Mario de Noronha Neto

Bio: Mario de Noronha Neto is an academic researcher from International Federation of Sport Climbing. The author has contributed to research in topics: MIMO-OFDM & Network packet. The author has an hindex of 2, co-authored 5 publications receiving 62 citations. Previous affiliations of Mario de Noronha Neto include Centro Federal de Educação Tecnológica de Minas Gerais.

Analysis and Performance Optimization of LoRa Networks With Time and Antenna Diversity

Abstract: Low power wide area network (LPWAN) technologies are increasingly catching the attention of the Internet-of-Things market and have brought the need for reliable knowledge about the performance of such networks. This paper is concerned with the performance and scalability of LoRa networks, a leading LPWAN technology. Several recently published articles have analyzed the ability of LoRa networks to scale, i.e., their ability to support increased traffic and number of nodes. This paper proposes to employ message replication and gateways with multiple receive antennas to achieve, respectively, time and spatial diversity. The paper presents the proposed schemes and evaluates them through theoretical analysis and computer simulations. Results show that LoRa networks are highly sensitive to the increase in user and traffic density, but both message replication and multiple antennas can enhance performance. Message replication has an optimum number of message copies for each network configuration, and its utilization is more beneficial in low-density networks, while the use of multiple receive antennas at the gateway is always beneficial.

Exploiting Time Diversity of LoRa Networks Through Optimum Message Replication

Abstract: LoRA networks have been gaining momentum as an accessible and open solution for massive connectivity in the Internet-of- Things. Besides the popularity, however, academic research has shown that the technology has limitations. In particular to the connectivity argument, it became clear that massive coverage comes at the price of severely reduced duty cycles, and the increased number of users in the network significantly elevates packet loss due to collisions. In this paper, we exploit time diversity to increase the probability of successful packet delivery in LoRA uplink. We build on previous work to model the outage and coverage probabilities of LoRA channels and analyze the use of message replication to create signal diversity. We observed that there is an optimum number of message replicas that minimizes outage probability and avoids high collision probability. We validate the proposed model using numerical simulations.

Cooperative Diversity Scheme with Two Relay Stations and Linear Coherent Detection

Abstract: A new cooperative diversity scheme with two relay stations and linear coherent detection at the destination node is proposed in this paper. We consider that a perfect CSI is available at the destination node, as well to the relay stations, allowing each relay station to perform optimal beamforming. In order to evaluate the effect of a quantized feedback link between the destination node and the relay stations, we also consider that the destination node sends, additionally, b more bits to the relays. Using these b bits, the relay stations can apply a correction factor to the detected symbol and then send it to the destination node which performs a linear coherent detection. In our proposal, the communication between the relay stations is not allowed. The performance of the proposed scheme is compared with the well known MRC receiver technique with four receive antennas in order to show that the proposed and the MRC schemes achieve the same diversity order. In addition, the influence of the number of feedback bits and the SNR between the transmit node and relay stations are also addressed.

Sobre a Obtenção de Diversidade Adicional em Sistemas V-BLAST OFDM através do Desbalanceamento I/Q

Abstract: A generalized receiver model for OFDM MIMO communication systems using direct RF conversion is presented and analysed. This type of conversion causes some impairments to the received signal, such as the I/Q imbalance. However, the new receiver model makes use of this imperfection to improve transmission performance. It can be shown that I/Q imbalance at the transmitter side of a multicarrier system adds some frequency diversity to the signal, that, if correctly processed at the receiver, may provide considerable system performance gains. Simulation results considering a MIMO OFDM system show that, by exploitinng the I/Q imbalance effects, considerable SNR gains may be obtained over an ideal system without I/Q imbalance. Keywords— I/Q imbalance, OFDM, MIMO, dirty RF

Exploiting I/Q Imbalance in Direct Conversion Transceivers for Improving the Performance of a V-BLAST OFDM System

Abstract: A receiver for a MIMO OFDM communication system using direct conversion transceivers is proposed. The novel receiver takes advantage of the I/Q imbalance inherent to the direct conversion operation. It can be shown that the I/Q imbal- ance in multicarrier communication systems creates an additional frequency diversity. By adequately exploiting such diversity at the receiver, the overall performance can be considerably improved. Simulation results considering a MIMO OFDM system using V- BLAST show that, when exploiting the I/Q imbalance, gains of up to 5 dB at a BER of 10 −4 can be obtained with respect to the ideal system, without I/Q imbalance.

