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: "on the convergence of massive mimo systems"
  Abstract: In this paper we examine convergence properties of massive MIMO systems with the aim of determining the number of antennas required for massive MIMO gains. We consider three characteristics of a channel matrix and study their asymptotic behaviour. Furthermore, we derive ZF SNR and MF SINR for a scenario of unequal receive powers. In our results we include the effects of spatial correlation. We show that the rate of convergence of channel metrics is much slower than that of the ZF/MF precoder properties.

Connected through hyperedge HE-1 (induced by source paper "performance scaling law for multi cell multi user massive mimo"):
  with members:
    - "impact of general channel aging conditions on the downlink performance of massive mimo"
    - "pilot length optimization for spatially correlated multi user mimo channel estimation"
    - "performance analysis and scaling law of mrc mrt relaying with csi error in massive mimo systems"
    - "massive mimo ten myths and one critical question"
    - "sum rate and power scaling of massive mimo systems with channel aging"
    - "massive mimo with non ideal arbitrary arrays hardware scaling laws and circuit aware design"
    - "power scaling of uplink massive mimo systems with arbitrary rank channel means"
    - "blind pilot decontamination"

Connected through hyperedge HE-2 (induced by source paper "performance analysis of massive mimo networks with random unitary pilot matrices"):
  with members:
    - "massive mimo has unlimited capacity"
    - "multi cell multiuser massive mimo networks user capacity analysis and pilot design"
    - "on uplink user capacity for massive mimo cellular networks"
    - "uplink linear receivers for multi cell multiuser mimo with pilot contamination large system analysis"
    - "massive mimo for maximal spectral efficiency how many users and pilots should be allocated"
    - "five disruptive technology directions for 5g"
    - "scaling up mimo opportunities and challenges with very large arrays"

Connected through hyperedge HE-3 (induced by source paper "near optimal hybrid processing for massive mimo systems via matrix decomposition"):
  with members:
    - "low power analog to digital conversion in millimeter wave systems impact of resolution and bandwidth on performance"
    - "spatially common sparsity based adaptive channel estimation and feedback for fdd massive mimo"
    - "hybrid block diagonalization for massive multiuser mimo systems"
    - "hybrid mimo architectures for millimeter wave communications phase shifters or switches"
    - "mmwave massive mimo based wireless backhaul for the 5g ultra dense network"
    - "subspace estimation and decomposition for hybrid analog digital millimetre wave mimo systems"
    - "channel estimation and hybrid precoding for millimeter wave cellular systems"
    - "massive mimo for next generation wireless systems"

Connected through hyperedge HE-4 (induced by source paper "on the convergence and performance of mf precoding in distributed massive mu mimo systems"):
  with members:
    - "dealing with interference in distributed large scale mimo systems a statistical approach"
    - "massive mimo for next generation wireless systems"
    - "downlink training techniques for fdd massive mimo systems open loop and closed loop training with memory"
    - "blind pilot decontamination"
    - "noncoherent trellis coded quantization a practical limited feedback technique for massive mimo systems"
    - "massive mu mimo downlink tdd systems with linear precoding and downlink pilots"
    - "scaling up mimo opportunities and challenges with very large arrays"
    - "effects of channel aging in massive mimo systems"

Connected through hyperedge HE-5 (induced by source paper "limited feedback hybrid precoding for multi user millimeter wave systems"):
  with members:
    - "channel estimation and hybrid precoding for millimeter wave cellular systems"
    - "spatially sparse precoding in millimeter wave mimo systems"
    - "millimeter wave beamforming for wireless backhaul and access in small cell networks"
    - "coding the beams improving beamforming training in mmwave communication system"
    - "antenna combining for the mimo downlink channel"
    - "mimo broadcast channels with finite rate feedback"

Connected through hyperedge HE-6 (induced by source paper "on the impact of antenna topologies for massive mimo systems"):
  with members:
    - "small cell in band wireless backhaul in massive mimo systems a cooperation of next generation techniques"
    - "kronecker product correlation model and limited feedback codebook design in a 3d channel model"
    - "massive mimo and small cells improving energy efficiency by optimal soft cell coordination"
    - "scaling up mimo opportunities and challenges with very large arrays"
    - "energy and spectral efficiency of very large multiuser mimo systems"

Connected through hyperedge HE-7 (induced by source paper "deployment issues for massive mimo systems"):
  with members:
    - "on the impact of antenna topologies for massive mimo systems"
    - "on the convergence and performance of mf precoding in distributed massive mu mimo systems"
    - "massive mimo for next generation wireless systems"
    - "what will 5g be"
    - "scaling up mimo opportunities and challenges with very large arrays"

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)