Stability of synchronous queued RFID networks

Queued Radio Frequency Identification (RFID) networks arise naturally in many applications, where tags are grouped into batches, and each batch must be processed before the next reading job starts. In these cases, the system must be able to handle all incoming jobs, keeping the queue backlogs bounded. This property is called stability. Besides, in RFID networks, it is common that some readers cannot operate at the same time, due to mutual interferences. This fact reduces the maximum traffic that readers can process since they have to share the channel. Synchronous networks share the channel using a TDMA approach. The goal of this work is to analytically determine whether a synchronous queued RFID network attains stable operation under a given incoming traffic. Stability depends on the service rate, which is characterized in this paper using an exact numerical method based on a recursive analytical approach, overcoming the limitations of previous works, which were based on simplifications. We also address different flow optimization problems, such as computing the maximum joint traffic that a network can process stably, selecting the minimal number of readers to process a given total load, or determining the optimal timeslot duration, which are novel in the RFID literature.Ministerio de Economía, Industria y Competitividad | Ref. TEC2016-76465-C2-1-

Stability of synchronous queued RFID networks

Queued Radio Frequency Identification (RFID) networks arise naturally in many applications, where tags are grouped into batches, and each batch must be processed before the next reading job starts. In these cases, the system must be able to handle all incoming jobs, keeping the queue backlogs bounded. This property is called stability. Besides, in RFID networks, it is common that some readers cannot operate at the same time, due to mutual interferences. This fact reduces the maximum traffic that readers can process since they have to share the channel. Synchronous networks share the channel using a TDMA approach. The goal of this work is to analytically determine whether a synchronous queued RFID network attains stable operation under a given incoming traffic. Stability depends on the service rate, which is characterized in this paper using an exact numerical method based on a recursive analytical approach, overcoming the limitations of previous works, which were based on simplifications. We also address different flow optimization problems, such as computing the maximum joint traffic that a network can process stably, selecting the minimal number of readers to process a given total load, or determining the optimal timeslot duration, which are novel in the RFID literature.This work was supported by the Project AIM, (AEI/FEDER, EU) under Grant TEC2016-76465-C2-1-R

LPDQ: a self-scheduled TDMA MAC protocol for one-hop dynamic lowpower wireless networks

Current Medium Access Control (MAC) protocols for data collection scenarios with a large number of nodes that generate bursty traffic are based on Low-Power Listening (LPL) for network synchronization and Frame Slotted ALOHA (FSA) as the channel access mechanism. However, FSA has an efficiency bounded to 36.8% due to contention effects, which reduces packet throughput and increases energy consumption. In this paper, we target such scenarios by presenting Low-Power Distributed Queuing (LPDQ), a highly efficient and low-power MAC protocol. LPDQ is able to self-schedule data transmissions, acting as a FSA MAC under light traffic and seamlessly converging to a Time Division Multiple Access (TDMA) MAC under congestion. The paper presents the design principles and the implementation details of LPDQ using low-power commercial radio transceivers. Experiments demonstrate an efficiency close to 99% that is independent of the number of nodes and is fair in terms of resource allocation.Peer ReviewedPostprint (author’s final draft

Towards Robust Deep Reinforcement Learning for Traffic Signal Control: Demand Surges, Incidents and Sensor Failures

Reinforcement learning (RL) constitutes a promising solution for alleviating the problem of traffic congestion. In particular, deep RL algorithms have been shown to produce adaptive traffic signal controllers that outperform conventional systems. However, in order to be reliable in highly dynamic urban areas, such controllers need to be robust with the respect to a series of exogenous sources of uncertainty. In this paper, we develop an open-source callback-based framework for promoting the flexible evaluation of different deep RL configurations under a traffic simulation environment. With this framework, we investigate how deep RL-based adaptive traffic controllers perform under different scenarios, namely under demand surges caused by special events, capacity reductions from incidents and sensor failures. We extract several key insights for the development of robust deep RL algorithms for traffic control and propose concrete designs to mitigate the impact of the considered exogenous uncertainties.Comment: 8 page

Remote control and monitoring of power systems

Includes synopsis.Includes bibliographical references (leaves 87-93).Power systems are typically complex and can be affected by their environment in ways that cannot be completely predicted by their designers. It is thus imperative that monitoring is considered as part of the design of new power systems. Due to the associated costs of maintenance, repair, and downtime, monitoring these systems is particularly important when the installations are remote. Remote locations benefit greatly from renewable energy sources. As a result, this work focuses on a novel Hybrid Inverter system developed by Optimal Power Solutions Pty. Ltd. (OPS). This system uses renewable energy sources, grid power, and diesel generators together with a bi-directional inverter to supply a remote location with grid-quality power

INVESTIGATING PRESENT AND FUTURE INTERACTIONS BETWEEN RADIO FREQUENCY IDENTIFICATION, ADDITIVE MANUFACTURING AND SUPPLY CHAIN MANAGEMENT

A screening experiment was paired with research observing the past, present and futures of additive manufacturing (a.k.a. rapid prototyping, 3D printing), radio frequency identification, and supply chain management. The experiment tested different properties of objects created with a desktop fused deposition modelling printer to observe if any single factors or interactions affected the read range of embedded passive UHF RFID inlay. The combination of material and infill percentage had a statistically significant effect on read range, however the analysis is weak since the data could not justify the normality assumption of ANOVA. Furthermore, the size of the effect was small enough to deny any practical difference. From the experiment and research, several presently capable interactions between AM and RFID were commented on. Future interactions between AM, RFID and SCM were also discussed, and a common relationship to physical objects was drawn

Industry 4.0: Industrial IoT Enhancement and WSN Performance Analysis

L'abstract è presente nell'allegato / the abstract is in the attachmen

A real-time packet scheduling system for a 6LoWPAN industrial application

Nowadays, the industrial Wireless Sensor Networks (WSN) are crucial for the monitoring and control of the modern smart factory floor that is relying on them for critical applications and tasks that were performed by wired systems in the past. For this reason, it is required that the transmission mechanisms of wireless sensor networks are efficient and robust and that they guarantee realtime responses with low data losses. Furthermore, it is required that they utilize common networking standards, such as the Internet Protocol (IP), that provides interoperability with already existing infrastructures and offers widely tested security and transmission control protocols. The theoretical part of this document focuses on the description of the current panorama of the industrial WSN, its applications, design challenges and standardizations. It describes the 6LoWPAN standard and the wireless transmission technology that it uses for its lower layers, the IEEE 802.15.4 protocol. Later, it describes the principles behind the wireless scheduling, a state-of-the-art in the IEEE 802.15.4 scheduled channel access and the features of the most used operating systems for WSN. The practical part presents the real-time packet scheduling system for a 6LoWPAN industrial application proposed by this thesis work that adapts the HSDPA scheduling mechanisms to the IEEE 802.15.4 beacon-enabled mode. The system implemented manages the channel access by allocating Guaranteed Time Slots to sensor nodes according to the priority given by three scheduling algorithms that can be selected according to the traffic condition of the network. The system proposed was programmed using Contiki OS. It is based on the eSONIA 6LoWPAN firmware developed for the European Research Project and it was deployed on the FAST WSN for testing. The results, discussion and conclusions are documented at the final sections of this part