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: "orthogonal time frequency space modulation"
  Abstract: This paper introduces a new two-dimensional modulation technique called Orthogonal Time Frequency Space (OTFS) modulation. OTFS has the novel and important feature of being designed in the delay-Doppler domain. When coupled with a suitable equalizer, OTFS modulation is able to exploit the full channel diversity over both time and frequency. Moreover, it converts the fading, time-varying wireless channel experienced by modulated signals such as OFDM into a time-independent channel with a complex channel gain that is essentially constant for all symbols. #R##N#This design obviates the need for transmitter adaptation, and greatly simplifies system operation. The paper describes the basic operating principles of OTFS as well as a possible implementation as an overlay to current or anticipated standardized systems. OTFS is shown to provide significant performance improvement in systems with high Doppler, short packets, and/or large antenna array. In particular, simulation results indicate at least several dB of block error rate performance improvement for OTFS over OFDM in all of these settings.

Connected through hyperedge HE-1 (induced by source paper "channel estimation for orthogonal time frequency space otfs massive mimo"):
  with members:
    - "mimo otfs in high doppler fading channels signal detection and channel estimation"
    - "otfs a new generation of modulation addressing the challenges of 5g"
    - "embedded pilot aided channel estimation for otfs in delay doppler channels"
    - "on otfs modulation for high doppler fading channels"
    - "interference cancellation and iterative detection for orthogonal time frequency space modulation"
    - "a simple two stage equalizer with simplified orthogonal time frequency space modulation over rapidly time varying channels"
    - "low complexity modem structure for ofdm based orthogonal time frequency space modulation"
    - "millimeter wave vehicular communication to support massive automotive sensing"

Connected through hyperedge HE-2 (induced by source paper "multiple access in the delay doppler domain using otfs modulation"):
  with members:
    - "on the diversity of otfs modulation in doubly dispersive channels"
    - "mimo otfs in high doppler fading channels signal detection and channel estimation"
    - "otfs a new generation of modulation addressing the challenges of 5g"
    - "embedded pilot aided channel estimation for otfs in delay doppler channels"
    - "interference cancellation and iterative detection for orthogonal time frequency space modulation"
    - "a simple two stage equalizer with simplified orthogonal time frequency space modulation over rapidly time varying channels"
    - "low complexity modem structure for ofdm based orthogonal time frequency space modulation"

Connected through hyperedge HE-3 (induced by source paper "orthogonal time frequency space otfs modulation based radar system"):
  with members:
    - "embedded pilot aided channel estimation for otfs in delay doppler channels"
    - "on otfs modulation for high doppler fading channels"
    - "interference cancellation and iterative detection for orthogonal time frequency space modulation"
    - "low complexity modem structure for ofdm based orthogonal time frequency space modulation"

Connected through hyperedge HE-4 (induced by source paper "embedded pilot aided channel estimation for otfs in delay doppler channels"):
  with members:
    - "otfs a new generation of modulation addressing the challenges of 5g"
    - "interference cancellation and iterative detection for orthogonal time frequency space modulation"
    - "low complexity equalization for orthogonal time and frequency signaling otfs"
    - "analysis of discrete time mimo ofdm based orthogonal time frequency space modulation"
    - "orthogonal precoding for ultra reliable wireless communication links"
    - "low complexity modem structure for ofdm based orthogonal time frequency space modulation"

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)