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: "optimization of a power splitting protocol for two way multiple energy harvesting relay system"
  Abstract: Energy harvesting (EH) combined with cooperative communications constitutes a promising solution for future wireless technologies. They enable additional efficiency and increased lifetime to wireless networks. This paper investigates a multiple-relay selection scheme for an EH-based two-way relaying (TWR) system. All relays are considered as EH nodes that harvest energy from renewable energy and radio frequency (RF) sources. Some of them are selected to forward data to the destinations. The power splitting (PS) protocol, by which the EH node splits the input RF signal into two components for EH and information transmission, is adopted at the relay nodes. The objective is to jointly optimize i) the set of selected relays, ii) their PS ratios, and iii) their transmit power levels in order to maximize data rate-based utilities over multiple coherent time slots. A joint-optimization solution based on geometric programming (GP) and binary particle swarm optimization is proposed to solve non-convex problems for two utility functions reflecting the level of fairness in the TWR transmission. Numerical results illustrate the system's behavior versus various parameters and show that the performance of the proposed scheme is very close to that of the optimal branch-and-bound method and that GP outperforms the dual problem-based method.

Connected through hyperedge HE-1 (induced by source paper "joint power splitting and relay selection in energy harvesting communications for iot networks"):
  with members:
    - "when internet of things meets blockchain challenges in distributed consensus"
    - "cooperative ambient backscatter communications for green internet of things"
    - "incentive mechanism design for wireless energy harvesting based internet of things"
    - "practical non linear energy harvesting model and resource allocation for swipt systems"
    - "optimal cooperative power allocation for energy harvesting enabled relay networks"
    - "outage probability of energy harvesting relay aided cooperative networks over rayleigh fading channel"
    - "power allocation strategies in energy harvesting wireless cooperative networks"
    - "exploiting network cooperation in green wireless communication"

Connected through hyperedge HE-2 (induced by source paper "robust transmissions in wireless powered multi relay networks with chance interference constraints"):
  with members:
    - "from d2d to ds2d prolonging the battery life of mobile devices via ds2d communications"
    - "an overview of sustainable green 5g networks"
    - "separation framework an enabler for cooperative and d2d communication for future 5g networks"
    - "practical non linear energy harvesting model and resource allocation for swipt systems"
    - "multiuser mimo wireless energy transfer with coexisting opportunistic communication"
    - "wireless networks with rf energy harvesting a contemporary survey"
    - "distributed resource allocation for relay aided device to device communication a message passing approach"
    - "physical layer multicasting by stochastic transmit beamforming and alamouti space time coding"

Connected through hyperedge HE-3 (induced by source paper "system outage performance for three step two way energy harvesting df relaying"):
  with members:
    - "heterogeneous power splitting based two way df relaying with non linear energy harvesting"
    - "simultaneous information and energy flow for iot relay systems with crowd harvesting"
    - "simultaneous wireless information and power transfer in modern communication systems"
    - "wireless networks with rf energy harvesting a contemporary survey"
    - "relaying protocols for wireless energy harvesting and information processing"
    - "a simple cooperative diversity method based on network path selection"

Connected through hyperedge HE-4 (induced by source paper "multi band rf energy and spectrum harvesting in cognitive radio networks"):
  with members:
    - "energy harvesting wireless communications a review of recent advances"
    - "wireless networks with rf energy harvesting a contemporary survey"
    - "what will 5g be"

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.NI(Networking and Internet Architecture)