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: "joint source and relay optimization for interference mimo relay networks"
  Abstract: This paper considers multiple-input multiple-output (MIMO) relay communication in multi-cellular (interference) systems in which MIMO source-destination pairs communicate simultaneously. It is assumed that due to severe attenuation and/or shadowing effects, communication links can be established only with the aid of a relay node. The aim is to minimize the maximal mean-square-error (MSE) among all the receiving nodes under constrained source and relay transmit powers. Both one- and two-way amplify-and-forward (AF) relaying mechanisms are considered. Since the exactly optimal solution for this practically appealing problem is intractable, we first propose optimizing the source, relay, and receiver matrices in an alternating fashion. Then we contrive a simplified semidefinite programming (SDP) solution based on the error covariance matrix decomposition technique, avoiding the high complexity of the iterative process. Numerical results reveal the effectiveness of the proposed schemes.

Connected through hyperedge HE-1 (induced by source paper "truth telling mechanism for secure two way relay communications with energy harvesting revenue"):
  with members:
    - "secure beamforming for mimo two way communications with an untrusted relay"
    - "relaying protocols for wireless energy harvesting and information processing"
    - "truthful mechanisms for secure communication in wireless cooperative system"
    - "mimo broadcasting for simultaneous wireless information and power transfer"

Connected through hyperedge HE-2 (induced by source paper "energy harvesting enabled mimo relaying through time switching"):
  with members:
    - "wireless information and energy transfer for two hop non regenerative mimo ofdm relay networks"
    - "mimo broadcasting for simultaneous wireless information and power transfer"

Connected through hyperedge HE-3 (induced by source paper "constructive interference based secure precoding a new dimension in physical layer security"):
  with members:
    - "probabilistically robust swipt for secrecy misome systems"
    - "transmit precoding for interference exploitation in the underlay cognitive radio z channel"
    - "symbol level multiuser miso precoding for multi level adaptive modulation"
    - "secure m psk communication via directional modulation"
    - "directional modulation via symbol level precoding a way to enhance security"
    - "constructive multiuser interference in symbol level precoding for the miso downlink channel"
    - "exploiting known interference as green signal power for downlink beamforming optimization"
    - "rethinking the role of interference in wireless 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)