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: "massive mimo systems with hardware constrained base stations"
  Abstract: Massive multiple-input multiple-output (MIMO) systems are cellular networks where the base stations (BSs) are equipped with unconventionally many antennas. Such large antenna arrays offer huge spatial degrees-of-freedom for transmission optimization; in particular, great signal gains, resilience to imperfect channel knowledge, and small inter-user interference are all achievable without extensive inter-cell coordination. The key to cost-efficient deployment of large arrays is the use of hardware-constrained base stations with low-cost antenna elements, as compared to today's expensive and power-hungry BSs. Low-cost transceivers are prone to hardware imperfections, but it has been conjectured that the excessive degrees-of-freedom of massive MIMO would bring robustness to such imperfections. We herein prove this claim for an uplink channel with multiplicative phase-drift, additive distortion noise, and noise amplification. Specifically, we derive a closed-form scaling law that shows how fast the imperfections increase with the number of antennas.

Connected through hyperedge HE-1 (induced by source paper "ergodic capacity evaluation of wireless thz fiber extenders"):
  with members:
    - "wireless terahertz system architectures for networks beyond 5g"
    - "low cost cognitive radios against spectrum scarcity"
    - "terahertz technologies to deliver optical network quality of experience in wireless systems beyond 5g"
    - "i q imbalance self interference coordination"
    - "millimeter wave cellular networks a mac layer perspective"
    - "a new look at dual hop relaying performance limits with hardware impairments"
    - "optimal coordinated beamforming in the multicell downlink with transceiver impairments"
    - "mimo transmission with residual transmit rf impairments"

Connected through hyperedge HE-2 (induced by source paper "analysis and augmented spatial processing for uplink ofdma mu mimo receiver with transceiver i q imbalance and external interference"):
  with members:
    - "massive mimo systems with non ideal hardware energy efficiency estimation and capacity limits"
    - "massive mimo for next generation wireless systems"
    - "circuit aware design of energy efficient massive mimo systems"
    - "massive mimo for maximal spectral efficiency how many users and pilots should be allocated"
    - "five disruptive technology directions for 5g"
    - "energy and spectral efficiency of very large multiuser mimo systems"

Connected through hyperedge HE-3 (induced by source paper "massive mimo with non ideal arbitrary arrays hardware scaling laws and circuit aware design"):
  with members:
    - "capacity of simo and miso phase noise channels with common separate oscillators"
    - "uplink performance of time reversal mrc in massive mimo systems subject to phase noise"
    - "massive mimo performance evaluation based on measured propagation data"
    - "optimal multiuser transmit beamforming a difficult problem with a simple solution structure"
    - "on the impact of oscillator phase noise on the uplink performance in a massive mimo ofdm system"
    - "filter bank multicarrier for massive mimo"
    - "massive mimo systems with non ideal hardware energy efficiency estimation and capacity limits"
    - "massive mimo for next generation wireless systems"

Connected through hyperedge HE-4 (induced by source paper "spectrum sensing under hardware constraints"):
  with members:
    - "a new look at dual hop relaying performance limits with hardware impairments"
    - "mimo transmission with residual transmit rf impairments"

Connected through hyperedge HE-5 (induced by source paper "circuit aware design of energy efficient massive mimo systems"):
  with members:
    - "massive mimo systems with non ideal hardware energy efficiency estimation and capacity limits"
    - "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)