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: "optimal cell clustering and activation for energy saving in load coupled wireless networks"
  Abstract: Optimizing activation and deactivation of base station transmissions provides an instrument for improving energy efficiency in cellular networks. In this paper, we study the problem of performing cell clustering and setting the activation time of each cluster, with the objective of minimizing the sum energy, subject to a time constraint of serving the users' traffic demand. Our optimization framework accounts for inter-cell interference, and, thus, the users' achievable rates depend on cluster formation. We provide mathematical formulations and analysis, and prove the problem's NP hardness. For problem solution, we first apply an optimization method that successively augments the set of variables under consideration, with the capability of approaching global optimum. Then, we derive a second solution algorithm to deal with the trade-off between optimality and the combinatorial nature of cluster formation. Numerical results demonstrate that our solutions achieve more than 40% energy saving over existing schemes, and that the solutions we obtain are within a few percent of deviation from global optimum.

Connected through hyperedge HE-1 (induced by source paper "a note on decoding order in optimizing multi cell noma"):
  with members:
    - "a robust machine learning method for cell load approximation in wireless networks"
    - "a framework for optimizing multi cell noma delivering demand with less resource"
    - "resource optimization with load coupling in multi cell noma"
    - "on optimal power allocation for downlink non orthogonal multiple access systems"
    - "energy aware wireless relay selection in load coupled ofdma cellular networks"
    - "load optimization with user association in cooperative and load coupled lte networks"
    - "dynamic user clustering and power allocation for uplink and downlink non orthogonal multiple access noma systems"
    - "elementary properties of positive concave mappings with applications to network planning and optimization"

Connected through hyperedge HE-2 (induced by source paper "maximum throughput scheduling for multi connectivity in millimeter wave networks"):
  with members:
    - "on the temporal effects of mobile blockers in urban millimeter wave cellular scenarios"
    - "initial access in 5g mmwave cellular networks"
    - "the transitional behavior of interference in millimeter wave networks and its impact on medium access control"

Connected through hyperedge HE-3 (induced by source paper "resource optimization with load coupling in multi cell noma"):
  with members:
    - "a robust machine learning method for cell load approximation in wireless networks"
    - "a framework for optimizing multi cell noma delivering demand with less resource"
    - "on optimal power allocation for downlink non orthogonal multiple access systems"
    - "energy aware wireless relay selection in load coupled ofdma cellular networks"
    - "sub channel assignment power allocation and user scheduling for non orthogonal multiple access networks"
    - "load optimization with user association in cooperative and load coupled lte networks"
    - "elementary properties of positive concave mappings with applications to network planning and optimization"
    - "power and channel allocation for non orthogonal multiple access in 5g systems tractability and computation"

Connected through hyperedge HE-4 (induced by source paper "power control for multi cell networks with non orthogonal multiple access"):
  with members:
    - "resource optimization in multi cell noma"
    - "a survey on non orthogonal multiple access for 5g networks research challenges and future trends"
    - "sub channel assignment power allocation and user scheduling for non orthogonal multiple access networks"
    - "energy efficient transmission design in non orthogonal multiple access"
    - "load optimization with user association in cooperative and load coupled lte networks"
    - "a minorization maximization method for optimizing sum rate in the downlink of non orthogonal multiple access systems"
    - "power and channel allocation for non orthogonal multiple access in 5g systems tractability and computation"
    - "non orthogonal multiple access in multi cell networks theory performance and practical challenges"

Connected through hyperedge HE-5 (induced by source paper "resource optimization in multi cell noma"):
  with members:
    - "a framework for optimizing multi cell noma delivering demand with less resource"
    - "on optimal power allocation for downlink non orthogonal multiple access systems"
    - "energy aware wireless relay selection in load coupled ofdma cellular networks"
    - "load optimization with user association in cooperative and load coupled lte networks"
    - "elementary properties of positive concave mappings with applications to network planning and optimization"
    - "energy efficiency of distributed signal processing in wireless networks a cross layer analysis"
    - "non orthogonal multiple access in multi cell networks theory performance and practical challenges"
    - "power and load coupling in cellular networks for energy optimization"

Connected through hyperedge HE-6 (induced by source paper "a framework for optimizing multi cell noma delivering demand with less resource"):
  with members:
    - "energy aware wireless relay selection in load coupled ofdma cellular networks"
    - "load optimization with user association in cooperative and load coupled lte networks"
    - "energy efficiency of distributed signal processing in wireless networks a cross layer analysis"
    - "non orthogonal multiple access in multi cell networks theory performance and practical challenges"
    - "analysis of cell load coupling for lte network planning and optimization"

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)