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: "near optimal hybrid analog and digital precoding for downlink mmwave massive mimo systems"
  Abstract: Millimeter wave (mmWave) massive MIMO can achieve orders of magnitude increase in spectral and energy efficiency, and it usually exploits the hybrid analog and digital precoding to overcome the serious signal attenuation induced by mmWave frequencies. However, most of hybrid precoding schemes focus on the full-array structure, which involves a high complexity. In this paper, we propose a near-optimal iterative hybrid precoding scheme based on the more realistic subarray structure with low complexity. We first decompose the complicated capacity optimization problem into a series of ones easier to be handled by considering each antenna array one by one. Then we optimize the achievable capacity of each antenna array from the first one to the last one by utilizing the idea of successive interference cancelation (SIC), which is realized in an iterative procedure that is easy to be parallelized. It is shown that the proposed hybrid precoding scheme can achieve better performance than other recently proposed hybrid precoding schemes, while it also enjoys an acceptable computational complexity.

Connected through hyperedge HE-1 (induced by source paper "hybrid precoder and combiner design with low resolution phase shifters in mmwave mimo systems"):
  with members:
    - "energy efficient transceiver design for hybrid sub array architecture mimo systems"
    - "alternating minimization algorithms for hybrid precoding in millimeter wave mimo systems"
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "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"
    - "limited feedback hybrid precoding for multi user millimeter wave systems"
    - "turbo like beamforming based on tabu search algorithm for millimeter wave massive mimo systems"
    - "near optimal hybrid processing for massive mimo systems via matrix decomposition"

Connected through hyperedge HE-2 (induced by source paper "genetic algorithm assisted hybrid beamforming for wireless fronthaul"):
  with members:
    - "hybrid analog and digital beamforming for mmwave ofdm large scale antenna arrays"
    - "spatially sparse precoding in millimeter wave mimo systems"

Connected through hyperedge HE-3 (induced by source paper "joint hybrid precoder and combiner design for mmwave spatial multiplexing transmission"):
  with members:
    - "alternating minimization algorithms for hybrid precoding in millimeter wave mimo systems"
    - "an overview of signal processing techniques for millimeter wave mimo systems"

Connected through hyperedge HE-4 (induced by source paper "auxiliary beam pair enabled aod and aoa estimation in closed loop large scale mmwave mimo systems"):
  with members:
    - "a lse and sparse message passing based channel estimation for mmwave mimo systems"
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "low complexity channel estimation for millimeter wave systems with hybrid a d antenna processing"
    - "frequency selective hybrid precoding for limited feedback millimeter wave systems"
    - "beamforming tradeoffs for initial ue discovery in millimeter wave mimo systems"
    - "hybrid analog digital channel estimation and beamforming training throughput tradeoff"
    - "energy efficient hybrid analog and digital precoding for mmwave mimo systems with large antenna arrays"
    - "hybrid mimo architectures for millimeter wave communications phase shifters or switches"

Connected through hyperedge HE-5 (induced by source paper "alternating minimization algorithms for hybrid precoding in millimeter wave mimo systems"):
  with members:
    - "large scale convex optimization for ultra dense cloud ran"
    - "channel estimation and hybrid precoding for millimeter wave cellular systems"
    - "what will 5g be"
    - "millimeter wave cellular wireless networks potentials and challenges"
    - "spatially sparse precoding in millimeter wave mimo systems"
    - "low complexity hybrid precoding in massive multiuser mimo systems"
    - "group sparse beamforming for green cloud ran"
    - "throughput and energy efficiency analysis of small cell networks with multi antenna base stations"

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)