IEEE Standard for Local and Metropolitan Area Networks Part 16: Air Interface for Fixed Broadband Wireless Access Systems Draft Amendment: Management Information Base Extensions

Abstract: This document provides updates to IEEE Std 802.16's MIB for the MAC, PHY and asso- ciated management procedures in order to accommodate recent extensions to the standard.

A Survey of LoRaWAN for IoT: From Technology to Application

Abstract: LoRaWAN is one of the low power wide area network (LPWAN) technologies that have received significant attention by the research community in the recent years. It offers low-power, low-data rate communication over a wide range of covered area. In the past years, the number of publications regarding LoRa and LoRaWAN has grown tremendously. This paper provides an overview of research work that has been published from 2015 to September 2018 and that is accessible via Google Scholar and IEEE Explore databases. First, a detailed description of the technology is given, including existing security and reliability mechanisms. This literature overview is structured by categorizing papers according to the following topics: (i) physical layer aspects; (ii) network layer aspects; (iii) possible improvements; and (iv) extensions to the standard. Finally, a strengths, weaknesses, opportunities and threats (SWOT) analysis is presented along with the challenges that LoRa and LoRaWAN still face.

Grassmannian Beamforming for MIMO Amplify-and-Forward Relaying

Abstract: In this paper, we derive the optimal transmitter/ receiver beamforming vectors and relay weighting matrix for the multiple-input multiple-output amplify-and-forward relay channel. The direct link is considered in the problem model and the unquantized and quantized schemes are derived; then a modified quantizing scheme is presented which introduces a negligible degradation in the system performance but significantly reduces the required number of feedback bits,Finally,we carry out a reasonable improvement of the quantized and modified quantizing schemes .

Exploring LoRa for Long-range Through-wall Sensing

Abstract: Wireless signals have been extensively utilized for contactless sensing in the past few years. Due to the intrinsic nature of employing the weak target-reflected signal for sensing, the sensing range is limited. For instance, WiFi and RFID can achieve 3-6 meter sensing range while acoustic-based sensing is limited to less than one meter. In this work, we identify exciting sensing opportunities with LoRa, which is the new long-range communication technology designed for IoT communication. We explore the sensing capability of LoRa, both theoretically and experimentally. We develop the sensing model to characterize the relationship between target movement and signal variation, and propose novel techniques to increase LoRa sensing range to over 25 meters for human respiration sensing. We further build a prototype system which is capable of sensing both coarse-grained and fine-grained human activities. Experimental results show that (1) human respiration can still be sensed when the target is 25 meters away from the LoRa devices, and 15 meters away with a wall in between; and (2) human walking (both displacement and direction) can be tracked accurately even when the target is 30 meters away from the LoRa transceiver pair.

Analysis and Enhancement of the LoRaWAN Adaptive Data Rate Scheme

Abstract: The adaptive data rate (ADR) algorithm is a key component of the LoRaWAN protocol which controls the performance of a LoRaWAN Network. This modifies the data rate parameter of a device based on the current wireless conditions. In this article, we present substantive enhancements for the End Device and Network Server which reduce the convergence time for LoRaWAN devices to reach their optimal data rate. We extend the LoRaWAN module in ns-3 by adding ADR, enabling the simulation of realistic LoRaWAN networks, and add the implementation of the new enhancements in this module. The simulations show that these modifications can result in a significant reduction of the data rate convergence time for LoRaWAN devices and lead to an increased overall packet delivery rate for the network in a dynamic network environment. Our contributions are a publicly available implementation of ADR in ns-3, an analysis of the original algorithm behavior, and a novel version of the algorithm with enhancements that improve performance in every case while remaining easily integrable into an existing LoRaWAN system.