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: "antenna combining for the mimo downlink channel"
  Abstract: A multiple antenna downlink channel where limited channel feedback is available to the transmitter is considered. In a vector downlink channel (single antenna at each receiver), the transmit antenna array can be used to transmit separate data streams to multiple receivers only if the transmitter has very accurate channel knowledge, i.e., if there is high-rate channel feedback from each receiver. In this work it is shown that channel feedback requirements can be significantly reduced if each receiver has a small number of antennas and appropriately combines its antenna outputs. A combining method that minimizes channel quantization error at each receiver, and thereby minimizes multi-user interference, is proposed and analyzed. This technique is shown to outperform traditional techniques such as maximum-ratio combining because minimization of interference power is more critical than maximization of signal power in the multiple antenna downlink. Analysis is provided to quantify the feedback savings, and the technique is seen to work well with user selection and is also robust to receiver estimation error.

Connected through hyperedge HE-1 (induced by source paper "hybrid beamforming noma for mmwave communications"):
  with members:
    - "a new reconfigurable antenna mimo architecture for mmwave communication"
    - "multi beam noma for hybrid mmwave systems"
    - "reconfigurable antenna multiple access for 5g mmwave systems"
    - "non orthogonal multiple access based on hybrid beamforming for mmwave systems"
    - "non orthogonal multiple access common myths and critical questions"
    - "exploiting multiple antenna techniques for non orthogonal multiple access"
    - "modeling and analyzing millimeter wave cellular systems"
    - "energy efficient power allocation in millimeter wave massive mimo with non orthogonal multiple access"

Connected through hyperedge HE-2 (induced by source paper "cooperative limited feedback design for massive machine type communications"):
  with members:
    - "advanced quantizer designs for fdd based fd mimo systems using uniform planar arrays"
    - "exploiting trust degree for multiple antenna user cooperation"
    - "antenna grouping based feedback compression for fdd based massive mimo systems"
    - "five disruptive technology directions for 5g"
    - "multi user diversity vs accurate channel state information in mimo downlink channels"
    - "interference alignment through user cooperation for two cell mimo interfering broadcast channels"

Connected through hyperedge HE-3 (induced by source paper "limited feedback designs for machine type communications exploiting user cooperation"):
  with members:
    - "advanced quantizer designs for fdd based fd mimo systems using uniform planar arrays"
    - "towards massive connectivity support for scalable mmtc communications in 5g networks"
    - "exploiting trust degree for multiple antenna user cooperation"
    - "five disruptive technology directions for 5g"
    - "interference alignment through user cooperation for two cell mimo interfering broadcast channels"
    - "mimo broadcast channels with finite rate feedback"

Connected through hyperedge HE-4 (induced by source paper "an overview on resource allocation techniques for multi user mimo systems"):
  with members:
    - "low complexity downlink user selection for massive mimo systems"
    - "alternating minimization algorithms for hybrid precoding in millimeter wave mimo systems"
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "user association in 5g networks a survey and an outlook"
    - "cell free massive mimo versus small cells"
    - "mu mimo mac protocols for wireless local area networks a survey"
    - "on the number of rf chains and phase shifters and scheduling design with hybrid analog digital beamforming"
    - "hybrid digital and analog beamforming design for large scale antenna arrays"

Connected through hyperedge HE-5 (induced by source paper "symbol level and multicast precoding for multiuser multiantenna downlink a survey classification and challenges"):
  with members:
    - "channel estimation and performance analysis of one bit massive mimo systems"
    - "an overview on resource allocation techniques for multi user mimo systems"
    - "spatio temporal waveform design for multiuser massive mimo downlink with 1 bit receivers"
    - "joint beamforming and broadcasting in massive mimo"
    - "coordinate update algorithms for robust power loading for the mu miso downlink with outage constraints"
    - "energy efficient symbol level precoding in multiuser miso based on relaxed detection region"
    - "robust transmission in downlink multiuser miso systems a rate splitting approach"
    - "adaptive pilot clustering in heterogeneous massive mimo networks"

Connected through hyperedge HE-6 (induced by source paper "limited feedback hybrid precoding for multi user millimeter wave systems"):
  with members:
    - "on the convergence of massive mimo systems"
    - "channel estimation and hybrid precoding for millimeter wave cellular systems"
    - "spatially sparse precoding in millimeter wave mimo systems"
    - "millimeter wave beamforming for wireless backhaul and access in small cell networks"
    - "coding the beams improving beamforming training in mmwave communication system"
    - "mimo broadcast channels with finite rate feedback"

Connected through hyperedge HE-7 (induced by source paper "achievable rates of multi user millimeter wave systems with hybrid precoding"):
  with members:
    - "limited feedback hybrid precoding for multi user millimeter wave systems"
    - "channel estimation and hybrid precoding for millimeter wave cellular systems"
    - "spatially sparse precoding in millimeter wave mimo systems"

Connected through hyperedge HE-8 (induced by source paper "joint beamforming design for multi user wireless information and power transfer"):
  with members:
    - "robust beamforming for secure communication in systems with wireless information and power transfer"
    - "joint wireless information and energy transfer with reduced feedback in mimo interference channels"
    - "multiuser miso beamforming for simultaneous wireless information and power transfer"
    - "a practical cooperative multicell mimo ofdma network based on rank coordination"
    - "joint wireless information and energy transfer in a k user mimo interference channel"
    - "wireless information transfer with opportunistic energy harvesting"
    - "wireless information and power transfer architecture design and rate energy tradeoff"
    - "robust beamforming for wireless information and power transmission"

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)