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: "exploiting trust degree for multiple antenna user cooperation"
  Abstract: For a user cooperation system with multiple antennas, we consider trust degree-based cooperation techniques to explore the influence of the trustworthiness between users on the communication systems. For the system with two communication pairs, when one communication pair achieves its quality of service (QoS) requirement, they can help the transmission of the other communication pair according to the trust degree, which quantifies the trustworthiness between users in the cooperation. For given trust degree, we investigate the user cooperation strategies, which include the power allocation and precoder design for various antenna configurations. For single-input-single-output and multiple-input-single-output (MISO) cases, we provide the optimal power allocation and beamformer design that maximize the expected achievable rates while guaranteeing the QoS requirement. For a single-input-multiple-output (SIMO) case, we resort to semidefinite relaxation technique and block coordinate update method to solve the corresponding problem, and guarantee the rank-one solutions at each step. For a multiple-input-multiple-output (MIMO) case, as MIMO is the generalization of MISO and SIMO, the similarities among their problem structures inspire us to combine the methods from MISO and SIMO together to efficiently tackle MIMO case. Simulation results show that the trust degree information has a great effect on the performance of the user cooperation in terms of the expected achievable rate, and the proposed user cooperation strategies achieve high achievable rates for give trust degree.

Connected through hyperedge HE-1 (induced by source paper "cooperative limited feedback design for massive machine type communications"):
  with members:
    - "advanced quantizer designs for fdd based fd mimo systems using uniform planar arrays"
    - "antenna grouping based feedback compression for fdd based massive mimo systems"
    - "five disruptive technology directions for 5g"
    - "multi user diversity vs accurate channel state information in mimo downlink channels"
    - "interference alignment through user cooperation for two cell mimo interfering broadcast channels"
    - "antenna combining for the mimo downlink channel"

Connected through hyperedge HE-2 (induced by source paper "limited feedback designs for machine type communications exploiting user cooperation"):
  with members:
    - "advanced quantizer designs for fdd based fd mimo systems using uniform planar arrays"
    - "towards massive connectivity support for scalable mmtc communications in 5g networks"
    - "five disruptive technology directions for 5g"
    - "interference alignment through user cooperation for two cell mimo interfering broadcast channels"
    - "antenna combining for the mimo downlink channel"
    - "mimo broadcast channels with finite rate feedback"

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)