Publish/subscribe protocol in wireless sensor networks: improved reliability and timeliness

The rapidly-evolving demand of applications using wireless sensor networks in several areas such as building and industrial automation or smart cities, among other, makes it necessary to determine and provide QoS support mechanisms which can satisfy the requirements of applications. In this paper we propose a mechanism that establishes different QoS levels, based on Publish/Subscribe model for wireless networks to meet application requirements, to provide reliable delivery of packet and timeliness. The first level delivers packets in a best effort way. The second one intends to provide reliable packet delivery with a novel approach for Retransmission Timeout (RTO) calculation, which adjusts the RTO depending on the subscriber Packet Delivery Ratio (PDR). The third one provides the same reliable packet delivery as the second one, but in addition, it provides data aggregation trying to be efficient in terms of energy consumption and the use of network bandwidth. The last one provides timeliness in the packet delivery. We evaluate each QoS Level with several performance metrics such as PDR, Message Delivery Ratio, Duplicated and Retransmitted Packet Ratio and Packet Timeliness Ratio to demonstrate that our proposal provides significant improvements based on the increase of the PDR obtained.Peer ReviewedPostprint (author's final draft

Design and realization of precise indoor localization mechanism for Wi-Fi devices

Despite the abundant literature in the field, there is still the need to find a time-efficient, highly accurate, easy to deploy and robust localization algorithm for real use. The algorithm only involves minimal human intervention. We propose an enhanced Received Signal Strength Indicator (RSSI) based positioning algorithm for Wi-Fi capable devices, called the Dynamic Weighted Evolution for Location Tracking (DWELT). Due to the multiple phenomena affecting the propagation of radio signals, RSSI measurements show fluctuations that hinder the utilization of straightforward positioning mechanisms from widely known propagation loss models. Instead, DWELT uses data processing of raw RSSI values and applies a weighted posterior-probabilistic evolution for quick convergence of localization and tracking. In this paper, we present the first implementation of DWELT, intended for 1D location (applicable to tunnels or corridors), and the first step towards a more generic implementation. Simulations and experiments show an accuracy of 1m in more than 81% of the cases, and less than 2m in the 95%.Peer ReviewedPostprint (published version

Deep learning TCP for mitigating NLoS impairments in 5G mmWave

5G and beyond 5G are revolutionizing cellular and ubiquitous networks with new features and capabilities. The new millimeter-wave frequency band can provide high data rates for the new generations of mobile networks but suffers from NLoS caused by obstacles, which causes packet drops that mislead TCP because the protocol interprets all drops as an indication of network congestion. The principal flaw of TCP in such networks is that the root for packet drops is not distinguishable for TCP, and the protocol takes it for granted that all losses are due to congestion. This paper presents a new TCP based on deep learning that can outperform other common TCPs in terms of throughput, RTT, and congestion window fluctuation. The primary contribution of deep learning is providing the ability to distinguish various conditions in the network. The simulation results revealed that the proposed protocol could outperform conventional TCPs such as Cubic, NewReno, Highspeed, and BBR.This research was funded in part by the Spanish MCIN/AEI/ 10.13039/501100011033 through project PID2019-106808RA-I00", and by Secretaria d’Universitats i Recerca del departament d’Empresa i Coneixement de la Generalitat de Catalunya with the grant number 2021 SGR 00330.Peer ReviewedPostprint (published version

Challenges on the way of implementing TCP over 5G networks

5G cellular communication, especially with its hugely available bandwidth provided by millimeter-wave, is a promising technology to fulfill the coming high demand for vast data rates. These networks can support new use cases such as Vehicle to Vehicle and augmented reality due to its novel features such as network slicing along with the mmWave multi-gigabit-per-second data rate. Nevertheless, 5G cellular networks suffer from some shortcomings, especially in high frequencies because of the intermittent nature of channels when the frequency rises. Non-line of sight state, is one of the significant issues that the new generation encounters. This drawback is because of the intense susceptibility of higher frequencies to blockage caused by obstacles and misalignment. This unique characteristic can impair the performance of the reliable transport layer widely deployed protocol, TCP, in attaining high throughput and low latency throughout a fair network. As a result, the protocol needs to adjust the congestion window size based on the current situation of the network. However, TCP is not able to adjust its congestion window efficiently, and it leads to throughput degradation of the protocol. This paper presents a comprehensive analysis of reliable end-to-end communications in 5G networks. It provides the analysis of the effects of TCP in 5G mmWave networks, the discussion of TCP mechanisms and parameters involved in the performance over 5G networks, and a survey of current challenges, solutions, and proposals. Finally, a feasibility analysis proposal of machine learning-based approaches to improve reliable end-to-end communications in 5G networks is presented.This work was supported by the Secretaria d’Universitats i Recerca del Departament d’Empresa i Coneixement de la Generalitat de Catalunya under Grant 2017 SGR 376.Peer ReviewedPostprint (published version

