Alex Vallejo

Heterogeneous communication architecture for the smart grid

The smart grid concept provides a solution to the growing recognition that current utility grids need an ICT deployment infrastructure based upgrade to allow millions of potential market players to operate and to cope with distributed generation, wide-area situational awareness, demand response, electric storage, and efficient electric transportation. Smart grid deployment is mainly about defining the necessary standards for ICT solutions. The design of the communication network associated with the smart grid involves detailed analysis of its communication requirements, a proposal of the appropriate protocol architecture, the choice of the most suitable technologies for each case study, and a scheme for the resultant heterogeneous network management system. Given the smart grid use cases, this article is focused on proposing a heterogeneous communication paradigm for smart grids based on power line communications and wireless networks. The proposal is related to the framework of the ITU ubiquitous sensor network architecture using the ITU next-generation network model. This architecture allows for better management of the QoS in the smart grid and should facilitate interoperability with other technologies.

Survey and Performance Comparison of AMR Over PLC Standards

Automatic meter reading (AMR) is an application implemented by power utilities which is becoming increasingly important in the utilities sector. It could be included in the more general environment of demand side management, which satisfies the need for more improved communications. AMR offers a better financial return due to the inclusion of other applications. Although there are several international standards which address AMR, most deployments are currently using proprietary systems. This fact may reflect that current standards do not fully cover this area. Since the power network reaches all energy meters, a convenient way to deploy AMR is to use the power lines as a transmission medium. The present-day situation is that there is mounting pressure to deploy AMR systems in a bid to provide better management of the energy demand in a bid to reduce global warming and create a more sustainable electrical system in our environmentally conscious society. This paper is focused on analyzing different standards and specifications related to AMR over powerline communications (PLC). Furthermore, two of them are chosen, implemented, and simulated using the OPNET modeler. The main goal of the implemented applications is to obtain comparative results of the two most known standard applications in AMR over PLC.

Next-generation QoS control architectures for distribution smart grid communication networks

This article presents a proposal for applying the ITU-T end-to-end QoS control architecture for next-generation networks to the distribution smart grid communication networks. We propose the use of a QoS broker device to enhance the QoS in the smart grid electrical distribution access domains by providing a centralization of QoS management. Our proposal takes decisions based on current network data traffic flows, existing QoS policies and customer service level agreements and facilitates interoperability with other technology domains in order to achieve seamless end-to-end QoS. The key feature of this end-toend QoS control is the mapping of QoS parameters mainly between broadband power line and wireless technologies that principally serve the distribution smart grid but it can be applied to other communication technologies as well.

Simulation and modeling of the coexistence of polling and contention in PLC based AMR systems

MAC protocols for PLC networks must overcome difficulties stronger than those found in other systems such as the need to cope with several hops and with very noisy environments. Polling protocols are widely used in PLC based AMR (automatic meter reading) systems but they present several drawbacks, as their inherent impossibility to automatically associate new meters to the system. Contention protocols over PLC do allow for automatic association of new meters but they suffer from low efficiency basically due to the multihop nature of PLC based AMR systems. A combination of both types of protocols seems a wise option. One possibility is to partition the time into two periods, one for polling and another one for contention, but it requires resource consuming network-wide synchronization in a system that must be especially inexpensive. Another possibility is to superimpose both types of communication in a proper manner. The choice has advantages and disadvantages and affects also the topology control function. A simulation model of the PLC system has been carried out based on OPNET Modeler. The paper presents this model and results that basically compare the two aforementioned alternatives of protocol combination. An analytical model developed by the authors in a previous work is used to complement the simulation, allowing for the assessment of the system behavior in a stable topology situation.

