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 "energy efficiency optimization for downlink massive mimo with statistical csit"):
  Abstract: We investigate energy efficiency (EE) optimization for single-cell massive multiple-input multiple-output (MIMO) downlink transmission with only statistical channel state information (CSI) available at the base station. We first show that beam domain transmission is favorable for energy efficiency in the massive MIMO downlink, by deriving a closed-form solution for the eigenvectors of the optimal transmit covariance matrix. With this conclusion, the EE optimization problem is reduced to a real-valued power allocation problem, which is much easier to tackle than the original large-dimensional complex matrix-valued precoding design problem. We further propose an iterative water-filling-structured beam domain power allocation algorithm with low complexity and guaranteed convergence, exploiting the techniques from sequential optimization, fractional optimization, and random matrix theory. Numerical results demonstrate the near-optimal performance of our proposed statistical CSI aided EE optimization approach.

Includes members:
  Member "beam domain secure transmission for massive mimo communications":
    also connected through other hyperedges:
      (none)
  Member "fractional programming for communication systems part i power control and beamforming":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "millimeter wave communications with an intelligent reflector performance optimization and distributional reinforcement learning")
  Member "energy efficient multicell multigroup multicasting with joint beamforming and antenna selection":
    also connected through other hyperedges:
      - Hyperedge HE-2 (induced by source paper "secrecy rates for a channel with two senders and two receivers")
  Member "fdd massive mimo via ul dl channel covariance extrapolation and active channel sparsification":
    also connected through other hyperedges:
      - Hyperedge HE-3 (induced by source paper "statistical beamforming for fdd downlink massive mimo via spatial information extraction and beam selection")
  Member "network deployment for maximal energy efficiency in uplink with multislope path loss":
    also connected through other hyperedges:
      - Hyperedge HE-4 (induced by source paper "max min rate of cell free massive mimo uplink with optimal uniform quantization")
  Member "energy efficient beam coordination strategies with rate dependent processing power":
    also connected through other hyperedges:
      - Hyperedge HE-5 (induced by source paper "energy efficiency fairness for multi pair wireless powered relaying systems")
  Member "bdma for millimeter wave terahertz massive mimo transmission with per beam synchronization":
    also connected through other hyperedges:
      - Hyperedge HE-6 (induced by source paper "performance of high mobility mimo communications with doppler diversity")
  Member "free deterministic equivalents for the analysis of mimo multiple access channel":
    also connected through other hyperedges:
      - Hyperedge HE-7 (induced by source paper "beam domain secure transmission for massive mimo communications")

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)