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: "robust linear precoder design for multi cell downlink transmission"
  Abstract: Coordinated information processing by the base stations of multi-cell wireless networks enhances the overall quality of communication in the network. Such coordinations for optimizing any desired network-wide quality of service (QoS) necessitate the base stations to acquire and share some channel state information (CSI). With perfect knowledge of channel states, the base stations can adjust their transmissions for achieving a network-wise QoS optimality. In practice, however, the CSI can be obtained only imperfectly. As a result, due to the uncertainties involved, the network is not guaranteed to benefit from a globally optimal QoS. Nevertheless, if the channel estimation perturbations are confined within bounded regions, the QoS measure will also lie within a bounded region. Therefore, by exploiting the notion of robustness in the worst-case sense some worst-case QoS guarantees for the network can be asserted. We adopt a popular model for noisy channel estimates that assumes that estimation noise terms lie within known hyper-spheres. We aim to design linear transceivers that optimize a worst-case QoS measure in downlink transmissions. In particular, we focus on maximizing the worst-case weighted sum-rate of the network and the minimum worst-case rate of the network. For obtaining such transceiver designs, we offer several centralized (fully cooperative) and distributed (limited cooperation) algorithms which entail different levels of complexity and information exchange among the base stations.

Connected through hyperedge HE-1 (induced by source paper "non orthogonal unicast and broadcast transmission via joint beamforming and ldm in cellular networks"):
  with members:
    - "distributed optimization for coordinated beamforming in multicell multigroup multicast systems power minimization and sinr balancing"
    - "rate splitting for multi antenna non orthogonal unicast and multicast transmission spectral and energy efficiency analysis"
    - "joint beamforming and broadcasting in massive mimo"
    - "admm based fast algorithm for multi group multicast beamforming in large scale wireless systems"
    - "celltv on the benefit of tv distribution over cellular networks a case study"
    - "coordinated multicast beamforming in multicell networks"
    - "distributed robust multicell coordinated beamforming with imperfect csi an admm approach"

Connected through hyperedge HE-2 (induced by source paper "energy efficient precoder in multi user mimo systems with imperfect channel state information"):
  with members:
    - "totally distributed energy efficient transmission in mimo interference channels"
    - "what will 5g be"
    - "energy efficient resource allocation in wireless networks"

Connected through hyperedge HE-3 (induced by source paper "unraveling the rank one solution mystery of robust miso downlink transmit optimization a verifiable sufficient condition via a new duality result"):
  with members:
    - "coordinate update algorithms for robust power loading for the mu miso downlink with outage constraints"
    - "a parallel decomposition method for nonconvex stochastic multi agent optimization problems"
    - "a stochastic beamformed amplify and forward scheme in a multigroup multicast mimo relay network with per antenna power constraints"
    - "optimal multiuser transmit beamforming a difficult problem with a simple solution structure"
    - "physical layer multicasting by stochastic transmit beamforming and alamouti space time coding"
    - "distributed robust multicell coordinated beamforming with imperfect csi an admm approach"
    - "worst case robust multiuser transmit beamforming using semidefinite relaxation duality and implications"
    - "outage constrained robust transmit optimization for multiuser miso downlinks tractable approximations by conic optimization"

Connected through hyperedge HE-4 (induced by source paper "sum rate maximization for linearly precoded downlink multiuser miso systems with partial csit a rate splitting approach"):
  with members:
    - "miso networks with imperfect csit a topological rate splitting approach"
    - "robust transmission in downlink multiuser miso systems a rate splitting approach"
    - "a rate splitting strategy for massive mimo with imperfect csit"
    - "sum rate maximization for mu miso with partial csit using joint multicasting and broadcasting"
    - "rate analysis of two receiver miso broadcast channel with finite rate feedback a rate splitting approach"
    - "achieving max min fairness for mu miso with partial csit a multicast assisted transmission"
    - "optimal multiuser transmit beamforming a difficult problem with a simple solution structure"
    - "ammse optimization for multiuser miso systems with imperfect csit and perfect csir"

Connected through hyperedge HE-5 (induced by source paper "role of interference alignment in wireless cellular network optimization"):
  with members:
    - "joint beamforming and power control in coordinated multicell max min duality effective network and large system transition"
    - "multilevel topological interference management"
    - "on the feasibility of linear interference alignment for mimo interference broadcast channels with constant coefficients"
    - "genie chain and degrees of freedom of symmetric mimo interference broadcast channels"
    - "degrees of freedom of mimo cellular networks decomposition and linear beamforming design"
    - "on the degrees of freedom achievable through interference alignment in a mimo interference channel"
    - "a feasibility test for linear interference alignment in mimo channels with constant coefficients"
    - "degrees of freedom of mimo x networks spatial scale invariance one sided decomposability and linear feasibility"

Connected through hyperedge HE-6 (induced by source paper "robust transmission in downlink multiuser miso systems a rate splitting approach"):
  with members:
    - "sum rate maximization for linearly precoded downlink multiuser miso systems with partial csit a rate splitting approach"
    - "a rate splitting approach to robust multiuser miso transmission"
    - "a rate splitting strategy for massive mimo with imperfect csit"
    - "sum rate maximization for mu miso with partial csit using joint multicasting and broadcasting"
    - "rate analysis of two receiver miso broadcast channel with finite rate feedback a rate splitting approach"
    - "achieving max min fairness for mu miso with partial csit a multicast assisted transmission"
    - "aligned image sets under channel uncertainty settling a conjecture by lapidoth shamai and wigger on the collapse of degrees of freedom under finite precision csit"
    - "degrees of freedom of time correlated miso broadcast channel with delayed csit"

Connected through hyperedge HE-7 (induced by source paper "a rate splitting approach to robust multiuser miso transmission"):
  with members:
    - "a rate splitting strategy for massive mimo with imperfect csit"
    - "sum rate maximization for mu miso with partial csit using joint multicasting and broadcasting"
    - "rate analysis of two receiver miso broadcast channel with finite rate feedback a rate splitting approach"
    - "achieving max min fairness for mu miso with partial csit a multicast assisted transmission"
    - "degrees of freedom of time correlated miso broadcast channel with delayed csit"
    - "linear transceiver design for a mimo interfering broadcast channel achieving max min fairness"
    - "multiuser mimo achievable rates with downlink training and channel state feedback"
    - "mimo broadcast channels with finite rate feedback"

Connected through hyperedge HE-8 (induced by source paper "optimizing user association and activation fractions in heterogeneous wireless networks"):
  with members:
    - "distributed pricing based user association for downlink heterogeneous cellular networks"
    - "optimal user cell association for massive mimo wireless networks"
    - "analysis of cell load coupling for lte network planning and optimization"
    - "user association for load balancing in heterogeneous cellular networks"
    - "spatial sinr games combining base station placement and mobile association"

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)