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: "on the coexistence of macrocell spatial multiplexing and cognitive femtocells"
  Abstract: We study a two-tier macrocell/femtocell system where the macrocell base station is equipped with multiple antennas and makes use of multiuser MIMO (spatial multiplexing), and the femtocells are "cognitive". In particular, we assume that the femtocells are aware of the locations of scheduled macrocell users on every time-frequency slot, so that they can make decisions on their transmission opportunities accordingly. Femtocell base stations are also equipped with multiple antennas. We propose a scheme where the macrocell downlink (macro- DL) is aligned with the femtocells uplink (femto-UL) and, Vice Versa, the macrocell uplink (macro-UL) is aligned with the femtocells downlink femto-DL). Using a simple "interference temperature" power control in the macro-DL/femto-UL direction, and exploiting uplink/downlink duality and the Yates, Foschini and Miljanic distributed power control algorithm in the macro- UL/femto-DL direction, we can achieve an extremely attractive macro/femto throughput tradeoff region in both directions. We investigate the impact of multiuser MIMO spatial multiplexing in the macrocell under the proposed scheme, and find that large gains are achievable by letting the macrocell schedule groups of co-located users, such that the number of femtocells affected by the interference temperature power constraint is small.

Connected through hyperedge HE-1 (induced by source paper "coalitional games with overlapping coalitions for interference management in small cell networks"):
  with members:
    - "a study of trade off between opportunistic resource allocation and interference alignment in femtocell scenarios"
    - "price based resource allocation for spectrum sharing femtocell networks a stackelberg game approach"
    - "on providing downlink services in collocated spectrum sharing macro and femto networks"
    - "cooperative games with overlapping coalitions"
    - "power control in two tier femtocell networks"
    - "interference mitigation using uplink power control for two tier femtocell networks"
    - "femtocell networks a survey"

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)