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: "uplink pilot and data power control for single cell massive mimo systems with mrc"
  Abstract: This paper considers the jointly optimal pilot and data power allocation in single cell uplink massive MIMO systems. A closed form solution for the optimal length of the training interval is derived. Using the spectral efficiency (SE) as performance metric and setting a total energy budget per co- herence interval the power control is formulated as optimization problems for two different objective functions: the minimum SE among the users and the sum SE. The optimal power control policy is found for the case of maximizing the minimum SE by converting it to a geometric program (GP). Since maximizing the sum SE is an NP-hard problem, an efficient algorithm is developed for finding KKT (local maximum) points. Simulation results show the advantage of optimizing the power control over both pilot and data power, as compared to heuristic power control policies.

Connected through hyperedge HE-1 (induced by source paper "pilot power allocation through user grouping in multi cell massive mimo systems"):
  with members:
    - "power allocation schemes for multicell massive mimo systems"
    - "channel estimation in massive mimo systems"
    - "massive mimo with non ideal arbitrary arrays hardware scaling laws and circuit aware design"
    - "multipair full duplex relaying with massive arrays and linear processing"
    - "power scaling of uplink massive mimo systems with arbitrary rank channel means"
    - "dealing with interference in distributed large scale mimo systems a statistical approach"
    - "massive mimo multicasting in noncooperative cellular networks"
    - "massive mimo systems with non ideal hardware energy efficiency estimation and capacity limits"

Connected through hyperedge HE-2 (induced by source paper "optimal pilot and payload power control in single cell massive mimo systems"):
  with members:
    - "massive mimo with multi cell mmse processing exploiting all pilots for interference suppression"
    - "massive mimo performance evaluation based on measured propagation data"
    - "multiobjective signal processing optimization the way to balance conflicting metrics in 5g systems"
    - "massive mimo with optimal power and training duration allocation"
    - "joint optimization of power allocation and training duration for uplink multiuser mimo communications"
    - "optimal design of energy efficient multi user mimo systems is massive mimo the answer"
    - "massive mimo for maximal spectral efficiency how many users and pilots should be allocated"
    - "scaling up mimo opportunities and challenges with very large arrays"

Connected through hyperedge HE-3 (induced by source paper "joint pilot sequence design and power control for max min fairness in uplink massive mimo"):
  with members:
    - "graph coloring based pilot allocation to mitigate pilot contamination for multi cell massive mimo systems"
    - "smart pilot assignment for massive mimo"
    - "aspects of favorable propagation in massive mimo"
    - "massive mimo for next generation wireless systems"
    - "what will 5g be"
    - "massive mimo for maximal spectral efficiency how many users and pilots should be allocated"
    - "energy and spectral efficiency of very large multiuser mimo systems"
    - "pilot contamination and precoding in multi cell tdd systems"

Connected through hyperedge HE-4 (induced by source paper "power control in massive mimo with dynamic user population"):
  with members:
    - "joint power allocation and user association optimization for massive mimo systems"
    - "massive mimo for next generation wireless systems"
    - "joint beamforming and power control in coordinated multicell max min duality effective network and large system transition"
    - "scaling up mimo opportunities and challenges with very large arrays"
    - "energy and spectral efficiency of very large multiuser mimo systems"

Connected through hyperedge HE-5 (induced by source paper "joint power allocation and user association optimization for massive mimo systems"):
  with members:
    - "downlink power control for massive mimo cellular systems with optimal user association"
    - "massive mimo ten myths and one critical question"
    - "graph coloring based pilot allocation to mitigate pilot contamination for multi cell massive mimo systems"
    - "joint downlink base station association and power control for max min fairness computation and complexity"
    - "massive mimo performance evaluation based on measured propagation data"
    - "smart pilot assignment for massive mimo"
    - "optimal user cell association for massive mimo wireless networks"
    - "aspects of favorable propagation in massive mimo"

Connected through hyperedge HE-6 (induced by source paper "downlink power control for massive mimo cellular systems with optimal user association"):
  with members:
    - "joint power allocation and user association optimization for massive mimo systems"
    - "massive mimo ten myths and one critical question"
    - "joint downlink base station association and power control for max min fairness computation and complexity"
    - "massive mimo for next generation wireless systems"
    - "massive mimo and small cells improving energy efficiency by optimal soft cell coordination"
    - "user association for load balancing in heterogeneous cellular networks"
    - "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.IT(Information Theory)