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: "max min energy efficient beamforming for multicell multiuser joint transmission systems"
  Abstract: Energy efficient communication technology has attracted much attention due to the explosive growth of energy consumption in current wireless communication systems. In this letter we focus on fairness-based energy efficiency and aim to maximize the minimum user energy efficiency in the multicell multiuser joint beamforming system, taking both dynamic and static power consumptions into account. This optimization problem is a non-convex fractional programming problem and hard to tackle. In order to find its solution, the original problem is transformed into a parameterized polynomial subtractive form by exploiting the relationship between the user rate and the minimum mean square error, and using the fractional programming theorem. An iterative algorithm with proved convergence is then developed to achieve a near-optimal performance. Numerical results validate the effectiveness of the proposed solution and show that our algorithm significantly outperforms the max-min rate optimization algorithm in terms of maximizing the minimum energy efficiency.

Connected through hyperedge HE-1 (induced by source paper "rate splitting multiple access for multi antenna downlink communication systems spectral and energy efficiency tradeoff"):
  with members:
    - "cooperative rate splitting for miso broadcast channel with user relaying"
    - "cooperative rate splitting for miso broadcast channel with user relaying and performance benefits over cooperative noma"
    - "rate splitting unifying sdma oma noma and multicasting in miso broadcast channel a simple two user rate analysis"
    - "interference mitigation via rate splitting and common message decoding in cloud radio access networks"
    - "energy efficiency fairness for multi pair wireless powered relaying systems"
    - "rate splitting multiple access for coordinated multi point joint transmission"
    - "rate splitting multiple access for downlink communication systems bridging generalizing and outperforming sdma and noma"
    - "rate splitting for multi antenna non orthogonal unicast and multicast transmission spectral and energy efficiency analysis"

Connected through hyperedge HE-2 (induced by source paper "energy efficiency maximization for c rans discrete monotonic optimization penalty and ell _ 0 approximation methods"):
  with members:
    - "globally optimal beamforming design for downlink comp transmission with limited backhaul capacity"
    - "elastic net boosting energy efficiency and resource utilization in 5g c rans"
    - "understanding the computational requirements of virtualized baseband units using a programmable cloud radio access network testbed"
    - "recent advances in cloud radio access networks system architectures key techniques and open issues"
    - "energy efficiency of downlink transmission strategies for cloud radio access networks"
    - "fronthaul constrained cloud radio access networks insights and challenges"
    - "backhaul limited asymmetric cooperation for mimo cellular networks via semidefinite relaxation"
    - "sparse beamforming and user centric clustering for downlink cloud radio access network"

Connected through hyperedge HE-3 (induced by source paper "energy efficient transmission strategies for comp downlink overview extension and numerical comparison"):
  with members:
    - "energy efficient coordinated multi cell multi group multicast beamforming with antenna selection"
    - "energy efficient beam coordination strategies with rate dependent processing power"
    - "energy efficient scheduling and power allocation in downlink ofdma networks with base station coordination"
    - "on the optimum energy efficiency for flat fading channels with rate dependent circuit power"
    - "framework for link level energy efficiency optimization with informed transmitter"
    - "a quantitative measure of fairness and discrimination for resource allocation in shared computer systems"

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)