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: "multipair two way relay network with harvest then transmit users resolving pairwise uplink downlink coupling"
  Abstract: While two-way relaying is a promising way to enhance the spectral efficiency of wireless networks, the imbalance of relay-user distances may lead to excessive wireless power at the nearby users. To exploit the excessive power, the recently proposed harvest-then-transmit technique can be applied. However, it is well known that harvest-then-transmit introduces uplink-downlink coupling for a user. Together with the codependent relationship between paired users and interference among multiple user pairs, wirelessly powered two-way relay network suffers from the unique pairwise uplink-downlink coupling, and the joint uplink-downlink network design is nontrivial. To this end, for the one pair users case, we show that a global optimal solution can be obtained. For the general case of multipair users, based on the rank-constrained difference of convex program, a convergence guaranteed iterative algorithm with an efficient initialization is proposed. Furthermore, a lower bound to the performance of the optimal solution is derived by introducing virtual receivers at relay. Numerical results on total transmit power show that the proposed algorithm achieves a transmit power value close to the lower bound.

Connected through hyperedge HE-1 (induced by source paper "angle aware user cooperation for secure massive mimo in rician fading channel"):
  with members:
    - "machine intelligence at the edge with learning centric power allocation"
    - "robust and secure wireless communications via intelligent reflecting surfaces"
    - "vulnerabilities of massive mimo systems to pilot contamination attacks"
    - "resource allocation for secure irs assisted multiuser miso systems"
    - "physical layer security in uav systems challenges and opportunities"
    - "intelligent reflecting surface enhanced wireless network via joint active and passive beamforming"
    - "on low resolution adcs in practical 5g millimeter wave massive mimo systems"
    - "a survey of physical layer security techniques for 5g wireless networks and challenges ahead"

Connected through hyperedge HE-2 (induced by source paper "joint communication and motion energy minimization in ugv backscatter communication"):
  with members:
    - "joint trajectory and communication design for multi uav enabled wireless networks"
    - "inference from randomized transmissions by many backscatter sensors"
    - "multistatic scatter radio sensor networks for extended coverage"
    - "on the efficiency of far field wireless power transfer"
    - "internet of things iot a vision architectural elements and future directions"

Connected through hyperedge HE-3 (induced by source paper "massive mimo multicast beamforming via accelerated random coordinate descent"):
  with members:
    - "multi quality multicast beamforming based on scalable video coding"
    - "massive mimo for next generation wireless systems"
    - "energy and spectral efficiency of very large multiuser mimo systems"

Connected through hyperedge HE-4 (induced by source paper "charge then forward wireless powered communication for multiuser relay networks"):
  with members:
    - "joint power allocation and beamforming for energy efficient two way multi relay communications"
    - "power allocation for secure swipt systems with wireless powered cooperative jamming"
    - "capacity of the two hop relay channel with wireless energy transfer from relay to source and energy transmission cost"
    - "artificial noise aided secrecy information and power transfer in ofdma systems"
    - "wireless powered communication opportunities and challenges"
    - "wireless powered relays in cooperative communications time switching relaying protocols and throughput analysis"
    - "harvest then cooperate wireless powered cooperative communications"
    - "wireless powered cooperative communications via a hybrid relay"

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)