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: "capacity of gaussian mimo bidirectional broadcast channels"
  Abstract: We consider the broadcast phase of a three-node network, where a relay node establishes a bidirectional communication between two nodes using a spectrally efficient two-phase decode-and-forward protocol. In the first phase the two nodes transmit their messages to the relay node. Then the relay node decodes the messages and broadcasts a re-encoded composition of them in the second phase. We consider Gaussian MIMO channels and determine the capacity region for the second phase which we call the Gaussian MIMO bidirectional broadcast channel.

Connected through hyperedge HE-1 (induced by source paper "achievable rate regions and outer bounds for a multi pair bi directional relay network"):
  with members:
    - "the multi way relay channel"
    - "capacity of the gaussian two way relay channel to within 1 2 bit"
    - "the mimo wireless switch relaying can increase the multiplexing gain"
    - "capacity region of the deterministic multi pair bi directional relay network"
    - "bits through relay cascades with half duplex constraint"
    - "broadcast capacity region of two phase bidirectional relaying"
    - "to code or not to code in multi hop relay channels"
    - "on the capacity and diversity multiplexing tradeoff of the two way relay channel"

Connected through hyperedge HE-2 (induced by source paper "on two way communications for cooperative multiple source pairs through a multi antenna relay"):
  with members:
    - "differential modulation for bi directional relaying with analog network coding"
    - "optimal beamforming for two way multi antenna relay channel with analogue network coding"
    - "physical layer network coding"

Connected through hyperedge HE-3 (induced by source paper "bi directional half duplex protocols with multiple relays"):
  with members:
    - "capacity region of the deterministic multi pair bi directional relay network"
    - "broadcast capacity region of two phase bidirectional relaying"
    - "to code or not to code in multi hop relay channels"
    - "on the capacity and diversity multiplexing tradeoff of the two way relay channel"
    - "achievable rate regions for bi directional relaying"
    - "performance bounds for bi directional coded cooperation protocols"
    - "a simple cooperative diversity method based on network path selection"

Connected through hyperedge HE-4 (induced by source paper "optimal beamforming for two way multi antenna relay channel with analogue network coding"):
  with members:
    - "broadcast capacity region of two phase bidirectional relaying"
    - "joint physical layer coding and network coding for bi directional relaying"
    - "the capacity of two way relay channel"
    - "physical layer network coding"
    - "performance bounds for bi directional coded cooperation protocols"

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)