Performance analysis of orthogonal spacetime block codes over Nakagami-q MIMO RFID backscattering channels

The authors employ the conditional moment generating function approach to analyse the performance of orthogonal space-time block codes over Nakagami-q (Hoyt) multiple-input multiple-output radio frequency identification backscattering channels. New exact and asymptotic symbol error rate expressions are derived for the case of two and four receiving antennas N = 2, 4 . The exact expressions are in the form of a sum of infinite series while the asymptotic ones are in the closed form. The diversity order that the system can achieve is found to be L, where L is the number of tag antennas, and the performance of this system is found to be more sensitive to the channel condition (the q parameter) of the forward link than that of the backscattering link. The theoretical results (exact and asymptotic) are verified through comparison with simulation results

Estimation of FBMC/OQAM Fading Channels Using Dual Kalman Filters

We address the problem of estimating time-varying fading channels in filter bank multicarrier (FBMC/OQAM) wireless systems based on pilot symbols. The standard solution to this problem is the least square (LS) estimator or the minimum mean square error (MMSE) estimator with possible adaptive implementation using recursive least square (RLS) algorithm or least mean square (LMS) algorithm. However, these adaptive filters cannot well-exploit fading channel statistics. To take advantage of fading channel statistics, the time evolution of the fading channel is modeled by an autoregressive process and tracked by Kalman filter. Nevertheless, this requires the autoregressive parameters which are usually unknown. Thus, we propose to jointly estimate the FBMC/OQAM fading channels and their autoregressive parameters based on dual optimal Kalman filters. Once the fading channel coefficients at pilot symbol positions are estimated by the proposed method, the fading channel coefficients at data symbol positions are then estimated by using some interpolation methods such as linear, spline, or low-pass interpolation. The comparative simulation study we carried out with existing techniques confirms the effectiveness of the proposed method

Affine Projection Algorithm Based Decision Fusion for Cooperative Spectrum Sensing In Cognitive Radio Networks

Spectrum sensing is a main function in cognitive radio networks to detect the spectrum holes or unused spectrum. Cooperative spectrum sensing schemes are recently suggested and they provide fast and accurate results. In this paper, we suggested a new adaptive and cooperative spectrum sensing technique based on the affine projection algorithm (APA). In this method, each secondary user (SU) takes a binary decision by its local sensing of the spectrum using energy detector. Local decisions are then forward to the fusion center (FC), where definitive decision is taken on the status of the spectrum using adaptive filters. In our suggested technique, APA updates the weights of the adaptive filter by using the current and the 1 delayed input signal vectors. Simulation results indicate that the suggested approach provides faster convergence speed and less steady state mean square error than the existing methods that are based on the normalized least mean square (NLMS) or the so-called kernel least mean square (KLMS) algorithm

Overlay Cognitive Radio Based on OFDM with Channel Estimation Issues

Cognitive radio (CR) has been proposed as a technology to improve the spectrum efficiency by giving an opportunistic access of the licensed-user spectra to unlicensed users. We consider an overlay CR consisting of a primary macro-cell and cognitive small cells of cooperative secondary base stations (SBS). We suggest studying a CR where an orthogonal frequency division multiplexing is used for both the primary users (PU) and the secondary users (SU). In order to cancel the interferences, a precoding is required at the SBS. Therefore, we first derive the interferences expression due to SU at the PU receiver. Then, zero forcing beamforming (ZFBF) is considered to cancel the interferences. However, applying ZFBF depends on the channels between the SBS and the PU. A channel estimation is hence necessary. For this purpose, we propose to approximate the channel by an autoregressive process (AR) and to consider the channel estimation issue by using a training sequence. The received signals, also called the observations, are considered to be disturbed by an additive white measurement noise. In that case, the AR parameters and the channel can be jointly estimated from the received noisy signal by using a recursive approach. Nevertheless, the corresponding state space representation of the system is non-linear. Then, we propose to carry out a complementary study by compare non-linear Kalman filter based approaches

Distributed M-ary hypothesis testing for decision fusion in multiple-input multiple output wireless sensor networks

