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: "heterogeneous cellular networks using wireless backhaul fast admission control and large system analysis"
  Abstract: We consider a heterogeneous cellular network with densely underlaid small cell access points (SAPs). Wireless backhaul provides the data connection from the core network to SAPs. To serve as many SAPs and their corresponding users as possible with guaranteed data rates, admission control of SAPs needs to be performed in wireless backhaul. Such a problem involves joint design of transmit beamformers, power control, and selection of SAPs. In order to tackle such a difficult problem, we apply    $\ell_1$  -relaxation and propose an iterative algorithm for the    $\ell_1$  -relaxed problem. The selection of SAPs is made based on the outputs of the iterative algorithm, and we prove such an algorithm converges locally. Furthermore, this algorithm is fast and enjoys low complexity for small-to-medium sized systems. However, its solution depends on the actual channel state information, and resuming the algorithm for each new channel realization may be unrealistic for large systems. Therefore, we make use of the random matrix theory and also propose an iterative algorithm for large systems. Such a large-system iterative algorithm can produce the asymptotically optimum solution for the    $\ell_1$  -relaxed problem, which only requires large-scale channel coefficients irrespective of the actual channel realization. Near optimum results are achieved by our proposed algorithms in simulations.

Connected through hyperedge HE-1 (induced by source paper "secrecy outage and diversity analysis of multiple cooperative source destination pairs"):
  with members:
    - "modulation and multiple access for 5g networks"
    - "physical layer security in heterogeneous networks with jammer selection and full duplex users"
    - "physical layer security for spectrum sharing systems"
    - "on secrecy performance of antenna selection aided mimo systems against eavesdropping"
    - "artificial noise aided secure transmission in large scale spectrum sharing networks"
    - "location based beamforming for enhancing secrecy in rician wiretap channels"
    - "physical layer security in heterogeneous cellular networks"
    - "secrecy transmit beamforming for heterogeneous networks"

Connected through hyperedge HE-2 (induced by source paper "joint precoding and power control in small cell networks with proportional rate miso bc backhaul"):
  with members:
    - "secure distributed on device learning networks with byzantine adversaries"
    - "robust energy efficient beamforming in misome swipt systems with proportional secrecy rate"
    - "cache enabled physical layer security for video streaming in backhaul limited cellular networks"
    - "fronthaul aware group sparse precoding and signal splitting in swipt c ran"
    - "interference alignment and soft space reuse based cooperative transmission for multi cell massive mimo networks"
    - "downlink energy efficiency of power allocation and wireless backhaul bandwidth allocation in heterogeneous small cell networks"
    - "fronthauling for 5g lte u ultra dense cloud small cell networks"

Connected through hyperedge HE-3 (induced by source paper "enhanced group sparse beamforming for green cloud ran a random matrix approach"):
  with members:
    - "layered group sparse beamforming for cache enabled green wireless networks"
    - "energy efficiency of downlink transmission strategies for cloud radio access networks"
    - "content centric sparse multicast beamforming for cache enabled cloud ran"
    - "wireless communications in the era of big data"
    - "fronthaul constrained cloud radio access networks insights and challenges"
    - "large scale convex optimization for dense wireless cooperative networks"
    - "robust group sparse beamforming for multicast green cloud ran with imperfect csi"
    - "are we approaching the fundamental limits of wireless network densification"

Connected through hyperedge HE-4 (induced by source paper "topological interference management with user admission control via riemannian optimization"):
  with members:
    - "fundamental tradeoff between storage and latency in cache aided wireless interference networks"
    - "a fundamental tradeoff between computation and communication in distributed computing"
    - "alternating minimization algorithms for hybrid precoding in millimeter wave mimo systems"
    - "low rank matrix completion for topological interference management by riemannian pursuit"
    - "low rank tensor completion a riemannian manifold preconditioning approach"
    - "an overview of low rank matrix recovery from incomplete observations"
    - "wireless communications in the era of big data"
    - "are we approaching the fundamental limits of wireless network densification"

Connected through hyperedge HE-5 (induced by source paper "analysis of massive mimo enabled downlink wireless backhauling for full duplex small cells"):
  with members:
    - "joint downlink cell association and bandwidth allocation for wireless backhauling in two tier hetnets with large scale antenna arrays"
    - "small cell in band wireless backhaul in massive mimo systems a cooperation of next generation techniques"
    - "5g wireless backhaul networks challenges and research advances"
    - "full duplex cloud radio access networks an information theoretic viewpoint"
    - "optimal user cell association for massive mimo wireless networks"
    - "hybrid full half duplex system analysis in heterogeneous wireless networks"
    - "cognitive and energy harvesting based d2d communication in cellular networks stochastic geometry modeling and analysis"
    - "evolution toward 5g multi tier cellular wireless networks an interference management perspective"

Connected through hyperedge HE-6 (induced by source paper "smoothed lp minimization for green cloud ran with user admission control"):
  with members:
    - "large scale convex optimization for dense wireless cooperative networks"
    - "robust group sparse beamforming for multicast green cloud ran with imperfect csi"
    - "large scale convex optimization for ultra dense cloud ran"
    - "heterogeneous cloud radio access networks a new perspective for enhancing spectral and energy efficiencies"
    - "what will 5g be"
    - "millimeter wave cellular wireless networks potentials and challenges"
    - "sparse beamforming and user centric clustering for downlink cloud radio access network"
    - "group sparse beamforming for green cloud ran"

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)