Lamartine V. de Souza

Impact of non-stationary noise on xDSL systems : an experimental analysis

Broadband services require data rates that can only be achieved by using relatively high spectrum frequencies. At such high frequencies, the DSL (Digital Subscriber Line) signal is more susceptible to external noise sources, such as radio frequency interference and impulsive noise. This paper aims to characterize how the impulsive noise impacts on services and applications for a broadband system using an ADSL2+ loop. The first approach was to use the impulsive noise defined in the standards G.996.1 (Test Procedures for DSL Transceivers) from ITU-T and TR-048 (ADSL Interoperability Test Plan) from DSL Forum. In this approach we have also used a HDSL (High Bit Rate DSL) and white noise disturbers on the line. The impulsive noises c1 and c2 (defined in G.996.1) are injected into the circuit at the CO (Central Office) end and CPE (Customer Premises Equipment) end of the loop simulator. Additionally, it was analyzed the spikes of noises impact on the ADSL2+ line. In this case, pre-defined models of NEXT (Near-end crosstalk) and white noise are injected on CO and CPE side, simultaneously. Metrics like packet rate, lost packet count, bandwidth, short-term average transfer delay, and errored seconds are used to characterize the DSL loop under the noise impairments.

Multimedia transmission on Amazon region using wireless broadband networks

This work presents results for multimedia transmission using wireless broadband networks installed in some remote cities in Amazon region. In 15 cities at State of Pará, Brazil, the local government is installing wireless networks to provide wideband internet access to public agents, such as schools, hospitals, police stations and office buildings in a great project named NavegaPará. Each city has a base station working on 5.7 GHz and serving around 30 subscribers, which use an individual broadband transceiver (IBT) to access the network. The aggregate throughput (downstream + upstream) for each client is 7 Mbps, 14 Mbps or 30 Mbps depending on the installed equipment and the distance between the base station and the client unit. It is presented a typical scenario for multimedia transmission using the available infrastructure. In this case, an IBT is connected directly to a computer, which is connected to a video camera transmitting video traffic. The available infrastructure is useful for broadcasting the public television signal (Funtelpa) in uncovered areas of State of Pará. Metrics such as throughput and latency are collected and analyzed. Obtained results show that multimedia transmission using NavegaPará infrastructure has satisfactory results.

Performance evaluation of IPTV traffic over pDSL

The increasing trend of triple play traffic transmission (voice, video and data) over internet is a worldwide phenomenon. However, to get a satisfactory communication, we need study the process on end-the-end way. Into regions with little infrastructure of telecommunications, one of the concerns is about used technologies of access. This work presents an analysis based on an IPTV (Television Internet Protocol) transmission generated on two combined technologies of access, PLC (PowerLine Communications) and ADSL2+ (Asymmetric Digital Subscriber Line), using a combination of electric network and telephony infrastructure, called of pDSL. This technology is a viable combination for regions with poor infrastructure of telecommunications. The results are evaluated with intention to present the viability of this kind of the telecommunication environment and with a simulation for extrapolation study.

Characterization of Subscriber Local Loop by Measures and Analysis of Frequency and Impulse Responses

This paper presents methodologies that could be used for characterizing subscriber telephone loops that carry DSL services (ADSL and ADSL2+), by determination and analysis of frequency response, time domain reflectometry, and impulse response of the line. From this analysis, the subscriber loop length, identification and location of impairments such as bridged taps, gauge changes, and open ended termination across the line are carried out. To verify the methodologies presented, results obtained from measurements are drawn and compared to results obtained from computational simulations.

Data Mining Applied to Diagnose Diseases Caused by Lymphotropic Virus: a Performance Analysis

This paper proposes a new methodology to diagnose the rheumatology manifestations and HTLV-I-Associated Myelopathy/Tropical Spastic Paraparesis, or HAM/TSP, in patients who have Lymphotropic virus of T cells in Humans or HTLV of type I and II. Computational intelligence algorithms are used to classify HTLV patient carriers with or without the presence of rheumatology manifestations and of HAM / TSP. A benchmarking is performed among artificial neural intelligence, naive bayes, Bayesian networks and decision tree to evaluate the most suitable technique for solving this application issue. The obtained results demonstrate the potential of the methodology on the helping non-specialist doctors to classify the patient with the disease suspicion.

