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 "broadbeam for massive mimo systems"):
  Abstract: Massive MIMO has been identified as one of the promising disruptive air interface techniques to address the huge capacity requirement of 5G wireless communications. For practical deployment of such systems, the control message needs to be broadcast to all users reliably in the cell using broadbeam. A perfect broadbeam is expected to have the same radiated power in all directions to cover users in any place in a cell. In this paper, we will show that there is no non-trivial solution for perfect broadbeam. Therefore, we develop a method for generating broadbeam that can allow tiny fluctuation in radiated power. Overall, this can serve as an ingredient for practical deployment of the massive MIMO systems.

Includes members:
  Member "massive mimo 10 myths and one grand question":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "a spatial basis coverage approach for uplink training and scheduling in massive mimo systems")
  Member "transmit radiation pattern invariance in mimo radar with application to doa estimation":
    also connected through other hyperedges:
      - Hyperedge HE-2 (induced by source paper "energy efficient beamforming for massive mimo public channel")
  Member "a generalized spatial correlation model for 3d mimo channels based on the fourier coefficients of power spectrums":
    also connected through other hyperedges:
      - Hyperedge HE-3 (induced by source paper "asymptotic max min sinr analysis of reconfigurable intelligent surface assisted miso systems")
  Member "massive mimo for next generation wireless systems":
    also connected through other hyperedges:
      - Hyperedge HE-4 (induced by source paper "joint power control and lsfd for wireless powered cell free massive mimo")
  Member "preliminary results on 3d channel modeling from theory to standardization":
    also connected through other hyperedges:
      - Hyperedge HE-5 (induced by source paper "understanding uav cellular communications from existing networks to massive mimo")
  Member "five disruptive technology directions for 5g":
    also connected through other hyperedges:
      - Hyperedge HE-6 (induced by source paper "deep learning enabled optimization of downlink beamforming under per antenna power constraints algorithms and experimental demonstration")
  Member "scaling up mimo opportunities and challenges with very large arrays":
    also connected through other hyperedges:
      - Hyperedge HE-7 (induced by source paper "downlink secrecy rate of one bit massive mimo system with active eavesdropping")
  Member "constant envelope multi user precoding for frequency selective massive mimo systems":
    also connected through other hyperedges:
      - Hyperedge HE-8 (induced by source paper "fdd massive mimo based on efficient downlink channel reconstruction")

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)