This paper presents some results of analysis of using several types of common Ethernet cables (LAN cables) in last section of access networks. The main goal of the article is to answer the question whether (if so, under what conditions and to what extent) we should consider the type of specific Ethernet cable when using it in a FTTB environment. Four branded and two unbranded CAT5e Ethernet cables are used for measurements. Additionally, a DSL cable with diameter of 0.4 mm is used for comparison purposes. The results are collected and mutually compared under similar loop conditions (good loop). All of the results of measurements are collected in operating conditions.

The main aim of this paper is to analyse correlation between adjacent images in a video sequence. Adjacent images with a slow or fast changeable scene in a video have high correlation which shows consistency in the video sequence therefore it can be the proof of normal reproduction of video service. Due to QoS (Quality of service) problems, especially over lossy network, appearance of different visual degradations in frames (images) during delivery of video service to end users can happen very often. In that case, adjacent images in the video sequence have low correlation which can be used as an indicator the problem occurred in some part of the network. In addition, the paper analyses correlation correspondent to polygons i.e. parts of adjacent images in the video sequence in order to discover a degree of influence visual degradations to user’s QoE (Quality of Experience). In order to check this aim, tested degraded and non-degraded video sequence was captured using IPTV system of one significant market power provider and processed in offline mod with Python script created especially for this purpose.

The aim of this paper is comparing a simulation model with real IPTV (Internet Protocol TeleVision) scenario in access network. In real IPTV scenarios, it is known that packet losses appear suddenly and might have an "explosive" character, especially in DSL (Digital Subscriber Line) case. In addition, these packet losses usually appear in groups and lead to huge degradation of the video service, which decreases customer’s QoE (Quality of Experience) level. Hence, estimation of this degradation in access network is important and the paper explained one simulation model based on SSIM (Structural Similarity Index) analysis, which can be used as one perceptive video quality assessment by imitating a real environment with packet losses. To check this, we compared our simulation model with the real IPTV video distributed over DSL (Digital Subscriber Line) and exposed to different packet loss appearances.

During delivery of video service, most of management control systems are able to collect useful data from different OSI layers that help in indication quality of video service. Recently, a mathematical model has been proposed which, only with a help of data collected at PHY (physical) and MAC (Media Access Control) layers and after appearance of certain degradations in transmission channel, estimates QoS (Quality of Service) indicators and then objective QoE (Quality of Experience). In this paper, we analyse that mathematical model, but only in the case of sudden occurrence of significant disturbance in transmission channel. In addition, we have chosen AIC criterion instead of the vector one in order to define the size of L-value. Validation and verification of the model are done in DSL (Digital Subscriber Line) environment during IPTV (Internet Protocol Television) service delivering and NS2 respectively.

This paper, on the basis of experimental research of the system in exploitation, identifies the main disadvantages of the existing troubleshooting scenarios for IPTV over xDSL. Also, this paper shows how the process of troubleshooting can be made more efficient in practice, with the already existing test solutions and other possibilities of test devices and xDSL transceivers.

The blind additive white Gaussian noise level estimation is an important and a challenging area of digital image processing with numerous applications including image denoising and image segmentation. In this paper, a novel block-based noise level estimation algorithm is proposed. The algorithm relies on the artificial neural network to perform a complex image patch analysis in the singular value decomposition (SVD) domain and to evaluate noise level estimates. The algorithm exhibits the capacity to adjust the effective singular value tail length with respect to the observed noise levels. The results of comparative analysis show that the proposed ANN-based algorithm outperforms the alternative single stage block-based noise level estimating algorithm in the SVD domain in terms of mean square error (MSE) and average error for all considered choices of block size. The most significant improvements in MSE levels are obtained at low noise levels. For some test images, such as “Car” and “Girlface”, at σ = 1 , these improvements can be as high as 99% and 98.5%, respectively. In addition, the proposed algorithm eliminates the error-prone manual parameter fine-tuning and automates the entire noise level estimation process.

This article presents a review of the investigation of the possibility of increasing the efficiency of existing line test solutions for troubleshooting testing for IPTV over xDSL, by the results of experimental research on real system under commercial exploitation. At the beginning of this article the main weaknesses of the existing troubleshooting testing are described. In the continuation of the article the physical layer parameters of xDSL transceiver are listed. In the reset this article provides a few specific examples of xDSL lines with their physical layer parameters of xDSL transceivers followed by analysis how they can be used for the purposes of more efficient measurement of parameters of copper pairs.

This paper presents a simple comparison between line conditions produced by using two types of local loops which operate in VDSL (Very-high-bit-rate speed Digital Subscriber line) environment. The object of observation is copper transmission line that remains in access network after replacing copper wires from CO (Central Office) to DP (Distribution Point) with optical fibres, i.e. after implementing a FTTB (Fibre to the Building/Basement) solution. Two borderline loop types from opposite edges are used: purposefully manufactured DSL indoor cable and ordinary flat telephone indoor cable. The paper gives at first a short overview of previously introduced and verified short loop model in DSL, followed by brief description of its leading testing scenarios. After that, major testing scenarios are implemented on two observed loop types under same conditions. An explanation of obtained results with appropriate discussion is done at the end. Primary loop coefficients and transfer functions are used as observed quantities. All results of measurements and observations are collecting on real system in operation conditions.

This paper shows a review investigation the possibility of increasing the efficiency of existing line test solutions for troubleshooting IPTV over xDSL, by the results of experimental research on real system under commercial exploitation. At the beginning of this paper the main weaknesses of the existing troubleshooting testing are described. In the rest of the paper the parameters of the physical layer of xDSL transceiver are listed, followed by analysis how they can be used for the purposes of more efficient measurement of parameters of copper pairs.

Accurate and fast estimation of noise levels from medical images has numerous applications in medical image processing, including image enhancement, image segmentation and feature extraction. In this paper, a block-based noise level estimation algorithm in SVD domain is proposed. The proposed algorithm employs the non-overlapping block image segmentation to estimate homogenous image regions. Each homogenous block is used to obtain an independent noise level estimates in SVD domain. For any particular image, the overall noise level estimate is ascertained by averaging over the set of noise level estimates associated with the homogenous image blocks. In this paper, the optimal size of image segmentation blocks is evaluated systematically over a large dataset of x-ray images. The experimental results show that the proposed method offers numerous advantages over some alternative SVD domain method.