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: "deploying dense networks for maximal energy efficiency small cells meet massive mimo"
  Abstract: How would a cellular network designed for maximal energy efficiency look like? To answer this fundamental question, tools from stochastic geometry are used in this paper to model future cellular networks and obtain a new lower bound on the average uplink spectral efficiency. This enables us to formulate a tractable uplink energy efficiency (EE) maximization problem and solve it analytically with respect to the density of base stations (BSs), the transmit power levels, the number of BS antennas and users per cell, and the pilot reuse factor. The closed-form expressions obtained from this general EE maximization framework provide valuable insights on the interplay between the optimization variables, hardware characteristics, and propagation environment. Small cells are proved to give high EE, but the EE improvement saturates quickly with the BS density. Interestingly, the maximal EE is achieved by also equipping the BSs with multiple antennas and operate in a "massive MIMO" fashion, where the array gain from coherent detection mitigates interference and the multiplexing of many users reduces the energy cost per user.

Connected through hyperedge HE-1 (induced by source paper "energy efficiency optimization for downlink massive mimo with statistical csit"):
  with members:
    - "beam domain secure transmission for massive mimo communications"
    - "fractional programming for communication systems part i power control and beamforming"
    - "energy efficient multicell multigroup multicasting with joint beamforming and antenna selection"
    - "fdd massive mimo via ul dl channel covariance extrapolation and active channel sparsification"
    - "network deployment for maximal energy efficiency in uplink with multislope path loss"
    - "energy efficient beam coordination strategies with rate dependent processing power"
    - "bdma for millimeter wave terahertz massive mimo transmission with per beam synchronization"
    - "free deterministic equivalents for the analysis of mimo multiple access channel"

Connected through hyperedge HE-2 (induced by source paper "multiple antenna technologies for beyond 5g"):
  with members:
    - "intelligent reflecting surface versus decode and forward how large surfaces are needed to beat relaying"
    - "robust trajectory and resource allocation design for secure uav aided communications"
    - "a new look at cell free massive mimo making it practical with dynamic cooperation"
    - "scalability aspects of cell free massive mimo"
    - "cascaded channel estimation for large intelligent metasurface assisted massive mimo"
    - "robust and secure wireless communications via intelligent reflecting surfaces"
    - "channel estimation for intelligent reflecting surface assisted multiuser communications framework algorithms and analysis"
    - "resource allocation for secure irs assisted multiuser miso systems"

Connected through hyperedge HE-3 (induced by source paper "a distributed multi rf chain hybrid mmwave scheme for small cell systems"):
  with members:
    - "a tutorial on beam management for 3gpp nr at mmwave frequencies"
    - "multi beam noma for hybrid mmwave systems"
    - "multi cell hybrid millimeter wave systems pilot contamination and interference mitigation"
    - "optimal resource allocation for power efficient mc noma with imperfect channel state information"
    - "millimeter wave mimo prototype measurements and experimental results"
    - "measurement results for millimeter wave pure los mimo channels"
    - "multi user precoding and channel estimation for hybrid millimeter wave systems"
    - "cell free massive mimo versus small cells"

Connected through hyperedge HE-4 (induced by source paper "spectral efficiency analysis in dense massive mimo networks"):
  with members:
    - "network deployment for maximal energy efficiency in uplink with multislope path loss"
    - "massive mimo has unlimited capacity"
    - "performance impact of base station antenna heights in dense cellular networks"
    - "impact of los nlos propagation and path loss in ultra dense cellular networks"
    - "are we approaching the fundamental limits of wireless network densification"
    - "5g ultra dense cellular networks"
    - "downlink cellular network analysis with multi slope path loss models"
    - "massive mimo for next generation wireless systems"

Connected through hyperedge HE-5 (induced by source paper "non coherent joint transmission in poisson cellular networks under pilot contamination"):
  with members:
    - "stochastic geometry based uplink analysis of massive mimo systems with fractional pilot reuse"
    - "modeling and analysis of cellular networks using stochastic geometry a tutorial"
    - "channel hardening and favorable propagation in cell free massive mimo with stochastic geometry"
    - "cell free massive mimo versus small cells"
    - "analyzing uplink sinr and rate in massive mimo systems using stochastic geometry"
    - "on stochastic geometry modeling of cellular uplink transmission with truncated channel inversion power control"
    - "a tractable model for noncoherent joint transmission base station cooperation"
    - "a tractable approach to coverage and rate in cellular networks"

Connected through hyperedge HE-6 (induced by source paper "stochastic geometry based uplink analysis of massive mimo systems with fractional pilot reuse"):
  with members:
    - "johnson mehl cell based analysis of ul cellular network with coupled user and bs locations"
    - "fog massive mimo a user centric seamless hot spot architecture"
    - "massive mimo has unlimited capacity"
    - "modeling and analysis of cellular networks using stochastic geometry a tutorial"
    - "a primer on cellular network analysis using stochastic geometry"
    - "user point processes in cellular networks"
    - "poisson hole process theory and applications to wireless networks"
    - "massive mimo enabled full duplex cellular networks"

Connected through hyperedge HE-7 (induced by source paper "modeling and performance of uplink cache enabled massive mimo heterogeneous networks"):
  with members:
    - "toward a realistic assessment of multiple antenna hcns residual additive transceiver hardware impairments and channel aging"
    - "impact of general channel aging conditions on the downlink performance of massive mimo"
    - "downlink mimo hcns with residual transceiver hardware impairments"
    - "cluster content caching an energy efficient approach to improve quality of service in cloud radio access networks"
    - "impact of user mobility on optimal linear receivers in cellular networks"
    - "an uplink interference analysis for massive mimo systems with mrc and zf receivers"
    - "massive mimo with non ideal arbitrary arrays hardware scaling laws and circuit aware design"
    - "analyzing uplink sinr and rate in massive mimo systems using stochastic geometry"

Connected through hyperedge HE-8 (induced by source paper "fog massive mimo a user centric seamless hot spot architecture"):
  with members:
    - "a novel alternative to cloud ran for throughput densification coded pilots and fast user packet scheduling at remote radio heads"
    - "realizing the tactile internet haptic communications over next generation 5g cellular networks"
    - "modeling and analysis of cellular networks using stochastic geometry a tutorial"
    - "ergodic spectral efficiency in mimo cellular networks"
    - "unique coverage in boolean models"
    - "system level performance evaluation of lte v2x network"
    - "an uplink downlink duality for cloud radio access network"
    - "rrh based massive mimo with on the fly pilot contamination control"

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)