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: "downlink energy efficiency of power allocation and wireless backhaul bandwidth allocation in heterogeneous small cell networks"
  Abstract: The widespread application of wireless services and dense devices access have triggered huge energy consumption. Because of the environmental and financial considerations, energy-efficient design in wireless networks becomes an inevitable trend. To the best of the authors' knowledge, energy-efficient orthogonal frequency division multiple access heterogeneous small cell optimization comprehensively considering energy efficiency maximization, power allocation, wireless backhaul bandwidth allocation, and user Quality of Service is a novel approach and research direction, and it has not been investigated. In this paper, we study the energy-efficient power allocation and wireless backhaul bandwidth allocation in orthogonal frequency division multiple access heterogeneous small cell networks. Different from the existing resource allocation schemes that maximize the throughput, the studied scheme maximizes energy efficiency by allocating both transmit power of each small cell base station to users and bandwidth for backhauling, according to the channel state information and the circuit power consumption. The problem is first formulated as a non-convex nonlinear programming problem and then it is decomposed into two convex subproblems. A near optimal iterative resource allocation algorithm is designed to solve the resource allocation problem. A suboptimal low-complexity approach is also developed by exploring the inherent structure and property of the energy-efficient design. Simulation results demonstrate the effectiveness of the proposed algorithms by comparing with the existing schemes.

Connected through hyperedge HE-1 (induced by source paper "energy and spectral efficiency tradeoff in ofdma networks via antenna selection strategy"):
  with members:
    - "joint user association and resource allocation in the uplink of heterogeneous networks"
    - "energy efficiency maximization via joint sub carrier assignment and power control for ofdma full duplex networks"
    - "multi objective optimization for energy and spectral efficiency tradeoff in in band full duplex ibfd communication"
    - "spectral and energy efficiency trade offs in cellular networks"
    - "an overview of sustainable green 5g networks"
    - "optimal joint power and subcarrier allocation for full duplex multicarrier non orthogonal multiple access systems"
    - "energy efficient heterogeneous cellular networks with spectrum underlay and overlay access"

Connected through hyperedge HE-2 (induced by source paper "joint precoding and power control in small cell networks with proportional rate miso bc backhaul"):
  with members:
    - "secure distributed on device learning networks with byzantine adversaries"
    - "robust energy efficient beamforming in misome swipt systems with proportional secrecy rate"
    - "cache enabled physical layer security for video streaming in backhaul limited cellular networks"
    - "fronthaul aware group sparse precoding and signal splitting in swipt c ran"
    - "interference alignment and soft space reuse based cooperative transmission for multi cell massive mimo networks"
    - "fronthauling for 5g lte u ultra dense cloud small cell networks"
    - "heterogeneous cellular networks using wireless backhaul fast admission control and large system analysis"

Connected through hyperedge HE-3 (induced by source paper "joint optimization of fronthaul compression and bandwidth allocation in uplink h cran with large system analysis"):
  with members:
    - "message passing in c ran joint user activity and signal detection"
    - "fronthaul compression and transmit beamforming optimization for multi antenna uplink c ran"
    - "gaussian message passing iterative detection for mimo noma systems with massive access"
    - "contract based interference coordination in heterogeneous cloud radio access networks"
    - "system architecture and key technologies for 5g heterogeneous cloud radio access networks"
    - "cloud radio access network virtualizing wireless access for dense heterogeneous systems"
    - "energy efficient design of mimo heterogeneous networks with wireless backhaul"
    - "heterogeneous cloud radio access networks a new perspective for enhancing spectral and energy efficiencies"

Connected through hyperedge HE-4 (induced by source paper "energy efficient resource allocation in noma heterogeneous networks"):
  with members:
    - "spectrum and energy efficient beamspace mimo noma for millimeter wave communications using lens antenna array"
    - "energy efficient user association and power allocation in millimeter wave based ultra dense networks with energy harvesting base stations"
    - "energy efficient power allocation in millimeter wave massive mimo with non orthogonal multiple access"
    - "optimal joint power and subcarrier allocation for full duplex multicarrier non orthogonal multiple access 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)