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: "otfs orthogonal time frequency space"
  Abstract: In this paper we introduce a new 2D modulation technique called OTFS (Orthogonal Time Frequency & Space) that transforms information carried in the Delay-Doppler coordinate system to the familiar time-frequency domain utilized by traditional modulation schemes such as OFDM, CDMA and TDMA. OTFS converts the fading, time-varying wireless channel into a non-fading, time-independent interaction revealing the underlying geometry of the wireless channel. In this new formulation, all QAM symbols experience the same channel and all Delay-Doppler diversity branches of the channel are coherently combined. Reference signal multiplexing is done in the time-independent Delay-Doppler domain, achieving high density pilot packing, which is a crucial requirement for Massive MIMO. Regardless of the Doppler scenario, OTFS enables approaching channel capacity through linear scaling of throughput with MIMO order, thus realizing the full promise of Massive MIMO throughput gains even in challenging 5G deployment settings.

Connected through hyperedge HE-1 (induced by source paper "non orthogonal multiple access with orthogonal time frequency space signal transmission"):
  with members:
    - "otfs noma an efficient approach for exploiting heterogenous user mobility profiles"
    - "low complexity lmmse receiver for otfs"
    - "robust beamforming design for otfs noma"
    - "on the diversity of uncoded otfs modulation in doubly dispersive channels"
    - "a survey on non orthogonal multiple access for 5g networks research challenges and future trends"
    - "fundamental limits of low density spreading noma with fading"
    - "sub channel assignment power allocation and user scheduling for non orthogonal multiple access networks"
    - "dynamic user clustering and power allocation for uplink and downlink non orthogonal multiple access noma systems"

Connected through hyperedge HE-2 (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"
    - "orthogonal time frequency space modulation"
    - "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"

Connected through hyperedge HE-3 (induced by source paper "on the diversity of uncoded otfs modulation in doubly dispersive channels"):
  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"
    - "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"

Connected through hyperedge HE-4 (induced by source paper "low complexity linear equalizers for otfs exploiting two dimensional fast fourier transform"):
  with members:
    - "otfs noma an efficient approach for exploiting heterogenous user mobility profiles"
    - "on the diversity of uncoded otfs modulation in doubly dispersive channels"
    - "embedded pilot aided channel estimation for otfs in delay doppler channels"
    - "interference cancellation and iterative detection for orthogonal time frequency space modulation"

Connected through hyperedge HE-5 (induced by source paper "orthogonal time frequency space modulation"):
  with members:
    - "on otfs modulation for high doppler fading channels"
    - "a simple two stage equalizer with simplified orthogonal time frequency space modulation over rapidly time varying channels"
    - "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"
    - "comparison of the achievable rates in ofdm and single carrier modulation with i i d inputs"
    - "what will 5g be"

Connected through hyperedge HE-6 (induced by source paper "mimo otfs in high doppler fading channels signal detection and channel estimation"):
  with members:
    - "otfs a new generation of modulation addressing the challenges of 5g"
    - "on otfs modulation for high doppler fading channels"
    - "a simple two stage equalizer with simplified orthogonal time frequency space modulation over rapidly time varying channels"
    - "analysis of discrete time mimo ofdm based orthogonal time frequency space modulation"
    - "low complexity modem structure for ofdm based orthogonal time frequency space modulation"

Connected through hyperedge HE-7 (induced by source paper "on the diversity of otfs modulation in doubly dispersive channels"):
  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"
    - "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-8 (induced by source paper "on otfs modulation for high doppler fading channels"):
  with members:
    - "a simple two stage equalizer with simplified orthogonal time frequency space modulation over rapidly time varying channels"
    - "analysis of discrete time mimo ofdm based orthogonal time frequency space modulation"
    - "low complexity modem structure for ofdm based orthogonal time frequency space modulation"
    - "near optimal detection in mimo systems using gibbs sampling"

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)