Diego L. Cardoso

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.

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.

Towards the parallel computing based on quality of service

Despite the existence of a series of applications that demand high performance computing, there are two strong restrictions to the effective use of parallel computing applications: (1) the high costs in the environments of parallel computing (typically, clusters and parallel machines) and (2) the dedicated approach of these architectures (fact that generates a great degree of idleness of these platforms). This paper presents an architecture to provide parallel computing in traditional environments (nondedicated networks), called MPI-QoS, which is based on the concepts of quality of service (QoS) to assure low response times necessary to this kind of computation.

Green-fuzzy - An intelligent user allocation model for macro-femto co-channel networks

The concept of femtocell aims to combine fixed-line broadband access with mobile telephony using low cost and power third and fourth generation base stations in the subscribers homes. Femtocells are self-configurable, however, can limit the quality of service (QoS) and reduce the efficiency of the network, since it uses old assignment standards, such as the power level of the signal. Thus, this paper presents a proposal for optimized allocation of users in a macro-femto co-channel network, in order to maximize the QoS of the applications and energy efficiency, toward the concept of green networks. A fuzzy inference system is implemented to define which network the mobile phone should connect; the model is flexible, allowing different analyzes, and adaptable to the specific characteristics of the telephone companies. Results showed that the model proposed can improve energy efficiency up to 25%, when compared to traditional QoS approaches.

A bandwidth scheduler for triple play services based on fuzzy theory

The search for improvement in the process of diffusion of information has led to many advances in access technologies. In initiatives for digital/social inclusion, this improvement is of utter importance, particularly in scenarios where the infrastructure becomes a barrier in communication. An alternative to improve communication and thus providing quality of service is to adjust the use of resources/bandwidth required by the applications. This paper presents an application-scheduling algorithm, based on fuzzy logic, to optimize the use of bandwidth and guarantee QoS for existing applications. Simulations were made from a built testbed for xDSL technology; results showed that the proposed scheduler is able to optimize the channel, guaranteeing minimum levels of QoS based on the particular needs and characteristics of each application.

A Novel Probabilistic Approach for Analysis and Planning of Large Capillarity Broadband Networks Based on ADSL2+ Technology

The increasingly spread of information through digital media raises new realities in the worlds present scenario and, thus, new technologies have been emerging in order to streamline the process of disseminating information and providing quality access to such information by the population. The Next Generation Network (NGN) holds tremendous potential, with a promise to merge the transmission of data, voice, video and other media into a single network; unfortunately, several developing countries do not have the necessary infra-structure to implement NGN technology. The main concern in these networks is not the backbone or the transport layer, but in the last mile itself. Last mile has become a popular keyword to indicate the technology which connects the End User to the Network backbone.

Multimedia Transmission over Optic, DSL and PLC Systems

This work presents an analysis based on an multimedia transmission generated on optical fiber backbone and two combined access technologies, PLC (Power Line Communications) and ADSL2+ (Asymmetric Digital Subscriber Line), called of pDSL. This paper points a case study of multimedia traffic using pDSL combination with intention to present measured and simulated results that prove the proposal solution viability.

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.

A markovian performance model for resource allocation scheduling on GNU/Linux

The current paper addresses the problem of quality of service (QoS) provisioning in a general purpose operating system (GPOS), in this case GNU/Linux. Particularly, we propose to change the CPU allocation in that OS by reserving a percentage of a CPU capacity in order to ensure the QoS provisioning according to the QoS demand of each process. In order to investigate the effectiveness of that approach, Markovian models are proposed to represent the dynamics of the systems. Results show that the OS with reservation outperforms the system without it, but also that there is a performance tradeoff in the OS with reservation in such a way that an improvement in the QoS perceived by processes using the reserved capacity is done at a cost of a degradation in the QoS perceived by the other processes.

Clustering techniques for data network planning in Smart Grids

Smart Grid, a modern approach to electricity distribution, requires innovation on various fronts. Communication is a key component of Smart Grid applicability. To satisfy Quality of Service (QoS) needs when deciding on network structure and topology, especially in urban areas, artificial intelligence techniques may be applied. Techniques such as clustering methods or genetic algorithms are useful to resolve this optimization problem. Choice of network topology for a specific electrical grid is also important. This choice influences the resulting QoS and network implementation price. This paper uses graph theory formulation to create a model. This model is designed to optimize topology of data network while accounting for delay constrains. Since this problem belongs to class NP-hard, this paper indicates appropriate clustering methods that best suit a given Smart Grid scenario in terms of QoS. A typical wireless network planning scenario of electric energy distribution is used as a case study. Each resulting cluster will contain a base station to attend the needs of Smart Grid Intelligent electronic devices in its cluster area. The algorithms K-medoids and K-means had the best performance with K-medoids bringing financial benefits regarding base station deployment.