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: "energy and spectral efficiency of very large multiuser mimo systems"
  Abstract: A multiplicity of autonomous terminals simultaneously transmits data streams to a compact array of antennas. The array uses imperfect channel-state information derived from transmitted pilots to extract the individual data streams. The power radiated by the terminals can be made inversely proportional to the square-root of the number of base station antennas with no reduction in performance. In contrast if perfect channel-state information were available the power could be made inversely proportional to the number of antennas. Lower capacity bounds for maximum-ratio combining (MRC), zero-forcing (ZF) and minimum mean-square error (MMSE) detection are derived. A MRC receiver normally performs worse than ZF and MMSE. However as power levels are reduced, the cross-talk introduced by the inferior maximum-ratio receiver eventually falls below the noise level and this simple receiver becomes a viable option. The tradeoff between the energy efficiency (as measured in bits/J) and spectral efficiency (as measured in bits/channel use/terminal) is quantified. It is shown that the use of moderately large antenna arrays can improve the spectral and energy efficiency with orders of magnitude compared to a single-antenna system.

Connected through hyperedge HE-1 (induced by source paper "downlink secrecy rate of one bit massive mimo system with active eavesdropping"):
  with members:
    - "robust designs of beamforming and power splitting for distributed antenna systems with wireless energy harvesting"
    - "secure massive mimo communication with low resolution dacs"
    - "on the uplink achievable rate for massive mimo with 1 bit adc and superimposed pilots"
    - "data aided secure massive mimo transmission with active eavesdropping"
    - "secure massive mimo systems with limited rf chains"
    - "secure transmission with large numbers of antennas and finite alphabet inputs"
    - "jamming resistant receivers for the massive mimo uplink"
    - "beamforming and power splitting designs for an aided secure multi user mimo swipt systems"

Connected through hyperedge HE-2 (induced by source paper "performance analysis of quantized uplink massive mimo ofdm with oversampling under adjacent channel interference"):
  with members:
    - "massive mu mimo ofdm uplink with hardware impairments modeling and analysis"
    - "throughput analysis of massive mimo uplink with low resolution adcs"
    - "channel estimation and performance analysis of one bit massive mimo systems"
    - "linear precoding with low resolution dacs for massive mu mimo ofdm downlink"
    - "uplink performance of wideband massive mimo with one bit adcs"
    - "mixed adc massive mimo detectors performance analysis and design optimization"
    - "massive mimo ten myths and one critical question"
    - "one bit massive mimo channel estimation and high order modulations"

Connected through hyperedge HE-3 (induced by source paper "power scaling laws and near field behaviors of massive mimo and intelligent reflecting surfaces"):
  with members:
    - "intelligent reflecting surface versus decode and forward how large surfaces are needed to beat relaying"
    - "spatially stationary model for holographic mimo small scale fading"
    - "propagation modeling and analysis of reconfigurable intelligent surfaces for indoor and outdoor applications in 6g wireless systems"
    - "beyond max snr joint encoding for reconfigurable intelligent surfaces"
    - "towards smart and reconfigurable environment intelligent reflecting surface aided wireless network"
    - "reconfigurable intelligent surfaces bridging the gap between scattering and reflection"
    - "intelligent reflecting surface enhanced wireless network via joint active and passive beamforming"
    - "beyond massive mimo the potential of data transmission with large intelligent surfaces"

Connected through hyperedge HE-4 (induced by source paper "massive mimo asymptotics for ray based propagation channels"):
  with members:
    - "mimo channel hardening a physical model based analysis"
    - "channel hardening in massive mimo a measurement based analysis"
    - "energy efficiency and asymptotic performance evaluation of beamforming structures in doubly massive mimo mmwave systems"
    - "a random access protocol for pilot allocation in crowded massive mimo systems"
    - "uplink analysis of large mu mimo systems with space constrained arrays in ricean fading"
    - "no downlink pilots are needed in tdd massive mimo"
    - "massive mimo ten myths and one critical question"
    - "asymptotic orthogonality analysis of time domain sparse massive mimo channels"

Connected through hyperedge HE-5 (induced by source paper "spectral efficiency analysis of cell free massive mimo systems with zero forcing detector"):
  with members:
    - "downlink precoding with mixed statistical and imperfect instantaneous csi for massive mimo systems"
    - "enhanced max min sinr for uplink cell free massive mimo systems"
    - "on the total energy efficiency of cell free massive mimo"
    - "performance analysis for massive mimo downlink with low complexity approximate zero forcing precoding"
    - "pilot power allocation through user grouping in multi cell massive mimo systems"
    - "energy efficient downlink transmission for multicell massive das with pilot contamination"
    - "energy efficiency in cell free massive mimo with zero forcing precoding design"
    - "cell free massive mimo versus small cells"

Connected through hyperedge HE-6 (induced by source paper "performance of multi cell massive mimo systems with interference decoding"):
  with members:
    - "large scale fading decoding in cellular massive mimo systems with spatially correlated channels"
    - "massive mimo has unlimited capacity"
    - "gaussian multiple access via compute and forward"
    - "uplink interference reduction in large scale antenna systems"
    - "joint power allocation and user association optimization for massive mimo systems"
    - "robust pilot decontamination based on joint angle and power domain discrimination"
    - "optimal achievable rates for interference networks with random codes"
    - "system architecture and key technologies for 5g heterogeneous cloud radio access networks"

Connected through hyperedge HE-7 (induced by source paper "real time implementation aspects of large intelligent surfaces"):
  with members:
    - "energy efficient multi user miso communication using low resolution large intelligent surfaces"
    - "intelligent reflecting surface enhanced wireless network via joint active and passive beamforming"
    - "massive mimo in sub 6 ghz and mmwave physical practical and use case differences"
    - "capacity degradation with modeling hardware impairment in large intelligent surface"
    - "beyond massive mimo the potential of data transmission with large intelligent surfaces"
    - "beamforming optimization for intelligent reflecting surface with discrete phase shifts"
    - "reconfigurable intelligent surfaces for energy efficiency in wireless communication"
    - "intelligent reflecting surface enhanced wireless network joint active and passive beamforming design"

Connected through hyperedge HE-8 (induced by source paper "joint frame design and resource allocation for ultra reliable and low latency vehicular networks"):
  with members:
    - "optimized power control for massive mimo with underlaid d2d communications"
    - "ultra reliable and low latency communications for connected vehicles challenges and solutions"
    - "superimposed pilots are superior for mitigating pilot contamination in massive mimo"
    - "a two stage allocation scheme for delay sensitive services in dense vehicular networks"
    - "high reliability and low latency for vehicular networks challenges and solutions"
    - "generalized cross layer designs for generic half duplex multicarrier wireless networks with frequency reuse"
    - "reliable and efficient autonomous driving the need for heterogeneous vehicular networks"
    - "information spectrum approach to second order coding rate in channel coding"

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)