Improving the selection of MPRs in OLSR protocol: a survey of methods and techniques

Multi Point Relays (MPRs) are those nodes that are calculated and determined by the Optimized Link State Routing protocol (OLSR) in order to minimize and avoid overload inside the Mobile Ad hoc Network (MANET). In this paper, we will present a synthetic study of many techniques and methods for calculating and selecting the MPR nodes using a set of criteria namely energy, mobility, bandwidth, the quality of links, etc. The result of this study shows that most techniques consider a limited number of metrics for selecting the MPR nodes and therefore they are insufficient to allow the OLSR protocol to be quite complete and efficient because several metrics can occur at the same time in the real execution environment

Development of a hardware emulator of a nanosatellite gyroscope

The gyroscope sensor has multiple applications in consumer electronics, aircraft navigation, and control systems. Significant errors that match the corresponding data are a typical disadvantage of this sensor. This needs to be done by making error models that can be used to get the right level of measurement accuracy. For high-precision space applications, the navigation design system should take into account the angle random walk (N), bias instability error (B), and rate random walk (K) of the BMG160 gyroscope. For this reason, this paper shows how to use Allan Variance (AVAR) and Power Spectral Density (PSD) for the experimental identification and modeling of the stochastic parameters of the Bosch BMG160 gyroscope embedded in a nanosatellite in order to get an accurate gyroscope model. This work also demonstrates the principle of operation of the equivalent electronic model intended to carry out advanced simulations without recourse to the real material in order to avoid the problem of bad manipulation and availability of the material in order to reduce the time and cost of development. The interpretation of the Allan curves and the PSD obtained from the measurements collected over a long period is presented, as well as a comparison between the real raw data of the BMG160 gyroscope and the designed hardware emulator in both the time and frequency domains. This is done to evaluate the accuracy of the gyroscope model emulating the real sensor in laboratory simulations. The experimental results show that the signals from the emulator and the BMG160 gyroscope are quite close. Therefore, the proposed prototype could be an optimal solution for laboratory calculations and simulation

Software calibration for AK8963 magnetometer based on optimal ellipsoidal fitting

With the rapid development of mechatronics, systems in package (SiP), in particular the MPU-9250 inertial measurement Unit 9DOF (MPU-6050 6DOF and AK8963 3DOF), are becoming ubiquitous in applications for autonomous navigation purposes. Nevertheless, they suffer from some accuracy problems related to axis misalignment, disturbances, and deviation over time that make them unable to work autonomously for a long time. This paper will present a simple and practical calibration method using a least-squares based ellipsoid fitting method to calibrate and compensate for the error interference of the AK8963 sensor. Towards the end of this paper, a comparison between before and after the calibration is presented to study the software compensation effect and the stability of the magnetic sensor under study

Orbit Calculation and Doppler Correction Algorithm in a LEO Satellite Small Ground Terminal

It is an important technological challenge to ensure a LEO satellite ground terminal autonomy as well as to make it small, lightweight and power efficient along with the ability to predict the satellite visibility passes. Another important feature is to make it able to compensate for Doppler on the satellite link with an economical method. In this paper, an orbit and Doppler calculation methodology has been developed for a general orbital model. The algorithm that manages the ground terminal automatic operation ensures many advantages and is adapted to a microcontroller programming. Inputs to the algorithm are time, position and keplerian elements from NORAD. The NORAD elements are injected in the terminal memory via its serial port once before it is deployed on the operation field. Time is provided by a real time clock read and written by the terminal microcontroller. Terminal geographic position is provided by an internal integrated miniature GPS which makes the terminal free to move anywhere on the terrestrial globe and still be able to contact the satellite without any reprogramming. The orbit calculation methodology used expresses the satellite coordinates in the terminal relative topocentric (horizontal) coordinate system which easily yield the values of elevation and azimuth angles along with the slant range. This is achieved by means of satellite vector transformations through different coordinate systems. Doppler shift is obtained by deriving the slant range in time. A simple methodology for Doppler correction is also proposed in this paper and is adapted for low cost transceivers

A low-cost IMU/GPS position accuracy experimental study using extended kalman filter data fusion in real environments

In a three-dimensional environment, the navigation of a vehicle in airspace, terrestrial space, or maritime space presents complex aspects concerning the determination of its position, its orientation, and the stability of the processing of the asynchronous data coming from the various sensors during navigation. In this context, this paper presents an experimental analysis of the position accuracy estimated by a low-cost inertial measurement unit coupled, by the extended Kalman data fusion algorithm, with a system of absolute measurements of a positioning system received from a GPS which designates the global positioning system. The different scenarios of the experimental study carried out during this work concerned three tests in a real environment, such as the navigation in a course inside the city of Rabat/Morocco with a moderate speed, a section on the highway at a speed of 120 Km/h and a circular path around a roundabout. The experimental results proved that the low-cost sensors studied are a good candidate for civil navigation applications

Study and design of an active magnetorquer actuator model for nanosatellites

This paper focuses on the study and the design of an air core magnetorquer model dedicated to the 1U CubeSat (10×10×10 cm3). The objective is to obtain a solution which is able to provide accurate attitude control while having the smallest possible dimensions, electrical power, and total mass. To this end, the first part will provide theoretical mathematical knowledge on the laws of the coil to design an electromagnetic air core actuator. Then, this paper presents comparisons of the performances obtained by varying the type of material and the shape of the coil. Towards the end, the effect of temperature variation in LEO orbit is taken into consideration to predict the generated magnetic moment

Secure WiFi-Direct Using Key Exchange for IoT Device-to-Device Communications in a Smart Environment

With the rapid growth of Internet of Things (IoT) devices around the world, thousands of mobile users share many data with each other daily. IoT communication has been developed in the past few years to ensure direct connection among mobile users. However, wireless vulnerabilities exist that cause security concerns for IoT device-to-device (D2D) communication. This has become a serious debate, especially in smart environments where highly sensitive information is exchanged. In this paper, we study the security requirements in IoT D2D communication. In addition, we propose a novel authentication approach called Secure Key Exchange with QR Code (SeKeQ) to verify user identity by ensuring an automatic key comparison and providing a shared secret key using Diffie-Hellman key agreement with an SHA-256 hash. To evaluate the performance of SeKeQ, we ran a testbed using devices with a WiFi-Direct communication interface. The obtained results depict that our proposal can offer the required security functions including key exchange, data confidentiality, and integrity. In addition, our proposal can reach the same security performances as MANA (Manual Authentication) and UMAC (Universal-Hashing Message Authentication Code) but with 10 times fewer key computations and reduced memory occupancy

A novel autonomous remote system applied in agriculture using transmission control protocol

An internet of things (IoT) irrigation system is challenged by several issues, such as cost, energy consumption, and data storage. This paper proposes a novel energy-efficient, cost-effective IoT system called "NewAgriCom" to monitor agricultural field water flow. NewAgriCom works with an embedded energy harvesting system, is an autonomous remote supervisory control and data acquisition (SCADA) based on a general packet radio service (GPRS) cellular network that effectively communicates irrigation field data to the Node.js server using SIM808 EVBV3.2 modem. In javascript object notation (JSON) format, data is transmitted over the hypertext transfer protocol (HTTP) protocol to the MySQL database. Then data are transferred to the proposed IoT platform, which gives us a hand to control actuators, visualise, store and download the data. NewAgriCom can significantly reduce water consumption. It can set a schedule to control water automatically at specific times in various modes, including normal, light, and deep sleep modes. It regularly provides the location, time, signal strength, and the state of actuators with the identifier of every device remotely on the IoT Platform