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: "toward a realistic assessment of multiple antenna hcns residual additive transceiver hardware impairments and channel aging"
  Abstract: Given the critical dependence of broadcast channels by the accuracy of channel state information at the transmitter (CSIT), we develop a general downlink model with zero-forcing precoding, applied in realistic heterogeneous cellular systems with multiple-antenna base stations (BSs). Specifically, we take into consideration imperfect CSIT due to pilot contamination, channel aging due to users relative movement, and unavoidable residual additive transceiver hardware impairments (RATHIs). Assuming that the BSs are Poisson distributed, the main contributions focus on the derivations of the upper bound of the coverage probability and the achievable user rate for this general model. We show that both the coverage probability and the user rate are dependent on the imperfect CSIT and RATHIs. More concretely, we quantify the resultant performance loss of the network due to these effects. We depict that the uplink RATHIs have equal impact, but the downlink transmit BS distortion has a greater impact than the receive hardware impairment of the user. Thus, the transmit BS hardware should be of better quality than user's receive hardware. Furthermore, we characterise both the coverage probability and user rate in terms of the time variation of the channel. It is shown that both of them decrease with increasing user mobility, but after a specific value of the normalized Doppler shift, they increase again. Actually, the time variation, following the Jakes autocorrelation function, mirrors this effect on coverage probability and user rate. Finally, we consider space-division multiple access (SDMA), single-user beamforming (SU-BF), and baseline single-input single-output transmission. A comparison among these schemes reveals that the coverage by means of SU-BF outperforms SDMA in terms of coverage.

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:
    - "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"
    - "downlink mimo hcns with residual transceiver hardware impairments"
    - "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:
    - "downlink mimo hcns with residual transceiver hardware impairments"
    - "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 "achieving phase coherency and gain stability in active antenna arrays for sub 6 ghz fdd and tdd fd mimo challenges and solutions"):
  with members:
    - "channel reciprocity calibration in tdd hybrid beamforming massive mimo systems"
    - "a framework for over the air reciprocity calibration for tdd massive mimo systems"
    - "overview of full dimension mimo in lte advanced pro"
    - "massive mimo performance with imperfect channel reciprocity and channel estimation error"
    - "reciprocity calibration for massive mimo proposal modeling and validation"
    - "uplink performance of time reversal mrc in massive mimo systems subject to phase noise"
    - "massive mimo with non ideal arbitrary arrays hardware scaling laws and circuit aware design"

Connected through hyperedge HE-4 (induced by source paper "modeling and performance of uplink cache enabled massive mimo heterogeneous networks"):
  with members:
    - "impact of general channel aging conditions on the downlink performance of massive mimo"
    - "downlink mimo hcns with residual transceiver hardware impairments"
    - "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"

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)