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 performance of massive mimo under general channel aging conditions"
  Abstract: Massive multiple-input multiple-output (MIMO) is a promising technology aiming at achieving high spectral efficiency by deploying a large number of base station (BS) antennas using coherent combining. Channel aging due to user mobility is a significant degrading factor of such systems. In addition, cost efficiency of massive MIMO is a prerecuisite for their deployment, that leads to low cost antenna elements inducing high phase noise. Since phase is time-dependent, it contributes to channel aging. For this reason, we present a novel joint channel-phase noise model, that enables us to study the downlink of massive MIMO with maximum ratio transmission (MRT) precoder under these conditions by means of the deterministic equivalent of the achievable sum-rate. Among the noteworthy outcomes is that the degradation due to user mobility dominates over the effect of phase noise. Nevertheless, we demonstrate that the joint effects of phase noise and user mobility do not degrade the power scaling law $1/\sqrt{M}$ ($M$ is the number of BS antennas), as has been established in massive MIMO systems with imperfect channel state information.

Connected through hyperedge HE-1 (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"
    - "downlink mimo hcns with residual transceiver hardware impairments"
    - "sum rate and power scaling of massive mimo systems with channel aging"

Connected through hyperedge HE-2 (induced by source paper "impact of general channel aging conditions on the downlink performance of massive mimo"):
  with members:
    - "massive mimo ten myths and one critical question"
    - "massive mimo 10 myths and one grand question"
    - "sum rate and power scaling of massive mimo systems with channel aging"
    - "impact of user mobility on optimal linear receivers in cellular networks"
    - "uplink performance of time reversal mrc in massive mimo systems subject to phase noise"
    - "uplink performance of conventional and massive mimo cellular systems with delayed csit"
    - "massive mimo with non ideal arbitrary arrays hardware scaling laws and circuit aware design"
    - "on the impact of oscillator phase noise on the uplink performance in a massive mimo ofdm system"

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)