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: "opportunistic downlink interference alignment for multi cell mimo networks"
  Abstract: In this paper, we propose an opportunistic downlink interference alignment (ODIA) for interference-limited cellular downlink, which intelligently combines user scheduling and downlink IA techniques. The proposed ODIA not only efficiently reduces the effect of inter-cell interference from other-cell base stations (BSs) but also eliminates intra-cell interference among spatial streams in the same cell. We show that the minimum number of users required to achieve a target degrees-of-freedom (DoF) can be fundamentally reduced, i.e., the fundamental user scaling law can be improved by using the ODIA, compared with the existing downlink IA schemes. In addition, we adopt a limited feedback strategy in the ODIA framework, and then analyze the number of feedback bits required for the system with limited feedback to achieve the same user scaling law of the ODIA as the system with perfect CSI. We also modify the original ODIA in order to further improve sum-rate, which achieves the optimal multiuser diversity gain, i.e., $\log\log N$, per spatial stream even in the presence of downlink inter-cell interference, where $N$ denotes the number of users in a cell. Simulation results show that the ODIA significantly outperforms existing interference management techniques in terms of sum-rate in realistic cellular environments. Note that the ODIA operates in a non-collaborative and decoupled manner, i.e., it requires no information exchange among BSs and no iterative beamformer optimization between BSs and users, thus leading to an easier implementation.

Connected through hyperedge HE-1 (induced by source paper "sum rate maximization of multicell miso networks with limited information exchange"):
  with members:
    - "a deep learning framework for optimization of miso downlink beamforming"
    - "coordinated regularized zero forcing precoding for multicell miso systems with limited feedback"
    - "joint transmission with limited backhaul connectivity"
    - "analysis of massive mimo enabled downlink wireless backhauling for full duplex small cells"
    - "sinr and throughput scaling in ultradense urban cellular networks"
    - "on the spatial degrees of freedom of multicell and multiuser mimo channels"
    - "on feasibility of interference alignment in mimo interference networks"
    - "downlink interference alignment"

Connected through hyperedge HE-2 (induced by source paper "multi stream opportunistic network decoupling relay selection and interference management"):
  with members:
    - "multi cell aware opportunistic random access for machine type communications"
    - "real interference alignment exploiting the potential of single antenna systems"
    - "advanced interference management technique potentials and limitations"
    - "parallel opportunistic routing in wireless networks"
    - "opportunistic interference alignment for mimo interfering multiple access channels"
    - "multi cell random beamforming achievable rate and degrees of freedom region"
    - "opportunistic relaying in wireless networks"
    - "degrees of freedom of the k user m times n mimo interference channel"

Connected through hyperedge HE-3 (induced by source paper "hybrid beamforming for 5g millimeter wave multi cell networks"):
  with members:
    - "hybrid beamforming via the kronecker decomposition for the millimeter wave massive mimo systems"
    - "a novel millimeter wave channel simulator and applications for 5g wireless communications"
    - "spatially sparse precoding in millimeter wave mimo systems"
    - "base station cooperation on the downlink large system analysis"

Connected through hyperedge HE-4 (induced by source paper "interference aware opportunistic random access in dense iot networks"):
  with members:
    - "mu mimo mac protocols for wireless local area networks a survey"
    - "massive machine type communications in 5g physical and mac layer solutions"
    - "opportunistic interference alignment for random access networks"
    - "maximum sum rate of slotted aloha with capture"
    - "coded slotted aloha a graph based method for uncoordinated multiple access"
    - "cooperative slotted aloha for multi base station systems"
    - "scalable synchronization and reciprocity calibration for distributed multiuser mimo"
    - "can one achieve multiuser diversity in uplink multi cell networks"

Connected through hyperedge HE-5 (induced by source paper "multi cell aware opportunistic random access for machine type communications"):
  with members:
    - "massive machine type communications in 5g physical and mac layer solutions"
    - "opportunistic interference alignment for random access networks"
    - "maximum sum rate of slotted aloha with capture"
    - "coded slotted aloha a graph based method for uncoordinated multiple access"
    - "cooperative slotted aloha for multi base station systems"
    - "scalable synchronization and reciprocity calibration for distributed multiuser mimo"
    - "can one achieve multiuser diversity in uplink multi cell networks"
    - "opportunistic interference mitigation achieves optimal degrees of freedom in wireless multi cell uplink networks"

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)