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: "a tight upper bound on bit error rate of joint ofdm and multi carrier index keying"
  Abstract: This letter investigates performance enhancement by the concept of multi-carrier index keying in orthogonal frequency division multiplexing (OFDM) systems. For the performance evaluation, a tight closed-form approximation of the bit error rate (BER) is derived introducing the expression for the number of bit errors occurring in both the index domain and the complex domain, in the presence of both imperfect and perfect detection of active multi-carrier indices. The accuracy of the derived BER results for various cases are validated using simulations, which can provide accuracy within 1 dB at favorable channels.

Connected through hyperedge HE-1 (induced by source paper "single carrier index modulation for iot uplink"):
  with members:
    - "a variational inference based detection method for repetition coded generalized spatial modulation"
    - "index modulation techniques for 5g wireless networks"
    - "multiple input multiple output ofdm with index modulation"

Connected through hyperedge HE-2 (induced by source paper "uplink and downlink transceiver design for ofdm with index modulation in multi user networks"):
  with members:
    - "generalized space and frequency index modulation"
    - "multiple input multiple output ofdm with index modulation"

Connected through hyperedge HE-3 (induced by source paper "on multiple input multiple output ofdm with index modulation for next generation wireless networks"):
  with members:
    - "multiple input multiple output ofdm with index modulation"
    - "what will 5g be"
    - "practical implementation of spatial modulation"

Connected through hyperedge HE-4 (induced by source paper "multiple input multiple output ofdm with index modulation"):
  with members:
    - "what will 5g be"

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)