DSP based platform for an enhanced HF channel simulator

With the aim of improving existing tools for testing new HF transmission systems, this article describes a modification of the basic Watterson (1970) model which can be implemented without any extra added complexity with a general purpose DSP card running an a PC IBM compatible.Peer ReviewedPostprint (published version

Performance analysis of a hybrid ARQ system in half duplex transmission at 2400 BPS

Hybrid ARQ/FEC protocols have been proposed to provide high data link integrities whilst keeping at the same time a high mean throughput rate. Nevertheless, hybrid ARQ strategies offer a lot of choices and none of them can be considered the optimum in any case. Three alternative protocol strategies using BCH codes are evaluated and the HF channel models used for the tests are discussed.Peer ReviewedPostprint (published version

X-Type Interface for Management of Multidomain Multitechnology Networks

The specification and implementation of Xcoop interfaces has received great attention in the last few years. In fact, the appropriate design of this system component is a key aspect for efficient and seamless co-operative management. In this context it is worth mentioning the EURESCOM P408 project and the standards of the European Telecommunication Standards Institute (ETSI) in Europe and the ITU-T and Telemanagement Forum related work worldwide. The Xcoop specification presented in this paper, produced as part of the results of the project MISA co-funded by the Commission of the European Union, is a step ahead in the evolution of this system interface. Distinguished from preceding works, this one allows interactions between management systems independently to the underlying network technology, ATM, SDH or hybrid. This is achieved by defining appropriate functionality and an information model, indeed, where the specific characteristics of ATM and SDH resources are abstracted and merged in common classes.Peer ReviewedPostprint (published version

A price based load balancing scheme for multi-operator wireless access networks

We study a load balancing strategy, based on the price offered by the base stations to the end-users who are willing to establish a connection. The proposed scheme is compared with a pure load balancing procedure, in a scenario comprising two different operators.We study the impact of modifying the price offered by the base stations, in terms of the achieved load balancing, as well as considering the revenue obtained by the operators. Furthermore, we also enhance the two former access selection schemes, by incorporating the willingness of reducing the number of handovers, so as to analyze the impact over this particular parameter, and over all the previous results. The whole work is conducted over a proprietary event-based simulation tool, which offers the required degree of flexibility and low computational overhead.Preprin

A reinforcement learning approach for Virtual Network Function Chaining and sharing in softwarized networks

​© 2021 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Cognizant of the ease with which softwarized functions can be dynamically scaled according to real time resource requirements, and the fact that multiple services can have common VNFs in their chaining, this paper tackles the problem of cost effective deployment of online services from the perspective of sharing their VNF instances. First, we formally formulate the deployment problem under VNFs sharing. Secondly, given the NP-hard nature of the above problem, we propose a reinforcement learning (RL) algorithm capable of making intelligent placement decisions while considering multiple conflicting costs. Costs of transmission, VNF instantiation or energy consumption, among others. Thanks to the intelligence of the RL algorithm, simulation results show that the performance of the proposed algorithm is within a 14% margin and similar to an optimal solution in terms of request provisioning cost and acceptance ratio, respectively. Moreover, the algorithm results in more than a 20% and a 70% improvement in terms of request deployment cost and time compared to a state-of-the-art algorithm, and up to more than a 40% improvement in terms of cost compared to an algorithm that greedily minimizes the transmission or VNF activation costs.Postprint (author's final draft

Resource allocation and management techniques for network slicing in WiFi networks

© 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Network slicing has recently been proposed as one of the main enablers for 5G networks; it is bound to cope with the increasing and heterogeneous performance requirements of these systems. To "slice" a network is to partition a shared physical network into several self-contained logical pieces (slices) that can be tailored to offer different functional or performance requirements. Moreover, a defining characteristic of the slicing paradigm is to provide resource isolation as well as efficient use of resources. In this context, the thesis described in this paper contributes to the problem of slicing WiFi networks by proposing a solution to the problem of enforcing and controlling slices in WiFi Access Points. The focus of the research is on a variant of network slicing called QoS Slicing, in which slices have specific performance requirements. In this document, we describe the two main contributions of our research, a resource allocation mechanism to assign resources to slices, and a solution to enforce and control slices with performance requirements in WiFi Access Points.This work has been supported by the European Commission and the Spanish Government (Fondo Europeo de Desarrollo Regional, FEDER) by means of the EU H2020 NECOS (777067) and ADVICE (TEC2015-71329) projects.Peer ReviewedPostprint (author's final draft

