The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Many communication systems today encounter the problem of data transmission over a channel with inter-symbol interference (ISI). The purpose of this paper is to develop a low-complexity, iterative soft-decision feedback equalization (SDFE) receiver for severe, frequency selective ISI channels. The proposed SDFE algorithm offers a novel approach to combat error propagation. In addition, its computational...
Decision feedback equalizers are used in wireless and mobile communications to reduce the intersymbol interference that is caused by the time dispersive channel. Here, an adaptive decision feedback equalizer is presented with a new adaptive algorithm. The algorithm uses sign normalized block based least mean square algorithm, and achieves a significant reduction of computational complexity. The proposed...
Frequency-domain filtered single carrier (SC)-FDMA signal has properties of reduced peak-to-average power ratio (PAPR) and increased frequency diversity gain. However, if the carrier-frequency separation is kept the same as in the case of the transmit filter roll-off factor α=0, the adjacent users' signal spectra overlap and the multi-user interference (MUI) is produced. In our previous work, we proposed...
In the single-carrier (SC) transmission, minimum mean square error frequency-domain equalization (MMSE-FDE) can achieve a good bit error rate (BER) performance in a frequency-selective fading channel. The conventional FDE requires the insertion of cyclic prefix (CP) to make the received signal block to be a circular convolution of the transmit signal and the channel. Overlap FDE requires no CP insertion...
Inter-symbol in0terference is a major limitation of wireless communications. It degrades the performance significantly if the delay spread is comparable or higher than the symbol duration. To mitigate ISI equalization need to be incorporated at the receiver end. Two of the most popular equalization algorithms are zero forcing (ZF) equalizer and minimum mean square (MMSE) equalizer. The paper shows...
A two-stage data detection algorithm is presented to simplify the receiver structure for long intersymbol interference (ISI) channel. After partial ISI elimination by a minimum mean square error (MMSE) equalizer, the following fast windowed Chase equalization (FWCE) can ensure bit error rate (BER) performance approaching the maximum likelihood sequence detection (MLSD). Compared with the WCE algorithm,...
The paper compares the performance of a baseband multiple-input single-output (MISO) ultra-wideband system (UWB), incorporating two types of pre-distortion: time reversal (TR) and a constrained least squares (CLS) pre-equalizer. For the CLS, a simple cost function is proposed which can be easily solved with a gradient based algorithm. Results show that the CLS scheme provides a good inter-symbol interference...
In recent year, to achieve a high data rate and high quality multimedia service in wireless communication systems, orthogonal frequency division multiplexing (OFDM) is attractive and widely studied. Moreover, orthogonal frequency division multiple access (OFDMA) which is combined OFDM and frequency division multiple access (FDMA) provides each user with a fraction of the available number of subcarriers...
Several normalized least mean square (NLMS) based minimum mean square error (MMSE) adaptive detection algorithms have been proposed in recent years in order to mitigate the inter symbol interference (ISI) in the ultra wideband (UWB) systems. In this paper, we propose an improved NLMS (INLMS) based MMSE adaptive detection algorithm that can choose different step size adaptively and can solve the conflicting...
For multiple access high data rate UWB systems, the inter-symbol-interference (ISI) and multiple access interference(MAI) will influence the performance of the systems. In this paper, a Rake receiver structure is presented with adjusting the tap weights adaptively using recursive least squares(RLS) algorithm, in which the optimal parameters of RLS algorithm can be determined by part of the channel...
We utilize a pair of decision feedback equalizers (DFEs) operating in opposite directions in turbo equalization setting to remove the effect of intersymbol interference (ISI) at the receiver. With a specific residual interference processing strategy proposed, the bi-directional DFE (BiDFE) are free from any significant error propagation. A diversity combining scheme is also proposed that effectively...
Communication systems that perform iterations between equalizer and decoder at the receiver are known as iterative or turbo equalization systems. These iterative systems can achieve large performance gains (in terms of bit error rates) when compared to their non-iterative counterparts. A major issue in such schemes is that optimal equalization methods are too complex for practical implementation when...
This paper presents the application of wilcoxon machines learning technique for artificial neural network in channel equalization application. The equalizer mitigates the effect of co-channel interference, inter-symbol interference in the presence of additive white Gaussian noise (AWGN). The performance of this proposed Multilayer Perceptron Network equalizer trained with wilcoxon learning has been...
Wireless communication system are affected by intersymbol interference, co-channel interference in the presence of additive white Gaussian noise. Different equalization techniques have been used to mitigate these effects using artificial neural networks based multilayer perceptron network, radial basis function, fuzzy system, functional link artificial neural networks and etc, conventionally linear...
In this paper we investigate non-linear precoding solutions for the problem of broadband multiple-input multiple-output (MIMO) systems. Based on a broadband singular value decomposition (BSVD) we can decouple a broadband MIMO channel into independent dispersive spectrally majorised single-input single-output (SISO) subchannels. Bit loading is proposed to optimally utilise these SISO subchannels after...
This paper investigates the joint detection method for TD-SCDMA system, and derives an improved approach to eliminate inter-symbol interference (ISI) in condition of multipath channel. Analysis for the received signals exhibits its characteristics of PARAllel profiles with LINear Dependencies (PARALIND) model. The proposed blind PALALIND algorithm utilizes no channel parameter for detection, and performs...
This paper proposes different criteria for user pairing for a virtual multiple-input multiple-output (V-MIMO) single-carrier frequency-division multiple access (SC-FDMA) transmission over intersymbol interference (ISI) channels. Two users, equipped with a single antenna each, transmit their data in the same time slot and frequency band. The receiver at the base station (BS) is assumed to have two...
The classical channel estimation method in TDS-OFDM is carried out based on the PN sequence in the GI which suffers from the intersymbol interference of the previous OFDM data symbols. This paper presents a novel data-aided channel estimation method to refine the initial channel estimation obtained from PN sequence. The data symbols are rebuilt based on the log-likelihood ratio (LLR) from the output...
The bit error rate (BER) performance improvement of single-carrier signal transmissions using one-tap frequency-domain pre-equalization (pre-FDE) is limited by the residual inter-symbol interference (ISI). Recently, we proposed a joint Tomlinson-Harashima precoding (THP) and pre-FDE (called joint THP/pre-FDE) to improve the BER performance by removing the residual ISI. In this paper, to further improve...
In this work, we base on multi-layered perceptron neural networks with backpropagation algorithm (MLP/BP) to construct multi-input multi-output (MIMO) decision feedback equalizers (DFEs). The proposal is used to recover distorted 16-point quadrature amplitude modulation (16-QAM) signal. From the simulations, we note that the proposed approach can recover severe distorted signals as well as suppress...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.