ICA-Based Receiver for An Optimal Separation of CDMA Signals

Automatic Control and Computer Sciences, 2007

To improve the performances of the wireless mobile communication system, a statistical method is illustrated in this paper. It consists in separating the signals at the reception of communication systems based on code division multiple access technology. The idea is to optimize the separation of the various users sharing the same frequency and temporal resources using the emergent statistical method of independent component analysis (ICA). ICA makes it possible to extract emitted signals that are as statistically independent as possible. The bit error rate and the signal to noise ratio are used as criteria for evaluating the performances of the ICA receiver. Adding white Gaussian noise to the input signal channel and the Rayleigh channel (fading channel) cases has been considered. A comparative study with conventional receivers such as the RAKE, the matched filter (MF), and the minimum mean-squared error is carried out. The obtained results show the superiority of an ICA receiver compared to an MF receiver.

Asilomar Conference on Signals, Systems & Computers, 2004

ICA based blind source separation methods suffer from inherent scaling and permutation ambiguities , which would cause problems in a DS-CDMA multiuser detection and MAI mitigation scenario. Recently ICA methods incorporating prior information about the desired user's code were proposed as an add-on to the subspace MMSE detector. In this paper, we propose a Q-R decomposition based technique to initialize

Computing Research Repository, 2010

Commercial cellular networks, like the systems based on DS-CDMA, face many types of interferences such as multi-user interference inside each sector in a cell to interoperate interference. Independent Component Analysis (ICA) has been used as an advanced preprocessing tool for blind suppression of interfering signals in DS-CDMA communication systems. The role of ICA is to provide an interference-mitigated signal to the conventional detection. This paper evaluates the performance of some major ICA algorithms like Cardoso's joint approximate diagonalization of eigen matrices (JADE), Hyvarinen's fixed point algorithm and Comon's algorithm to solve the symbol estimation problem of the multi users in a DSCDMA communication system. The main focus is on blind separation of convolved CDMA mixture and the improvement of the downlink symbol estimation. The results of numerical experiment are compared with those obtained by the Single User Detection (SUD) receiver, ICA detector and combined SUD-ICA detector.

EURASIP Journal on Advances in Signal Processing, 2014

The multicarrier code division multiple access (MC-CDMA) technique has received considerable interest for its potential application to future wireless communication systems due to its high data rate. A common problem regarding the blind multiuser detectors used in MC-CDMA systems is that they are extremely sensitive to the complex channel environment. Besides, the perturbation of colored noise may negatively affect the performance of the system. In this paper, a new coherent detection method will be proposed, which utilizes the modified fast independent component analysis (FastICA) algorithm, based on approximate negentropy maximization that is subject to the second-order cone programming (SOCP) constraint. The aim of the proposed coherent detection is to provide robustness against small-to-medium channel estimation mismatch (CEM) that may arise from channel frequency response estimation error in the MC-CDMA system, which is modulated by downlink binary phase-shift keying (BPSK) under colored noise. Noncoherent demodulation schemes are preferable to coherent demodulation schemes, as the latter are difficult to implement over time-varying fading channels. Differential phase-shift keying (DPSK) is therefore the natural choice for an alternative modulation scheme. Furthermore, the new blind differential SOCP-based ICA (SOCP-ICA) detection without channel estimation and compensation will be proposed to combat Doppler spread caused by time-varying fading channels in the DPSK-modulated MC-CDMA system under colored noise. In this paper, numerical simulations are used to illustrate the robustness of the proposed blind coherent SOCP-ICA detector against small-to-medium CEM and to emphasize the advantage of the blind differential SOCP-ICA detector in overcoming Doppler spread.

2000

2 DETERMINISTIC METHODS 9 2.1 INSTANTANEOUS MIXTURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.1.1 ILSP and ILSE algorithms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2.1.2 Analytical constant modulus algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2.1.3 Closed form solution based on linear coding . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 2.2 SUBSPACE METHOD FOR ISI CANCELLATION . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Neurocomputing - IJON, 2006

This paper proposes two novel blind receivers for Multiple-Input Multiple-Output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) wireless communi- cation systems using Independent Component Analysis (ICA). They increase the spectral eciency compared to conventional systems, without any training/pilot data required. The rst proposed receiver, termed ICA-MMSE, uses ICA in one sub- carrier of OFDM and a linear Minimum Mean Squared Error (MMSE) approach to unmix the remaining subcarriers. The second proposed receiver, termed ICA- MMSE+SIC, uses ICA-MMSE as a rst stage and iterative Successive Interference Cancellation (SIC) as a second stage to improve the performance. Simulations show that ICA-MMSE+SIC can obtain performance close to the case with perfect chan- nel knowledge at the receiver and both methods outperform a previously proposed ICA based method considerably.

IEEE Access, 2020

This paper concentrates on investigating an enhanced independent component analysis (ICA) method for blind separation of signals corrupted by noise in wireless communications. Because of the traditional classical ICA methods that always have an inadequate capacity of anti-noise or insufficient separable ability in noise circumstance without satisfying practical application requirements. For this reason, two mechanisms are conducted to establish the modified cost function and fulfill the optimization assignment in the process of constituting an enhanced ICA algorithm. This proposed algorithm can benefit tremendously from the derived minimum bit error rate (BER) criterion and the novel adaptive moment estimation (Adam) optimization approach. In this work, firstly, the novel cost function is obtained according to minimum BER fused into maximum likelihood (ML) principle-based ICA cost function. Furthermore, by utilizing Adam processing, the task of blind separation of mixed signals is implemented via optimizing this modified cost function. Lastly, theoretical analysis and experiment results corroborate the better effectiveness and robustness of the proposed enhanced ICA algorithm compared with a series of popular representative ICA methods.

Int'l J. of Communications, Network and System Sciences, 2010

Interleaved Division Multiple Access (IDMA) is a new access scheme that has been proposed in the literature to increase the capacity of wireless channels. The performance of such systems depends on the accuracy of the channel state information at the receiver. In this paper, a Noisy-Independent Component Analysis (N-ICA) based IDMA receiver for multiple access communication channels is proposed. The N-ICA component is applied as a post processor. Unlike other IDMA receivers, the proposed scheme detects and separates the transmitted symbols without channel state information tracking. The performance of the proposed technique is presented in terms of raw bit error rate (BER) without channel coding for different signal to noise ratios (SNR). Simulation results demonstrate that N-ICA post processor provides an improvement in performance in BER in loaded systems. When the system is not loaded, the proposed post processor has the same performance as conventional IDMA receiver with less iterations leading to a complexity reduction.

Proceedings of the International Conference on Wireless Information Networks and Systems, 2010

Interleaved Division Multiple Access (IDMA) is a new access scheme that has been proposed in the literature to increase the capacity of wireless channels. The performance of such systems depends on the accuracy of the channel state information (CSI) at the receiver. In this paper, a Noisy-Independent Component Analysis (N-ICA) based IDMA receiver for multiple access communication channels is proposed and compared to classical receivers. The N-ICA component is applied as a post processor. The estimation of CSI will often have some measurement errors, which degrade the accuracy of symbol detection. Using blind methods, this overhead can be eliminated. Simulation results demonstrate that N-ICA post processor provides an improvement in performance in terms of bit error rate (BER) in loaded systems and it offers an efficient alternative to systems with block channel estimation. When the system is not loaded, the proposed post processor presents the same performance as conventional IDMA receiver with less iterations leading to a complexity reduction.