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25 years ago, Barcelona organised Olympic Games under coob leadership. Design policy and results adopted then really impressed internationally. It might be considered an early example of design management good practices. Design policy concerned iconic buildings as much as humble designs of visual signs, signals, sport devices, tools and even souvenirs. The aim of this article is to display this policy as explained first hand by one of its managers, Mr Jaume Masferrer, then a very young member of coob. It is thus an exercise of collection data through oral history applied to Design Management.

Estamos interesadas en contribuir a una visión estética de las cosas cotidianas, al discutir el tema a través del contexto fenomenológico de las cosas “diseñadas” desde el lado del usuario, es decir, como manifestación de la auto-creación (autopoiesis) y la percepción del tiempo. Nuestro trabajo se centra principalmente en el “uso” como un acto de dar sentido a la vida cotidiana. Algunos principios: tratos del diseño con la memoria y el tiempo presente la tradición y la innovación, lo permanente y lo efímero. Siendo el individuo un ser perceptivo, y ser dada la percepción de un horizonte que no puede ser definido por la eficiencia, un producto (artefacto, cosa) está abierto a una diversidad de interpretaciones. Esta declaración será iluminada con el concepto de significado en blanco (concepto que hemos creado y se explicará a lo largo del documento completo). El fondo de nuestro discurso se coloca más allá de la personalización de las cosas cotidianas: las cosas siguen viviendo y llevar a cabo después de ser adquirido. Por lo tanto, nos centramos en el universo de micro-dimensión de las ficciones que permiten a la gente a estar rodeado de cosas que tienen significado a pesar de que ya no tienen una función. Las conclusiones de nuestro trabajo se centran tanto en los usuarios de diseño y la práctica del diseño como un acto de dar sentido a la vida cotidiana. Por lo tanto, llegar a ese punto, tenemos la intención de aclarar el concepto de significado con el fin de contribuir a la estética de la belleza está en uso.

This paper presents a novel autonomous management system for satellite-based Non-Terrestrial Networks (NTN). It addresses the challenges of managing the operations of Low Earth Orbit (LEO) constellations for the Internet of Things (IoT), emphasizing intermittent connectivity and resource constraints. This work contributes with the description of the scheduler module alongside a customized formulation of a novel multi-objective optimization problem and its associated mathematical framework. The resultant optimization algorithm is elaborated. This Constellation Management System (CMS) is validated through a real-world scenario, revealing substantial improvements of up to 40% in task assignment and throughput rates when compared to a best-effort baseline. This study underscores the CMS’s potential to enhance IoT communication with LEO constellations through resource-efficient and business-aware satellite operations scheduling.

The Internet of Things (IoT) paradigm has already progressed from an emerging technology to an incredibly fast-growing field. Defined as one of the three key services in 5th Generation (5G), massive Machine Type Communications (mMTC) are intended to enable the wide-spread adoption of IoT services across the globe. Satellite-based Non-Terrestrial Networks (NTN) are crucial in providing connectivity with global coverage including rural and offshore areas, which are fundamental for supporting important use cases in future networks. A rapidly growing market for IoT devices with mMTC applications using NarrowBand-IoT (NB-IoT) will represent a large share of user equipment (UE) in such areas. While standardization efforts for NTN are underway for forthcoming 3GPP releases, they focus on transparent payload architectures where the satellite platform is necessarily connected to a ground station gateway to be able to provide satellite access services to IoT devices, thus requiring complex ground segment infrastructure in low Earth orbit (LEO) constellation deployments to achieve global coverage. In contrast, satellite network deployments targeting the delivery of delay-tolerant IoT applications using NB-IoT, which are a major mMTC use case, can benefit from architectures based on the use of regenerative payloads in the satellite and support for Store and Forward (S&F) operation where satellite access can remain operational even at times when the satellite is not connected to a ground station. In particular, such an approach would allow for extending satellite service coverage in areas where satellites cannot be connected to ground stations (e.g. maritime or very remote areas with lack of ground-stations infrastructures), improving ground segment affordability by enabling operation with fewer ground-stations and allowing more robust operation of the satellite under intermittent feeder link operation. In this paper, we provide a high-level design of an extended 3GPP architecture featuring store and forward mechanisms for IoT NTN delay-tolerant applications that address the previous challenges, as well as a laboratory validation of said architecture for a specific use case.

