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: "a comparative study of downlink mimo cellular networks with co located and distributed base station antennas"
  Abstract: Despite the common belief that substantial capacity gains can be achieved by using more antennas at the base-station (BS) side in cellular networks, the effect of BS antenna topology on the capacity scaling behavior is little understood. In this paper, we present a comparative study on the ergodic capacity of a downlink single-user multiple-input-multiple-output (MIMO) system where BS antennas are either co-located at the center or grouped into uniformly distributed antenna clusters in a circular cell. By assuming that the number of BS antennas and the number of user antennas go to infinity with a fixed ratio $L\gg 1$, the asymptotic analysis reveals that the average per-antenna capacities in both cases logarithmically increase with $L$, but in the orders of $\log_2 L$ and $\tfrac{\alpha}{2}\log_2 L$, for the co-located and distributed BS antenna layouts, respectively, where $\alpha>2$ denotes the path-loss factor. The analysis is further extended to the multi-user case where a 1-tier (7-cell) MIMO cellular network with $K\gg 1$ uniformly distributed users in each cell is considered. By assuming that the number of BS antennas and the number of user antennas go to infinity with a fixed ratio $L\gg K$, an asymptotic analysis is presented on the downlink rate performance with block diagonalization (BD) adopted at each BS. It is shown that the average per-antenna rates with the co-located and distributed BS antenna layouts scale in the orders of $\log_2 \tfrac{L}{K}$ and $\log_2 \frac{(L-K+1)^{\alpha/2}}{K}$, respectively. The rate performance of MIMO cellular networks with small cells is also discussed, which highlights the importance of employing a large number of distributed BS antennas for the next-generation cellular networks.

Connected through hyperedge HE-1 (induced by source paper "group sparse precoding for cloud ran with multiple user antennas"):
  with members:
    - "joint precoding and rrh selection for user centric green mimo c ran"
    - "energy efficiency of downlink transmission strategies for cloud radio access networks"
    - "a survey of sparse representation algorithms and applications"
    - "robust group sparse beamforming for multicast green cloud ran with imperfect csi"
    - "large scale convex optimization for ultra dense cloud ran"
    - "sparse beamforming and user centric clustering for downlink cloud radio access network"
    - "group sparse beamforming for green cloud ran"
    - "asymptotic rate analysis of downlink multi user systems with co located and distributed antennas"

Connected through hyperedge HE-2 (induced by source paper "power minimization in distributed antenna systems using non orthogonal multiple access and mutual successive interference cancellation"):
  with members:
    - "robust designs of beamforming and power splitting for distributed antenna systems with wireless energy harvesting"
    - "optimal resource allocation for power efficient mc noma with imperfect channel state information"

Connected through hyperedge HE-3 (induced by source paper "cell free massive mimo versus small cells"):
  with members:
    - "cell free massive mimo uniformly great service for everyone"
    - "deploying dense networks for maximal energy efficiency small cells meet massive mimo"
    - "harmonized cellular and distributed massive mimo load balancing and scheduling"
    - "large scale mimo versus network mimo for multicell interference mitigation"
    - "dealing with interference in distributed large scale mimo systems a statistical approach"
    - "energy efficient large scale distributed antenna system l das for multiple users"
    - "interference reduction in multi cell massive mimo systems i large scale fading precoding and decoding"
    - "downlink mimo hetnets modeling ordering results and performance analysis"

Connected through hyperedge HE-4 (induced by source paper "downlink rate analysis for virtual cell based large scale distributed antenna systems"):
  with members:
    - "spectral efficiency of dynamic coordinated beamforming a stochastic geometry approach"
    - "joint power and antenna selection optimization in large cloud radio access networks"
    - "what will 5g be"
    - "energy efficient large scale distributed antenna system l das for multiple users"
    - "interference coordination random clustering and adaptive limited feedback"
    - "scaling up mimo opportunities and challenges with very large arrays"
    - "asymptotic rate analysis of downlink multi user systems with co located and distributed antennas"
    - "networked mimo with clustered linear precoding"

Connected through hyperedge HE-5 (induced by source paper "fingerprinting based positioning in distributed massive mimo systems"):
  with members:
    - "cell free massive mimo uniformly great service for everyone"
    - "massive mimo for next generation wireless systems"
    - "energy efficient large scale distributed antenna system l das for multiple users"
    - "gaussian processes for nonlinear signal processing an overview of recent advances"

Connected through hyperedge HE-6 (induced by source paper "cell free massive mimo uniformly great service for everyone"):
  with members:
    - "large scale mimo versus network mimo for multicell interference mitigation"
    - "massive mimo for next generation wireless systems"

Connected through hyperedge HE-7 (induced by source paper "communication using a large scale array of ubiquitous antennas a geometry approach"):
  with members:
    - "performance analysis and location optimization for massive mimo systems with circularly distributed antennas"
    - "dealing with interference in distributed large scale mimo systems a statistical approach"
    - "scaling up mimo opportunities and challenges with very large arrays"
    - "on capacity of large scale mimo multiple access channels with distributed sets of correlated antennas"
    - "a coordinated approach to channel estimation in large scale multiple antenna systems"
    - "femtocell networks a survey"

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)