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: "energy efficient power allocation in millimeter wave massive mimo with non orthogonal multiple access"
  Abstract: In this letter, we investigate the energy efficiency (EE) problem in a millimeter wave (mmWave) massive MIMO (mMIMO) system with non-orthogonal multiple access (NOMA). Multiple two-user clusters are formulated according to their channel correlation and gain difference. Following this, we propose a hybrid analog/digital precoding scheme for the low radio frequency (RF) chains structure at the base station (BS). On this basis, we formulate a power allocation problem aiming to maximize the EE under users' quality of service (QoS) requirements and per-cluster power constraint. An iterative algorithm is proposed to obtain the optimal power allocation. Simulation results show that the proposed NOMA achieves superior EE performance than that of conventional OMA.

Connected through hyperedge HE-1 (induced by source paper "energy efficient hybrid precoding design for integrated multicast unicast millimeter wave communications with swipt"):
  with members:
    - "hybrid precoding based millimeter wave massive mimo noma with simultaneous wireless information and power transfer"
    - "joint optimization of computation and communication power in multi user massive mimo systems"
    - "energy efficient transceiver design for hybrid sub array architecture mimo systems"
    - "joint base station clustering and beamforming for non orthogonal multicast and unicast transmission with backhaul constraints"
    - "joint beamforming and broadcasting in massive mimo"
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "on the spectral efficiency and security enhancements of noma assisted multicast unicast streaming"
    - "energy efficiency optimization of 5g radio frequency chain systems"

Connected through hyperedge HE-2 (induced by source paper "secure millimeter wave cloud radio access networks relying on microwave multicast fronthaul"):
  with members:
    - "hybrid precoding based millimeter wave massive mimo noma with simultaneous wireless information and power transfer"
    - "optimized base station cache allocation for cloud radio access network with multicast backhaul"
    - "safeguarding millimeter wave communications against randomly located eavesdroppers"
    - "adaptive coding and modulation for large scale antenna array based aeronautical communications in the presence of co channel interference"
    - "robust an aided beamforming and power splitting design for secure miso cognitive radio with swipt"
    - "energy efficient joint congestion control and resource optimization in heterogeneous cloud radio access networks"
    - "content centric sparse multicast beamforming for cache enabled cloud ran"
    - "secure communications in millimeter wave ad hoc networks"

Connected through hyperedge HE-3 (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-4 (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"
    - "resource allocation for downlink noma systems key techniques and open issues"
    - "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-5 (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"
    - "resource allocation for downlink noma systems key techniques and open issues"
    - "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"

Connected through hyperedge HE-6 (induced by source paper "codebook based max min energy efficient resource allocation for uplink mmwave mimo noma systems"):
  with members:
    - "capacity achieving mimo noma iterative lmmse detection"
    - "energy efficient power allocation in uplink mmwave massive mimo with noma"
    - "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"
    - "non orthogonal multiple access in large scale heterogeneous networks"
    - "resource allocation for downlink noma systems key techniques and open issues"
    - "capacity comparison between mimo noma and mimo oma with multiple users in a cluster"
    - "an overview of signal processing techniques for millimeter wave mimo systems"

Connected through hyperedge HE-7 (induced by source paper "energy efficient power allocation in uplink mmwave massive mimo with noma"):
  with members:
    - "spectrum and energy efficient beamspace mimo noma for millimeter wave communications using lens antenna array"
    - "power domain non orthogonal multiple access noma in 5g systems potentials and challenges"
    - "resource allocation for downlink noma systems key techniques and open issues"
    - "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"
    - "capacity comparison between mimo noma and mimo oma with multiple users in a cluster"
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "spatially sparse precoding in millimeter wave mimo systems"

Connected through hyperedge HE-8 (induced by source paper "hybrid beamforming noma for mmwave communications"):
  with members:
    - "a new reconfigurable antenna mimo architecture for mmwave communication"
    - "multi beam noma for hybrid mmwave systems"
    - "reconfigurable antenna multiple access for 5g mmwave systems"
    - "non orthogonal multiple access based on hybrid beamforming for mmwave systems"
    - "non orthogonal multiple access common myths and critical questions"
    - "exploiting multiple antenna techniques for non orthogonal multiple access"
    - "modeling and analyzing millimeter wave cellular systems"
    - "joint power allocation and beamforming for non orthogonal multiple access noma in 5g millimeter wave communications"

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)