "a survey of physical layer security techniques for 5g wireless networks and challenges ahead"
    - "physical layer cryptography through massive mimo"
    - "linear precoding of data and artificial noise in secure massive mimo systems"
    - "sum secrecy rate maximization for full duplex two way relay networks using alamouti based rank two beamforming"
    - "performance of lattice coset codes on universal software radio peripherals"
    - "secure m psk communication via directional modulation"
    - "finite blocklength bounds for wiretap channels"
    - "physical layer security in millimeter wave cellular networks"

Connected through hyperedge HE-5 (induced by source paper "on the secrecy performance of swipt receiver architectures with multiple eavesdroppers"):
  with members:
    - "secrecy outage for wireless sensor networks"
    - "secrecy outage of swipt in the presence of cooperating eavesdroppers"
    - "secure communications with cooperative jamming optimal power allocation and secrecy outage analysis"
    - "physical layer security jamming theoretical limits and practical designs in wireless networks"
    - "artificial noise aided secrecy information and power transfer in ofdma systems"
    - "simultaneous wireless information and power transfer in modern communication systems"
    - "opportunistic wireless energy harvesting in cognitive radio networks"
    - "simultaneous information and power transfer for broadband wireless systems"

Connected through hyperedge HE-6 (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"
    - "relaying strategies for wireless powered mimo relay networks"
    - "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-7 (induced by source paper "robust secure transmission of using main lobe integration based leakage beamforming in directional modulation mu mimo systems"):
  with members:
    - "relay selection improves the security reliability trade off in cognitive radio systems"
    - "robust beamforming for security in mimo wiretap channels with imperfect csi"
    - "the secrecy capacity of the mimo wiretap channel"

Connected through hyperedge HE-8 (induced by source paper "power efficient and secure wpcns with hardware impairments and non linear eh circuit"):
  with members:
    - "spectral efficiency of multipair massive mimo two way relaying with hardware impairments"
    - "fundamental green tradeoffs progresses challenges and impacts on 5g networks"
    - "max min fair beamforming for swipt systems with non linear eh model"
    - "power allocation for secure swipt systems with wireless powered cooperative jamming"
    - "robust resource allocation for mimo wireless powered communication networks based on a non linear eh model"
    - "analysis and design of secure massive mimo systems in the presence of hardware impairments"
    - "on the spectral efficiency of massive mimo systems with low resolution adcs"
    - "wireless powered communication networks an overview"

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)