Triple play service under the impact of nonstationary noise in a DSL system: an Amazon approach

The Brazilian Amazon has sui generis characteristics that affect strongly the communication technologies, such as high humidity and temperature. These characteristics cause impact in the existent infrastructure, especially in twisted-pair copper lines. At the moment, new services are based on multimedia applications, as voice over internet protocol (VoIP), video on demand (VoD), and internet protocol television (IPTV). Such services use digital broadband networks such as ADSL2+ (Asymmetric Digital Subscriber Line) to transmit the data. Broadband services require data rates which can only be achieved by using relatively high spectrum frequencies. At high frequencies the DSL signal is more susceptible to external noise sources, such as radio frequency interference and impulsive noise. For this purpose, an experimental setup has been built at UFPA that consists of noise generator, traffic generator, real cables, modems and DSLAM (digital subscriber line access multiplexer). This paper aims at characterizing how the noise impacts on triple play services for a broadband system using a DSL loop on Amazon environment. The objective of the noise impact experimentation is to observe the behavior of a DSL system under more realistic but controlled line conditions. Metrics as lost packet, jitter, latency, and throughput are used to characterize the triple play service in a DSL loop under the noise impact. Through the real experiments and controlled loop conditions, this paper allow identify, from application level point of view, how robust DSL system is in respect to noise occurrence. Additionally, it is described a methodology for noise impact measurements using a DSL system.

New Applications Using PLCs in Access Networks

Access Networks in telecommunications, such as digital subscriber lines (DSL) and wireless broadband networks (WBN) have become so popular that these systems are now found in almost all regions. The widespread use of these systems has brought about the need for research into new ways of resolving, or at the very least, minimizing the impact of problems that affect the performance of these systems. In terms of DSL systems, crosstalk is one of the main performance limiting factors, principally when operating at high frequencies, as is the case with VDSL (very-high-bit-rate DSL) networks. Consequently, the required high data rates of VDSL systems may not be achievable if crosstalk levels are excessive. Across WBN systems, the existence of co-channel interference increases the systems noise levels and also degrades the networks overall performance. It may be impossible therefore, depending on the noise level, to get even minimum system access. It is therefore necessary to plan a way of controlling these noise levels across both access networks. Programmable logic controllers (PLCs) are the main types of controllers used within the industry. One of their characteristics is the fact that they can operate within aggressive environments (for example, at high temperatures or within high humidity levels) as well as having high operational speeds in comparison with corresponding electro-mechanic control systems; the PLC becoming a highly efficient control device with multiple usage possibilities. Hence, the use of PLCs across access networks opens up additional fields of application for this type of device, especially due to the fact that up until now, the PLC’s widest form of use has been in the industrial sector. Additionally, the robustness, flexibility and speed of the PLC allows it to be used across access networks without any additional need for major configuration changes to already installed equipment, i.e.; the implementation of a PLC into a system does not generate excessive costs or require excessively specialized configurations. PLC application will focus on automated configurations in order to reduce system noise on access networks (DSL and WBN) with the intention of making sure the performance levels of these systems are not degraded in any way and are also able to operate within the expected performance parameters. In this chapter, we propose alternative PLC applications on two types of broadband networks. Basic concepts about DSL networks and wireless broadband networks are presented in section 2. In section 3 the application of PLC on broadband networks is discussed. Final comments are presented in section 4.

A methodology for measurements of basic parameters in a xDSL system

In order to qualify a subscriber loops for xDSL transmission, basic parameters like transfer function, scattering parameter S11 and characteristic impedance should be known. The aim of this paper is to present a test methodology for measurements of these basic parameters. The characteristic impedance is measured by open/short method and it is compared with the terminated measurement method defined in IEC (International Electrotechnical Commission) 611156-1. Transfer function and scattering parameter S11 of DSL loop are also measured on a real cable. The methodology is based on measurements of a 0.4 mm, 10 pairs, balanced twisted-pair cable of 1400 m of length. In order to improve the analysis of results, we compared the measurements from real cable with results from wireline simulators. The measurement of parameters of xDSL copper loop is done in an infrastructure set up in the LABIT (Technological Innovation in Telecommunications Lab) at UFPA (Federal University of Para), that consist of a wireline simulators, a precision impedance analyzer, and a network analyzer. The results show a difference between the measurements performed with real cables and wireline simulators for transfer function parameter. Characteristic impedance obtained by both methods presented quite similar results.