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: "two layer decoding in cellular massive mimo systems with spatial channel correlation"
  Abstract: This paper studies a two-layer decoding method that mitigates inter-cell interference in multi-cell Massive MIMO systems. In layer one, each base station (BS) estimates the channels to intra-cell users and uses the estimates for local decoding on each BS, followed by a second decoding layer where the BSs cooperate to mitigate inter-cell interference. An uplink achievable spectral efficiency (SE) expression is computed for arbitrary two-layer decoding schemes, while a closed-form expression is obtained for correlated Rayleigh fading channels, maximum-ratio combining (MRC), and large-scale fading decoding (LSFD) in the second layer. We formulate a non-convex sum SE maximization problem with both the data power and LSFD vectors as optimization variables and develop an algorithm based on the weighted MMSE (minimum mean square error) approach to obtain a stationary point with low computational complexity.

Connected through hyperedge HE-1 (induced by source paper "channel correlation diversity in mu mimo systems analysis and measurements"):
  with members:
    - "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"
    - "massive mimo performance evaluation based on measured propagation data"
    - "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-2 (induced by source paper "large scale fading decoding in cellular massive mimo systems with spatially correlated channels"):
  with members:
    - "uplink massive mimo for channels with spatial correlation"
    - "massive mimo has unlimited capacity"
    - "performance of cell free massive mimo systems with mmse and lsfd receivers"
    - "uplink interference reduction in large scale antenna systems"
    - "smart pilot assignment for massive mimo"
    - "massive mimo with non ideal arbitrary arrays hardware scaling laws and circuit aware design"
    - "what will 5g be"
    - "massive mimo for maximal spectral efficiency how many users and pilots should be allocated"

Connected through hyperedge HE-3 (induced by source paper "performance of cell free massive mimo with rician fading and phase shifts"):
  with members:
    - "a new look at cell free massive mimo making it practical with dynamic cooperation"
    - "ubiquitous cell free massive mimo communications"
    - "large scale fading decoding in cellular massive mimo systems with spatially correlated channels"
    - "performance of cell free massive mimo systems with mmse and lsfd receivers"
    - "uplink interference reduction in large scale antenna systems"
    - "cell free massive mimo versus small cells"
    - "scalable synchronization and reciprocity calibration for distributed multiuser mimo"

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)