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: "optimal beamforming for gaussian mimo wiretap channels with two transmit antennas"
  Abstract: A Gaussian multiple-input multiple-output wiretap channel in which the eavesdropper and legitimate receiver are equipped with arbitrary numbers of antennas and the transmitter has two antennas is studied in this paper. Under an average power constraint, the optimal input covariance to obtain the secrecy capacity of this channel is unknown, in general. In this paper, the input covariance matrix required to achieve the capacity is determined. It is shown that the secrecy capacity of this channel can be achieved by linear precoding. The optimal precoding and power allocation schemes that maximize the achievable secrecy rate, and thus achieve the capacity, are developed subsequently. The secrecy capacity is then compared with the achievable secrecy rate of generalized singular value decomposition (GSVD)-based precoding, which is the best previously proposed technique for this problem. Numerical results demonstrate that substantial gain can be obtained in secrecy rate between the proposed and GSVD-based precodings.

Connected through hyperedge HE-1 (induced by source paper "interplay between noma and other emerging technologies a survey"):
  with members:
    - "secure relaying in non orthogonal multiple access trusted and untrusted scenarios"
    - "securing downlink massive mimo noma networks with artificial noise"
    - "lens based millimeter wave reconfigurable antenna noma"
    - "what role can noma play in massive mimo"
    - "noma an information theoretic perspective"
    - "joint power and time allocation for noma mec offloading"
    - "multi beam noma for hybrid mmwave systems"
    - "exploiting full half duplex user relaying in noma systems"

Connected through hyperedge HE-2 (induced by source paper "noma an information theoretic perspective"):
  with members:
    - "rate splitting multiple access for downlink communication systems bridging generalizing and outperforming sdma and noma"
    - "power domain non orthogonal multiple access noma in 5g systems potentials and challenges"
    - "approximate capacity region of the mac ic mac"
    - "gsvd based precoding in mimo systems with integrated services"
    - "non orthogonal multiple access in multi cell networks theory performance and practical challenges"
    - "the application of mimo to non orthogonal multiple access"
    - "fairness for non orthogonal multiple access in 5g systems"
    - "a general mimo framework for noma downlink and uplink transmission based on signal alignment"

Connected through hyperedge HE-3 (induced by source paper "deep learning based precoding for the mimo gaussian wiretap channel"):
  with members:
    - "a rotation based method for precoding in gaussian mimome channels"
    - "interplay between noma and other emerging technologies a survey"
    - "end to end learning of communications systems without a channel model"
    - "deep learning for the gaussian wiretap channel"
    - "deep learning in mobile and wireless networking a survey"
    - "an introduction to deep learning for the physical layer"
    - "deep residual learning for image recognition"
    - "delving deep into rectifiers surpassing human level performance on imagenet classification"

Connected through hyperedge HE-4 (induced by source paper "a rotation based method for precoding in gaussian mimome channels"):
  with members:
    - "noma an information theoretic perspective"
    - "optimal signaling for secure communications over gaussian mimo wiretap channels"
    - "an algorithm for global maximization of secrecy rates in gaussian mimo wiretap channels"
    - "full rank solutions for the mimo gaussian wiretap channel with an average power constraint"
    - "cooperative jamming for secure communications in mimo relay networks"
    - "towards the secrecy capacity of the gaussian mimo wire tap channel the 2 2 1 channel"
    - "transmitter optimization for achieving secrecy capacity in gaussian mimo wiretap channels"
    - "the secrecy capacity of the mimo wiretap channel"

Connected through hyperedge HE-5 (induced by source paper "security reliability tradeoff for distributed antenna systems in heterogeneous cellular networks"):
  with members:
    - "game based approach for qos provisioning and interference management in heterogeneous networks"
    - "intelligent interference exploitation for heterogeneous cellular networks against eavesdropping"
    - "energy efficiency analysis of heterogeneous cellular networks with extra cell range expansion"
    - "secrecy optimized resource allocation for device to device communication underlaying heterogeneous networks"
    - "safeguarding decentralized wireless networks using full duplex jamming receivers"
    - "relay selection for wireless communications against eavesdropping a security reliability trade off perspective"
    - "a survey on wireless security technical challenges recent advances and future trends"
    - "physical layer security in heterogeneous cellular 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)