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: "secrecy sum rates for multi user mimo regularized channel inversion precoding"
  Abstract: In this paper, we propose a linear precoder for the downlink of a multi-user MIMO system with multiple users that potentially act as eavesdroppers. The proposed precoder is based on regularized channel inversion (RCI) with a regularization parameter α and power allocation vector chosen in such a way that the achievable secrecy sum-rate is maximized. We consider the worst-case scenario for the multi-user MIMO system, where the transmitter assumes users cooperate to eavesdrop on other users. We derive the achievable secrecy sum-rate and obtain the closed-form expression for the optimal regularization parameter αLS of the precoder using large-system analysis. We show that the RCI precoder with αLS outperforms several other linear precoding schemes, and it achieves a secrecy sum-rate that has same scaling factor as the sum-rate achieved by the optimum RCI precoder without secrecy requirements. We propose a power allocation algorithm to maximize the secrecy sum-rate for fixed α. We then extend our algorithm to maximize the secrecy sum-rate by jointly optimizing α and the power allocation vector. The jointly optimized precoder outperforms RCI with αLS and equal power allocation by up to 20 percent at practical values of the signal-to-noise ratio and for 4 users and 4 transmit antennas.

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"
    - "stepwise transmit antenna selection in downlink massive multiuser mimo"
    - "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"

Connected through hyperedge HE-2 (induced by source paper "data aided secure massive mimo transmission under the pilot contamination attack"):
  with members:
    - "a survey of physical layer security techniques for 5g wireless networks and challenges ahead"
    - "pilot spoofing attack by multiple eavesdroppers"
    - "multiple antennas secure transmission under pilot spoofing and jamming attack"
    - "secure transmission with large numbers of antennas and finite alphabet inputs"
    - "massive mimo pilot decontamination and channel interpolation via wideband sparse channel estimation"
    - "analysis and design of secure massive mimo systems in the presence of hardware impairments"
    - "performance limits of massive mimo systems based on bayes optimal inference"
    - "secure massive mimo transmission with an active eavesdropper"

Connected through hyperedge HE-3 (induced by source paper "secure communication for spatially sparse millimeter wave massive mimo channels via hybrid precoding"):
  with members:
    - "secure massive mimo communication with low resolution dacs"
    - "secure users oriented downlink miso noma"
    - "a hardware efficient analog network structure for hybrid precoding in millimeter wave systems"
    - "performance analysis of multi cell millimeter wave massive mimo networks with low precision adcs"
    - "low complexity reconfigurable mimo for millimeter wave communications"
    - "a survey of physical layer security techniques for 5g wireless networks and challenges ahead"
    - "millimeter wave communications with reconfigurable antennas"
    - "millimeter wave mimo channel estimation using overlapped beam patterns and rate adaptation"

Connected through hyperedge HE-4 (induced by source paper "secure regularized zero forcing for multiuser mimome channels"):
  with members:
    - "on robustness of massive mimo systems against passive eavesdropping under antenna selection"
    - "glse precoders for massive mimo systems analysis and applications"
    - "nonlinear precoders for massive mimo systems with general constraints"
    - "asymptotics of nonlinear lse precoders with applications to transmit antenna selection"
    - "physical layer security for massive mimo an overview on passive eavesdropping and active attacks"
    - "applications of large random matrices in communications engineering"
    - "linear precoding for broadcast channels with confidential messages under transmit side channel correlation"
    - "large system analysis of linear precoding in miso broadcast channels with confidential messages"

Connected through hyperedge HE-5 (induced by source paper "jammer assisted resource allocation in secure ofdma with untrusted users"):
  with members:
    - "principles of physical layer security in multiuser wireless networks a survey"
    - "on the complexity of joint subcarrier and power allocation for multi user ofdma systems"
    - "on tractability aspects of optimal resource allocation in ofdma systems"
    - "interference assisted secret communication"
    - "power and subcarrier allocation for physical layer security in ofdma based broadband wireless networks"
    - "a quantitative measure of fairness and discrimination for resource allocation in shared computer systems"

Connected through hyperedge HE-6 (induced by source paper "beam domain secure transmission for massive mimo communications"):
  with members:
    - "free deterministic equivalents for the analysis of mimo multiple access channel"
    - "linear precoding of data and artificial noise in secure massive mimo systems"
    - "massive mimo ten myths and one critical question"
    - "secure communications in millimeter wave ad hoc networks"
    - "pilot reuse for massive mimo transmission over spatially correlated rayleigh fading channels"
    - "massive mimo for next generation wireless systems"
    - "downlink training techniques for fdd massive mimo systems open loop and closed loop training with memory"
    - "principles of physical layer security in multiuser wireless networks a survey"

Connected through hyperedge HE-7 (induced by source paper "data aided secure massive mimo transmission with active eavesdropping"):
  with members:
    - "secure transmission with large numbers of antennas and finite alphabet inputs"
    - "analysis and design of secure massive mimo systems in the presence of hardware impairments"
    - "performance limits of massive mimo systems based on bayes optimal inference"
    - "secure massive mimo transmission with an active eavesdropper"
    - "large scale mimo relaying techniques for physical layer security af or df"
    - "secret key agreement with large antenna arrays under the pilot contamination attack"
    - "securing massive mimo at the physical layer"
    - "what will 5g be"

Connected through hyperedge HE-8 (induced by source paper "cell edge aware precoding for downlink massive mimo cellular networks"):
  with members:
    - "distributed optimization of hierarchical small cell networks a gnep framework"
    - "massive mimo ten myths and one critical question"
    - "operating massive mimo in unlicensed bands for enhanced coexistence and spatial reuse"
    - "energy efficient design of mimo heterogeneous networks with wireless backhaul"
    - "a stochastic geometry framework for analyzing pairwise cooperative cellular networks"
    - "three practical aspects of massive mimo intermittent user activity pilot synchronism and asymmetric deployment"
    - "fractional pilot reuse in massive mimo systems"
    - "a tractable model for noncoherent joint transmission base station cooperation"

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)