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: "beamforming and power splitting designs for an aided secure multi user mimo swipt systems"
  Abstract: In this paper, an energy harvesting scheme for a multi-user multiple-input-multiple-output (MIMO) secrecy channel with artificial noise (AN) transmission is investigated. Joint optimization of the transmit beamforming matrix, the AN covariance matrix, and the power splitting ratio is conducted to minimize the transmit power under the target secrecy rate, the total transmit power, and the harvested energy constraints. The original problem is shown to be non-convex, which is tackled by a two-layer decomposition approach. The inner layer problem is solved through semi-definite relaxation, and the outer problem, on the other hand, is shown to be a single- variable optimization that can be solved by one-dimensional (1- D) line search. To reduce computational complexity, a sequential parametric convex approximation (SPCA) method is proposed to find a near-optimal solution. The work is then extended to the imperfect channel state information case with norm-bounded channel errors. Furthermore, tightness of the relaxation for the proposed schemes are validated by showing that the optimal solution of the relaxed problem is rank-one. Simulation results demonstrate that the proposed SPCA method achieves the same performance as the scheme based on 1-D but with much lower complexity.

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"
    - "interference alignment and soft space reuse based cooperative transmission for multi cell massive mimo networks"

Connected through hyperedge HE-2 (induced by source paper "energy efficiency optimization for secure transmission in miso cognitive radio network with energy harvesting"):
  with members:
    - "robust designs of beamforming and power splitting for distributed antenna systems with wireless energy harvesting"
    - "enhancing phy security of miso noma swipt systems with a practical non linear eh model"
    - "resource allocation for secure miso noma cognitive radios relying on swipt"
    - "secure communications with cooperative jamming optimal power allocation and secrecy outage analysis"
    - "physical layer security jamming theoretical limits and practical designs in wireless networks"
    - "secure energy efficiency optimization for miso cognitive radio network with energy harvesting"
    - "limited feedback scheme for device to device communications in 5g cellular networks with reliability and cellular secrecy outage constraints"
    - "joint offloading and computing optimization in wireless powered mobile edge computing systems"

Connected through hyperedge HE-3 (induced by source paper "energy efficient cooperative secure transmission in multi uav enabled wireless networks"):
  with members:
    - "secrecy energy efficiency maximization for uav enabled mobile relaying"
    - "uav aided offloading for cellular hotspot"
    - "securing uav communications via joint trajectory and power control"
    - "energy minimization for wireless communication with rotary wing uav"
    - "robust trajectory and transmit power design for secure uav communications"
    - "secure uav communication with cooperative jamming and trajectory control"
    - "placement optimization of uav mounted mobile base stations"
    - "joint trajectory and communication design for multi uav enabled wireless networks"

Connected through hyperedge HE-4 (induced by source paper "robust designs of beamforming and power splitting for distributed antenna systems with wireless energy harvesting"):
  with members:
    - "some new research trends in wirelessly powered communications"
    - "robust beamforming for secure communication in systems with wireless information and power transfer"
    - "secure and green swipt in distributed antenna networks with limited backhaul capacity"
    - "joint transmit beamforming and receive power splitting for miso swipt systems"
    - "application of smart antenna technologies in simultaneous wireless information and power transfer"
    - "transmission schemes based on sum rate analysis in distributed antenna systems"
    - "mimo broadcasting for simultaneous wireless information and power transfer"
    - "outage constrained robust transmit optimization for multiuser miso downlinks tractable approximations by conic optimization"

Connected through hyperedge HE-5 (induced by source paper "energy harvesting fairness in an aided secure mu mimo swipt systems with cooperative jammer"):
  with members:
    - "robust beamforming for secure communication in systems with wireless information and power transfer"
    - "secure beamforming for mimo broadcasting with wireless information and power transfer"
    - "secure communication with a wireless powered friendly jammer"
    - "spatially selective artificial noise aided transmit optimization for miso multi eves secrecy rate maximization"
    - "mimo broadcasting for simultaneous wireless information and power transfer"

Connected through hyperedge HE-6 (induced by source paper "an aided secure transmission in multi user mimo swipt systems"):
  with members:
    - "secure beamforming for mimo broadcasting with wireless information and power transfer"
    - "secrecy wireless information and power transfer with miso beamforming"
    - "spatially selective artificial noise aided transmit optimization for miso multi eves secrecy rate maximization"
    - "mimo broadcasting for simultaneous wireless information and power transfer"

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)