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: "opportunistic spatial orthogonalization and its application in fading cognitive radio networks"
  Abstract: Opportunistic Spatial Orthogonalization (OSO) is a cognitive radio scheme that allows the existence of secondary users and hence increases the system throughput, even if the primary user occupies all the frequency bands all the time. Notably, this throughput advantage is obtained without sacrificing the performance of the primary user, if the interference margin is carefully chosen. The key idea is to exploit the spatial dimensions to orthogonalize users and hence minimize interference. However, unlike the time and frequency dimensions, there is no universal basis for the set of all multi-dimensional spatial channels, which motivated the development of OSO. On one hand, OSO can be viewed as a multi-user diversity scheme that exploits the channel randomness and independence. On the other hand, OSO can be interpreted as an opportunistic interference alignment scheme, where the interference from multiple secondary users is opportunistically aligned at the direction that is orthogonal to the primary user's signal space. In the case of multiple-input multiple-output (MIMO) channels, the OSO scheme can be interpreted as "riding the peaks" over the eigen-channels, and ill-conditioned MIMO channel, which is traditionally viewed as detrimental, is shown to be beneficial with respect to the sum throughput. Throughput advantages are thoroughly studied, both analytically and numerically.

Connected through hyperedge HE-1 (induced by source paper "contextual bandit learning for machine type communications in the null space of multi antenna systems"):
  with members:
    - "a vision of 6g wireless systems applications trends technologies and open research problems"
    - "sleeping multi armed bandit learning for fast uplink grant allocation in machine type communications"
    - "a directed information learning framework for event driven m2m traffic prediction"
    - "fast uplink grant for machine type communications challenges and opportunities"
    - "deep learning for signal authentication and security in massive internet of things systems"
    - "massive connectivity with massive mimo part ii achievable rate characterization"
    - "random access schemes in wireless systems with correlated user activity"
    - "massive connectivity with massive mimo part i device activity detection and channel estimation"

Connected through hyperedge HE-2 (induced by source paper "opportunistic network decoupling with virtual full duplex operation in multi source interfering relay networks"):
  with members:
    - "on the degrees of freedom of the large scale interfering two way relay network"
    - "codebook based opportunistic interference alignment"
    - "real interference alignment exploiting the potential of single antenna systems"
    - "opportunistic downlink interference alignment"
    - "parallel opportunistic routing in wireless networks"
    - "opportunistic interference alignment for mimo interfering multiple access channels"
    - "degrees of freedom of two hop wireless networks everyone gets the entire cake"
    - "opportunistic interference mitigation achieves optimal degrees of freedom in wireless multi cell uplink networks"

Connected through hyperedge HE-3 (induced by source paper "opportunistic scheduling of machine type communications as underlay to cellular networks"):
  with members:
    - "a primer on 3gpp narrowband internet of things nb iot"
    - "massive machine type communications in 5g physical and mac layer solutions"
    - "fundamentals of throughput maximization with random arrivals for m2m communications"
    - "opportunistic interference alignment for mimo interfering multiple access channels"
    - "improving macrocell small cell coexistence through adaptive interference draining"
    - "from spectrum pooling to space pooling opportunistic interference alignment in mimo cognitive networks"

Connected through hyperedge HE-4 (induced by source paper "on the achievable dof and user scaling law of opportunistic interference alignment in 3 transmitter mimo interference channels"):
  with members:
    - "mimo interference alignment over correlated channels with imperfect csi"
    - "cooperative algorithms for mimo interference channels"
    - "sum rates rate allocation and user scheduling for multi user mimo vector perturbation precoding"
    - "interference alignment with analog channel state feedback"
    - "from spectrum pooling to space pooling opportunistic interference alignment in mimo cognitive networks"
    - "interference alignment under limited feedback for mimo interference channels"
    - "interference alignment with limited feedback"
    - "degrees of freedom of the k user m times n mimo interference channel"

Connected through hyperedge HE-5 (induced by source paper "parallel opportunistic routing in wireless networks"):
  with members:
    - "on capacity scaling in arbitrary wireless networks"
    - "opportunistic relaying in wireless networks"
    - "throughput scaling laws for wireless networks with fading channels"
    - "the effect of fading channel inversion and threshold scheduling on ad hoc networks"
    - "hierarchical cooperation achieves optimal capacity scaling in ad hoc networks"

Connected through hyperedge HE-6 (induced by source paper "a distributed approach to interference alignment in ofdm based two tiered networks"):
  with members:
    - "achieving massive mimo spectral efficiency with a not so large number of antennas"
    - "from spectrum pooling to space pooling opportunistic interference alignment in mimo cognitive networks"
    - "femtocell networks a survey"

Connected through hyperedge HE-7 (induced by source paper "opportunistic interference mitigation achieves optimal degrees of freedom in wireless multi cell uplink networks"):
  with members:
    - "real interference alignment exploiting the potential of single antenna systems"
    - "parallel opportunistic routing in wireless networks"
    - "interference alignment with limited feedback on two cell interfering two user mimo mac"
    - "from spectrum pooling to space pooling opportunistic interference alignment in mimo cognitive networks"
    - "opportunistic relaying in wireless networks"
    - "ergodic interference alignment"
    - "exploiting opportunistic multiuser detection in decentralized multiuser mimo systems"
    - "opportunistic interference alignment in mimo interference channels"

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)