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: "optimal base station deployment for small cell networks with energy efficient power control"
  Abstract: In this paper, how to optimally deploy base station density in a small cell network with energy-efficient power control was investigated. Base stations (BSs) and users form two independent Poisson point processes (PPPs) in the network. Since user-centric cell association may lead to void cells that do not have any users, the power of each BS is controlled in either all-on or on-off mode depending on whether its cell is void or not. The average cell rates for each power control mode are first found and their corresponding energy efficiency is also characterized. The optimal BS density that maximizes the energy efficiency under a given user density is theoretically proved to exist and its value can be found numerically. Both analytical and simulated results indicate that on-off power control is significantly superior to all-on power control in terms of energy efficiency if BSs are deployed based on their optimal energy-efficient density.

Connected through hyperedge HE-1 (induced by source paper "delay optimal biased user association in heterogeneous networks"):
  with members:
    - "random cell association and void probability in poisson distributed cellular networks"
    - "optimizing user association and spectrum allocation in hetnets a utility perspective"
    - "traffic driven spectrum allocation in heterogeneous networks"
    - "an overview of load balancing in hetnets old myths and open problems"
    - "what will 5g be"
    - "joint resource partitioning and offloading in heterogeneous cellular networks"
    - "offloading in heterogeneous networks modeling analysis and design insights"
    - "load aware modeling and analysis of heterogeneous cellular networks"

Connected through hyperedge HE-2 (induced by source paper "fundamentals of the downlink green coverage and energy efficiency in heterogeneous networks"):
  with members:
    - "energy efficient cell activation user association and spectrum allocation in heterogeneous networks"
    - "random cell association and void probability in poisson distributed cellular networks"
    - "optimal cell load and throughput in green small cell networks with generalized cell association"
    - "throughput and energy efficiency analysis of small cell networks with multi antenna base stations"
    - "energy efficiency evaluation of cellular networks based on spatial distributions of traffic load and power consumption"
    - "joint resource partitioning and offloading in heterogeneous cellular networks"
    - "offloading in heterogeneous networks modeling analysis and design insights"
    - "heterogeneous cellular networks with flexible cell association a comprehensive downlink sinr analysis"

Connected through hyperedge HE-3 (induced by source paper "optimal cell load and throughput in green small cell networks with generalized cell association"):
  with members:
    - "random cell association and void probability in poisson distributed cellular networks"
    - "d2d enhanced heterogeneous cellular networks with dynamic tdd"
    - "optimal discrete power control in poisson clustered ad hoc networks"
    - "a traffic load balancing framework for software defined radio access networks powered by hybrid energy sources"
    - "throughput and energy efficiency analysis of small cell networks with multi antenna base stations"
    - "joint resource partitioning and offloading in heterogeneous cellular networks"
    - "average rate of downlink heterogeneous cellular networks over generalized fading channels a stochastic geometry approach"
    - "heterogeneous cellular networks with flexible cell association a comprehensive downlink sinr analysis"

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)