Nowadays, several wireless communication solutions targeted at low-power devices (e.g. sensors, actuators) compete for market dominance. As a consequence, the deployment of the Internet of Things is slowed by fragmentation. However, Cross-Technology Communication (CTC) has appeared as a solution capable of bridging the compatibility gap between non-interoperable devices. In this way, we propose using Wake-up Radio (WuR) to achieve high rate bidirectional CTC, introducing WuR assisted CTC (WuR-CTC). Although WuR was originally proposed to reduce radio power consumption, it provides a secondary communications channel that can be used for high-speed and bidirectional CTC. With WuR-CTC, we demonstrate that WuR can lead to interoperability between non-compatible wireless devices, therefore, providing a compelling reason for the harmonization of the nascent WuR specifications. This article presents a WuR-CTC solution implemented on an heterogeneous testbed with IEEE 802.11 and IEEE 802.15.4 devices. The resulting testbed achieves reliable CTC with an effective throughput of 26.7 kbps. Moreover, the addition of WuR to the testbed devices provides energy savings, and, in a clear advantage over traditional duty-cycled solutions, allows devices to asynchronously maintain communications.

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.

5G era opens a new horizon toward communication with new features and capabilities. The new mobile generation comes up with a multi-gigabit per second data rate along with its huge available bandwidths provided by millimeter-wave frequency bands. Dispensing a fully connected world throughout low latency is the supreme aim for 5G networks. However, attaining high-speed, reliable communication is challenging in the new generation, especially in scenarios with numerous obstacles such as the urban one. As the frequency rises, the signal’s penetration power declines, which can mislead TCP in adjusting the sending rate because TCP cannot distinguish that a packet drop in a network is due to congestion or other shortcomings of the network such as blockage or random packet drops. This paper proposes a new TCP based on Fuzzy logic, which strives to prevent performance reduction in urban deployments. The Fuzzy rules are implemented in the congestion avoidance phase of the new protocol to adjust the sending rate intelligently and prevent blockage impacts. The ultimate aim of the protocol is to control the sending rate based on the current situation of the network so it can attain the highest possible performance. Moreover, it tries to reach its goal through low latency and keep the average sending rate as small as possible to restrain the buffer exhaustion. The extensive conducted simulations showed that the newly proposed protocol could attain higher performance compared to BBR, HighSpeed, Cubic, and NewReno in terms of throughput, RTT, and sending rate adjustment in the urban scenario.

Upcoming Low Earth Orbit Satellite Networks will provide low-latency and high downlink capacity necessary for future broadband communications and Earth Observation missions. This architecture was proposed at the beginning of the 90's, although it has just recently re-gained popularity thanks to the so-called Mega-Constellations. This network is composed of satellites that have Inter-Satellite Links (ISL) to communicate between them. Due to the satellite motion, an ISL is a temporal contact between two satellites characterized by a lifetime in which the communication remains feasible. The determination of a route between distant satellites is a challenging problem in this context. However, the satellite follows a well-known deterministic orbit trajectory, being feasible the prediction of its position by propagating a trajectory model over time. The Contact Graph Routing protocol uses this feature to determine the evolution of the routes by pre-computing on-ground a planning of the satellite contacts. This centralized ground-dependent solution cannot be directly applied in the Internet of Satellites paradigm, which proposes the autonomous deployment of heterogeneous satellite networks without pre-assuming any specific satellite system architecture. Following this concept, the present work proposes a distributed algorithm by which a satellite predicts neighbor contacts, and generates a global contact plan without trajectory propagation. To achieve this solution, an ISL has been modeled as a “close approach” between two satellites, which is characterized by their relative motion. The present work details the predictive algorithm, and evaluates its performance in two scenarios with a hybrid satellite constellation and a mega-constellation.

