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: "stepwise transmit antenna selection in downlink massive multiuser mimo"
  Abstract: Due to the large power consumption in RF-circuitry of massive MIMO systems, practically relevant performance measures such as energy efficiency or bandwidth efficiency are neither necessarily monotonous functions of the total transmit power nor the number of active antennas. Optimal antenna selection is however computationally infeasible in these systems. In this paper, we propose an iterative algorithm to optimize the transmit power and the subset of selected antennas subject to non-monotonous performance measures in massive multiuser MIMO settings. Numerical results are given for energy efficiency and demonstrate that for several settings the optimal number of selected antennas reported by the proposed algorithm is significantly smaller than the total number of transmit antennas. This fact indicates that antenna selection in several massive MIMO scenarios not only reduces the hardware complexity and RF-costs, but also enhances the energy efficiency of the system.

Connected through hyperedge HE-1 (induced by source paper "robustness of low complexity massive mimo architectures against passive eavesdropping"):
  with members:
    - "papr limited precoding in massive mimo systems with reflect and transmit array antennas"
    - "on robustness of massive mimo systems against passive eavesdropping under antenna selection"
    - "glse precoders for massive mimo systems analysis and applications"
    - "scalable and energy efficient millimeter massive mimo architectures reflect array and transmit array antennas"
    - "optimal transmit antenna selection for massive mimo wiretap channels"
    - "asymptotics of nonlinear lse precoders with applications to transmit antenna selection"
    - "asymptotics of transmit antenna selection impact of multiple receive antennas"
    - "hybrid analog digital precoding revisited under realistic rf modeling"

Connected through hyperedge HE-2 (induced by source paper "millimeter wave massive mimo systems relying on generalized sub array connected hybrid precoding"):
  with members:
    - "spatial lobes division based low complexity hybrid precoding and diversity combining for mmwave iot systems"
    - "non uniform quantization codebook based hybrid precoding to reduce feedback overhead in millimeter wave mimo systems"
    - "on the energy efficiency of mimo hybrid beamforming for millimeter wave systems with nonlinear power amplifiers"
    - "downlink precoding with mixed statistical and imperfect instantaneous csi for massive mimo systems"
    - "pilot power allocation through user grouping in multi cell massive mimo systems"
    - "codebook based hybrid precoding for millimeter wave multiuser systems"
    - "alternating minimization algorithms for hybrid precoding in millimeter wave mimo systems"
    - "an overview of signal processing techniques for millimeter wave mimo systems"

Connected through hyperedge HE-3 (induced by source paper "a fair comparison between spatial modulation and antenna selection in massive mimo systems"):
  with members:
    - "index modulation techniques for 5g wireless networks"
    - "massive mimo for next generation wireless systems"

Connected through hyperedge HE-4 (induced by source paper "glse precoders for massive mimo systems analysis and applications"):
  with members:
    - "nonlinear precoders for massive mimo systems with general constraints"
    - "the stochastic interpolation method a simple scheme to prove replica formulas in bayesian inference"
    - "asymptotics of nonlinear lse precoders with applications to transmit antenna selection"
    - "asymptotics of transmit antenna selection impact of multiple receive antennas"
    - "energy efficient coordinated multi cell multi group multicast beamforming with antenna selection"
    - "a new class of nonlinear precoders for hardware efficient massive mimo systems"
    - "the replica symmetric prediction for compressed sensing with gaussian matrices is exact"
    - "rsb decoupling property of map estimators"

Connected through hyperedge HE-5 (induced by source paper "on robustness of massive mimo systems against passive eavesdropping under antenna selection"):
  with members:
    - "iterative antenna selection for secrecy enhancement in massive mimo wiretap channels"
    - "asymptotics of nonlinear lse precoders with applications to transmit antenna selection"
    - "asymptotics of transmit antenna selection impact of multiple receive antennas"
    - "asymptotic performance analysis of spatially reconfigurable antenna arrays"
    - "optimal number of transmit antennas for secrecy enhancement in massive mimome channels"
    - "secrecy and energy efficiency in massive mimo aided heterogeneous c ran a new look at interference"
    - "on secrecy performance of antenna selection aided mimo systems against eavesdropping"
    - "physical layer security for massive mimo an overview on passive eavesdropping and active attacks"

Connected through hyperedge HE-6 (induced by source paper "energy efficient extended sub connected architecture for hybrid precoding in millimeter wave massive mimo systems"):
  with members:
    - "spatial lobes division based low complexity hybrid precoding and diversity combining for mmwave iot systems"
    - "non uniform quantization codebook based hybrid precoding to reduce feedback overhead in millimeter wave mimo systems"
    - "downlink precoding with mixed statistical and imperfect instantaneous csi for massive mimo systems"
    - "pilot power allocation through user grouping in multi cell massive mimo systems"
    - "alternating minimization algorithms for hybrid precoding in millimeter wave mimo systems"
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "low rf complexity technologies to enable millimeter wave mimo with large antenna array for 5g wireless communications"
    - "dynamic subarrays for hybrid precoding in wideband mmwave mimo systems"

Connected through hyperedge HE-7 (induced by source paper "iterative antenna selection for secrecy enhancement in massive mimo wiretap channels"):
  with members:
    - "nonlinear precoders for massive mimo systems with general constraints"
    - "asymptotics of nonlinear lse precoders with applications to transmit antenna selection"
    - "asymptotics of transmit antenna selection impact of multiple receive antennas"
    - "physical layer security for massive mimo an overview on passive eavesdropping and active attacks"
    - "low complexity hybrid precoding in massive multiuser mimo systems"
    - "the secrecy capacity of the mimo wiretap channel"
    - "multiuser mimo achievable rates with downlink training and channel state feedback"

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)