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 performance evaluation based on measured propagation data"
  Abstract: Massive MIMO, also known as very-large MIMO or large-scale antenna systems, is a new technique that potentially can offer large network capacities in multi-user scenarios. With a massive MIMO system, we consider the case where a base station equipped with a large number of antenna elements simultaneously serves multiple single-antenna users in the same time-frequency resource. So far, investigations are mostly based on theoretical channels with independent and identically distributed (i.i.d.) complex Gaussian coefficients, i.e., i.i.d. Rayleigh channels. Here, we investigate how massive MIMO performs in channels measured in real propagation environments. Channel measurements were performed at 2.6 GHz using a virtual uniform linear array (ULA), which has a physically large aperture, and a practical uniform cylindrical array (UCA), which is more compact in size, both having 128 antenna ports. Based on measurement data, we illustrate channel behavior of massive MIMO in three representative propagation conditions, and evaluate the corresponding performance. The investigation shows that the measured channels, for both array types, allow us to achieve performance close to that in i.i.d. Rayleigh channels. It is concluded that in real propagation environments we have characteristics that can allow for efficient use of massive MIMO, i.e., the theoretical advantages of this new technology can also be harvested in real channels.

Connected through hyperedge HE-1 (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-2 (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-3 (induced by source paper "code domain noma in massive mimo when is it needed"):
  with members:
    - "what is the benefit of code domain noma in massive mimo"
    - "what role can noma play in massive mimo"
    - "gaussian message passing for overloaded massive mimo noma"
    - "massive mimo has unlimited capacity"
    - "massive mimo performance tdd versus fdd what do measurements say"
    - "power domain non orthogonal multiple access noma in 5g systems potentials and challenges"
    - "fundamental limits of low density spreading noma with fading"
    - "a coordinated approach to channel estimation in large scale multiple antenna systems"

Connected through hyperedge HE-4 (induced by source paper "non bayesian activity detection large scale fading coefficient estimation and unsourced random access with a massive mimo receiver"):
  with members:
    - "improved scaling law for activity detection in massive mimo systems"
    - "on the fly large scale channel gain estimation for massive antenna array base stations"
    - "techniques for improving the finite length performance of sparse superposition codes"
    - "on the restricted isometry of the columnwise khatri rao product"
    - "sparse activity detection for massive connectivity"
    - "massive connectivity with massive mimo part ii achievable rate characterization"
    - "sparse signal processing for grant free massive connectivity a future paradigm for random access protocols in the internet of things"
    - "massive connectivity with massive mimo part i device activity detection and channel estimation"

Connected through hyperedge HE-5 (induced by source paper "dynamic resource allocation in co located and cell free massive mimo"):
  with members:
    - "dynamic scheduling and power control in uplink massive mimo with random data arrivals"
    - "ubiquitous cell free massive mimo communications"
    - "large scale fading decoding in cellular massive mimo systems with spatially correlated channels"
    - "making cell free massive mimo competitive with mmse processing and centralized implementation"
    - "dynamic power control for packets with deadlines"
    - "performance of cell free massive mimo systems with mmse and lsfd receivers"
    - "optimal pilot and payload power control in single cell massive mimo systems"
    - "channel hardening and favorable propagation in cell free massive mimo with stochastic geometry"

Connected through hyperedge HE-6 (induced by source paper "balance queueing and retransmission latency optimal massive mimo design"):
  with members:
    - "delay performance of the multiuser miso downlink under imperfect csi and finite length coding"
    - "outage of periodic downlink wireless networks with hard deadlines"
    - "massive mimo has unlimited capacity"
    - "on the ergodic rate lower bounds with applications to massive mimo"
    - "delay performance of miso wireless communications"
    - "massive mimo ten myths and one critical question"
    - "on noisy arq in block fading channels"
    - "massive mimo for next generation wireless systems"

Connected through hyperedge HE-7 (induced by source paper "channel correlation diversity in mu mimo systems analysis and measurements"):
  with members:
    - "two layer decoding in cellular massive mimo systems with spatial channel correlation"
    - "large scale fading decoding in cellular massive mimo systems with spatially correlated channels"
    - "uplink massive mimo for channels with spatial correlation"
    - "capacity scaling of massive mimo in strong spatial correlation regimes"
    - "massive mimo has unlimited capacity"
    - "on the matrix inversion approximation based on neumann series in massive mimo systems"
    - "power scaling of uplink massive mimo systems with arbitrary rank channel means"
    - "linear precoding based on polynomial expansion large scale multi cell mimo systems"

Connected through hyperedge HE-8 (induced by source paper "joint transmit and circuit power minimization in massive mimo with downlink sinr constraints when to turn on massive mimo"):
  with members:
    - "employing antenna selection to improve energy efficiency in massive mimo systems"
    - "on the ergodic rate lower bounds with applications to massive mimo"
    - "massive mimo ten myths and one critical question"
    - "energy efficiency in massive mimo based 5g networks opportunities and challenges"
    - "energy efficiency of massive mimo coping with daily load variation"
    - "impact of transceiver power consumption on the energy efficiency of zero forcing detector in massive mimo systems"
    - "what will 5g be"
    - "optimal design of energy efficient multi user mimo systems is massive mimo the answer"

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)