We present a novel convex-optimization-based solution to blind linear multiuser detection in direct-sequence CDMA systems. The solution is based on a convex low-rank approximation of the linearly constrained constant modulus cost function, thus guaranteeing its global minimization. Further, it can be cast as a semidefinite program, implying that it can be solved using interior-point techniques with polynomial time complexity. The solution is parameter free and is shown to be superior to existing solutions in terms of output SINR and BER, especially for a small number of samples.

%B IEEE Signal Processing Letters %P 1 - 1 %8 01/2019 %G eng %U https://ieeexplore.ieee.org/document/8718546 %! IEEE Signal Process. Lett. %R 10.1109/LSP.9710.1109/LSP.2019.2918001 %0 Journal Article %J Signal Processing %D 2019 %T Constant modulus algorithms via low-rank approximation %A Amir Adler %A Wax, Mati %XWe present a novel convex-optimization-based approach to the solutions of a family of problems involving constant modulus signals. The family of problems includes the constant modulus and the constrained constant modulus, as well as the modified constant modulus and the constrained modified constant modulus. These solutions are shown to constitute semidefinite programs (SDP), thus enabling efficient interior-point methods with polynomial time complexity. The performance of the proposed solutions, demonstrated in several simulated experiments for the task of blind beamforming, is shown to be superior to existing methods.

%B Signal Processing %V 160 %P 263 - 270 %8 07/2019 %G eng %U https://linkinghub.elsevier.com/retrieve/pii/S0165168419300568 %! Signal Processing %R 10.1016/j.sigpro.2019.02.007 %0 Conference Paper %B 27th European Signal Processing Conference, EUSIPCO 2019 %D 2019 %T Direct Localization by Partly Calibrated Arrays: A Relaxed Maximum Likelihood Solution %A Amir Adler %A Mati Wax %XWe present a novel relaxed maximum likelihood solution to the problem of direct localization of multiple narrowband sources by partly calibrated arrays, i.e., arrays composed of fully calibrated subarrays yet lacking inter-array calibration. The proposed solution is based on eliminating analytically all the nuisance parameters in the problem, thus reducing the likelihood function to a maximization problem involving only the location of the sources. The performance of the solution is demonstrated via simulations.

%B 27th European Signal Processing Conference, EUSIPCO 2019 %C A Coruna, Spain %8 07/2019 %G eng %U http://eusipco2019.org/technical-program %0 Generic %D 2018 %T Constant Modulus Algorithms via Low-Rank Approximation %A Amir Adler %A Mati Wax %K Constant modulus %K convex optimization %K trace norm %XWe present a novel convex-optimization-based approach to the solutions of a family of problems involving constant modulus signals. The family of problems includes the constant modulus and the constrained constant modulus, as well as the modified constant modulus and the constrained modified constant modulus. The usefulness of the proposed solutions is demonstrated for the tasks of blind beamforming and blind multiuser detection. The performance of these solutions, as we demonstrate by simulated data, is superior to existing methods.

%8 04/2018 %2http://hdl.handle.net/1721.1/114672

%0 Conference Paper %B 2018 IEEE Statistical Signal Processing Workshop (SSP) %D 2018 %T Constant Modulus Beamforming Via Low-Rank Approximation %A Amir Adler %A Mati Wax %XWe present novel convex-optimization-based solutions to the problem of blind beamforming of constant modulus signals, and to the related problem of linearly constrained blind beamforming of constant modulus signals. These solutions are based on a low-rank approximation, ensure global optimality and are parameter free, namely, do not contain any tuneable parameters and do not require any a-priori parameter settings. The proposed approach outperforms state-of-the-art both in terms of the number of required samples for convergence, and in terms of the beamformer output SINR.

%B 2018 IEEE Statistical Signal Processing Workshop (SSP) %C Freiburg im Breisgau, Germany %@ 978-1-5386-1571-3 %G eng %U https://ieeexplore.ieee.org/document/8450799/ %R 10.1109/SSP.2018.8450799