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: "fairness for non orthogonal multiple access in 5g systems"
  Abstract: In non-orthogonal multiple access (NOMA) downlink, multiple data flows are superimposed in the power domain and user decoding is based on successive interference cancellation. NOMA’s performance highly depends on the power split among the data flows and the associated power allocation (PA) problem. In this letter, we study NOMA from a fairness standpoint and we investigate PA techniques that ensure fairness for the downlink users under i) instantaneous channel state information (CSI) at the transmitter, and ii) average CSI. Although the formulated problems are non-convex, we have developed low-complexity polynomial algorithms that yield the optimal solution in both cases considered.

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"
    - "resource allocation for downlink noma systems key techniques and open issues"
    - "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"

Connected through hyperedge HE-2 (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-3 (induced by source paper "clustered millimeter wave networks with non orthogonal multiple access"):
  with members:
    - "cache enabled hetnets with millimeter wave small cells"
    - "user association and resource allocation in unified noma enabled heterogeneous ultra dense networks"
    - "exploiting multiple access in clustered millimeter wave networks noma or oma"
    - "modeling and analysis of d2d millimeter wave networks with poisson cluster processes"
    - "optimal user scheduling and power allocation for millimeter wave noma systems"
    - "modeling and analyzing millimeter wave cellular systems"
    - "coverage analysis for millimeter wave networks the impact of directional antenna arrays"
    - "non orthogonal multiple access in large scale heterogeneous networks"

Connected through hyperedge HE-4 (induced by source paper "downlink analysis of noma enabled cellular networks with 3gpp inspired user ranking"):
  with members:
    - "downlink analysis for the typical cell in poisson cellular networks"
    - "noma in the uplink delay analysis with imperfect csi and finite length coding"
    - "meta distribution of downlink non orthogonal multiple access noma in poisson networks"
    - "downlink non orthogonal multiple access noma in poisson networks"
    - "stochastic geometry based uplink analysis of massive mimo systems with fractional pilot reuse"
    - "accuracy of distance based ranking of users in the analysis of noma systems"
    - "non orthogonal multiple access in large scale heterogeneous networks"
    - "a survey on non orthogonal multiple access for 5g networks research challenges and future trends"

Connected through hyperedge HE-5 (induced by source paper "noma an information theoretic perspective"):
  with members:
    - "rate splitting multiple access for downlink communication systems bridging generalizing and outperforming sdma and noma"
    - "power domain non orthogonal multiple access noma in 5g systems potentials and challenges"
    - "optimal beamforming for gaussian mimo wiretap channels with two transmit antennas"
    - "approximate capacity region of the mac ic mac"
    - "gsvd based precoding in mimo systems with integrated services"
    - "non orthogonal multiple access in multi cell networks theory performance and practical challenges"
    - "the application of mimo to non orthogonal multiple access"
    - "a general mimo framework for noma downlink and uplink transmission based on signal alignment"

Connected through hyperedge HE-6 (induced by source paper "intelligent reflecting surface assisted non orthogonal multiple access"):
  with members:
    - "large intelligent surface antennas lisa making reflective radios smart"
    - "a simple design of irs noma transmission"
    - "reliability analysis of large intelligent surfaces liss rate distribution and outage probability"
    - "cooperative ambient backscatter communications for green internet of things"
    - "achievable rate maximization by passive intelligent mirrors"
    - "intelligent reflecting surface enhanced wireless network via joint active and passive beamforming"
    - "joint pilot and payload power control for uplink mimo noma with mrc sic receivers"
    - "reconfigurable intelligent surfaces for energy efficiency in wireless communication"

Connected through hyperedge HE-7 (induced by source paper "uav data collection over noma backscatter networks uav altitude and trajectory optimization"):
  with members:
    - "3 d placement of an unmanned aerial vehicle base station for maximum coverage of users with different qos requirements"
    - "ultra reliable uav communication using altitude and cooperation diversity"
    - "efficient 3d placement of a uav using particle swarm optimization"
    - "lora backscatter enabling the vision of ubiquitous connectivity"
    - "backscatter communications for internet of things theory and applications"
    - "joint trajectory and communication design for multi uav enabled wireless networks"
    - "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"

Connected through hyperedge HE-8 (induced by source paper "secure users oriented downlink miso noma"):
  with members:
    - "exploiting inter user interference for secure massive non orthogonal multiple access"
    - "secure communications in noma system subcarrier assignment and power allocation"
    - "secrecy sum rate maximization in non orthogonal multiple access"
    - "relay selection for cooperative noma"
    - "on the spectral efficiency and security enhancements of noma assisted multicast unicast streaming"
    - "optimal joint power and subcarrier allocation for full duplex multicarrier non orthogonal multiple access systems"
    - "on the design of secure non orthogonal multiple access systems"
    - "energy efficient transmission design in non orthogonal multiple access"

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)