Since the appearance of 5G, Internet of Things (IoT) has gained an increased interest, with multiple technologies emerging and converging to cover different user needs. One of the biggest challenges today is to have global IoT coverage, ensuring seamless communication with IoT devices placed in rural and even remote areas. Satellite constellations, and in particular CubeSats orbiting in Low Earth Orbit, can provide a solution to these challenges. Out of the technologies available, LoRa (Long Range) has a great potential for implementation in space-to-Earth satellite communications. As the space-to-Earth channel is different with respect to the conventional Earth-to-Earth one, it is important to asses the capabilities of LoRa in this new environment. This paper presents a study of different LoRa device configurations to identify the constrains for each one and determine which one is better for particular mission requirements. Also, the effect of ionospheric scintillation is assessed with a SDR-based (Software-Defined Radio) test set-up that evaluates the performance of this technology against with Humprey's ionospheric scintillation model. This phenomena produces deep signal intensity fadings and phase fluctuations in equatorial regions, and mainly phase fluctuations in high latitudes. The obtained metrics are the received power and the packet delivery ratio as a function of the intensity scintillation index, and show the robustness of the LoRa modulation in these new environments.

Earth Observation applications are demanding higher spatial resolution and shorter revisit times than existing systems, which can be met by ad-hoc constellations of Federated Satellite Systems. These systems are distributed satellite architectures which rely on the collaboration between satellites that share unused resources, such as memory storage, computing capabilities, or downlink opportunities. In the same context, the Internet of Satellites paradigm expands the federation concept to a multi-hop scenario, without predefining a particular satellite system architecture, and deploying temporal satellite networks. The basis of both concepts is the offer of unused satellite resources as services. Therefore, it is necessary that satellites notify their availability to the other satellites that compose the system. This work presents a novel Opportunistic Service Availability Dissemination Protocol, which allows a satellite to publish an available service to be consumed by others. Details of the protocol behavior, and packet formats are presented as part of the protocol definition. The protocol has been verified in a realistic scenario composed of Earth Observation satellites, and the Telesat mega-constellation as network backbone. The achieved results demonstrate the benefits of using a protocol as the proposed one, which in some cases even doubles the amount of data that can be downloaded. To the best of our knowledge, this proposal is the first protocol that allows deploying opportunistic services for Federated Satellite Systems.

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.

The 3Cat-4 mission aims at demonstrating the capabilities of a CubeSat to perform Earth Observation (EO) by integrating a combined GNSS-R and Microwave Radiometer payload into a 1-Unit CubeSat. One of the greatest challenges is the design of an antenna that respects the 1-Unit CubeSat envelope while operating at the different frequency bands: Global Positioning System (GPS) L1 and Galileo E1 band (1575 MHz), GPS L2 band (1227 MHz), and the microwave radiometry band (1400–1427 MHz). Moreover, it requires between 8 and 12 dB of directivity depending on the band whilst providing at least 10 dB of front-to-back lobe ratio in L1 and L2 GPS bands. After a trade-off analysis on the type of antenna that could be used, a helix antenna was found to be the most suitable option to comply with the requirements, since it can be stowed during launch and deployed once in orbit. This article presents the antenna design from a radiation performance point of view starting with a theoretical analysis, then presenting the numerical simulations, the measurements in an Engineering Model (EM), and finally the final design and performance of the Flight Model (FM).

Current standardization process for Wake-up Radio (WuR) within the IEEE 802.11 Working Group, known as the IEEE 802.11ba, has brought interest to the IEEE 802.11-related technologies for the implementation of WuR systems. This paper proposes a new WuR system, where the Wake-up Transmitter (WuTx) is based on the legacy IEEE 802.11 Orthogonal Frequency Division Modulation (OFDM) Physical Layer (PHY) specification. Using the IEEE 802.11, OFDM PHY makes it possible for an IEEE 802.11a/g/n/ac transmitter to operate as WuTx for this WuR system. The WuTx generates a Wake-up Signal (WuS) coded with an amplitude-based digital modulation, achieving a bit rate of 250 kbps. This modulation, which we call Peak-Flat modulation, can be received using low-power receivers. A simulated proof of concept of the WuTx based on the IEEE 802.11g is presented and evaluated using MATLAB WLAN Toolbox. A method to generate the Peak-Flat modulated WuS from an IEEE 802.11a/g standard-compliant transmitter, using only software-level access, is explained. In addition, two possible low-power Wake-up Receiver (WuRx) architectures capable of decoding the presented modulation are proposed. The design of those receivers is generic enough to be used as a reference to compare the performance of the Peak-Flat Modulation with the other state-of-the-art approaches. The evaluation results conclude that the Peak-Flat modulation has similar performance compared to the other IEEE 802.11 WuR solutions on the reference receivers. Moreover, this solution provides a notorious advantage: legacy OFDM-based IEEE 802.11 transmitters can generate the Peak-Flat modulated WuS.

