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: "on the distribution of the sum of gamma gamma variates and applications in rf and optical wireless communications"
  Abstract: The Gamma-Gamma (GG) distribution has recently attracted the interest within the research community due to its involvement in various communication systems. In the context of RF wireless communications, GG distribution accurately models the power statistics in composite shadowing/fading channels as well as in cascade multipath fading channels, while in optical wireless (OW) systems, it describes the fluctuations of the irradiance of optical signals distorted by atmospheric turbulence. Although GG channel model offers analytical tractability in the analysis of single input single output (SISO) wireless systems, difficulties arise when studying multiple input multiple output (MIMO) systems, where the distribution of the sum of independent GG variates is required. In this paper, we present a novel simple closed-form approximation for the distribution of the sum of independent, but not necessarily identically distributed GG variates. It is shown that the probability density function (PDF) of the GG sum can be efficiently approximated either by the PDF of a single GG distribution, or by a finite weighted sum of PDFs of GG distributions. To reveal the importance of the proposed approximation, the performance of RF wireless systems in the presence of composite fading, as well as MIMO OW systems impaired by atmospheric turbulence, are investigated. Numerical results and simulations illustrate the accuracy of the proposed approach.

Connected through hyperedge HE-1 (induced by source paper "performance of two way relaying over α μ fading channels in hybrid rf fso wireless networks"):
  with members:
    - "impact of pointing errors on the performance of mixed rf fso dual hop transmission systems"
    - "a new formula for the ber of binary modulations with dual branch selection over generalized k"
    - "performance analysis of mimo mrc in double correlated rayleigh environments"

Connected through hyperedge HE-2 (induced by source paper "on the multivariate gamma gamma distribution with arbitrary correlation and applications in wireless communications"):
  with members:
    - "on the ergodic capacity of mimo free space optical systems over turbulence channels"
    - "unified performance analysis of mixed radio frequency free space optical dual hop transmission systems"
    - "statistical characterization of kappa mu shadowed fading"

Connected through hyperedge HE-3 (induced by source paper "error rate and power allocation analysis of regenerative networks under generalized fading conditions"):
  with members:
    - "analytic solutions to a marcum q function based integral and application in energy detection of unknown signals over multipath fading channels"
    - "power allocation strategies in energy harvesting wireless cooperative networks"
    - "ergodic capacity comparison of different relay precoding schemes in dual hop af systems with co channel interference"
    - "wireless information and power transfer with full duplex relaying"
    - "cooperative energy harvesting networks with spatially random users"

Connected through hyperedge HE-4 (induced by source paper "entropy and channel capacity under optimum power and rate adaptation over generalized fading conditions"):
  with members:
    - "analytic solutions to a marcum q function based integral and application in energy detection of unknown signals over multipath fading channels"
    - "analytic expressions and bounds for special functions and applications in communication theory"

Connected through hyperedge HE-5 (induced by source paper "analytic performance evaluation of m qam based decode and forward relay networks over enriched multipath fading channels"):
  with members:
    - "analytic solutions to a marcum q function based integral and application in energy detection of unknown signals over multipath fading channels"
    - "a comparative study of relaying schemes with decode and forward over nakagami m fading channels"

Connected through hyperedge HE-6 (induced by source paper "unified performance analysis of mixed radio frequency free space optical dual hop transmission systems"):
  with members:
    - "impact of pointing errors on the performance of mixed rf fso dual hop transmission systems"
    - "a new formula for the ber of binary modulations with dual branch selection over generalized k"

Connected through hyperedge HE-7 (induced by source paper "on the ergodic capacity of mimo free space optical systems over turbulence channels"):
  with members:
    - "outage probability of the gaussian mimo free space optical channel with ppm"

Connected through hyperedge HE-8 (induced by source paper "analytic performance evaluation of m qam based decode and forward relay networks over nakagami q hoyt fading channels"):
  with members:
    - "analytic solutions to a marcum q function based integral and application in energy detection of unknown signals over multipath fading 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)