human: Given a hyperedge-centered hypergraph: <hypergraph>, where the center hyperedge is induced by one source paper and its member nodes are the cited papers.

Details of the hypergraph:
Center hyperedge (induced by source paper "covariance matrix estimation for massive mimo"):
  Abstract: We propose a novel pilot structure for covariance matrix estimation in massive multiple-input multiple-output systems in which each user transmits two pilot sequences, with the second pilot sequence multiplied by a random phase shift. The covariance matrix of a particular user is obtained by computing the sample cross-correlation of the channel estimates obtained from the two pilot sequences. This approach relaxes the requirement that all the users transmit their uplink pilots over the same set of symbols. We derive expressions for the achievable rate and the mean-squared error of the covariance matrix estimate when the proposed method is used with staggered pilots. The performance of the proposed method is compared with existing methods through simulations.

Includes members:
  Member "massive mimo has unlimited capacity":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "joint power control and lsfd for wireless powered cell free massive mimo")
  Member "superimposed pilots are superior for mitigating pilot contamination in massive mimo":
    also connected through other hyperedges:
      - Hyperedge HE-2 (induced by source paper "joint frame design and resource allocation for ultra reliable and low latency vehicular networks")
  Member "massive mimo pilot decontamination and channel interpolation via wideband sparse channel estimation":
    also connected through other hyperedges:
      - Hyperedge HE-3 (induced by source paper "joint activity detection and channel estimation for mmw thz wideband massive access")
  Member "massive mimo with imperfect channel covariance information":
    also connected through other hyperedges:
      - Hyperedge HE-4 (induced by source paper "scalable cell free massive mimo systems")
  Member "downlink performance of superimposed pilots in massive mimo systems":
    also connected through other hyperedges:
      - Hyperedge HE-5 (induced by source paper "massive mimo forward link analysis for cellular networks")
  Member "pilot contamination is not a fundamental asymptotic limitation in massive mimo":
    also connected through other hyperedges:
      - Hyperedge HE-6 (induced by source paper "machine learning for geometrically consistent angular spread function estimation in massive mimo")
  Member "superimposed pilots are superior for mitigating pilot contamination in massive mimo part ii performance analysis and hybrid system design":
    also connected through other hyperedges:
      (none)
  Member "massive mimo for next generation wireless systems":
    also connected through other hyperedges:
      - Hyperedge HE-7 (induced by source paper "joint power control and lsfd for wireless powered cell free massive mimo")

Question: Please tell me which class the source paper 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)