The space segment has been evolved from monolithic to distributed satellite systems. One of these distributed systems is called the federated satellite system (FSS) which aims at establishing a win-win collaboration between satellites to improve their mission performance by using the unused on-board resources. The FSS concept requires sporadic and direct communications between satellites, using inter satellite links. However, this point-to-point communication is temporal and thus it can break existent federations. Therefore, the conception of a multi-hop scenario needs to be addressed. This is the goal of the Internet of satellites (IoSat) paradigm which, as opposed to a common backbone, proposes the creation of a network using a peer-to-peer architecture. In particular, the same satellites take part of the network by establishing intermediate collaborations to deploy a FSS. This paradigm supposes a major challenge in terms of network definition and routing protocol. Therefore, this paper not only details the IoSat paradigm, but it also analyses the different satellite network models. Furthermore, it evaluates the routing protocol candidates that could be used to implement the IoSat paradigm.

The operational network of individual observation nodes project evaluated the benefits of applying distributed satellite system (DSS) architectures to Earth observation. One of its outcomes is the identification of Arctic services as top priority current user needs that require near-real-time observations. Using inter-satellite communications (ISC) capabilities, a federated satellite system (FSS) can establish a win-win collaboration between two spacecrafts to provide these services. However, as a FSS is established during the contact between two satellites, the service duration is limited. Therefore, the Internet of satellites (IoSat) paradigm promotes the use of multi-hop sporadic networks to deploy FSS. In this paper, the routing protocol (which identifies routes between a source-destination pair) becomes crucial. One of the most extended networks is the mobile ad-hoc network (MANET), in which nodes are constantly moving and changing the network topology. In principle, applying MANET technologies in the IoSat context would provide self-organization, self-configuration, and flexibility to satellite systems. The optimized linkstate routing (OLSR) protocol is the predominant solution in MANET, because it quickly reacts against topology changes. This paper aims at studying the benefits of using satellite networks with MANET solutions (e.g. OLSR) for polar satellite missions. The results presented in this article demonstrate that the access time is significantly improved, and thus these new Arctic services can be achieved.

With the number of nonhuman devices expected to significantly overtake human users of long-term evolution networks, it is no surprise that First Responders in mission critical (MC) operations will need to interact with an increasing number of unmanned devices, “bots”or drones. In this paper, we propose the MC “bot”concept as an entity capable of gathering environmental/situational information and triggering certain automated actions without the need of human intervention. We prove that in certain circumstances these bots can help quickly resolve emergency situations and complement traditional centralized coordination from dispatch control rooms. We explain how such “bots”relate to and expand the 3GPP MC Communications architecture framework, considering different architectural approaches and complexity levels. Importantly, because First Responders must remain focused, hands free, and context aware most of the time, we cover specifically the case where man-machine interaction is based on voice communication without having to use hands or look at a screen. It is hence of particular interest to convert “bot”interactions into audio information exchanged over push-to-talk communication services, be it through the cellular network or leveraging the 3GPP device-to-device capability. This paper is complemented with theoretical use cases as well as description and multimedia material of a prototype implementation of a concept emulator.

Natural disasters and catastrophes are responsible for numerous casualties and important economic losses. They can be monitored either with in-situ or spaceborne instruments. However, these monitoring systems are not optimal for an early detection and constant monitoring. An optimisation of these systems could benefit from networks of Internet of Things (IoT) sensors on the Earth’s surface, capable of automatically triggering on-demand executions of the spaceborne instruments. However, having a vast amount of sensors communicating at once with one satellite in view also poses a challenge in terms of the medium access layer (MAC), since, due to packet collisions, packet losses can occur. As part of this study, the monitoring requirements for an ideal spatial nodes density and measurement update frequencies of those sensors are provided. In addition, a study is performed to compare different MAC protocols, and to assess the sensors density that can be achieved with each of these protocols, using the LoRa technology, and concluding the feasibility of the monitoring requirements identified.

