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: "impact of cfo estimation on the performance of zf receiver in massive mu mimo systems"
  Abstract: In this paper, we study the impact of carrier frequency offset (CFO) estimation/compensation on the information rate performance of the zero-forcing (ZF) receiver in the uplink of a multiuser (MU) massive multiple-input–multiple-output (MIMO) system. Analysis of the derived closed-form expression of the per-user information rate reveals that, with the increasing number of BS antennas    $M$  , an    $\mathcal{O}(\sqrt{M})$   array gain is achievable, which is the same as that achieved in the ideal zero CFO scenario. Moreover, it is observed that, compared with the ideal zero CFO case, the performance degradation in the presence of residual CFO (after CFO compensation) is the same for both ZF and MRC.

Connected through hyperedge HE-1 (induced by source paper "frequency synchronization for uplink massive mimo systems"):
  with members:
    - "constant envelope pilot based low complexity cfo estimation in massive mu mimo systems"
    - "impact of frequency selectivity on the information rate performance of cfo impaired single carrier massive mu mimo uplink"
    - "low complexity cfo estimation for multi user massive mimo systems"
    - "pilot reuse for massive mimo transmission over spatially correlated rayleigh fading channels"
    - "massive mimo for next generation wireless systems"
    - "downlink training techniques for fdd massive mimo systems open loop and closed loop training with memory"
    - "scaling up mimo opportunities and challenges with very large arrays"
    - "a coordinated approach to channel estimation in large scale multiple antenna systems"

Connected through hyperedge HE-2 (induced by source paper "information theoretic performance of periodogram based cfo estimation in massive mu mimo systems"):
  with members:
    - "constant envelope pilot based low complexity cfo estimation in massive mu mimo systems"
    - "impact of frequency selectivity on the information rate performance of cfo impaired single carrier massive mu mimo uplink"
    - "low complexity cfo estimation for multi user massive mimo systems"
    - "uplink performance of time reversal mrc in massive mimo systems subject to phase noise"
    - "what will 5g be"
    - "five disruptive technology directions for 5g"
    - "scaling up mimo opportunities and challenges with very large arrays"
    - "energy and spectral efficiency of very large multiuser mimo systems"

Connected through hyperedge HE-3 (induced by source paper "impact of frequency selectivity on the information rate performance of cfo impaired single carrier massive mu mimo uplink"):
  with members:
    - "low complexity cfo estimation for multi user massive mimo systems"
    - "uplink performance of time reversal mrc in massive mimo systems subject to phase noise"
    - "what will 5g be"
    - "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)