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 beamforming techniques for non orthogonal multiple access systems with bounded channel uncertainties"
  Abstract: We propose a robust beamforming design for non-orthogonal multiple access-based multiple-input single-output downlink systems. In particular, the robust power minimization problem is studied with imperfect channel state information, where the beamformers are designed by incorporating norm-bounded channel uncertainties to provide the required quality of service at each user. This robust scheme is developed based on the worst-case performance optimization framework. In terms of beamforming vectors, the original robust design is not convex; therefore, the robust beamformers cannot be obtained directly. To circumvent this non-convex issue, the original intractable problem is reformulated into a convex problem, where the non-convex constraint is converted into a linear matrix inequality by exploiting S-Procedure. Simulation results are provided to demonstrate the effectiveness of the proposed robust design.

Connected through hyperedge HE-1 (induced by source paper "resource allocation technique for hybrid tdma noma system with opportunistic time assignment"):
  with members:
    - "energy efficient joint user rb association and power allocation for uplink hybrid noma oma"
    - "optimal resource allocation for power efficient mc noma with imperfect channel state information"
    - "power domain non orthogonal multiple access noma in 5g systems potentials and challenges"
    - "resource allocation for downlink noma systems key techniques and open issues"
    - "power efficient resource allocation for mc noma with statistical channel state information"
    - "a minorization maximization method for optimizing sum rate in the downlink of non orthogonal multiple access systems"
    - "fairness for non orthogonal multiple access in 5g systems"

Connected through hyperedge HE-2 (induced by source paper "non orthogonal multiple access for 5g and beyond"):
  with members:
    - "downlink non orthogonal multiple access with limited feedback"
    - "optimal user scheduling and power allocation for millimeter wave noma systems"
    - "coordinated multi point comp transmission in downlink multi cell noma systems models and spectral efficiency performance"
    - "low complexity receiver for multi level polar coded modulation in non orthogonal multiple access"
    - "massive non orthogonal multiple access for cellular iot potentials and limitations"
    - "power domain non orthogonal multiple access noma in 5g systems potentials and challenges"
    - "modulation and multiple access for 5g networks"
    - "an optimization perspective of the superiority of noma compared to conventional oma"

Connected through hyperedge HE-3 (induced by source paper "beamforming techniques for non orthogonal multiple access in 5g cellular networks"):
  with members:
    - "exploiting multiple antenna techniques for non orthogonal multiple access"
    - "secure communications with cooperative jamming optimal power allocation and secrecy outage analysis"
    - "physical layer security jamming theoretical limits and practical designs in wireless networks"
    - "limited feedback scheme for device to device communications in 5g cellular networks with reliability and cellular secrecy outage constraints"
    - "design of massive mimo noma with limited feedback"
    - "a minorization maximization method for optimizing sum rate in the downlink of non orthogonal multiple access systems"
    - "the application of mimo to non orthogonal multiple access"
    - "fairness for non orthogonal multiple access in 5g systems"

Connected through hyperedge HE-4 (induced by source paper "non orthogonal multiple access assisted multi region geocast"):
  with members:
    - "secrecy sum rate maximization in non orthogonal multiple access"
    - "optimal joint power and subcarrier allocation for full duplex multicarrier non orthogonal multiple access systems"
    - "energy efficient transmission design in non orthogonal multiple access"
    - "a minorization maximization method for optimizing sum rate in the downlink of non orthogonal multiple access systems"
    - "conic quadratic formulations for wireless communications design"
    - "fairness for non orthogonal multiple access in 5g systems"
    - "a general mimo framework for noma downlink and uplink transmission based on signal alignment"
    - "weighted fair multicast multigroup beamforming under per antenna power constraints"

Connected through hyperedge HE-5 (induced by source paper "optimal power allocation scheme for non orthogonal multiple access with alpha fairness"):
  with members:
    - "design of massive mimo noma with limited feedback"
    - "cooperative non orthogonal multiple access with simultaneous wireless information and power transfer"
    - "the application of mimo to non orthogonal multiple access"
    - "fairness for non orthogonal multiple access in 5g systems"
    - "a general mimo framework for noma downlink and uplink transmission based on signal alignment"
    - "on the performance of non orthogonal multiple access in 5g systems with randomly deployed users"
    - "an axiomatic theory of fairness in network resource allocation"
    - "a quantitative measure of fairness and discrimination for resource allocation in shared computer 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)