Presently, the Earth Observation community is demanding applications that provide low latency and high downlink capabilities. An increase in downlink contacts becomes essential to meet these new requirements. The Federated Satellite Systems concept addresses this demand by promoting satellite collaborations to share unused downlink opportunities. These collaborations are established opportunistically and temporarily, posing multiple technology challenges to be implemented in-orbit. This work contributes to the definition of the Federation Deployment Control Protocol which formalizes a mechanism to fairly establish and manage these collaborations by employing a negotiation process between the satellites. Moreover, this manuscript presents the results of a validation campaign of this protocol with three stratospheric balloons. In summary, more than 27 federations with 63.0% of throughput were established during the field campaign. Some of these federations were used to download data to the ground, and others were established to balance data storage between balloons. These federations allowed also the extension of the coverage of a ground station with a federation that relayed data through a balloon, and the achievement of a hybrid scenario with one balloon forwarding data from a ground device. The results demonstrate that the proposed protocol is functional and ready to be embedded in a CubeSat mission.

In this paper, we present the design of a Constrained Application Protocol (CoAP) proxy able to interconnect Web applications based on Hypertext Transfer Protocol (HTTP) and WebSocket with CoAP based Wireless Sensor Networks. Sensor networks are commonly used to monitor and control physical objects or environments. Smart Cities represent applications of such a nature. Wireless Sensor Networks gather data from their surroundings and send them to a remote application. This data flow may be short or long lived. The traditional HTTP long-polling used by Web applications may not be adequate in long-term communications. To overcome this problem, we include the WebSocket protocol in the design of the CoAP proxy. We evaluate the performance of the CoAP proxy in terms of latency and memory consumption. The tests consider long and short-lived communications. In both cases, we evaluate the performance obtained by the CoAP proxy according to the use of WebSocket and HTTP long-polling.

We propose a novel analytical model to study fragmentation methods in wireless sensor networks adopting the Constrained Application Protocol (CoAP) and the IEEE 802.15.4 standard for medium access control (MAC). The blockwise transfer technique proposed in CoAP and the 6LoWPAN fragmentation are included in the analysis. The two techniques are compared in terms of reliability and delay, depending on the traffic, the number of nodes and the parameters of the IEEE 802.15.4 MAC. The results are validated trough Monte Carlo simulations. To the best of our knowledge this is the first study that evaluates and compares analytically the performance of CoAP blockwise transfer and 6LoWPAN fragmentation. A major contribution is the possibility to understand the behavior of both techniques with different network conditions. Our results show that 6LoWPAN fragmentation is preferable for delay-constrained applications. For highly congested networks, the blockwise transfer slightly outperforms 6LoWPAN fragmentation in terms of reliability.

In this paper we present the design and implementation of the Constrained Application Protocol (CoAP) for TinyOS, which we refer to as TinyCoAP. CoAP seeks to apply the same application transfer paradigm and basic features of HTTP to constrained networks, while maintaining a simple design and low overhead. The design constraints of Wireless Sensor Networks (WSNs) require special attention in the design process of the CoAP implementation. We argue that better performance and minimal resource consumption can be achieved developing a native library for the operating system embedded in the network. TinyOS already includes in its distribution an implementation of CoAP called CoapBlip. However, this is based on a library not originally designed to meet the requirements of TinyOS. We demonstrate the effectiveness of our approach by a comprehensive performance evaluation. In particular, we test and evaluate TinyCoAP and CoapBlip in a real scenario, as well as solutions based on HTTP. The evaluation is performed in terms of latency, memory occupation, and energy consumption. Furthermore, we evaluate the reliability of each solution by measuring the goodput obtained in a channel affected by Rayleigh fading. We also include a study on the effects that high workloads have on a server.

