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: "sum rate analysis of a reduced feedback ofdma downlink system employing joint scheduling and diversity"
  Abstract: We consider joint scheduling and diversity to enhance the benefits of multiuser diversity in an orthogonal frequency-division multiple access (OFDMA) downlink system. The OFDMA spectrum is assumed to consist of NRB resource blocks and the reduced feedback scheme consists of each user feeding back channel quality information (CQI) for only the best-NFB resource blocks. Assuming largest normalized CQI scheduling and a general value for NFB, we develop a unified framework to analyze the sum rate of the system for both the quantized and nonquantized CQI feed- back schemes. Based on this framework, we provide closed-form expressions for the sum rate for three different multiantenna transmitter schemes; transmit antenna selection (TAS), orthogonal space time block codes (OSTBC) and cyclic delay diversity (CDD). Furthermore, we approximate the sum rate expression and determine the feedback ratio (NFB/NRB) required to achieve a sum rate comparable to the sum rate obtained by a full feedback scheme.

Connected through hyperedge HE-1 (induced by source paper "an analytical framework for heterogeneous partial feedback design in heterogeneous multicell ofdma networks"):
  with members:
    - "a tutorial on the optimization of amplify and forward mimo relay systems"
    - "modeling and analysis of k tier downlink heterogeneous cellular networks"
    - "refim a practical interference management in heterogeneous wireless access networks"
    - "information exchange limits in cooperative mimo networks"
    - "downlink interference alignment"
    - "adaptive limited feedback for sum rate maximizing beamforming in cooperative multicell systems"
    - "resource allocation for downlink cellular ofdma systems part i optimal allocation"

Connected through hyperedge HE-2 (induced by source paper "performance analysis of heterogeneous feedback design in an ofdma downlink with partial and imperfect feedback"):
  with members:
    - "design and analysis of multi user sdma systems with noisy limited csit feedback"
    - "limited feedback for temporally correlated mimo channels with other cell interference"
    - "on the mutual information distribution of ofdm based spatial multiplexing exact variance and outage approximation"

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)