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: "optimal linear precoding in multi user mimo systems a large system analysis"
  Abstract: We consider the downlink of a single-cell multi-user MIMO system in which the base station makes use of N antennas to communicate with K single-antenna user equipments (UEs) randomly positioned in the coverage area. In particular, we focus on the problem of designing the optimal linear precoding for minimizing the total power consumption while satisfying a set of target signal-to-interference-plus-noise ratios (SINRs). To gain insights into the structure of the optimal solution and reduce the computational complexity for its evaluation, we analyze the asymptotic regime where N and K grow large with a given ratio and make use of recent results from large system analysis to compute the asymptotic solution. Then, we concentrate on the asymptotically design of heuristic linear precoding techniques. Interestingly, it turns out that the regularized zero-forcing (RZF) precoder is equivalent to the optimal one when the ratio between the SINR requirement and the average channel attenuation is the same for all UEs. If this condition does not hold true but only the same SINR constraint is imposed for all UEs, then the RZF can be modified to still achieve optimality if statistical information of the UE positions is available at the BS. Numerical results are used to evaluate the performance gap in the finite system regime and to make comparisons among the precoding techniques.

Connected through hyperedge HE-1 (induced by source paper "waveforms for the massive mimo downlink amplifier efficiency distortion and performance"):
  with members:
    - "massive mimo with non ideal arbitrary arrays hardware scaling laws and circuit aware design"
    - "optimal multiuser transmit beamforming a difficult problem with a simple solution structure"
    - "massive mimo systems with non ideal hardware energy efficiency estimation and capacity limits"
    - "massive mimo for next generation wireless systems"
    - "constant envelope multi user precoding for frequency selective massive mimo systems"
    - "per antenna constant envelope precoding for large multi user mimo systems"
    - "par aware large scale multi user mimo ofdm downlink"
    - "energy and spectral efficiency of very large multiuser mimo systems"

Connected through hyperedge HE-2 (induced by source paper "out of band radiation measure for mimo arrays with beamformed transmission"):
  with members:
    - "waveforms for the massive mimo downlink amplifier efficiency distortion and performance"
    - "analysis of massive mimo with hardware impairments and different channel models"
    - "optimal multiuser transmit beamforming a difficult problem with a simple solution structure"
    - "massive mimo systems with non ideal hardware energy efficiency estimation and capacity limits"
    - "massive mimo for next generation wireless systems"
    - "on the impact of hardware impairments on massive mimo"

Connected through hyperedge HE-3 (induced by source paper "interference management in 5g reverse tdd hetnets with wireless backhaul a large system analysis"):
  with members:
    - "large system analysis of the energy consumption distribution in multi user mimo systems with mobility"
    - "small cell in band wireless backhaul in massive mimo systems a cooperation of next generation techniques"
    - "wireless backhaul networks capacity bound scalability analysis and design guidelines"
    - "linear precoding based on polynomial expansion large scale multi cell mimo systems"
    - "massive mimo for next generation wireless systems"
    - "what will 5g be"
    - "optimal design of energy efficient multi user mimo systems is massive mimo the answer"
    - "large system analysis of cooperative multi cell downlink transmission via regularized channel inversion with imperfect csit"

Connected through hyperedge HE-4 (induced by source paper "large system analysis of the energy consumption distribution in multi user mimo systems with mobility"):
  with members:
    - "interference management in 5g reverse tdd hetnets with wireless backhaul a large system analysis"
    - "optimal multiuser transmit beamforming a difficult problem with a simple solution structure"
    - "energy consumption in multi user mimo systems impact of user mobility"
    - "effects of mobility on user energy consumption and total throughput in a massive mimo system"
    - "optimal design of energy efficient multi user mimo systems is massive mimo the answer"
    - "optimal power allocation and user loading for multiuser miso channels with regularized channel inversion"
    - "scaling up mimo opportunities and challenges with very large arrays"
    - "large system analysis of linear precoding in correlated miso broadcast channels under limited feedback"

Connected through hyperedge HE-5 (induced by source paper "large system analysis of base station cooperation for power minimization"):
  with members:
    - "asymptotic analysis of multicell massive mimo over rician fading channels"
    - "interference management in 5g reverse tdd hetnets with wireless backhaul a large system analysis"
    - "large system analysis of the energy consumption distribution in multi user mimo systems with mobility"
    - "optimal multiuser transmit beamforming a difficult problem with a simple solution structure"
    - "large scale mimo versus network mimo for multicell interference mitigation"
    - "large system analysis of cooperative multi cell downlink transmission via regularized channel inversion with imperfect csit"
    - "scaling up mimo opportunities and challenges with very large arrays"
    - "large system analysis of linear precoding in correlated miso broadcast channels under limited feedback"

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)