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: "power allocation and time domain artificial noise design for wiretap ofdm with discrete inputs"
  Abstract: Optimal power allocation for orthogonal frequency division multiplexing (OFDM) wiretap channels with Gaussian channel inputs has already been studied in some previous works from an information theoretical viewpoint. However, these results are not sufficient for practical system designs. One reason is that discrete channel inputs, such as quadrature amplitude modulation (QAM) signals, instead of Gaussian channel inputs, are deployed in current practical wireless systems to maintain moderate peak transmission power and receiver complexity. In this paper, we investigate the power allocation and artificial noise design for OFDM wiretap channels with discrete channel inputs. We first prove that the secrecy rate function for discrete channel inputs is nonconcave with respect to the transmission power. To resolve the corresponding nonconvex secrecy rate maximization problem, we develop a low-complexity power allocation algorithm, which yields a duality gap diminishing in the order of O(1/√N), where N is the number of subcarriers of OFDM. We then show that independent frequency-domain artificial noise cannot improve the secrecy rate of single-antenna wiretap channels. Towards this end, we propose a novel time-domain artificial noise design which exploits temporal degrees of freedom provided by the cyclic prefix of OFDM systems to jam the eavesdropper and boost the secrecy rate even with a single antenna at the transmitter. Numerical results are provided to illustrate the performance of the proposed design schemes.

Connected through hyperedge HE-1 (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-2 (induced by source paper "securing ofdm based wireless links using temporal artificial noise injection"):
  with members:
    - "hybrid spatio temporal artificial noise design for secure mimome ofdm systems"
    - "principles of physical layer security in multiuser wireless networks a survey"
    - "secured communication over frequency selective fading channels a practical vandermonde precoding"

Connected through hyperedge HE-3 (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"
    - "multi antenna relay aided wireless physical layer security"
    - "enhancing wireless information and power transfer by exploiting multi antenna techniques"
    - "simultaneous wireless information and power transfer in modern communication systems"

Connected through hyperedge HE-4 (induced by source paper "artificial noise injection for securing single antenna systems"):
  with members:
    - "on secrecy metrics for physical layer security over quasi static fading channels"
    - "artificial noise aided secrecy information and power transfer in ofdma systems"
    - "achieving secrecy without knowing the number of eavesdropper antennas"
    - "secure on off transmission design with channel estimation errors"
    - "improving physical layer secrecy using full duplex jamming receivers"
    - "rethinking the secrecy outage formulation a secure transmission design perspective"
    - "secure transmission with artificial noise over fading channels achievable rate and optimal power allocation"

Connected through hyperedge HE-5 (induced by source paper "hybrid spatio temporal artificial noise design for secure mimome ofdm systems"):
  with members:
    - "physical layer security in heterogeneous cellular networks"
    - "artificial noise aided secure multi antenna transmission with limited feedback"
    - "massive mimo for next generation wireless systems"
    - "principles of physical layer security in multiuser wireless networks a survey"
    - "filter design with secrecy constraints the mimo gaussian wiretap channel"
    - "secure transmission with artificial noise over fading channels achievable rate and optimal power allocation"
    - "secured communication over frequency selective fading channels a practical vandermonde precoding"

Connected through hyperedge HE-6 (induced by source paper "artificial noise aided secrecy information and power transfer in ofdma systems"):
  with members:
    - "secrecy wireless information and power transfer in fading wiretap channel"
    - "energy harvesting for physical layer security in ofdma networks"
    - "secrecy wireless information and power transfer with miso beamforming"
    - "multiuser miso beamforming for simultaneous wireless information and power transfer"
    - "energy efficient resource allocation in multiuser ofdm systems with wireless information and power transfer"
    - "resource allocation for secure communication in systems with wireless information and power transfer"
    - "spectral efficient optimization in ofdm systems with wireless information and power transfer"
    - "wireless information and power transfer in multiuser ofdm systems"

Connected through hyperedge HE-7 (induced by source paper "an artificial noise aided hybrid ts ps scheme for ofdm based swipt systems"):
  with members:
    - "artificial noise aided secrecy information and power transfer in ofdma systems"
    - "energy harvesting for physical layer security in ofdma networks"
    - "wireless information and power transfer in multiuser ofdm systems"
    - "wireless information and power transfer energy efficiency optimization in ofdma systems"
    - "mimo broadcasting for simultaneous wireless information and power transfer"

Connected through hyperedge HE-8 (induced by source paper "an minimum reconfiguration probability routing algorithm for rwa in all optical networks"):
  with members:
    - "routing in all optical networks using recursive state space technique"

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)