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: "differential distributed space time coding with imperfect synchronization in frequency selective channels"
  Abstract: Differential distributed space-time coding (D-DSTC) is a cooperative transmission technique that can improve diversity in wireless relay networks in the absence of channel information. Conventionally, it is assumed that channels are flat-fading and relays are perfectly synchronized at the symbol level. However, due to the delay spread in broadband systems and the distributed nature of relay networks, these assumptions may be violated. Hence, inter-symbol interference (ISI) may appear. This paper proposes a new differential encoding and decoding process for D-DSTC systems with multiple relays over slow frequency-selective fading channels with imperfect synchronization. The proposed method overcomes the ISI caused by frequency-selectivity and is robust against synchronization errors while not requiring any channel information at the relays and destination. Moreover, the maximum possible diversity with a decoding complexity similar to that of the conventional D-DSTC is attained. Simulation results are provided to show the performance of the proposed method in various scenarios.

Connected through hyperedge HE-1 (induced by source paper "an analysis of two user uplink asynchronous non orthogonal multiple access systems"):
  with members:
    - "downlink non orthogonal multiple access with limited feedback"
    - "a survey on non orthogonal multiple access for 5g networks research challenges and future trends"
    - "asynchronous physical layer network coding symbol misalignment estimation and its effect on decoding"
    - "interference mitigation using asynchronous transmission and sampling diversity"
    - "asynchronous orthogonal differential decoding for multiple access channels"
    - "asynchronous physical layer network coding"

Connected through hyperedge HE-2 (induced by source paper "an analysis of uplink asynchronous non orthogonal multiple access systems"):
  with members:
    - "downlink non orthogonal multiple access with limited feedback"
    - "a survey on non orthogonal multiple access for 5g networks research challenges and future trends"
    - "interference mitigation using asynchronous transmission and sampling diversity"
    - "asynchronous orthogonal differential decoding for multiple access channels"

Connected through hyperedge HE-3 (induced by source paper "a survey on mimo transmission with discrete input signals technical challenges advances and future trends"):
  with members:
    - "asymptotic performance analysis of a k hop amplify and forward relay mimo channel"
    - "iterative distributed minimum total mse approach for secure communications in mimo interference channels"
    - "asymptotic analysis of su mimo channels with transmitter noise and mismatched joint decoding"
    - "secure massive mimo transmission with an active eavesdropper"
    - "interference aligned space time transmission with diversity for the 2 times 2 x network"
    - "space time encoded miso broadcast channel with outdated csit an error rate and diversity performance analysis"
    - "high snr asymptotics of mutual information for discrete constellations with applications to bicm"
    - "what will 5g be"

Connected through hyperedge HE-4 (induced by source paper "on the performance of mrc receiver with unknown timing mismatch a large scale analysis"):
  with members:
    - "interference mitigation using asynchronous transmission and sampling diversity"
    - "power scaling of uplink massive mimo systems with arbitrary rank channel means"
    - "asynchronous orthogonal differential decoding for multiple access channels"
    - "scalable synchronization and reciprocity calibration for distributed multiuser mimo"
    - "scaling up mimo opportunities and challenges with very large arrays"
    - "energy and spectral efficiency of very large multiuser mimo systems"

Connected through hyperedge HE-5 (induced by source paper "interference mitigation using asynchronous transmission and sampling diversity"):
  with members:
    - "asynchronous orthogonal differential decoding for multiple access channels"

Connected through hyperedge HE-6 (induced by source paper "differential modulation for asynchronous two way relay systems over frequency selective fading channels"):
  with members:
    - "a distributed differential space time coding scheme with analog network coding in two way relay networks"

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)