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: "an esprit based approach for 2 d localization of incoherently distributed sources in massive mimo systems"
  Abstract: In this paper, an approach of estimating signal parameters via rotational invariance technique (ESPRIT) is proposed for two-dimensional (2-D) localization of incoherently distributed (ID) sources in large-scale/massive multiple-input multiple-output (MIMO) systems. The traditional ESPRIT-based methods are valid only for one-dimensional (1-D) localization of the ID sources. By contrast, in the proposed approach the signal subspace is constructed for estimating the nominal azimuth and elevation direction-of-arrivals and the angular spreads. The proposed estimator has closed-form expressions and hence it does not have to search over the entire feasible field. Therefore, it imposes significantly lower computational complexity than the conventional 2-D estimation approaches. Our analysis shows that the estimation performance of the proposed approach improves when the large-scale/massive MIMO systems are employed. The approximate Cramer-Rao bound of the proposed estimator for the 2-D localization is also derived. Numerical results demonstrate that albeit the proposed estimation method is comparable with the traditional 2-D estimators in terms of performance, it benefits from a remarkably lower computational complexity

Connected through hyperedge HE-1 (induced by source paper "tracking position and orientation through millimeter wave lens mimo in 5g systems"):
  with members:
    - "optimal precoders for tracking the aod and aoa of a mmwave path"
    - "direct localization for massive mimo"
    - "error bounds for uplink and downlink 3d localization in 5g mmwave systems"
    - "multi user millimeter wave mimo with full dimensional lens antenna array"
    - "compressive channel estimation and tracking for large arrays in mm wave picocells"
    - "joint device positioning and clock synchronization in 5g ultra dense networks"
    - "frequency selective hybrid precoding for limited feedback millimeter wave systems"
    - "tracking angles of departure and arrival in a mobile millimeter wave channel"

Connected through hyperedge HE-2 (induced by source paper "position and orientation estimation through millimeter wave mimo in 5g systems"):
  with members:
    - "direct localization for massive mimo"
    - "error bounds for uplink and downlink 3d localization in 5g mmwave systems"
    - "compressive channel estimation and tracking for large arrays in mm wave picocells"
    - "joint device positioning and clock synchronization in 5g ultra dense networks"
    - "cognitive indoor positioning and tracking using multipath channel information"
    - "frequency selective hybrid precoding for limited feedback millimeter wave systems"
    - "fingerprinting based positioning in distributed massive mimo systems"
    - "compressed sensing based multi user millimeter wave systems how many measurements are needed"

Connected through hyperedge HE-3 (induced by source paper "transmitter beam selection in millimeter wave mimo with in band position aiding"):
  with members:
    - "new beam tracking technique for millimeter wave band communications"
    - "position aided beam alignment for millimeter wave backhaul systems with large phased arrays"
    - "millimeter wave mimo channel estimation using overlapped beam patterns and rate adaptation"
    - "beampattern based tracking for millimeter wave communication systems"
    - "hierarchical codebook design for beamforming training in millimeter wave communication"
    - "millimeter wave vehicular communication to support massive automotive sensing"
    - "tracking mm wave channel dynamics fast beam training strategies under mobility"
    - "channel estimation and hybrid precoding for millimeter wave cellular systems"

Connected through hyperedge HE-4 (induced by source paper "low complexity downlink user selection for massive mimo systems"):
  with members:
    - "a novel scheme for downlink opportunistic interference alignment"
    - "optimal design of energy efficient multi user mimo systems is massive mimo the answer"
    - "spectral and energy spectral efficiency optimization of joint transmit and receive beamforming based multi relay mimo ofdma cellular networks"
    - "resource allocation for cost minimization in limited feedback mu mimo systems with delay guarantee"
    - "scaling up mimo opportunities and challenges with very large arrays"
    - "on capacity of large scale mimo multiple access channels with distributed sets of correlated antennas"
    - "large system analysis of linear precoding in correlated miso broadcast channels under limited feedback"
    - "training and feedback optimization for multiuser mimo downlink"

Connected through hyperedge HE-5 (induced by source paper "beam tracking for uav mounted satcom on the move with massive antenna array"):
  with members:
    - "a new view of multi user hybrid massive mimo non orthogonal angle division multiple access"
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "spatial temporal bem and channel estimation strategy for massive mimo time varying systems"
    - "enabling uav cellular with millimeter wave communication potentials and approaches"
    - "wireless communications with unmanned aerial vehicles opportunities and challenges"
    - "channel estimation and hybrid precoding for millimeter wave cellular systems"
    - "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 "direct localization for massive mimo"):
  with members:
    - "fingerprinting based positioning in distributed massive mimo systems"
    - "massive mimo for next generation wireless systems"
    - "emerging technologies and research challenges for 5g wireless networks"
    - "scaling up mimo opportunities and challenges with very large arrays"
    - "towards a mathematical theory of super resolution"
    - "collaborative beamforming for distributed wireless ad hoc sensor networks"

Connected through hyperedge HE-7 (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"
    - "near optimal hybrid analog and digital precoding for downlink mmwave massive 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"

Connected through hyperedge HE-8 (induced by source paper "large scale mimo is capable of eliminating power thirsty channel coding for wireless transmission of hevc h 265 video"):
  with members:
    - "fifty years of mimo detection the road to large scale mimos"
    - "achieving maximum energy efficiency in multi relay ofdma cellular networks a fractional programming approach"
    - "scaling up mimo opportunities and challenges with very large arrays"
    - "energy and spectral efficiency of very large multiuser 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)