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: "energy efficient small cell with spectrum power trading"
  Abstract: In this paper, we investigate spectrum-power trading between a small cell (SC) and a macro cell (MC), where the SC consumes power to serve the macro cell users (MUs) in exchange for some bandwidth from the MC. Our goal is to maximize the system energy efficiency (EE) of the SC while guaranteeing the quality of service of each MU as well as small cell users (SUs). Specifically, given the minimum data rate requirement and the bandwidth provided by the MC, the SC jointly optimizes MU selection, bandwidth allocation, and power allocation while guaranteeing its own minimum required system data rate. The problem is challenging due to the binary MU selection variables and the fractional- form objective function. We first show that the bandwidth of an MU is shared with at most one SU in the SC. Then, for a given MU selection, the optimal bandwidth and power allocation is obtained by exploiting the fractional programming. To perform MU selection, we first introduce the concept of the trading EE to characterize the data rate obtained as well as the power consumed for serving an MU. We then reveal a sufficient and necessary condition for serving an MU without considering the total power constraint and the minimum data rate constraint: the trading EE of the MU should be higher than the system EE of the SC. Based on this insight, we propose a low complexity MU selection method and also investigate the optimality condition. Simulation results verify our theoretical findings and demonstrate that the proposed resource allocation achieves near-optimal performance.

Connected through hyperedge HE-1 (induced by source paper "joint trajectory and communication design for multi uav enabled wireless networks"):
  with members:
    - "securing uav communications via joint trajectory and power control"
    - "the sky is not the limit lte for unmanned aerial vehicles"
    - "placement optimization of uav mounted mobile base stations"
    - "securing uav communications via trajectory optimization"
    - "fundamental green tradeoffs progresses challenges and impacts on 5g networks"
    - "joint trajectory and communication design for uav enabled multiple access"
    - "cyclical multiple access in uav aided communications a throughput delay tradeoff"
    - "efficient deployment of multiple unmanned aerial vehicles for optimal wireless coverage"

Connected through hyperedge HE-2 (induced by source paper "joint trajectory and communication design for uav enabled multiple access"):
  with members:
    - "placement optimization of uav mounted mobile base stations"
    - "joint trajectory and communication design for multi uav enabled wireless networks"
    - "cyclical multiple access in uav aided communications a throughput delay tradeoff"
    - "efficient deployment of multiple unmanned aerial vehicles for optimal wireless coverage"
    - "energy efficient uav communication with trajectory optimization"
    - "an overview of sustainable green 5g networks"
    - "wireless communications with unmanned aerial vehicles opportunities and challenges"
    - "mobile edge computing via a uav mounted cloudlet optimization of bit allocation and path planning"

Connected through hyperedge HE-3 (induced by source paper "an overview of sustainable green 5g networks"):
  with members:
    - "ultra dense small cell networks turning density into energy efficiency"
    - "green 5g heterogeneous networks through dynamic small cell operation"
    - "wireless powered communication opportunities and challenges"
    - "millimeter wave mimo with lens antenna array a new path division multiplexing paradigm"
    - "how many small cells can be turned off via vertical offloading under a separation architecture"
    - "simultaneous wireless information and power transfer in modern communication systems"
    - "wireless networks with rf energy harvesting a contemporary survey"
    - "what will 5g be"

Connected through hyperedge HE-4 (induced by source paper "spectrum power trading for energy efficient small cell"):
  with members:
    - "fundamental green tradeoffs progresses challenges and impacts on 5g networks"
    - "energy efficient resource allocation for wireless powered communication networks"
    - "joint energy and spectrum cooperation for cellular communication systems"

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)