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: "backhaul limited asymmetric cooperation for mimo cellular networks via semidefinite relaxation"
  Abstract: Multicell cooperation has recently attracted tremendous attention because of its ability to eliminate intercell interference and increase spectral efficiency. However, the enormous amount of information being exchanged, including channel state information and user data, over backhaul links may deteriorate the network performance in a realistic system. This paper adopts a backhaul cost metric that considers the number of active directional cooperation links, which gives a first order measurement of the backhaul loading required in asymmetric Multiple-Input Multiple-Output (MIMO) cooperation. We focus on a downlink scenario for multi-antenna base stations and single-antenna mobile stations. The design problem is minimizing the number of active directional cooperation links and jointly optimizing the beamforming vectors among the cooperative BSs subject to signal-to-interference-and-noise-ratio (SINR) constraints at the mobile station. This problem is non-convex and solving it requires combinatorial search. A practical algorithm based on smooth approximation and semidefinite relaxation is proposed to solve the combinatorial problem efficiently. We show that semidefinite relaxation is tight with probability 1 in our algorithm and stationary convergence is guaranteed. Simulation results show the saving of backhaul cost and power consumption is notable compared with several baseline schemes and its effectiveness is demonstrated.

Connected through hyperedge HE-1 (induced by source paper "cloud edge coordinated processing low latency multicasting transmission"):
  with members:
    - "hybrid precoder design for cache enabled millimeter wave radio access networks"
    - "two level transmission scheme for cache enabled fog radio access networks"
    - "iteratively linearized reweighted alternating direction method of multipliers for a class of nonconvex problems"
    - "content placement in cache enabled sub 6 ghz and millimeter wave multi antenna dense small cell networks"
    - "air ground integrated vehicular network slicing with content pushing and caching"
    - "distributed optimization for coordinated beamforming in multicell multigroup multicast systems power minimization and sinr balancing"
    - "fog aided wireless networks for content delivery fundamental latency tradeoffs"
    - "random caching based cooperative transmission in heterogeneous wireless networks"

Connected through hyperedge HE-2 (induced by source paper "hybrid data sharing and compression strategy for downlink cloud radio access network"):
  with members:
    - "generalized compression strategy for the downlink cloud radio access network"
    - "fronthaul compression and precoding design for c rans over ergodic fading channels"
    - "distributed decode forward for relay networks"
    - "sparse beamforming and user centric clustering for downlink cloud radio access network"
    - "group sparse beamforming for green cloud ran"
    - "joint precoding and multivariate backhaul compression for the downlink of cloud radio access networks"
    - "linear precoding and equalization for network mimo with partial cooperation"
    - "compute and forward strategies for cooperative distributed antenna systems"

Connected through hyperedge HE-3 (induced by source paper "energy efficiency maximization for c rans discrete monotonic optimization penalty and ell _ 0 approximation methods"):
  with members:
    - "globally optimal beamforming design for downlink comp transmission with limited backhaul capacity"
    - "elastic net boosting energy efficiency and resource utilization in 5g c rans"
    - "understanding the computational requirements of virtualized baseband units using a programmable cloud radio access network testbed"
    - "recent advances in cloud radio access networks system architectures key techniques and open issues"
    - "energy efficiency of downlink transmission strategies for cloud radio access networks"
    - "fronthaul constrained cloud radio access networks insights and challenges"
    - "sparse beamforming and user centric clustering for downlink cloud radio access network"
    - "group sparse beamforming for green cloud ran"

Connected through hyperedge HE-4 (induced by source paper "joint millimeter wave fronthaul and ofdma resource allocation in ultra dense cran"):
  with members:
    - "locally orthogonal training design for cloud rans based on graph coloring"
    - "millimeter wave wireless communications new results for rural connectivity"
    - "content centric sparse multicast beamforming for cache enabled cloud ran"
    - "wireless communications in the era of big data"
    - "5g ultra dense cellular networks"
    - "large scale convex optimization for ultra dense cloud ran"
    - "optimized uplink transmission in multi antenna c ran with spatial compression and forward"
    - "optimized backhaul compression for uplink cloud radio access network"

Connected through hyperedge HE-5 (induced by source paper "secure video streaming in heterogeneous small cell networks with untrusted cache helpers"):
  with members:
    - "on the optimality of separation between caching and delivery in general cache networks"
    - "cache enabled physical layer security for video streaming in backhaul limited cellular networks"
    - "wireless caching technical misconceptions and business barriers"
    - "caching in the sky proactive deployment of cache enabled unmanned aerial vehicles for optimized quality of experience"
    - "on edge caching with secrecy constraints"
    - "energy efficiency of downlink networks with caching at base stations"
    - "cross layer optimization of fast video delivery in cache enabled relaying networks"
    - "5g ultra dense cellular networks"

Connected through hyperedge HE-6 (induced by source paper "layered group sparse beamforming for cache enabled green wireless networks"):
  with members:
    - "fog aided wireless networks for content delivery fundamental latency tradeoffs"
    - "flexible cache aided networks with backhauling"
    - "an efficient global algorithm for single group multicast beamforming"
    - "content centric sparse multicast beamforming for cache enabled cloud ran"
    - "cache aided interference channels"
    - "5g wireless backhaul networks challenges and research advances"
    - "two layer feature reduction for sparse group lasso via decomposition of convex sets"
    - "sparse beamforming and user centric clustering for downlink cloud radio access network"

Connected through hyperedge HE-7 (induced by source paper "cache enabled physical layer security for video streaming in backhaul limited cellular networks"):
  with members:
    - "wireless caching technical misconceptions and business barriers"
    - "fog computing based radio access networks issues and challenges"
    - "cache enabled physical layer security for video streaming in wireless networks with limited backhaul"
    - "on edge caching with secrecy constraints"
    - "cooperative caching and transmission design in cluster centric small cell networks"
    - "content centric sparse multicast beamforming for cache enabled cloud ran"
    - "fundamental limits of caching with secure delivery"
    - "joint optimization of radio and computational resources for multicell mobile edge computing"

Connected through hyperedge HE-8 (induced by source paper "fronthaul limited uplink ofdma in ultra dense cran with hybrid decoding"):
  with members:
    - "cross layer design for downlink multihop cloud radio access networks with network coding"
    - "joint millimeter wave fronthaul and ofdma resource allocation in ultra dense cran"
    - "recent advances in cloud radio access networks system architectures key techniques and open issues"
    - "content centric sparse multicast beamforming for cache enabled cloud ran"
    - "green ofdma resource allocation in cache enabled cran"
    - "wireless communications in the era of big data"
    - "large scale convex optimization for ultra dense cloud ran"
    - "optimized uplink transmission in multi antenna c ran with spatial compression and forward"

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)