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: "on the spectral efficiency of space constrained massive mimo with linear receivers"
  Abstract: In this paper, we investigate the spectral efficiency (SE) of massive multiple-input multiple-output (MIMO) systems with a large number of antennas at the base station (BS) accounting for physical space constraints. In contrast to the vast body of related literature, which considers fixed inter-element spacing, we elaborate on a practical topology in which an increase in the number of antennas in a fixed total space induces an inversely proportional decrease in the inter-antenna distance. For this scenario, we derive exact and approximate expressions, as well as simplified upper/lower bounds, for the SE of maximum-ratio combining (MRC), zero-forcing (ZF) and minimum mean-squared error receivers (MMSE) receivers. In particular, our analysis shows that the MRC receiver is non-optimal for space-constrained massive MIMO topologies. On the other hand, ZF and MMSE receivers can still deliver an increasing SE as the number of BS antennas grows large. Numerical results corroborate our analysis and show the effect of the number of antennas, the number of users, and the total antenna array space on the sum SE performance.

Connected through hyperedge HE-1 (induced by source paper "multipair massive mimo two way full duplex relay systems with hardware impairments"):
  with members:
    - "performance analysis of mixed adc massive mimo systems over rician fading channels"
    - "on the spectral efficiency of massive mimo systems with low resolution adcs"
    - "achievable rate of rician large scale mimo channels with transceiver hardware impairments"
    - "hardware impairments aware transceiver for full duplex massive mimo relaying"
    - "large scale mimo relaying techniques for physical layer security af or df"
    - "multipair full duplex relaying with massive arrays and linear processing"
    - "channel estimation for two way relay networks in the presence of synchronization errors"
    - "massive mimo systems with non ideal hardware energy efficiency estimation and capacity limits"

Connected through hyperedge HE-2 (induced by source paper "uplink analysis of large mu mimo systems with space constrained arrays in ricean fading"):
  with members:
    - "on the role of transmit correlation diversity in multiuser mimo systems"
    - "multi user massive mimo communication systems based on irregular antenna arrays"
    - "space constrained massive mimo hitting the wall of favorable propagation"
    - "power scaling of uplink massive mimo systems with arbitrary rank channel means"
    - "massive mimo for next generation wireless systems"
    - "millimeter wave channel modeling and cellular capacity evaluation"
    - "scaling up mimo opportunities and challenges with very large arrays"
    - "performance analysis of macrodiversity mimo systems with mmse and zf receivers in flat rayleigh fading"

Connected through hyperedge HE-3 (induced by source paper "impact of line of sight and unequal spatial correlation on uplink mu mimo systems"):
  with members:
    - "on the role of transmit correlation diversity in multiuser mimo systems"
    - "power scaling of uplink massive mimo systems with arbitrary rank channel means"
    - "achievable rates of fdd massive mimo systems with spatial channel correlation"
    - "millimeter wave channel modeling and cellular capacity evaluation"
    - "scaling up mimo opportunities and challenges with very large arrays"

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)