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: "downlink mimo hcns with residual transceiver hardware impairments"
  Abstract: A major limitation of heterogeneous cellular networks (HCNs) is the neglect of the additive residual transceiver hardware impairments (ARTHIs). The assumption of perfect hardware is quite strong and results in misleading conclusions. This paper models a general multiple-input multiple-output (MIMO) HCN with cell association by incorporating the RTHIs. We derive the coverage probability and shed light on the impact of the ARTHIs, when various transmission methods are applied. As the hardware quality decreases, the coverage probability worsens. Especially, this effect is more severe as the transmit power increases. Furthermore, we verify that in an HCN, it is better to employ at each base station as few transmit antennas as possible.

Connected through hyperedge HE-1 (induced by source paper "nuts and bolts of a realistic stochastic geometric analysis of mmwave hetnets hardware impairments and channel aging"):
  with members:
    - "toward a realistic assessment of multiple antenna hcns residual additive transceiver hardware impairments and channel aging"
    - "stochastic geometric coverage analysis in mmwave cellular networks with a realistic channel model"
    - "impact of general channel aging conditions on the downlink performance of massive mimo"
    - "rate splitting to mitigate residual transceiver hardware impairments in massive mimo systems"
    - "hybrid architectures with few bit adc receivers achievable rates and energy rate tradeoffs"
    - "achievable rate and energy efficiency of hybrid and digital beamforming receivers with low resolution adc"
    - "coverage in heterogeneous downlink millimeter wave cellular networks"
    - "massive mimo ten myths and one critical question"

Connected through hyperedge HE-2 (induced by source paper "sdn enabled mimo heterogeneous cooperative networks with flexible cell association"):
  with members:
    - "toward a realistic assessment of multiple antenna hcns residual additive transceiver hardware impairments and channel aging"
    - "user association in 5g networks a survey and an outlook"
    - "an overview of load balancing in hetnets old myths and open problems"
    - "a tractable model for noncoherent joint transmission base station cooperation"
    - "what will 5g be"
    - "downlink mimo hetnets modeling ordering results and performance analysis"
    - "downlink multi antenna heterogeneous cellular network with load balancing"
    - "heterogeneous cellular networks with flexible cell association a comprehensive downlink sinr analysis"

Connected through hyperedge HE-3 (induced by source paper "modeling and performance of uplink cache enabled massive mimo heterogeneous networks"):
  with members:
    - "toward a realistic assessment of multiple antenna hcns residual additive transceiver hardware impairments and channel aging"
    - "impact of general channel aging conditions on the downlink performance of massive mimo"
    - "cluster content caching an energy efficient approach to improve quality of service in cloud radio access networks"
    - "impact of user mobility on optimal linear receivers in cellular networks"
    - "deploying dense networks for maximal energy efficiency small cells meet massive mimo"
    - "an uplink interference analysis for massive mimo systems with mrc and zf receivers"
    - "massive mimo with non ideal arbitrary arrays hardware scaling laws and circuit aware design"
    - "analyzing uplink sinr and rate in massive mimo systems using stochastic geometry"

Connected through hyperedge HE-4 (induced by source paper "out of band radiation from antenna arrays clarified"):
  with members:
    - "impact of major rf impairments on mm wave communications using ofdm waveforms"
    - "analysis and design of secure massive mimo systems in the presence of hardware impairments"
    - "out of band radiation measure for mimo arrays with beamformed transmission"
    - "impact of residual transmit rf impairments on training based mimo systems"
    - "massive mimo systems with non ideal hardware energy efficiency estimation and capacity limits"
    - "on the impact of hardware impairments on massive mimo"

Connected through hyperedge HE-5 (induced by source paper "toward a realistic assessment of multiple antenna hcns residual additive transceiver hardware impairments and channel aging"):
  with members:
    - "impact of general channel aging conditions on the downlink performance of massive mimo"
    - "performance of massive mimo uplink with zero forcing receivers under delayed channels"
    - "cell edge aware precoding for downlink massive mimo cellular networks"
    - "mitigation of phase noise in massive mimo systems a rate splitting approach"
    - "rate splitting to mitigate residual transceiver hardware impairments in massive mimo systems"
    - "analysis and design of secure massive mimo systems in the presence of hardware impairments"
    - "sum rate and power scaling of massive mimo systems with channel aging"
    - "downlink performance of massive mimo under general channel aging conditions"

Connected through hyperedge HE-6 (induced by source paper "rate splitting to mitigate residual transceiver hardware impairments in massive mimo systems"):
  with members:
    - "impact of general channel aging conditions on the downlink performance of massive mimo"
    - "energy efficiency in mimo underlay and overlay device to device communications and cognitive radio systems"
    - "sum rate maximization for linearly precoded downlink multiuser miso systems with partial csit a rate splitting approach"
    - "miso networks with imperfect csit a topological rate splitting approach"
    - "robust transmission in downlink multiuser miso systems a rate splitting approach"
    - "a rate splitting strategy for max min fair multigroup multicasting"
    - "rate splitting for mimo wireless networks a promising phy layer strategy for lte evolution"
    - "a rate splitting strategy for massive mimo with imperfect csit"

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)