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: "massive mimo for next generation wireless systems"
  Abstract: Multi-user MIMO offers big advantages over conventional point-to-point MIMO: it works with cheap single-antenna terminals, a rich scattering environment is not required, and resource allocation is simplified because every active terminal utilizes all of the time-frequency bins. However, multi-user MIMO, as originally envisioned, with roughly equal numbers of service antennas and terminals and frequency-division duplex operation, is not a scalable technology. Massive MIMO (also known as large-scale antenna systems, very large MIMO, hyper MIMO, full-dimension MIMO, and ARGOS) makes a clean break with current practice through the use of a large excess of service antennas over active terminals and time-division duplex operation. Extra antennas help by focusing energy into ever smaller regions of space to bring huge improvements in throughput and radiated energy efficiency. Other benefits of massive MIMO include extensive use of inexpensive low-power components, reduced latency, simplification of the MAC layer, and robustness against intentional jamming. The anticipated throughput depends on the propagation environment providing asymptotically orthogonal channels to the terminals, but so far experiments have not disclosed any limitations in this regard. While massive MIMO renders many traditional research problems irrelevant, it uncovers entirely new problems that urgently need attention: the challenge of making many low-cost low-precision components that work effectively together, acquisition and synchronization for newly joined terminals, the exploitation of extra degrees of freedom provided by the excess of service antennas, reducing internal power consumption to achieve total energy efficiency reductions, and finding new deployment scenarios. This article presents an overview of the massive MIMO concept and contemporary research on the topic.

Connected through hyperedge HE-1 (induced by source paper "joint power control and lsfd for wireless powered cell free massive mimo"):
  with members:
    - "max min fair wireless powered cell free massive mimo for uncorrelated rician fading channels"
    - "optimal downlink transmission for cell free swipt massive mimo systems with active eavesdropping"
    - "scalability aspects of cell free massive mimo"
    - "scalable cell free massive mimo systems"
    - "massive mimo with spatially correlated rician fading channels"
    - "performance of cell free massive mimo with rician fading and phase shifts"
    - "multiple antenna technologies for beyond 5g"
    - "making cell free massive mimo competitive with mmse processing and centralized implementation"

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 "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-4 (induced by source paper "study of coarse quantization aware block diagonalization algorithms for mimo systems with low resolution"):
  with members:
    - "throughput analysis of massive mimo uplink with low resolution adcs"
    - "branch and bound precoding for multiuser mimo systems with 1 bit quantization"
    - "widely linear precoding for large scale mimo with iqi algorithms and performance analysis"
    - "linear precoding with low resolution dacs for massive mu mimo ofdm downlink"
    - "iterative detection and decoding algorithms for mimo systems in block fading channels using ldpc codes"
    - "robust adaptive beamforming based on low rank and cross correlation techniques"
    - "quantized precoding for massive mu mimo"
    - "adaptive reduced rank receive processing based on minimum symbol error rate criterion for large scale multiple antenna systems"

Connected through hyperedge HE-5 (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-6 (induced by source paper "cognitive radio networks an information theoretic perspective"):
  with members:
    - "noma an information theoretic perspective"
    - "non orthogonal multiple access common myths and critical questions"
    - "multi user cognitive interference channels a survey and new capacity results"
    - "the capacity of less noisy cognitive interference channels"
    - "inner and outer bounds for the gaussian cognitive interference channel and new capacity results"
    - "the capacity of more capable cognitive interference channels"
    - "superposition coding based bounds and capacity for the cognitive z interference channels"
    - "on the capacity of a class of cognitive z interference channels"

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 "covariance aided csi acquisition with non orthogonal pilots in massive mimo a large system performance analysis"):
  with members:
    - "massive mimo has unlimited capacity"
    - "pilot length optimization for spatially correlated multi user mimo channel estimation"
    - "snops short non orthogonal pilot sequences for downlink channel state estimation in fdd massive mimo"
    - "pilot reuse for massive mimo transmission over spatially correlated rayleigh fading channels"
    - "dealing with interference in distributed large scale mimo systems a statistical approach"
    - "achievable rates of fdd massive mimo systems with spatial channel correlation"
    - "five disruptive technology directions for 5g"
    - "scaling up mimo opportunities and challenges with very large arrays"

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)