Implementation and evaluation of Multi-hop routing in 6LoWPAN

6LoWPAN enables the transmission of IPv6 packets over LoWPAN networks. In order to make it possible, 6LoWPAN introduces an adaptation layer between network and link layers. This layer allows IPv6 packets to be adapted to the lower layers constraints. It provides fragmentation and reassembling of packets and header compression. It also can be involved in routing decisions. Depending on which layer is responsible of routing decisions 6LoWPAN divides routing in two categories: mesh under if the interested layer is the adaptation layer, route over if it is the network one. In this paper we compare the two routing solutions evaluating their performances in terms of end-to-end delay and round-trip time. All the performance evaluation has been realized in a real implementation of 6LoWPAN.Postprint (published version

How sufficient is TCP when deployed in 5G mmWave networks over the urban deployment?

© 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.By deploying the millimeter-wave wide spectrum in 5G networks, the new generation is capable of providing high data rates with low latencies. However, these frequencies have intermittent characteristics as their downside, which acts as a hurdle on the way of attaining high performances. This disadvantage can lower signals’ penetration power in reaching far distances or passing materials such as vehicles, walls, and even human bodies. As a result, having a reliable end-to-end connection throughout 5G millimeter-wave networks can be challenging because this burden is on the transport layer mostly exploited protocol, TCP, which is unable to perform sufficiently due to the fluctuation of the high-frequency channels. This paper aims to analyze TCP’s behavior in one of the 3GPP’s well-known scenarios called urban deployment. The detailed investigation of TCP over 5G millimeter-wave when used in a city and the impact of different parameters such as remote servers, RLC buffer size, different congestion control algorithms, and maximum segment size are discussed thoroughly throughout the paper. The results revealed that TCP could benefit from the edge server deployment due to the shorter control loop, and increasing maximum segment size can also enhance this superiority. Moreover, individual TCP variants react to various RLC buffer sizes differently. However, in general, increased throughput can be attained by deploying larger buffers at the cost of latency.This work was supported in part by the Secretaria d’Universitats i Recerca del Departament d’Empresa i Coneixement de la Generalitat de Catalunya under Grant 2017 SGR 376, and in part by the Spanish Government under Project PID2019-106808RA-I00 AEI/FEDER UE.Peer ReviewedPostprint (published version

Aplicación de métodos de compresión de cabeceras TCP/IP como optimización de las comunicaciones móviles

El protocolo TCP (Transmission Control Protocol) está implementado para actuar en redes fija s, donde las incidencias en la comunicación pueden interpreta rse como problemas de con ges tión. En entornos móviles, en cambio, los problemas son debidos a una alta tasa de error en bit (BER); la utilización del protocolo TCP en este tipo de entornos afecta negativamente a la efici encia de la transmisión. En este artíc ulo se presenta una solución pa ra optimizar la comunicación TCP: la compresión de cabeceras; concretamente se expone la necesidad de un algoritmo especifico para comunicaciones móviles y se valora la propuesta de compresión de cabeceras de la lETF .Peer Reviewe

Mycorrhizal Stimulation of Leaf Gas Exchange in Relation to Root Colonization, Shoot Size, Leaf Phosphorus and Nitrogen: A Quantitative Analysis of the Literature Using Meta-Regression

