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 tier precoding for fdd multi cell massive mimo time varying interference networks"
  Abstract: Massive MIMO is a promising technology in future wireless communication networks. However, it raises a lot of implementation challenges, for example, the huge pilot symbols and feedback overhead, requirement of real-time global CSI, large number of RF chains needed, and high computational complexity. We consider a two-tier precoding strategy for multi-cell massive MIMO interference networks, with an outer precoder for inter-cell/inter-cluster interference cancellation, and an inner precoder for intra-cell multiplexing. In particular, to combat with the computational complexity issue for the outer precoding, we propose a low complexity online iterative algorithm to track the outer precoder under time-varying channels. We follow an optimization technique and formulate the problem on the Grassmann manifold. We develop a low complexity iterative algorithm, which converges to the global optimal solution under static channels. In time-varying channels, we propose a compensation technique to offset the variation of the time-varying optimal solution. We show with our theoretical result that, under some mild conditions, perfect tracking of the target outer precoder using the proposed algorithm is possible. Numerical results demonstrate that the two-tier precoding with the proposed iterative compensation algorithm can achieve a good performance with a significant complexity reduction compared with the conventional two-tier precoding techniques in the literature.

Connected through hyperedge HE-1 (induced by source paper "time varying downlink channel tracking for quantized massive mimo networks"):
  with members:
    - "beamspace aware adaptive channel estimation for single carrier time varying massive mimo channels"
    - "interference alignment and soft space reuse based cooperative transmission for multi cell massive mimo networks"
    - "bayesian optimal data detector for mmwave ofdm system with low resolution adc"
    - "a gamp based low complexity sparse bayesian learning algorithm"
    - "mixed adc massive mimo detectors performance analysis and design optimization"
    - "uplink achievable rate for massive mimo systems with low resolution adc"
    - "spatially common sparsity based adaptive channel estimation and feedback for fdd massive mimo"
    - "training sequence design for feedback assisted hybrid beamforming in massive mimo systems"

Connected through hyperedge HE-2 (induced by source paper "downlink precoding with mixed statistical and imperfect instantaneous csi for massive mimo systems"):
  with members:
    - "massive mimo with imperfect channel covariance information"
    - "a rate splitting strategy for massive mimo with imperfect csit"
    - "massive mimo ten myths and one critical question"
    - "two stage subspace constrained precoding in massive mimo cellular systems"
    - "power scaling of uplink massive mimo systems with arbitrary rank channel means"
    - "dealing with interference in distributed large scale mimo systems a statistical approach"
    - "pilot beam pattern design for channel estimation in massive mimo systems"
    - "downlink training techniques for fdd massive mimo systems open loop and closed loop training with memory"

Connected through hyperedge HE-3 (induced by source paper "low overhead weighted graph coloring based two layer precoding for fdd massive mimo systems"):
  with members:
    - "dictionary learning based sparse channel representation and estimation for fdd massive mimo systems"
    - "massive mimo for next generation wireless systems"
    - "downlink training techniques for fdd massive mimo systems open loop and closed loop training with memory"
    - "scaling up mimo opportunities and challenges with very large arrays"
    - "joint spatial division and multiplexing for mm wave channels"

Connected through hyperedge HE-4 (induced by source paper "an overview on resource allocation techniques for multi user mimo systems"):
  with members:
    - "low complexity downlink user selection for massive mimo systems"
    - "alternating minimization algorithms for hybrid precoding in millimeter wave mimo systems"
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "user association in 5g networks a survey and an outlook"
    - "cell free massive mimo versus small cells"
    - "mu mimo mac protocols for wireless local area networks a survey"
    - "on the number of rf chains and phase shifters and scheduling design with hybrid analog digital beamforming"
    - "hybrid digital and analog beamforming design for large scale antenna arrays"

Connected through hyperedge HE-5 (induced by source paper "interference alignment and soft space reuse based cooperative transmission for multi cell massive mimo networks"):
  with members:
    - "structured compressive sensing based spatio temporal joint channel estimation for fdd massive mimo"
    - "on interference alignment with imperfect csi characterizations of outage probability ergodic rate and ser"
    - "two stage beamformer design for massive mimo downlink by trace quotient formulation"
    - "two stage subspace constrained precoding in massive mimo cellular systems"
    - "training sequence design for feedback assisted hybrid beamforming in massive mimo systems"
    - "downlink training techniques for fdd massive mimo systems open loop and closed loop training with memory"
    - "five disruptive technology directions for 5g"
    - "scaling up mimo opportunities and challenges with very large arrays"

Connected through hyperedge HE-6 (induced by source paper "robust transceiver design based on interference alignment for multi user multi cell mimo networks with channel uncertainty"):
  with members:
    - "two stage beamformer design for massive mimo downlink by trace quotient formulation"
    - "exploiting known interference as green signal power for downlink beamforming optimization"
    - "optimal multiuser transmit beamforming a difficult problem with a simple solution structure"
    - "rethinking the role of interference in wireless networks"
    - "spatially sparse precoding in millimeter wave mimo systems"
    - "grouping based interference alignment with ia cell assignment in multi cell mimo mac under limited feedback"
    - "multi cell random beamforming achievable rate and degrees of freedom region"
    - "outage probability and outage based robust beamforming for mimo interference channels with imperfect channel state information"

Connected through hyperedge HE-7 (induced by source paper "base station selection for massive mimo networks with two stage precoding"):
  with members:
    - "joint power allocation and user association optimization for massive mimo systems"
    - "two stage beamformer design for massive mimo downlink by trace quotient formulation"
    - "training sequence design for feedback assisted hybrid beamforming in massive mimo systems"
    - "scaling up mimo opportunities and challenges with very large arrays"

Connected through hyperedge HE-8 (induced by source paper "a generalized framework on beamformer design and csi acquisition for single carrier massive mimo systems in millimeter wave channels"):
  with members:
    - "enhancing the estimation of mm wave large array channels by exploiting spatio temporal correlation and sparse scattering"
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "channel acquisition for massive mimo ofdm with adjustable phase shift pilots"
    - "two stage beamformer design for massive mimo downlink by trace quotient formulation"
    - "spatially common sparsity based adaptive channel estimation and feedback for fdd massive mimo"
    - "pilot reuse for massive mimo transmission over spatially correlated rayleigh fading channels"
    - "channel estimation and hybrid precoding for millimeter wave cellular systems"
    - "pilot beam pattern design for channel estimation in massive mimo systems"

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)