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: "complexity analysis of joint subcarrier and power allocation for the cellular downlink ofdma system"
  Abstract: Consider the cellular downlink orthogonal frequency division multiple access (OFDMA) system where a single transmitter transmits signals to multiple receivers on multiple discrete subcarriers. To adapt fast channel fluctuations, the transmitter should be able to dynamically allocate subcarrier and power resources. Assuming perfect channel knowledge, we formulate the joint subcarrier and power allocation problem as two optimization problems: the first is the one of minimizing the total transmission power subject to quality of service constraints, and the second is the one of maximizing a system utility function subject to power budget constraints. In this letter, we show that both the aforementioned formulations of the joint subcarrier and power allocation problem are generally NP-hard. We also identify several subclasses of the problems, which are polynomial time solvable.

Connected through hyperedge HE-1 (induced by source paper "weighted sum rate maximization in multi carrier noma with cellular power constraint"):
  with members:
    - "optimal joint subcarrier and power allocation in noma is strongly np hard"
    - "optimal joint power and subcarrier allocation for mc noma systems"
    - "power and channel allocation for non orthogonal multiple access in 5g systems tractability and computation"
    - "a new noma approach for fair power allocation"
    - "on the complexity of joint subcarrier and power allocation for multi user ofdma systems"

Connected through hyperedge HE-2 (induced by source paper "optimal joint subcarrier and power allocation in noma is strongly np hard"):
  with members:
    - "power and channel allocation for non orthogonal multiple access in 5g systems tractability and computation"
    - "on the performance of non orthogonal multiple access in 5g systems with randomly deployed users"
    - "on the complexity of joint subcarrier and power allocation for multi user ofdma systems"

Connected through hyperedge HE-3 (induced by source paper "content caching and distribution in smart grid enabled wireless networks"):
  with members:
    - "greendelivery proactive content caching and push with energy harvesting based small cells"
    - "green energy aware avatar migration strategy in green cloudlet networks"
    - "joint spectrum and power allocation for multi node cooperative wireless systems"
    - "on green energy powered cognitive radio networks"
    - "the throughput outage tradeoff of wireless one hop caching networks"
    - "on tractability aspects of optimal resource allocation in ofdma systems"

Connected through hyperedge HE-4 (induced by source paper "dynamic spectrum management a complete complexity characterization"):
  with members:
    - "on the complexity of joint subcarrier and power allocation for multi user ofdma systems"
    - "on the scale algorithm for multiuser multicarrier power spectrum management"
    - "linear transceiver design for a mimo interfering broadcast channel achieving max min fairness"

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)