Arbuscular mycorrhizal (AM) symbiosis often stimulates gas exchange rates of the host plant. This may relate to mycorrhizal effects on host nutrition and growth rate, or the influence may occur independently of these. Using meta-regression, we tested the strength of the relationship between AM-induced increases in gas exchange, and AM size and leaf mineral effects across the literature. With only a few exceptions, AM stimulation of carbon exchange rate (CER), stomatal conductance (gs) and transpiration rate (E) has been significantly associated with mycorrhizal stimulation of shoot dry weight, leaf phosphorus, leaf nitrogen: phosphorus ratio and percent root colonization. The sizeable mycorrhizal stimulation of CER, by 49% over all studies, has been about twice as large as the mycorrhizal stimulation of gs and E (28% and 26%, respectively). Carbon exchange rate has been over twice as sensitive as gs and four times as sensitive as E to mycorrhizal colonization rates. The AM-induced stimulation of CER increased by 19% with each AM-induced doubling of shoot size; the AM effect was about half as large for gs and E. The ratio of leaf N to leaf P has been more closely associated with mycorrhizal influence on leaf gas exchange than leaf P alone. The mycorrhizal influence on CER has declined markedly over the 35 years of published investigations

Hacia una web independiente del dispositivo mediante CC/PP

Composite Capabilities/Preferences Profiles (CC/PP) es el nuevo lenguaje estándar creado por el World Wide Web Constortium (W3C) para que la gran diversidad de dispositivos que disponen, o dispondrán, de un acceso a Internet (móvil, PDA, PC, TV ... ), sean capaces de expresar sus capacidades y las preferencias del usuario mediante perfiles, tal y como su nombre indica. Para expresar estas características, los perfiles CC/PP emplean Resource Descripción Framework (RDF), otro estándar del W3C y pilar de la web semántica, el cual, a su vez, se encuentra construido sobre Extensible Markup Language (XML). La especificación User Agent Profile (UAProf) definida por la Open Mobile Alliance (OMA), antiguo W APForum, utiliza CC/PP para la descripción de los teléfonos móviles. Se puede entender como el primer gran desarrollo CC/PP y ya se encuentra incluido en los últimos dispositivos móviles, implicando la existencia actual de millones de dispositivos que usan CC/PP.Mediante CCIPP los dispositivos tienen la habilidad de enviar la información CCIPP conjuntamente con las peticiones HTTP a los servidores, de manera que éstos puedan procesar la información CC/PP y realizar la adaptación o selección de contenidos adecuados a las características del di spositivo, consiguiendo así una Web independiente del dispositivo, acercándose cada vez más a uno de las principales metas del W3C: El Acceso Universal a laWeb. En este artículo se pone de manifiesto la problemática actual de la negociación de contenidos utilizando HTTP/l.l y se describe la especificación CCIPP, el estándar propuesto por W3C para solucionar esta carencia, justificando sus claves de diseño. También se describe el estándar de la OMA, UAProf, la primera implementación de CCIPP para la descripción de los terminales móviles que se encuentra incluido en la nueva especificación W AP 2.0. Palabras clave- CC/PP, UAProJ, RDF, Adaptación de contenidos, móvil, WebPeer Reviewe

An improvement over TCP Vegas to enhance its performance in optical burst switching networks

This is a post-peer-review, pre-copyedit version of an article published in Optical review. The final authenticated version is available online at: http://dx.doi.org/10.1007/s10043-021-00652-w.The demand for high bandwidth on the Internet is growing drastically, and one of the solutions for tackling this problem is using optical networks. Burst switching is one of the techniques that can be used in optical networks to handle high traffic. Aside from the many advantages that this technique has, it suffers from a big flaw called burst contention. Optical burst switching (OBS) is a switching technique without any buffering system. As a result, when two bursts are trying to reserve one resource, one of them drops. This drawback can have a significant impact on the performance of some protocols like TCP because they have not been designed to perform in a network without any queuing system and cannot distinguish a drop is because of the congestion or contention. In this paper, a new algorithm called AVGR (Average of RTTs) is proposed based on some mathematical equations to prevent the degradation of TCP. It tries to calculate averages for some RTTs in three different periods. Then base on the obtained results, the congestion control mechanism will be modified. The primary goal of the algorithm is to determine the current status of the network and make proper decisions based on it.This work has been funded by the Secretaria d’Universitats i Recerca del Departament d’Empresa i Coneixement de la Generalitat de Catalunya (2017 SGR 376) and the Spanish Government under Project PID2019-106808RA-I00 AEI/FEDER UE.Peer ReviewedPostprint (author's final draft