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: "multi antenna relay aided wireless physical layer security"
  Abstract: With the growing popularity of mobile Internet, providing secure wireless services has become a critical issue. Physical layer security (PHY-security) has been recognized as an effective means to enhance wireless security by exploiting wireless medium characteristics, for example, fading, noise, and interference. A particularly interesting PHY-security technology is cooperative relay due to the fact that it helps to provide distributed diversity and shorten access distance. This article offers a tutorial on various multi-antenna relaying technologies to improve security at physical layer. The state-of-the-art research results on multi-antenna relay aided PHY-security as well as some secrecy performance optimization schemes are presented. In particular, we focus on large-scale MIMO relaying technology, which is effective in tackling various challenging issues for implementing wireless PHY-security, such as short-distance interception without eavesdropper CSI and with imperfect legitimate CSI. Moreover, the future directions are identified for further enhancement of secrecy performance.

Connected through hyperedge HE-1 (induced by source paper "secrecy outage analysis of non orthogonal spectrum sharing for heterogeneous cellular networks"):
  with members:
    - "security reliability tradeoff for distributed antenna systems in heterogeneous cellular networks"
    - "intelligent interference exploitation for heterogeneous cellular networks against eavesdropping"
    - "power domain non orthogonal multiple access noma in 5g systems potentials and challenges"
    - "a new look at physical layer security caching and wireless energy harvesting for heterogeneous ultra dense networks"
    - "physical layer security for spectrum sharing systems"
    - "artificial noise aided secure transmission in large scale spectrum sharing networks"
    - "location based beamforming and physical layer security in rician wiretap channels"
    - "physical layer security in millimeter wave cellular networks"

Connected through hyperedge HE-2 (induced by source paper "fixed region beamforming using frequency diverse subarray for secure mmwave wireless communications"):
  with members:
    - "a survey of physical layer security techniques for 5g wireless networks and challenges ahead"
    - "safeguarding millimeter wave communications against randomly located eavesdroppers"
    - "a survey on wireless security technical challenges recent advances and future trends"
    - "secure communications in millimeter wave ad hoc networks"
    - "robust beamforming for secure communication in systems with wireless information and power transfer"
    - "millimeter wave channel modeling and cellular capacity evaluation"

Connected through hyperedge HE-3 (induced by source paper "secure communications in noma system subcarrier assignment and power allocation"):
  with members:
    - "secure transmission with large numbers of antennas and finite alphabet inputs"
    - "sub channel assignment power allocation and user scheduling for non orthogonal multiple access networks"
    - "on the spectral efficiency and security enhancements of noma assisted multicast unicast streaming"
    - "secrecy wireless information and power transfer in fading wiretap channel"
    - "optimal joint power and subcarrier allocation for full duplex multicarrier non orthogonal multiple access systems"
    - "power and channel allocation for non orthogonal multiple access in 5g systems tractability and computation"
    - "multi phase smart relaying and cooperative jamming in secure cognitive radio networks"
    - "secure massive mimo transmission with an active eavesdropper"

Connected through hyperedge HE-4 (induced by source paper "physical layer service integration in 5g potentials and challenges"):
  with members:
    - "fundamental green tradeoffs progresses challenges and impacts on 5g networks"
    - "an overview of sustainable green 5g networks"
    - "gsvd based precoding in mimo systems with integrated services"
    - "robust artificial noise aided transmit design for multi user miso systems with integrated services"
    - "wireless powered communication opportunities and challenges"
    - "enhancing wireless information and power transfer by exploiting multi antenna techniques"
    - "simultaneous wireless information and power transfer in modern communication systems"
    - "wireless networks with rf energy harvesting a contemporary survey"

Connected through hyperedge HE-5 (induced by source paper "secure transmission with large numbers of antennas and finite alphabet inputs"):
  with members:
    - "physical layer security for spectrum sharing systems"
    - "linear precoding of data and artificial noise in secure massive mimo systems"
    - "a survey on wireless security technical challenges recent advances and future trends"
    - "secure massive mimo transmission with an active eavesdropper"
    - "large scale mimo relaying techniques for physical layer security af or df"
    - "low complexity mimo precoding with discrete signals and statistical csi"
    - "linear precoding for the mimo multiple access channel with finite alphabet inputs and statistical csi"
    - "dealing with interference in distributed large scale mimo systems a statistical approach"

Connected through hyperedge HE-6 (induced by source paper "robust and secure resource allocation for full duplex miso multicarrier noma systems"):
  with members:
    - "optimal resource allocation for power efficient mc noma with imperfect channel state information"
    - "resource allocation for secure full duplex ofdma radio systems"
    - "on optimal power allocation for downlink non orthogonal multiple access systems"
    - "secrecy sum rate maximization in non orthogonal multiple access"
    - "on the spectral efficiency and security enhancements of noma assisted multicast unicast streaming"
    - "optimal joint power and subcarrier allocation for full duplex multicarrier non orthogonal multiple access systems"
    - "sub channel and power allocation for non orthogonal multiple access relay networks with amplify and forward protocol"
    - "power and channel allocation for non orthogonal multiple access in 5g systems tractability and computation"

Connected through hyperedge HE-7 (induced by source paper "robust chance constrained optimization for power efficient and secure swipt systems"):
  with members:
    - "probabilistically robust swipt for secrecy misome systems"
    - "robust resource allocation for mimo wireless powered communication networks based on a non linear eh model"
    - "robust an aided beamforming and power splitting design for secure miso cognitive radio with swipt"
    - "safe and secure wireless power transfer networks challenges and opportunities in rf based systems"
    - "wireless powered communication networks an overview"
    - "multi objective resource allocation in full duplex swipt systems"
    - "secrecy wireless information and power transfer challenges and opportunities"
    - "ambient rf energy harvesting in ultra dense small cell networks performance and trade offs"

Connected through hyperedge HE-8 (induced by source paper "power constrained secrecy rate maximization for joint relay and jammer selection assisted wireless networks"):
  with members:
    - "a survey on wireless security technical challenges recent advances and future trends"
    - "joint relay and jammer selection improves the physical layer security in the face of csi feedback delays"
    - "improving physical layer security in wireless communications using diversity techniques"
    - "optimization of code rates in sisome wiretap channels"
    - "optimal relay selection for physical layer security in cooperative wireless networks"
    - "on cooperative relaying schemes for wireless physical layer security"
    - "joint relay and jammer selection for secure two way relay networks"
    - "cooperative jamming for secure communications in mimo relay 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)