The extensive usage of wireless sensor networks (WSNs) has led to the development of many power- and energy-efficient routing protocols. Cooperative routing in WSNs can improve performance in these types of networks. In this paper we discuss the existing proposals and we propose a routing algorithm for wireless sensor networks called Power Efficient Location-based Cooperative Routing with Transmission Power-upper-limit (PELCR-TP). The algorithm is based on the principle of minimum link power and aims to take advantage of nodes cooperation to make the link work well in WSNs with a low transmission power. In the proposed scheme, with a determined transmission power upper limit, nodes find the most appropriate next nodes and single-relay nodes with the proposed algorithm. Moreover, this proposal subtly avoids non-working nodes, because we add a Bad nodes Avoidance Strategy (BAS). Simulation results show that the proposed algorithm with BAS can significantly improve the performance in reducing the overall link power, enhancing the transmission success rate and decreasing the retransmission rate.

MQTT-S and CoAP are two protocols able to use the publish/subscribe model in Wireless Sensor Networks (WSNs). The high scalability provided by the publish/subscribe model may incur a high packet loss and therefore requires an efficient reliability mechanism to cope with this situation. The reliability mechanism of MQTT-S and CoAP employs a method which defines a fixed value for the retransmission timeout (RTO). This article argues that this method is not efficient for deploying publish/subscribe in WSN, because it may be unable to recover a packet, therefore resulting in a lower packet delivery ratio (PDR) at the subscriber nodes. This article proposes and evaluates an adaptive RTO method, which consists in using a Smooth Round-trip Time and multiplying it by a constant parameter (K). Thanks to this method, the reliability mechanism of MQTT-S and CoAP would be able to react properly to packet loss and would also be lightweight in terms of energy, memory and computing for sensor nodes where these resources are critical. We present a detailed evaluation of the effects of the K value on the calculation of the adaptive RTO method. We also establish the setting for obtaining the highest PDR on the subscriber nodes for single-hop and multi-hop scenarios. The results for single-hop scenario show that use of the appropriate K value for the adaptive RTO method increases the PDR up to 76% for MQTT-S and up to 38% for CoAP when compared with the use of fixed RTO method for both protocols, respectively. Meanwhile the same comparison for multi-hop scenario, the adaptive RTO method increases the PDR up to 36% for MQTT-S and up to 14% for CoAP.

Wireless Sensor Networks (WSNs) are attracting more and more interest since they offer a low-cost solution to the problem of providing a means to deploy large sensor networks in a number of application domains. We believe that a crucial aspect to facilitate WSN diffusion is to make them interoperable with external IP networks. This can be achieved by using the 6LoWPAN protocol stack. 6LoWPAN enables the transmission of IPv6 packets over WSNs based on the IEEE 802.15.4 standard. IPv6 packet size is considerably larger than that of IEEE 802.15.4 data frame. To overcome this problem, 6LoWPAN introduces an adaptation layer between the network and data link layers, allowing IPv6 packets to be adapted to the lower layer constraints. This adaptation layer provides fragmentation and header compression of IP packets. Furthermore, it also can be involved in routing decisions. Depending on which layer is responsible for routing decisions, 6LoWPAN divides routing in two categories: mesh under if the layer concerned is the adaptation layer and route over if it is the network layer. In this paper we analyze different routing solutions (route over, mesh under and enhanced route over) focusing on how they forward fragments. We evaluate their performance in terms of latency and energy consumption when transmitting IP fragmented packets. All the tests have been performed in a real 6LoWPAN implementation. After consideration of the main problems in forwarding of mesh frames in WSN, we propose and analyze a new alternative scheme based on mesh under, which we call controlled mesh under.

Indoor Positioning Systems (IPS) using Bluetooth Low Energy (BLE) technology are currently becoming real and available, which has made them grow in popularity and use. However, there are still plenty of challenges related to this technology, especially in terms of Received Signal Strength Indicator (RSSI) fluctuations due to the behaviour of the channels and the multipath effect, that lead to poor precision. In order to mitigate these effects, in this paper we propose and implement a real Indoor Positioning System based on Bluetooth Low Energy, that improves accuracy while reducing power consumption and costs. The three main proposals are: frequency diversity, Kalman filtering and a trilateration method what we have denominated “weighted trilateration”. The analysis of the results proves that all the proposals improve the precision of the system, which goes up to 1.82 m 90% of the time for a device moving in a middle-size room and 0.7 m for static devices. Furthermore, we have proved that the system is scalable and efficient in terms of cost and power consumption. The implemented approach allows using a very simple device (like a SensorTag) on the items to locate. The system enables a very low density of anchor points or references and with a precision better than existing solutions.