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: "asymptotic rate analysis of downlink multi user systems with co located and distributed antennas"
  Abstract: A great deal of efforts have been made on the performance evaluation of distributed antenna systems (DASs). Most of them assume a regular base-station (BS) antenna layout where the number of BS antennas is usually small. With the growing interest in cellular systems with large antenna arrays at BSs, it becomes increasingly important for us to study how the BS antenna layout affects the rate performance when a massive number of BS antennas are employed. #R##N#This paper presents a comparative study of the asymptotic rate performance of downlink multi-user systems with multiple BS antennas either co-located or uniformly distributed within a circular cell. Two representative linear precoding schemes, maximum ratio transmission (MRT) and zero-forcing beamforming (ZFBF), are considered, with which the effect of BS antenna layout on the rate performance is characterized. The analysis shows that as the number of BS antennas $L$ and the number of users $K$ grow infinitely while $L/K{\rightarrow}\upsilon$, the asymptotic average user rates with the co-located antenna (CA) layout for both MRT and ZFBF are logarithmic functions of the ratio $\upsilon$. With the distributed antenna (DA) layout, in contrast, the scaling behavior of the average user rate closely depends on the precoding schemes. With ZFBF, for instance, the average user rate grows unboundedly as $L, K{\rightarrow} \infty$ and $L/K{\rightarrow}\upsilon{>}1$, which indicates that substantial rate gains over the CA layout can be achieved when the number of BS antennas $L$ is large. The gain, nevertheless, becomes marginal when MRT is adopted.

Connected through hyperedge HE-1 (induced by source paper "spectral efficiency analysis of cell free massive mimo systems with zero forcing detector"):
  with members:
    - "downlink precoding with mixed statistical and imperfect instantaneous csi for massive mimo systems"
    - "enhanced max min sinr for uplink cell free massive mimo systems"
    - "on the total energy efficiency of cell free massive mimo"
    - "performance analysis for massive mimo downlink with low complexity approximate zero forcing precoding"
    - "pilot power allocation through user grouping in multi cell massive mimo systems"
    - "energy efficient downlink transmission for multicell massive das with pilot contamination"
    - "energy efficiency in cell free massive mimo with zero forcing precoding design"
    - "cell free massive mimo versus small cells"

Connected through hyperedge HE-2 (induced by source paper "rate analysis of cell free massive mimo noma with three linear precoders"):
  with members:
    - "what role can noma play in massive mimo"
    - "ubiquitous cell free massive mimo communications"
    - "interplay between noma and other emerging technologies a survey"
    - "downlink spectral efficiency of cell free massive mimo with full pilot zero forcing"
    - "signal processing for mimo noma present and future challenges"
    - "on the total energy efficiency of cell free massive mimo"
    - "power domain non orthogonal multiple access noma in 5g systems potentials and challenges"
    - "channel hardening and favorable propagation in cell free massive mimo with stochastic geometry"

Connected through hyperedge HE-3 (induced by source paper "performance of network assisted full duplex for cell free massive mimo"):
  with members:
    - "on the feasibility of full duplex large scale mimo cellular systems"
    - "cell free massive mimo versus small cells"
    - "full duplex emulation via spatial separation of half duplex nodes in a planar cellular network"
    - "why to decouple the uplink and downlink in cellular networks and how to do it"
    - "cell free massive mimo uniformly great service for everyone"
    - "interference management in 5g reverse tdd hetnets with wireless backhaul a large system analysis"
    - "compflex comp for in band wireless full duplex"
    - "in band alpha duplex scheme for cellular networks a stochastic geometry approach"

Connected through hyperedge HE-4 (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"
    - "a comparative study of downlink mimo cellular networks with co located and distributed base station antennas"
    - "sparse beamforming and user centric clustering for downlink cloud radio access network"
    - "group sparse beamforming for green cloud ran"

Connected through hyperedge HE-5 (induced by source paper "robust transmission for massive mimo downlink with imperfect csi"):
  with members:
    - "performance analysis of multi user massive mimo downlink under channel non reciprocity and imperfect csi"
    - "on optimizing feedback interval for temporally correlated mimo channels with transmit beamforming and finite rate feedback"
    - "analysis and augmented spatial processing for uplink ofdma mu mimo receiver with transceiver i q imbalance and external interference"
    - "free deterministic equivalents for the analysis of mimo multiple access channel"
    - "pilot reuse for massive mimo transmission over spatially correlated rayleigh fading channels"
    - "multi user linear precoding for multi polarized massive mimo system under imperfect csit"
    - "energy and spectral efficiency of very large multiuser mimo systems"
    - "statistical eigenmode transmission over jointly correlated mimo channels"

Connected through hyperedge HE-6 (induced by source paper "on energy efficient uplink multi user mimo with shared lna control"):
  with members:
    - "uplink performance of wideband massive mimo with one bit adcs"
    - "downlink achievable rate analysis in massive mimo systems with one bit dacs"
    - "energy efficiency of distributed signal processing in wireless networks a cross layer analysis"
    - "mixed adc massive mimo detectors performance analysis and design optimization"
    - "cell free massive mimo uniformly great service for everyone"
    - "capacity analysis of one bit quantized mimo systems with transmitter channel state information"
    - "large scale mimo versus network mimo for multicell interference mitigation"
    - "what will 5g be"

Connected through hyperedge HE-7 (induced by source paper "an overview of transmission theory and techniques of large scale antenna systems for 5g wireless communications"):
  with members:
    - "channel acquisition for massive mimo ofdm with adjustable phase shift pilots"
    - "mixed adc massive mimo detectors performance analysis and design optimization"
    - "performance analysis and location optimization for massive mimo systems with circularly distributed antennas"
    - "uplink achievable rate for massive mimo systems with low resolution adc"
    - "spatially common sparsity based adaptive channel estimation and feedback for fdd massive mimo"
    - "a stochastic geometry framework for analyzing pairwise cooperative cellular networks"
    - "structured compressive sensing based superimposed pilot design in downlink large scale mimo systems"
    - "fractional pilot reuse in massive mimo systems"

Connected through hyperedge HE-8 (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"
    - "a comparative study of downlink mimo cellular networks with co located and distributed base station antennas"
    - "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"

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)