Finite-Step Algorithms for Constructing Optimal CDMA Signature Sequences

Abstract

Abstract-A description of optimal sequences for direct-spread codedivision multiple access (S-CDMA) is a byproduct of recent characterizations of the sum capacity. This correspondence restates the sequence design problem as an inverse singular value problem and shows that the problem can be solved with finite-step algorithms from matrix theory. It proposes a new one-sided algorithm that is numerically stable and faster than previous methods.Index Terms-Algorithms, code-division multiple access (CDMA), inverse eigenvalue problems, optimal sequences, sum capacity.

Novel Low-Density Signature for Synchronous CDMA Systems Over AWGN Channel

“…The detection being used are the MMSE-based PPIC and the proposed iterative chip-level detector with maximum iteration (or stages) of 15. The MMSE detector will give an unconstrained MMSE estimate of the transmitted symbols and PPIC will smooth it further with the smoothing-coefficient varies in ascending-order from 0.6 to 0.8 6 with the same stepsize. Fig.…”

“…The equality comes from the fact that the sum of the squared cross-correlations among signatures is equal to Welch's lower bound devised in [2]. The real-valued WBE-based techniques have been proposed in [3], [4], while the complex valued ones can be found in [5] and [6]. Another techniques to handle overloading (or oversaturated) condition are the family of hierarchy of orthogonal subsets (HoS) have been proposed in [7]- [9].…”

Approximate equiangular tight frames for compressed sensing and CDMA applications

“…The design of WBE sequences for s-CDMA has gained a lot of interest in the last decades [15,43,44]. However, WBE sequences do not perform well when the number of users in the cell changes.…”

“…The experiments presented here involve the computation of interuser interference when employing the proposed frame vectors as codes of a CDMA system with variable number of users. The performance of the proposed frames in s-CDMA is compared to a method presented in [44] for spreading sequence design. The authors of [44] produce WBE sequences from an appropriate Gram matrix.…”

“…The performance of the proposed frames in s-CDMA is compared to a method presented in [44] for spreading sequence design. The authors of [44] produce WBE sequences from an appropriate Gram matrix. The construction of the Gram matrix is addressed as an inverse eigenvalue problem, which is solved using finite-step algorithms from matrix theory.…”