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: "non orthogonal multiple access for cooperative communications challenges opportunities and trends"
  Abstract: Non-orthogonal multiple access (NOMA) is a promising radio access technique for next-generation wireless networks. In this article, we investigate the NOMA-based cooperative relay network. We begin with an introduction of the existing relay-assisted NOMA systems by classifying them into three categories: uplink, downlink, and composite architectures. Then, we discuss their principles and key features, and provide a comprehensive comparison from the perspective of spectral efficiency, energy efficiency, and total transmit power. A novel strategy termed hybrid power allocation is further discussed for the composite architecture, which can reduce the computational complexity and signaling overhead at the expense of marginal sum rate degradation. Finally, major challenges, opportunities, and future research trends for the design of NOMA-based cooperative relay systems with other techniques are also highlighted to provide insights for researchers in this field.

Connected through hyperedge HE-1 (induced by source paper "a survey of rate optimal power domain noma schemes for enabling technologies of future wireless networks"):
  with members:
    - "generalized coordinated multipoint gcomp enabled noma outage capacity and power allocation"
    - "what role can noma play in massive mimo"
    - "uav data collection over noma backscatter networks uav altitude and trajectory optimization"
    - "uav communications for 5g and beyond recent advances and future trends"
    - "when full duplex wireless meets non orthogonal multiple access opportunities and challenges"
    - "on optimizing vlc networks for downlink multi user transmission a survey"
    - "beam design and user scheduling for nonorthogonal multiple access with multiple antennas based on pareto optimality"
    - "spatial modulation assisted multi antenna non orthogonal multiple access"

Connected through hyperedge HE-2 (induced by source paper "distributed rate control in downlink noma networks with reliability constraints"):
  with members:
    - "joint power control and rate allocation enabling ultra reliability and energy efficiency in simo wireless networks"
    - "hybrid resource scheduling for aggregation in massive machine type communication networks"
    - "rate control under finite blocklength for downlink cellular networks with reliability constraints"
    - "energy efficient resource allocation in noma heterogeneous networks"
    - "signal processing for mimo noma present and future challenges"
    - "power domain non orthogonal multiple access noma in 5g systems potentials and challenges"
    - "non orthogonal multiple access in large scale heterogeneous networks"
    - "aggregation and resource scheduling in machine type communication networks a stochastic geometry approach"

Connected through hyperedge HE-3 (induced by source paper "cooperative rate splitting for miso broadcast channel with user relaying and performance benefits over cooperative noma"):
  with members:
    - "rate splitting unifying sdma oma noma and multicasting in miso broadcast channel a simple two user rate analysis"
    - "energy efficiency of rate splitting multiple access and performance benefits over sdma and noma"
    - "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"
    - "rate splitting for max min fair multigroup multicast beamforming in overloaded systems"
    - "multiuser millimeter wave beamforming strategies with quantized and statistical csit"
    - "sum rate maximization for linearly precoded downlink multiuser miso systems with partial csit a rate splitting approach"
    - "robust transmission in downlink multiuser miso systems a rate splitting approach"

Connected through hyperedge HE-4 (induced by source paper "cooperative rate splitting for miso broadcast channel with user relaying"):
  with members:
    - "rate splitting unifying sdma oma noma and multicasting in miso broadcast channel a simple two user rate analysis"
    - "rate splitting for multi antenna non orthogonal unicast and multicast transmission spectral and energy efficiency analysis"
    - "rate splitting for max min fair multigroup multicast beamforming in overloaded systems"
    - "multiuser millimeter wave beamforming strategies with quantized and statistical csit"
    - "sum rate maximization for linearly precoded downlink multiuser miso systems with partial csit a rate splitting approach"
    - "robust transmission in downlink multiuser miso systems a rate splitting approach"
    - "rate splitting for mimo wireless networks a promising phy layer strategy for lte evolution"
    - "a rate splitting strategy for massive mimo with imperfect csit"

Connected through hyperedge HE-5 (induced by source paper "capacity and outage analysis of a dual hop decode and forward relay aided noma scheme"):
  with members:
    - "modeling and analysis of two way relay non orthogonal multiple access systems"
    - "performance analysis of a hybrid downlink uplink cooperative noma scheme"
    - "power domain non orthogonal multiple access noma in 5g systems potentials and challenges"
    - "a survey on non orthogonal multiple access for 5g networks research challenges and future trends"
    - "on the performance of noma based cooperative relaying systems over rician fading channels"
    - "outage performance for cooperative noma transmission with an af relay"
    - "dynamic user clustering and power allocation for uplink and downlink non orthogonal multiple access noma systems"
    - "towards 1 gbps ue in cellular systems understanding ultra dense small cell deployments"

Connected through hyperedge HE-6 (induced by source paper "generalized optimal two way relays subsets pairings in cloud based region cognitive networks"):
  with members:
    - "cognitive non orthogonal multiple access with cooperative relaying a new wireless frontier for 5g spectrum sharing"
    - "resource allocation and outage analysis for an adaptive cognitive two way relay network"
    - "cooperation in 5g hetnets advanced spectrum access and d2d assisted communications"
    - "performance of adaptive link selection with buffer aided relays in underlay cognitive networks"
    - "optimal relay selection for the parallel hybrid rf fso relay channel non buffer aided and buffer aided designs"
    - "separation framework an enabler for cooperative and d2d communication for future 5g networks"
    - "relay subset selection in wireless networks using partial decode and forward transmission"

Connected through hyperedge HE-7 (induced by source paper "uplink cooperative noma for cellular connected uav"):
  with members:
    - "capacity characterization of uav enabled two user broadcast channel"
    - "cellular connected uav uplink association power control and interference coordination"
    - "cellular connected uav potentials challenges and promising technologies"
    - "supporting uav cellular communications through massive mimo"
    - "mobile networks connected drones field trials simulations and design insights"
    - "multi beam uav communication in cellular uplink cooperative interference cancellation and sum rate maximization"
    - "cellular enabled uav communication a connectivity constrained trajectory optimization perspective"
    - "signal processing for mimo noma present and future challenges"

Connected through hyperedge HE-8 (induced by source paper "capacity enhanced cooperative d2d systems over rayleigh fading channels with noma"):
  with members:
    - "short packet downlink transmission with non orthogonal multiple access"
    - "spatial and frequency wideband effects in millimeter wave massive mimo systems"
    - "channel estimation for tdd fdd massive mimo systems with channel covariance computing"
    - "resource allocation for downlink noma systems key techniques and open issues"
    - "a survey on non orthogonal multiple access for 5g networks research challenges and future trends"
    - "on the performance of noma based cooperative relaying systems over rician fading channels"
    - "outage performance for cooperative noma transmission with an af relay"
    - "joint beamforming and power splitting control in downlink cooperative swipt noma 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)