Performance of a Policy-Based Management System in IPv6 Networks Using COPS-PR

To guarantee the correct QoS, the new generation core networks are best managed by the use of a centralized server. Most of these networks use DiffServ due to its scalability, an important feature for large networks. A Bandwidth Broker architecture is a policy-based management system which purpose is to manage DiffServ networks in a centralized manner performing admission control and policy deliveries to network nodes. This paper presents the implementation of a bandwidth broker architecture for the management of QoS in DiffServ dual networks (IPv4/IPv6). This implementation, which has been programmed in JAVA, uses COPS-PR as an intra-domain communication protocol and manages the policies based on SLA/SLS preconfigured by the administrator. The performance of the proposed architecture has been tested by implementing a real IPv6 DiffServ domain testbed controlled by the developed Bandwidth Broker. The results of these tests and the corresponding conclusions are also presented.

IPv6 conformance and interoperability testing

The fear of incompatibility issues between legacy IPv4 systems and new IPv6 implementations can delay the migration towards a full IPv6 native Internet. Network engineers need to ensure that heterogeneous IPv6 devices behaves consistently to the IPv6 specifications and correctly enterprise in a multi-vendor environment. This paper analyzes IPv6 conformance testing, a set of rigorous test methodologies that allows to throughout verify the quality of IPv6 devices during their entire life cycle, and can give confidence to the customers. We analyze the TAHI IPv6 conformance and interoperability test suite and present our conformance test results for the latest versions of IPv6 host implementations.

Evaluation of a Policy-Based QoS Management Architecture over an IPv6 DiffServ testbed

In this paper we present the implementation of a bandwidth broker architecture for the centralized management of the QoS in native IPv6 DiffServ networks in a multi-domain environment. The bandwidth broker has been programmed in JAVA and uses COPS-PR as an infra-domain communication protocol and SIBBSv6 as an inter-domain communication protocol. The latter protocol is also presented. SIBBSv6 is a variation of the SIBBS inter-domain communication protocol with some new features such as the IPv6 support. The evaluation of the proposed architecture has been tested by implementing a real IPv6 DiffServ testbed composed of three domains. Each of these domains is managed by the developed bandwidth broker named BBv6. The results of these tests and the corresponding conclusions are also presented.

End-to-end QoS management proposal for the ITU-T IMS/NGN architecture

The centralized management of the QoS in NGNs is currently one of the main lines of research in the networking sector. One of the tasks of the ITU-T organisation in this area is to develop a global architecture capable of managing end-to-end services to be used on future specifications. This paper presents a signalling architecture proposal for the end-to-end QoS management conforming the early ITU-T specifications for IMS/NGN networks, focusing on the transport sub layer. The viability of the architecture has been validated through the implementation of a GNU/Linux real testbed.

A Genetic-Based QoS Aware Routing for Ubiquitous Sensor Networks

This paper presents a first approach to a new QoS aware routing suitable for wireless and wired Ad-Hoc networks. The proposed algorithm is based on artificial intelligent techniques. Actually, it is a merge between a genetic algorithm and the TBR (Ticket Based Routing) algorithm. A better TBR performance is pursued in order to use the result in ubiquitous sensor access networks. It has been necessary to choose a routing protocol as a starting point and to define how artificial intelligent techniques will be applied in order to improve the overall performance. The resulting algorithm is an evolution of TBR, an on-demand routing protocol for Ad-Hoc networks that provides quality of service. The performance of TBR has been improved by reducing the load of routing packets in the network and by minimizing the communication latency due to its on-demand behavior. Moreover, with the genetic algorithm, the likelihood of finding the route optimum using several metrics has been increased. The main goal is the implementation of an approach that will make possible a future formal specification of evolutionary routing algorithm for USN. In this paper, first simulation results are presented. Moreover, the chromosome coding, crossover and mutation operators and the fitness evaluation formula are described.

QoS Broker based architecture design for the PLC access network

Broadband PLC seems to be gaining popularity as an access network technology so that the standardization efforts are rising notably. Broadband PLC gives the opportunity of delivering services such as telephony, TV and Internet through the power line, but also entails managing the Quality of Service that these applications need. In this paper, a centralized Quality of Service architecture for PLC access networks based on a QoS Broker is proposed. This architecture will allow for better managing of the QoS in the PLC domain and it should facilitate the interoperability with other technology domains. PLC Qos Broker architecture must be integrated with the core network in order to attain end-to-end QoS.