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 precoding for multiple antenna terminals"
  Abstract: The problem of energy-efficient precoding is investigated when the terminals in the system are equipped with multiple antennas. Considering static and fast-fading multiple-input multiple-output (MIMO) channels, the energy-efficiency is defined as the transmission rate to power ratio and shown to be maximized at low transmit power. The most interesting case is the one of slow fading MIMO channels. For this type of channels, the optimal precoding scheme is generally not trivial. Furthermore, using all the available transmit power is not always optimal in the sense of energy-efficiency [which, in this case, corresponds to the communication-theoretic definition of the goodput-to-power (GPR) ratio]. Finding the optimal precoding matrices is shown to be a new open problem and is solved in several special cases: 1. when there is only one receive antenna; 2. in the low or high signal-to-noise ratio regime; 3. when uniform power allocation and the regime of large numbers of antennas are assumed. A complete numerical analysis is provided to illustrate the derived results and stated conjectures. In particular, the impact of the number of antennas on the energy-efficiency is assessed and shown to be significant.

Connected through hyperedge HE-1 (induced by source paper "decision set optimization and energy efficient mimo communications"):
  with members:
    - "energy efficient mobile edge computation offloading for applications with shared data"
    - "mimo broadcast channels with finite rate feedback"

Connected through hyperedge HE-2 (induced by source paper "decision oriented communications application to energy efficient resource allocation"):
  with members:
    - "energy efficient communications in cdma networks a game theoretic analysis considering operating costs"

Connected through hyperedge HE-3 (induced by source paper "fundamental green tradeoffs progresses challenges and impacts on 5g networks"):
  with members:
    - "spectrum power trading for energy efficient small cell"
    - "power efficient resource allocation for full duplex radio distributed antenna networks"
    - "energy recycling full duplex radios for next generation networks"
    - "energy efficient resource allocation for wireless powered communication networks"
    - "multi objective optimization for robust power efficient and secure full duplex wireless communication systems"
    - "hybrid millimeter wave systems a novel paradigm for hetnets"
    - "coexistence of wi fi and heterogeneous small cell networks sharing unlicensed spectrum"
    - "on the spectral efficiency of full duplex small cell wireless systems"

Connected through hyperedge HE-4 (induced by source paper "interference coordination via power domain channel estimation"):
  with members:
    - "ultra dense small cell networks turning density into energy efficiency"
    - "coordination in distributed networks via coded actions with application to power control"
    - "resource allocation for energy efficient 3 way relay channels"
    - "compressive rate estimation with applications to device to device communications"
    - "energy aware competitive power allocation for heterogeneous networks under qos constraints"
    - "crawford sobel meet lloyd max on the grid"
    - "coded power control performance analysis"
    - "power optimization in random wireless networks"

Connected through hyperedge HE-5 (induced by source paper "energy efficiency optimization of 5g radio frequency chain systems"):
  with members:
    - "on the number of rf chains and phase shifters and scheduling design with hybrid analog digital beamforming"
    - "limited feedback hybrid precoding for multi user millimeter wave systems"
    - "5g ultra dense cellular networks"
    - "5g wireless backhaul networks challenges and research advances"
    - "channel estimation and hybrid precoding for millimeter wave cellular systems"
    - "impact of transceiver power consumption on the energy efficiency of zero forcing detector in massive mimo systems"
    - "spatially sparse precoding in millimeter wave mimo systems"
    - "optimal design of energy efficient multi user mimo systems is massive mimo the answer"

Connected through hyperedge HE-6 (induced by source paper "on the two user multi carrier joint channel selection and power control game"):
  with members:
    - "toward fully coordinated multi level multi carrier energy efficient networks"
    - "spectrum coordination in energy efficient cognitive radio networks"
    - "on the energy spectral efficiency trade off of the mrc receiver in massive mimo systems with transceiver power consumption"
    - "spectral efficiency and energy efficiency of ofdm systems impact of power amplifiers and countermeasures"
    - "quantifying potential energy efficiency gain in green cellular wireless networks"
    - "a game theoretic analysis for energy efficient heterogeneous networks"
    - "introducing hierarchy in energy games"
    - "femtocell networks a survey"

Connected through hyperedge HE-7 (induced by source paper "energy efficient power control a look at 5g wireless technologies"):
  with members:
    - "power control in networks with heterogeneous users a quasi variational inequality approach"
    - "energy aware competitive power allocation for heterogeneous networks under qos constraints"
    - "massive mimo with non ideal arbitrary arrays hardware scaling laws and circuit aware design"
    - "massive mimo systems with non ideal hardware energy efficiency estimation and capacity limits"
    - "energy efficient scheduling and power allocation in downlink ofdma networks with base station coordination"
    - "massive mimo for maximal spectral efficiency how many users and pilots should be allocated"
    - "five disruptive technology directions for 5g"
    - "energy efficiency optimization for mimo broadcast channels"

Connected through hyperedge HE-8 (induced by source paper "energy efficient cooperative network coding with joint relay scheduling and power allocation"):
  with members:
    - "wireless information and power transfer energy efficiency optimization in ofdma systems"
    - "relay selection with network coding in two way relay channels"
    - "distributed power allocation strategies for parallel relay networks"

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)