no code implementations • 11 Jun 2018 • Michel Kulhandjian, Claude D'Amours, Hovannes Kulhandjian, Halim Yanikomeroglu, Dimitris A. Pados, Gurgen Khachatrian
We consider the problem of designing a low-complexity decoder for antipodal uniquely decodable (UD) /errorless code sets for overloaded synchronous code-division multiple access (CDMA) systems, where the number of signals Kamax is the largest known for the given code length L. In our complexity analysis, we illustrate that compared to maximum-likelihood (ML) decoder, which has an exponential computational complexity for even moderate code lengths, the proposed decoder has a quasi-quadratic computational complexity.
no code implementations • 6 Oct 2016 • Panos P. Markopoulos, Sandipan Kundu, Shubham Chamadia, Dimitris A. Pados
It was shown recently that the $K$ L1-norm principal components (L1-PCs) of a real-valued data matrix $\mathbf X \in \mathbb R^{D \times N}$ ($N$ data samples of $D$ dimensions) can be exactly calculated with cost $\mathcal{O}(2^{NK})$ or, when advantageous, $\mathcal{O}(N^{dK - K + 1})$ where $d=\mathrm{rank}(\mathbf X)$, $K<d$ [1],[2].
no code implementations • 4 Sep 2013 • Panos P. Markopoulos, George N. Karystinos, Dimitris A. Pados
We describe ways to define and calculate $L_1$-norm signal subspaces which are less sensitive to outlying data than $L_2$-calculated subspaces.