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 "on the spectral efficiency for massive mimo systems with imperfect spacial covariance information"):
  Abstract: This paper studies the impact of imperfect channel covariance information on the uplink and downlink spectral efficiencies of a time division duplexed (TDD) massive multiple-input multiple-output (MIMO) system. Specifically, we derive analytical lower bounds on the uplink and downlink spectral efficiencies of a user with imperfect knowledge on channel vectors, as well as that of the channel covariance matrices, of the users. We consider a linear minimum mean squared estimator (LMMSE) and element-wise LMMSE channel estimation for the unknown channel in this paper. These analytical bounds enable us to choose the sample size for covariance matrix estimation to meet spectral efficiency requirements. The accurate agreement between derived bounds and simulated bounds based on random samples of channel vector and covariance matrices is shown.

Includes members:
  Member "covariance matrix estimation for massive mimo":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "scalable cell free massive mimo systems")
  Member "covariance matrix estimation in massive mimo":
    also connected through other hyperedges:
      - Hyperedge HE-2 (induced by source paper "scalable cell free massive mimo systems")
  Member "massive mimo has unlimited capacity":
    also connected through other hyperedges:
      - Hyperedge HE-3 (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-4 (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-5 (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-6 (induced by source paper "scalable cell free massive mimo systems")
  Member "path loss shadow fading and line of sight probability models for 5g urban macro cellular scenarios":
    also connected through other hyperedges:
      - Hyperedge HE-7 (induced by source paper "overview of millimeter wave communications for fifth generation 5g wireless networks with a focus on propagation models")
  Member "massive mimo for next generation wireless systems":
    also connected through other hyperedges:
      - Hyperedge HE-8 (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)