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: "secrecy and energy efficiency in massive mimo aided heterogeneous c ran a new look at interference"
  Abstract: In this paper, we investigate the potential benefits of the massive multiple-input multiple-output (MIMO) enabled heterogeneous cloud radio access network (C-RAN) in terms of the secrecy and energy efficiency (EE). In this network, both remote radio heads (RRHs) and massive MIMO macrocell base stations are deployed and soft fractional frequency reuse is adopted to mitigate the intertier interference. We first examine the physical layer security by deriving the area ergodic secrecy rate and secrecy outage probability. Our results reveal that the use of massive MIMO and C-RAN can greatly improve the secrecy performance. For C-RAN, a large number of RRHs achieves high area ergodic secrecy rate and low-secrecy outage probability, due to its powerful interference management. We find that for massive MIMO aided macrocells, having more antennas and serving more users improves secrecy performance. Then, we derive the EE of the heterogeneous C-RAN, illustrating that increasing the number of RRHs significantly enhances the network EE. Furthermore, it is indicated that allocating more radio resources to the RRHs can linearly increase the EE of RRH tier and improve the network EE without affecting the EE of the macrocells.

Connected through hyperedge HE-1 (induced by source paper "robustness of low complexity massive mimo architectures against passive eavesdropping"):
  with members:
    - "papr limited precoding in massive mimo systems with reflect and transmit array antennas"
    - "on robustness of massive mimo systems against passive eavesdropping under antenna selection"
    - "glse precoders for massive mimo systems analysis and applications"
    - "stepwise transmit antenna selection in downlink massive multiuser mimo"
    - "scalable and energy efficient millimeter massive mimo architectures reflect array and transmit array antennas"
    - "optimal transmit antenna selection for massive mimo wiretap channels"
    - "asymptotics of nonlinear lse precoders with applications to transmit antenna selection"
    - "asymptotics of transmit antenna selection impact of multiple receive antennas"

Connected through hyperedge HE-2 (induced by source paper "optimal downlink transmission for cell free swipt massive mimo systems with active eavesdropping"):
  with members:
    - "ubiquitous cell free massive mimo communications"
    - "cell free massive mimo networks optimal power control against active eavesdropping"
    - "spectral and energy efficiency of cell free massive mimo systems with hardware impairments"
    - "on the total energy efficiency of cell free massive mimo"
    - "energy efficiency in cell free massive mimo with zero forcing precoding design"
    - "cell free massive mimo versus small cells"
    - "wireless power transfer in massive mimo aided hetnets with user association"
    - "how much do downlink pilots improve cell free massive mimo"

Connected through hyperedge HE-3 (induced by source paper "on robustness of massive mimo systems against passive eavesdropping under antenna selection"):
  with members:
    - "stepwise transmit antenna selection in downlink massive multiuser mimo"
    - "iterative antenna selection for secrecy enhancement in massive mimo wiretap channels"
    - "asymptotics of nonlinear lse precoders with applications to transmit antenna selection"
    - "asymptotics of transmit antenna selection impact of multiple receive antennas"
    - "asymptotic performance analysis of spatially reconfigurable antenna arrays"
    - "optimal number of transmit antennas for secrecy enhancement in massive mimome channels"
    - "on secrecy performance of antenna selection aided mimo systems against eavesdropping"
    - "physical layer security for massive mimo an overview on passive eavesdropping and active attacks"

Connected through hyperedge HE-4 (induced by source paper "full duplex cloud radio access network stochastic design and analysis"):
  with members:
    - "self interference in full duplex multi user mimo channels"
    - "cross layer design for downlink multihop cloud radio access networks with network coding"
    - "echo state networks for proactive caching in cloud based radio access networks with mobile users"
    - "on the optimal fronthaul compression and decoding strategies for uplink cloud radio access networks"
    - "a stochastic analysis of network mimo systems"
    - "massive mimo enabled full duplex cellular networks"
    - "full duplex mimo small cell networks with interference cancellation"
    - "content centric sparse multicast beamforming for cache enabled cloud ran"

Connected through hyperedge HE-5 (induced by source paper "massive mimo enabled full duplex cellular networks"):
  with members:
    - "self interference in full duplex multi user mimo channels"
    - "large antenna analysis of multi cell full duplex networks"
    - "directional antennas for interference management in full duplex cellular networks"
    - "full duplex cloud ran with uplink downlink remote radio head association"
    - "full duplex cellular networks it works"
    - "statistical qos analysis of full duplex and half duplex heterogeneous cellular networks"
    - "analytical modeling of interference aware power control for the uplink of heterogeneous cellular networks"
    - "throughput analysis and optimization of wireless powered multiple antenna full duplex relay systems"

Connected through hyperedge HE-6 (induced by source paper "secure communications in millimeter wave ad hoc networks"):
  with members:
    - "artificial noise aided secure transmission in large scale spectrum sharing networks"
    - "performance analysis of outdoor mmwave ad hoc networks"
    - "physical layer security in millimeter wave cellular networks"
    - "physical layer security in heterogeneous cellular networks"
    - "tractable resource management with uplink decoupled millimeter wave overlay in ultra dense cellular networks"
    - "physical layer security in three tier wireless sensor networks a stochastic geometry approach"
    - "secrecy transmit beamforming for heterogeneous networks"
    - "millimeter wave cellular networks a mac layer perspective"

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.NI(Networking and Internet Architecture)