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: "distributed spatial multiplexing systems with hardware impairments and imperfect channel estimation under rank 1 rician fading channels"
  Abstract: The performance of a multiuser communication system with single-antenna transmitting terminals and a multi-antenna base-station receiver is analytically investigated. The system operates under independent and non-identically distributed rank-$1$ Rician fading channels with imperfect channel estimation and residual hardware impairments (compensation algorithms are assumed, which mitigate the main impairments) at the transceiver. The spatial multiplexing mode of operation is considered where all the users are simultaneously transmitting their streams to the receiver. Zero-forcing is applied along with successive interference cancellation (SIC) as a means for efficient detection of the received streams. New analytical closed-form expressions are derived for some important performance metrics, namely, the outage probability and ergodic capacity of the entire system. Both the analytical expressions and simulation results show the impact of imperfect channel estimation and hardware impairments to the overall system performance in the usage scenarios of massive MIMO and mmWave communication systems.

Connected through hyperedge HE-1 (induced by source paper "performance analysis of mixed adc massive mimo systems over rician fading channels"):
  with members:
    - "spatio temporal waveform design for multiuser massive mimo downlink with 1 bit receivers"
    - "bayes optimal joint channel and data estimation for massive mimo with low precision adcs"
    - "mixed adc massive mimo"
    - "mixed adc massive mimo uplink in frequency selective channels"
    - "on the spectral efficiency of massive mimo systems with low resolution adcs"
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "mixed adc massive mimo detectors performance analysis and design optimization"
    - "achievable rate of rician large scale mimo channels with transceiver hardware impairments"

Connected through hyperedge HE-2 (induced by source paper "all cognitive mimo a new multiuser detection approach with different priorities"):
  with members:
    - "simultaneous spectrum sensing and data reception for cognitive spatial multiplexing distributed systems"
    - "massive mimo ten myths and one critical question"
    - "massive mimo for next generation wireless systems"
    - "full duplex cooperative cognitive radio with transmit imperfections"
    - "cooperative cognitive networks optimal distributed and low complexity algorithms"
    - "effects of channel aging in massive mimo systems"
    - "energy and spectral efficiency of very large multiuser mimo systems"
    - "mimo diversity in the presence of double scattering"

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)