Updated taxonomy for the network and service management research field

Network and service management is an established research field within the general area of computer networks. A few years ago, an initial taxonomy, organizing a comprehensive list of terms and topics, was established through interviews with experts from both industry and academia. This taxonomy has since been used to better partition standardization efforts, identify classes of managed objects and improve the assignment of reviewers to papers submitted in the field. Because the field of network and service management is rapidly evolving, a biyearly update of the taxonomy was proposed. In this paper, a large-scale questionnaire is presented which was answered by experts in the field, evaluating the relevance of each individual topic for the next five years. Missing topics, which are likely to become relevant over the next few years, are identified as well. Furthermore, an analysis is performed of the records of papers submitted to major conferences in the area. Based on the obtained results, an updated version of the taxonomy is proposed.Peer ReviewedPostprint (author's final draft

A flexible protocol communications approach for a supervisory system

This paper deals with the communication protocol intended to control up to 1016 devices of a new supervisory system. It has been conceived in two complementary phases. The first one (Cycle-A) is intended to inform the Central Station of any event detected by the installed devices in less than two seconds. The second one allows to set up a link between the Central Station and a selected Local Station in order to request more information or to act on its devices for command or programming purposes. The dialog between the Central Station and the Local Station takes place on a two wire communication channel, also used to supply de current from the Central to all Local Stations.This paper deals with the communication protocol intended to control up to 1016 devices of a new supervisory system. It has been conceived in two complementary phases. The first one (Cycle-A) is intended to inform the Central Station of any event detected by the installed devices in less than two seconds. The second one allows to set up a link between the Central Station and a selected Local Station in order to request more information or to act on its devices for command or programming purposes. The dialog between the Central Station and the Local Station takes place on a two wire communication channel, also used to supply de current from the Central to all Local Stations.Peer ReviewedPostprint (published version

Resource slicing in virtual wireless networks: a survey

New architectural and design approaches for radio access networks have appeared with the introduction of network virtualization in the wireless domain. One of these approaches splits the wireless network infrastructure into isolated virtual slices under their own management, requirements, and characteristics. Despite the advances in wireless virtualization, there are still many open issues regarding the resource allocation and isolation of wireless slices. Because of the dynamics and shared nature of the wireless medium, guaranteeing that the traffic on one slice will not affect the traffic on the others has proven to be difficult. In this paper, we focus on the detailed definition of the problem, discussing its challenges. We also provide a review of existing works that deal with the problem, analyzing how new trends such as software defined networking and network function virtualization can assist in the slicing. We will finally describe some research challenges on this topic.Peer ReviewedPostprint (author's final draft

A deep reinforcement learning-based algorithm for reliability-aware multi-domain service deployment in smart ecosystems

The final publication is available at Springer via http://dx.doi.org/10.1007/s00521-020-05372-xThe transition towards full network virtualization will see services for smart ecosystems including smart metering, healthcare and transportation among others, being deployed as Service Function Chains (SFCs) comprised of an ordered set of virtual network functions. However, since such services are usually deployed in remote cloud networks, the SFCs may transcend multiple domains belonging to different Infrastructure Providers (InPs), possibly with differing policies regarding billing and Quality-of-service (QoS) guarantees. Therefore, efficiently allocating the exhaustible network resources to the different SFCs while meeting the stringent requirements of the services such as delay and QoS among others, remains a complex challenge, especially under limited information disclosure by the InPs. In this work, we formulate the SFC deployment problem across multiple domains focusing on delay constraints, and propose a framework for SFC orchestration which adheres to the privacy requirements of the InPs. Then, we propose a reinforcement learning (RL)-based algorithm for partitioning the SFC request across the different InPs while considering service reliability across the participating InPs. Such RL-based algorithms have the intelligence to infer undisclosed InP information from historical data obtained from past experiences. Simulation results, considering both online and offline scenarios, reveal that the proposed algorithm results in up to 10% improvement in terms of acceptance ratio and provisioning cost compared to the benchmark algorithms, with up to more than 90% saving in execution time for large networks. In addition, the paper proposes an enhancement to a state-of-the-art algorithm which results in up to 5% improvement in terms of provisioning cost.This work has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 777067 (NECOS project) and the national project TEC2015-71329-C2-2-R (MINECO/FEDER). This work is also supported by the " Fundamental Research Funds for the Central Universities " of China University of Petroleum (East China) under Grant 18CX02139APeer ReviewedPostprint (author's final draft