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 efficiency of cross tier base station cooperation in heterogeneous cellular networks"
  Abstract: Heterogeneous cellular networks (HetNets) are to be deployed for future wireless communication to meet the ever-increasing mobile traffic demand. However, the dense and random deployment of small cells and their uncoordinated operation raise important concerns about energy efficiency. Base station (BS) cooperation is set to play a key role in managing interference in the HetNets. In this paper, we consider BS cooperation in the downlink HetNets where BSs from different tiers within the respective cooperative clusters jointly transmit the same data to a typical user, and further optimize the energy efficiency performance. First, based on the proposed clustering model, we derive the spatial average rate using tools from stochastic geometry. Furthermore, we formulate a power minimization problem with a minimum spatial average rate constraint and derive an approximate result of the optimal received signal strength (RSS) thresholds. Building upon these results, we effectively address the problem of how to design appropriate RSS thresholds, taking into account the trade-off between spatial average rate and energy efficiency. Simulations show that our proposed clustering model is more energy-saving than the geometric clustering model, and under our proposed clustering model, deploying a two-tier HetNet is significantly more energy-saving compared to a macro-only network.

Connected through hyperedge HE-1 (induced by source paper "deploying dense networks for maximal energy efficiency small cells meet massive mimo"):
  with members:
    - "energy efficient future wireless networks a marriage between massive mimo and small cells"
    - "designing wireless broadband access for energy efficiency are small cells the only answer"
    - "interference management in 5g reverse tdd hetnets with wireless backhaul a large system analysis"
    - "massive mimo performance evaluation based on measured propagation data"
    - "massive mimo with non ideal arbitrary arrays hardware scaling laws and circuit aware design"
    - "massive mimo systems with non ideal hardware energy efficiency estimation and capacity limits"
    - "multiobjective signal processing optimization the way to balance conflicting metrics in 5g systems"
    - "impact of transceiver power consumption on the energy efficiency of zero forcing detector in massive mimo systems"

Connected through hyperedge HE-2 (induced by source paper "a comparison study of coupled and decoupled uplink heterogeneous cellular networks"):
  with members:
    - "capacity analysis of decoupled downlink and uplink access in 5g heterogeneous systems"
    - "efficiency analysis of decoupled downlink and uplink access in heterogeneous networks"
    - "analytical modeling of uplink cellular networks"
    - "heterogeneous cellular networks with flexible cell association a comprehensive downlink sinr analysis"

Connected through hyperedge HE-3 (induced by source paper "analysis and optimization of inter tier interference coordination in downlink multi antenna hetnets with offloading"):
  with members:
    - "spectral efficiency of dynamic coordinated beamforming a stochastic geometry approach"
    - "the mean interference to signal ratio and its key role in cellular and amorphous networks"
    - "user centric intercell interference nulling for downlink small cell networks"
    - "an overview of load balancing in hetnets old myths and open problems"
    - "massive mimo meets hetnet interference coordination through spatial blanking"
    - "location aware cross tier coordinated multipoint transmission in two tier cellular networks"
    - "a stochastic geometry analysis of inter cell interference coordination and intra cell diversity"
    - "hetnets and massive mimo modeling potential gains and performance 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)