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: "boost base station on off switching strategy for energy efficient massive mimo hetnets"
  Abstract: In this paper, we investigate the problem of optimal base station (BS) ON-OFF switching and user association in a heterogeneous network (HetNet) with massive MIMO, with the objective to maximize the system energy efficiency (EE). The joint BS ON-OFF switching and user association problem is formulated as an integer programming problem. We first develop a centralized scheme, in which we relax the integer constraints and employ a series of Lagrangian dual methods that transform the original problem into a standard linear programming (LP) problem. Due to the special structure of the LP, we prove that the optimal solution to the relaxed LP is also feasible and optimal to the original problem. We then propose a distributed scheme by formulating a repeated bidding game for users and BS's, and prove that the game converges to a Nash Equilibrium (NE). Simulation studies demonstrate that the proposed schemes can achieve considerable gains in EE over several benchmark schemes in all the scenarios considered.

Connected through hyperedge HE-1 (induced by source paper "resource allocation in green dense cellular networks complexity and algorithms"):
  with members:
    - "large scale spectrum allocation for cellular networks via sparse optimization"
    - "optimal user scheduling in energy harvesting wireless networks"
    - "scalable spectrum allocation and user association in networks with many small cells"
    - "online ski rental for on off scheduling of energy harvesting base stations"
    - "online energy efficient packet scheduling for a common deadline with and without energy harvesting"
    - "gate greening at the edges"
    - "energy efficient cell activation user association and spectrum allocation in heterogeneous networks"
    - "optimizing user association and spectrum allocation in hetnets a utility perspective"

Connected through hyperedge HE-2 (induced by source paper "dynamic resource allocation and activity management for energy efficiency and fairness in heterogeneous networks"):
  with members:
    - "activity management algorithm for improving energy efficiency of small cell base stations in 5g heterogeneous networks"
    - "femtocell networks a survey"

Connected through hyperedge HE-3 (induced by source paper "base station on off switching in 5g wireless networks approaches and challenges"):
  with members:
    - "energy aware traffic offloading for green heterogeneous networks"
    - "green 5g heterogeneous networks through dynamic small cell operation"
    - "how many small cells can be turned off via vertical offloading under a separation architecture"
    - "what will 5g be"
    - "base station sleeping and resource allocation in renewable energy powered cellular networks"
    - "adaptive power management for wireless base stations in a smart grid environment"

Connected through hyperedge HE-4 (induced by source paper "harvest the potential of massive mimo with multi layer techniques"):
  with members:
    - "user association in massive mimo hetnets"
    - "multipair full duplex relaying with massive arrays and linear processing"
    - "large scale mimo versus network mimo for multicell interference mitigation"
    - "massive mimo for next generation wireless systems"
    - "massive mimo and small cells improving energy efficiency by optimal soft cell coordination"
    - "electromagnetic lens focusing antenna enabled massive mimo performance improvement and cost reduction"
    - "achieving massive mimo spectral efficiency with a not so large number of antennas"

Connected through hyperedge HE-5 (induced by source paper "interference management in massive mimo hetnets a nested array approach"):
  with members:
    - "user association in massive mimo hetnets"
    - "harvest the potential of massive mimo with multi layer techniques"
    - "what will 5g be"
    - "massive mimo meets hetnet interference coordination through spatial blanking"
    - "massive mimo and small cells improving energy efficiency by optimal soft cell coordination"
    - "energy and spectral efficiency of very large multiuser mimo 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.NI(Networking and Internet Architecture)