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: "robust secure transmission of using main lobe integration based leakage beamforming in directional modulation mu mimo systems"
  Abstract: In this paper, we make an investigation of robust beamforming for secure directional modulation in the multiuser multiple-input and multiple-output systems in the presence of direction angle measurement errors. When statistical knowledge of direction angle measurement errors is unavailable, a novel robust beamforming scheme of combining main-lobe-integration and leakage is proposed to simultaneously transmit multiple different independent parallel confidential message streams to the associated multiple distinct desired users. The proposed scheme includes two steps: designing the beamforming vectors of the useful confidential messages and constructing artificial noise (AN) projection matrix. Here, in its first step, the beamforming vectors for the useful confidential messages of desired user   $k$   are given by minimizing the useful signal power leakage from the main-lobe of desired user   $k$    to the sum of main-lobes of the remaining desired directions plus main-lobes of all eavesdropper directions. In its second step, the AN projection matrix is constructed by simultaneously maximizing the AN power leakage to all eavesdropper directions such that all eavesdroppers are disrupted seriously, where AN is viewed by the transmitter as a useful signal for eavesdroppers. Due to independent beamforming vectors for different desired users, a more secure transmission is achieved. Compared with conventional nonrobust methods, the proposed method can provide a significant improvement in bit error rate along the desired directions and secrecy-sum-rate toward multiple desired users without needing the statistical property or distribution of angle measurement errors.

Connected through hyperedge HE-1 (induced by source paper "energy efficient alternating iterative secure structure of maximizing secrecy rate for directional modulation networks"):
  with members:
    - "alternating iterative secure structure between beamforming and power allocation for uav aided directional modulation networks"
    - "secure transmission with large numbers of antennas and finite alphabet inputs"
    - "artificial noise aided secure multicast precoding for directional modulation systems"
    - "low complexity and high resolution doa estimation for hybrid analog and digital massive mimo receive array"
    - "artificial noise aided secure transmission with directional modulation based on random frequency diverse arrays"
    - "optimal power allocation for artificial noise under imperfect csi against spatially random eavesdroppers"
    - "an overview of sustainable green 5g networks"
    - "secure massive mimo transmission in the presence of an active eavesdropper"

Connected through hyperedge HE-2 (induced by source paper "optimal power allocation for secure directional modulation networks with a full duplex uav user"):
  with members:
    - "secure uav communication with cooperative jamming and trajectory control"
    - "secure transmission with large numbers of antennas and finite alphabet inputs"
    - "joint trajectory and communication design for multi uav enabled wireless networks"
    - "securing uav communications via trajectory optimization"
    - "low complexity and high resolution doa estimation for hybrid analog and digital massive mimo receive array"
    - "wireless communications with unmanned aerial vehicles opportunities and challenges"
    - "relay selection improves the security reliability trade off in cognitive radio systems"

Connected through hyperedge HE-3 (induced by source paper "performance analysis of directional modulation with finite quantized rf phase shifters in analog beamforming structure"):
  with members:
    - "artificial noise aided secure multicast precoding for directional modulation systems"
    - "channel estimation and hybrid precoding for millimeter wave cellular systems"
    - "spatially sparse precoding in millimeter wave mimo systems"
    - "improving physical layer secrecy using full duplex jamming receivers"
    - "millimeter wave beamforming for wireless backhaul and access in small cell networks"
    - "coding the beams improving beamforming training in mmwave communication system"

Connected through hyperedge HE-4 (induced by source paper "artificial noisy mimo systems under correlated scattering rayleigh fading a physical layer security approach"):
  with members:
    - "enhancing the physical layer security of non orthogonal multiple access in large scale networks"
    - "artificial noise revisited"
    - "training and feedback optimization for multiuser mimo downlink"
    - "the secrecy capacity of the mimo wiretap channel"
    - "capacity and character expansions moment generating function and other exact results for mimo correlated channels"

Connected through hyperedge HE-5 (induced by source paper "alternating iterative secure structure between beamforming and power allocation for uav aided directional modulation networks"):
  with members:
    - "secure transmission with large numbers of antennas and finite alphabet inputs"
    - "joint trajectory and communication design for multi uav enabled wireless networks"
    - "artificial noise aided secure multicast precoding for directional modulation systems"
    - "interference alignment and soft space reuse based cooperative transmission for multi cell massive mimo networks"
    - "low complexity and high resolution doa estimation for hybrid analog and digital massive mimo receive array"
    - "overcoming endurance issue uav enabled communications with proactive caching"
    - "energy efficient uav communication with trajectory optimization"
    - "artificial noise aided secure transmission with directional modulation based on random frequency diverse arrays"

Connected through hyperedge HE-6 (induced by source paper "machine learning based high resolution doa measurement and robust dm for hybrid analog digital massive mimo transceiver"):
  with members:
    - "secure swipt for directional modulation aided af relaying networks"
    - "broadband doa estimation using convolutional neural networks trained with noise signals"
    - "hybrid analog and digital beamforming for mmwave ofdm large scale antenna arrays"
    - "alternating minimization algorithms for hybrid precoding in millimeter wave mimo systems"
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "transmit energy focusing for doa estimation in mimo radar with colocated antennas"

Connected through hyperedge HE-7 (induced by source paper "robust directional modulation design for secrecy rate maximization in multi user networks"):
  with members:
    - "secure routing with power optimization for ad hoc networks"
    - "physical layer security for spectrum sharing systems"
    - "a survey on wireless security technical challenges recent advances and future trends"
    - "physical layer security in heterogeneous cellular networks"

Connected through hyperedge HE-8 (induced by source paper "power allocation strategy of maximizing secrecy rate for secure directional modulation"):
  with members:
    - "artificial noise aided secure transmission in wiretap channels with transmitter side correlation"
    - "directional modulation via symbol level precoding a way to enhance security"
    - "relay selection improves the security reliability trade off in cognitive radio systems"
    - "secure massive mimo transmission in the presence of an active eavesdropper"

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)