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: "an overview of transmission theory and techniques of large scale antenna systems for 5g wireless communications"
  Abstract: To meet the future demand for huge traffic volume of wireless data service, the research on the fifth generation (5G) mobile communication systems has been undertaken in recent years. It is expected that the spectral and energy efficiencies in 5G mobile communication systems should be ten-fold higher than the ones in the fourth generation (4G) mobile communication systems. Therefore, it is important to further exploit the potential of spatial multiplexing of multiple antennas. In the last twenty years, multiple-input multiple-output (MIMO) antenna techniques have been considered as the key techniques to increase the capacity of wireless communication systems. When a large-scale antenna array (which is also called massive MIMO) is equipped in a base-station, or a large number of distributed antennas (which is also called large-scale distributed MIMO) are deployed, the spectral and energy efficiencies can be further improved by using spatial domain multiple access. This paper provides an overview of massive MIMO and large-scale distributed MIMO systems, including spectral efficiency analysis, channel state information (CSI) acquisition, wireless transmission technology, and resource allocation.

Connected through hyperedge HE-1 (induced by source paper "channel estimation and hybrid precoding for distributed phased arrays based mimo wireless communications"):
  with members:
    - "modeling and analyzing millimeter wave cellular systems"
    - "framework of channel estimation for hybrid analog and digital processing enabled massive mimo communications"
    - "5g cellular user equipment from theory to practical hardware design"
    - "alternating minimization algorithms for hybrid precoding in millimeter wave mimo systems"
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "codebook design for millimeter wave channel estimation with hybrid precoding structure"
    - "the world s first real time testbed for massive mimo design implementation and validation"
    - "hybrid digital and analog beamforming design for large scale antenna arrays"

Connected through hyperedge HE-2 (induced by source paper "performance of high mobility mimo communications with doppler diversity"):
  with members:
    - "bdma for millimeter wave terahertz massive mimo transmission with per beam synchronization"
    - "channel acquisition for massive mimo ofdm with adjustable phase shift pilots"
    - "pilot reuse for massive mimo transmission over spatially correlated rayleigh fading channels"
    - "large system analysis of linear precoding in correlated miso broadcast channels under limited feedback"

Connected through hyperedge HE-3 (induced by source paper "joint transmitter and receiver design for pattern division multiple access"):
  with members:
    - "pattern division multiple access with large scale antenna array"
    - "a survey on non orthogonal multiple access for 5g networks research challenges and future trends"
    - "energy efficient joint resource allocation and power control for d2d communications"
    - "design of massive mimo noma with limited feedback"
    - "advanced coordinated beamforming for the downlink of future lte cellular networks"
    - "on the spectral efficiency and security enhancements of noma assisted multicast unicast streaming"
    - "the application of mimo to non orthogonal multiple access"
    - "uplink contention based scma for 5g radio access"

Connected through hyperedge HE-4 (induced by source paper "pattern division multiple access with large scale antenna array"):
  with members:
    - "design of massive mimo noma with limited feedback"
    - "uplink contention based scma for 5g radio access"
    - "what will 5g be"

Connected through hyperedge HE-5 (induced by source paper "free deterministic equivalents for the analysis of mimo multiple access channel"):
  with members:
    - "channel acquisition for massive mimo ofdm with adjustable phase shift pilots"
    - "secure massive mimo transmission with an active eavesdropper"
    - "pilot reuse for massive mimo transmission over spatially correlated rayleigh fading channels"
    - "joint power and antenna selection optimization in large cloud radio access networks"
    - "pilot beam pattern design for channel estimation in massive mimo systems"
    - "massive mimo for next generation wireless systems"
    - "on capacity of large scale mimo multiple access channels with distributed sets of correlated antennas"
    - "random beamforming over quasi static and fading channels a deterministic equivalent approach"

Connected through hyperedge HE-6 (induced by source paper "secure massive mimo transmission with an active eavesdropper"):
  with members:
    - "channel acquisition for massive mimo ofdm with adjustable phase shift pilots"
    - "linear precoding of data and artificial noise in secure massive mimo systems"
    - "physical layer security in heterogeneous cellular networks"
    - "joint csit acquisition based on low rank matrix completion for fdd massive mimo systems"
    - "physical layer security in massive mimo"
    - "large scale mimo relaying techniques for physical layer security af or df"
    - "multi antenna relay aided wireless physical layer security"
    - "jamming aided secure communication in massive mimo rician channels"

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)