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: "resource allocation for downlink noma systems key techniques and open issues"
  Abstract: This article presents advances in resource allocation (RA) for downlink non-orthogonal multiple access (NOMA) systems, focusing on user pairing (UP) and power allocation (PA) algorithms. The former pairs the users to obtain the high capacity gain by exploiting the channel gain difference between the users, while the later allocates power to users in each cluster to balance system throughput and user fairness. Additionally, the article introduces the concept of cluster fairness and proposes the divideand- next largest difference-based UP algorithm to distribute the capacity gain among the NOMA clusters in a controlled manner. Furthermore, performance comparison between multiple-input multiple-output NOMA (MIMO-NOMA) and MIMO-OMA is conducted when users have pre-defined quality of service. Simulation results are presented, which validate the advantages of NOMA over OMA. Finally, the article provides avenues for further research on RA for downlink NOMA.

Connected through hyperedge HE-1 (induced by source paper "resource allocation technique for hybrid tdma noma system with opportunistic time assignment"):
  with members:
    - "energy efficient joint user rb association and power allocation for uplink hybrid noma oma"
    - "optimal resource allocation for power efficient mc noma with imperfect channel state information"
    - "power domain non orthogonal multiple access noma in 5g systems potentials and challenges"
    - "robust beamforming techniques for non orthogonal multiple access systems with bounded channel uncertainties"
    - "power efficient resource allocation for mc noma with statistical channel state information"
    - "a minorization maximization method for optimizing sum rate in the downlink of non orthogonal multiple access systems"
    - "fairness for non orthogonal multiple access in 5g systems"

Connected through hyperedge HE-2 (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-3 (induced by source paper "lattice coding for downlink multiuser transmission"):
  with members:
    - "downlink non orthogonal multiple access without sic for block fading channels an algebraic rotation approach"
    - "joint pilot and payload power control for uplink mimo noma with mrc sic receivers"
    - "short packet downlink transmission with non orthogonal multiple access"
    - "a multi beam noma framework for hybrid mmwave systems"
    - "optimal resource allocation for power efficient mc noma with imperfect channel state information"
    - "improved decoding and error floor analysis of staircase codes"
    - "performance analysis of a hybrid downlink uplink cooperative noma scheme"
    - "on non orthogonal multiple access with finite alphabet inputs in z channels"

Connected through hyperedge HE-4 (induced by source paper "non orthogonal multiple access noma how it meets 5g and beyond"):
  with members:
    - "securing downlink massive mimo noma networks with artificial noise"
    - "energy efficient joint user rb association and power allocation for uplink hybrid noma oma"
    - "capacity and outage analysis of a dual hop decode and forward relay aided noma scheme"
    - "energy efficient power allocation in uplink mmwave massive mimo with noma"
    - "optimal joint subcarrier and power allocation in noma is strongly np hard"
    - "power domain non orthogonal multiple access noma in 5g systems potentials and challenges"
    - "non orthogonal multiple access in large scale heterogeneous networks"
    - "a two phase power allocation scheme for crns employing noma"

Connected through hyperedge HE-5 (induced by source paper "exploiting noma for uav communications in large scale cellular networks"):
  with members:
    - "downlink non orthogonal multiple access noma in poisson networks"
    - "exploiting noma for multi beam uav communication in cellular uplink"
    - "user association and resource allocation in unified non orthogonal multiple access enabled heterogeneous ultra dense networks"
    - "connectivity and blockage effects in millimeter wave air to everything networks"
    - "uav aided offloading for cellular hotspot"
    - "modeling and analysis of two way relay non orthogonal multiple access systems"
    - "energy minimization for wireless communication with rotary wing uav"
    - "cellular enabled uav communication a connectivity constrained trajectory optimization perspective"

Connected through hyperedge HE-6 (induced by source paper "energy efficient resource allocation for secure noma enabled mobile edge computing networks"):
  with members:
    - "securing downlink massive mimo noma networks with artificial noise"
    - "joint power and time allocation for noma mec offloading"
    - "improving anti eavesdropping ability without eavesdropper s csi a practical secure transmission design perspective"
    - "joint computation and communication cooperation for energy efficient mobile edge computing"
    - "exploiting physical layer security for multiuser multicarrier computation offloading"
    - "edge computing aware noma for 5g networks"
    - "impact of non orthogonal multiple access on the offloading of mobile edge computing"
    - "robust and secure resource allocation for full duplex miso multicarrier noma systems"

Connected through hyperedge HE-7 (induced by source paper "securing downlink massive mimo noma networks with artificial noise"):
  with members:
    - "energy efficient joint user rb association and power allocation for uplink hybrid noma oma"
    - "energy efficient power allocation in uplink mmwave massive mimo with noma"
    - "exploiting inter user interference for secure massive non orthogonal multiple access"
    - "optimal resource allocation for power efficient mc noma with imperfect channel state information"
    - "power domain non orthogonal multiple access noma in 5g systems potentials and challenges"
    - "energy efficient power allocation in millimeter wave massive mimo with non orthogonal multiple access"
    - "noma in 5g systems exciting possibilities for enhancing spectral efficiency"
    - "a fair individual rate comparison between mimo noma and mimo oma"

Connected through hyperedge HE-8 (induced by source paper "energy efficient joint user rb association and power allocation for uplink hybrid noma oma"):
  with members:
    - "energy efficient power allocation in uplink mmwave massive mimo with noma"
    - "energy efficient noma enabled heterogeneous cloud radio access networks"
    - "power domain non orthogonal multiple access noma in 5g systems potentials and challenges"
    - "energy efficient power allocation in millimeter wave massive mimo with non orthogonal multiple access"
    - "joint power control and beamforming for uplink non orthogonal multiple access in 5g millimeter wave communications"
    - "noma in 5g systems exciting possibilities for enhancing spectral efficiency"
    - "a fair individual rate comparison between mimo noma and mimo oma"
    - "capacity comparison between mimo noma and mimo oma with multiple users in a cluster"

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)