In this study, the authors study binary decision fusion over a shared Rayleigh fading channel with multiple antennas at the decision fusion centre (DFC) in wireless sensor networks. Three fusion rules are derived for the DFC in the case of distributed M-ary hypothesis testing, where M is the number of hypothesis to be classified. Namely, the optimum maximum a posteriori (MAP) rule, the augmented quadratic discriminant analysis (A-QDA) rule and MAP observation bound. A comparative simulation study is carried out between the proposed fusion rules in-terms of detection performance and receiver operating characteristic (ROC) curves, where several parameters are taken into account such as the number of antennas, number of local detectors, number of hypothesis and signal-to-noise ratio. Simulation results show that the optimum (MAP) rule has better detection performance than A-QDA rule. In addition, increasing the number of antennas will improve the detection performance up to a saturation level, while increasing the number of the hypothesis will deteriorate the detection performance

Estimation of FBMC/OQAM Fading Channels Using Dual Kalman Filters

We address the problem of estimating time-varying fading channels in filter bank multicarrier (FBMC/OQAM) wireless systems based on pilot symbols. The standard solution to this problem is the least square (LS) estimator or the minimum mean square error (MMSE) estimator with possible adaptive implementation using recursive least square (RLS) algorithm or least mean square (LMS) algorithm. However, these adaptive filters cannot well-exploit fading channel statistics. To take advantage of fading channel statistics, the time evolution of the fading channel is modeled by an autoregressive process and tracked by Kalman filter. Nevertheless, this requires the autoregressive parameters which are usually unknown. Thus, we propose to jointly estimate the FBMC/OQAM fading channels and their autoregressive parameters based on dual optimal Kalman filters. Once the fading channel coefficients at pilot symbol positions are estimated by the proposed method, the fading channel coefficients at data symbol positions are then estimated by using some interpolation methods such as linear, spline, or low-pass interpolation. The comparative simulation study we carried out with existing techniques confirms the effectiveness of the proposed method

Contribution à la mise en oeuvre de récepteurs et de techniques d'estimation de canal pour les systèmes mobiles de DS-CDMA multi-porteuse

Ce mémoire traite du développement de récepteurs et de techniques déstimation de canal pour les systèmes mobiles sans fil de type DS-CDMA multi-porteuse. Deux problèmes principaux doivent être pris en compte dans ce cas. Premièrement, l'Interférence d'Accès Multiple (IAM) causée par d'autres utilisateurs. Deuxièmement, les propriétés des canaux de propagation dans les systèmes radio mobiles. Ainsi, dans la première partie du manuscrit, nous proposons deux structures adaptatives (dites détection séparée et détection jointe) pour la mise en oeuvre de récepteurs minimisant lérreur quadratique moyenne (MMSE), fondés sur un Algorithme de Projection Affine (APA). Ces récepteurs permettent de supprimer les IAM, notamment lorsque le canal d'évanouissement est invariant dans le temps. Cependant, comme ces récepteurs nécessitent les séquences d'apprentissage de chaque utilisateur actif, nous développons ensuite deux récepteurs adaptatifs dits aveugles, fondés sur un algorithme de type projection affine. Dans ce cas, seule la séquence d'étalement de l'utilisateur désiré est nécessaire. Quand les séquences d'étalement de tous les utilisateurs sont disponibles, un récepteur reposant sur le décorrélateur est aussi proposé et permet d'éliminer les IAM, sans qu'une période pour l'adaptation soit nécessaire. Dans la seconde partie, comme la mise en oeuvre de récepteurs exige léstimation du canal, nous proposons plusieurs algorithmes pour léstimation des canaux d'évanouissement de Rayleigh, variables dans le temps et produits dans les systèmes multi-porteuses. A cette fin, les canaux sont approximés par des processus autorégressifs (AR) d'ordre supérieur à deux. Le premier algorithme repose sur deux filtres de Kalman interactifs pour léstimation conjointe du canal et de ses paramètres AR. Puis, pour nous affranchir des hypothèses de gaussianité nécessaires à la mise en oeuvre d'un filtre optimal de Kalman, nous étudions la pertinence d'une structure fondée sur deux filtres H1 interactifs. Enfin, léstimation de canal peut ^etre vue telle un problème déstimation fondée sur un modèle à erreur- sur-les-variables (EIV). Les paramètres AR du canal et les variances de processus générateur et du bruit d'observation dans la représentation de léspace d'état du système sont dans ce cas estimés conjointement à partir du noyau des matrices d'autocorrélation appropriées.This dissertation deals with the development of receivers and channel estimation techniques for multi-carrier DS- CDMA mobile wireless systems. Two major problems should be taken into account in that case. Firstly, the Multiple Access Interference (MAI) caused by other users. Secondly, the multi-path fading of mobile wireless channels. In the first part of the dissertation, we propose two adaptive structures (called separate and joint detection) to design Minimum Mean Square Error (MMSE) receivers, based on the Affine Projection Algorithm (APA). These receivers are able to suppress the MAI, particularly when the fading channel is time-invariant. However, as they require a training sequence for every active user, we then propose two blind adaptive multiuser receiver structures based on a blind APA-like multiuser detector. In that case, only the knowledge of the spreading code of the desired user is required. When the spreading codes of all users are available, a decorrelating detector based receiver is proposed and is able to completely eliminate the MAI without any training. In the second part, as receiver design usually requires the estimation of the channel, we propose several training-based algorithms for the estimation of time-varying Rayleigh fading channels in multi-carrier systems. For this purpose, the fading channels are approximated by autoregressive (AR) processes whose order is higher than two. The first algorithm makes it possible to jointly estimate the channel and its AR parameters based on two-cross-coupled Kalman filters. Nevertheless, this filtering is based on restrictive Gaussian assumptions. To relax them, we investigate the relevance of a structure based on two-cross-coupled H1 filters. This method consists in minimizing the influence of the disturbances such as the additive noise on the estimation error. Finally, we propose to view the channel estimation as an Errors-In-Variables (EIV) issue. In that case, the channel AR parameters and the variances of both the driving process and the measurement noise in the state-space representation of the system are estimated from the null space of suitable correlation matrices

