Kernel Recursive Maximum Versoria Criterion Based Post-Distorter for VLC Using Kernel-Width Sampling

Abstract

Visible light communication (VLC) has emerged as a potential candidate for next generation wireless communication systems. However, nonlinear characteristics of light emitting diode (LED), user-mobility, and DC-bias fluctuations are the major factors that limit the throughput of a VLC link, and makes the overall additive distortion as non-Gaussian distributed. To mitigate this non-Gaussian noise processes encountered in VLC systems due to LED nonlinearity, and user-mobility, recently a random Fourier features (RFF) based kernel recursive maximum Versoria criterion (KRMVC) based post-distortion algorithm is proposed, which delivers better performance as compared to the classical polynomial series, and kernel recursive least squares (KRLS) algorithms due to the incorporation of higher order statistics of error. However, the performance of RFF-KRMVC algorithm is sensitive to the choice of kernel-width, and results in approximation errors due to imperfect choice of kernelwidth. This paper proposes a novel RFF-KRMVC algorithm using a kernel-width sampling (KWS) technique called as RFF-KWS-KRMVC, which implements the post-distortion under a hyperparameter-free finite memory budget. Furthermore, analytical expressions for mean square error, and error rate are quantified for the proposed RFF-KWS-KRMVC post-distorter, and corroborated by Monte-Carlo simulations performed over standard VLC channel models.

Combined kernel with parameter optimization for least squares support vector machine postdistorter in visible light communications

“…The parameters α and b can be easily obtained from Eq. (25) as, 34 which can be expressed as {b=lvTnormalΦ−1trueboldxfalse¯lvTnormalΦ−1lvboldα=normalΦ−1false(trueboldxfalse¯−boldlv·bfalse),where normalΦ−1 is the inverse matrix of Φ. According to Eqs.…”

“…The parameters α and b can be easily obtained from Eq. ( 25) as, 34 which can be expressed as E Q -T A R G E T ; t e m p : i n t r a l i n k -; e 0 2 7 ; 1 1 6 ; 7 2 3…”

Gauss–Newton iteration method for radial basis function-based postdistortions in visible light communication systems

“…The LED’s nonlinearity is described by the Rapps model, where the knee factor m is 2, the threshold voltage VTO is set to be 0.2 V, and the maximum allowable current Imax is 0.5 A. It should be noted that the parameters have been adopted by the industry, 8 , 14 , 16 so we also employ the system values during our simulations. The nonlinear characteristics are exhibited in Fig.…”

“…A novel RFF based kernel recursive maximum Versoria criterion (KRMVC) algorithm using a kernel-width sampling technique is proposed in Ref. 14, which exhibits better mean square error and bit error property in alleviating the nonlinearity.…”

“…12, the transient nonlinear response is described through nonlinear dynamic differential equation, and then a postdistorter is constructed to mitigate the nonlinearity. Jain et al 14 propose a postdistorter based on unsupervised normalized Hammerstein improved multistage clustering, which exhibits better mean square error and BER performance. A clustering algorithm based on K-means is studied in Ref.…”