Evaluation and Optimization of GSM Network in Jenien City, Palestine

This paper presents a case study about the evaluation and optimisation of GSM network in Jenien City, Palestine. Two approaches are used to evaluate the network performance, namely: key performance indicators (KPIs) and drive test. The initial evaluation of the network showed that about 0.76% of the initiated connections are dropped. In addition, about 7.76% of the collected samples from the drive test lie in level 4 which is the worst level in terms of signal quality and signal strength. Moreover, only 65.5% of the collected samples lie in level 1 which is the best level in terms of signal quality and strength. A new traffic channel (TCH) and broadcast control channel (BCCH) frequency plans are proposed to decrease TCH drop rate, reduce interference level and boost signal quality. The proposed plans are implemented into the network. Two kinds of optimisation procedures are adopted. The first one is manual optimisation while the second one is by using specific optimisation tools. According to the comparative study, we carried-out between the performance of the network before and after optimisation, the average TCH drop rate is reduced from 0.76% to 0.62%. In addition, the percentage of samples in level 1 is increased from 65.5% to 76.8% while the percentage of samples in level 4 is decreased from 7.76% to 5.16%.The authors would like to thank the Palestine Cellular Communications Co., Ltd (Jawwal) for their support of this research project

Performance Analysis of Energy Detector Over α − μ Fading Channels with Selection Combining

Energy detection is the most widely used technique in cognitive radio networks to enable opportunistic spectrum access. In this paper, the problem of energy detection of an unknown deterministic signal over fading channels is revisited. More particularly, a new closed-form mathematical expression is derived for the average probability of detection of the energy detector (ED) over α − μ generalized fading channels with selection combining (SC) diversity reception. The derived expression is general and includes as special cases Nakagami-m, Weibull, Gamma, Rayleigh and Exponential distributions. This expression is useful to quantify the performance improvement of the ED with SC diversity reception

Consumer Behavior Towards Introducing 3G Mobile in Palestine: The Case of Bethlehem Governorate

This research focuses on the factors that influence customers’ behavior towards the introduction of 3G cellular data in Bethlehem Governorate, in the West Bank (WB), Palestine, which was introduced at the beginning of 2018. Therefore, the main purpose of this paper is about the examination of the factors that influence consumers’ usage of 3G cellular data. The research framework was based on the theory of planned behavior (TPB) with the attitude, subjective norms, and perceived behavioral control factors. In addition to the extension of technology acceptance model (TAM), the proposed model included the perceived usefulness and perceived ease of use factors. The perceived enjoyment factor was added to the model along with the TPB and TAM in order to examine the influence on the behavioral intention to use 3G cellular data. A simple random sampling strategy of a sample size of 402 3G’s customers from Bethlehem Governorate in the WB, Palestine was applied. Targeted respondents include who tried either currently using 3G services throughout a questionnaire that was constructed for this purpose. The data was analyzed by employing structural equation modeling (SEM). The results indicate that perceived behavioral control, perceived enjoyment, and subjective norms are the influential factors. In contrast, perceived usefulness, perceived ease of use and attitude are not influencing the behavioral intention to use 3G mobile data services. Based upon the research findings, business implications, and limitations, further research was suggested were placed