Accurate indoor positioning of narrowband Internet-of-Things (IoT) sensors has drawn more attention in recent years. The introduction of Bluetooth Low Energy (BLE) technology is one of the latest developments of IoT and especially applicable for Ultra-Low Power (ULP) applications. BLE is an attractive technology for indoor positioning systems because of its low-cost deployment and reasonable accuracy. Efficient indoor positioning can be achieved by deducing the sensor position from the estimated signal Angle-of-Arrival (AoA) at multiple anchors. An anchor is a base station of known position and equipped with a narrowband multi-antenna array. However, the design and implementation of indoor positioning systems based on AoA measurements involve multiple challenges. The first part of this thesis mainly addresses the impact of hardware impairments on the accuracy of AoA measurements. In practice, the subspace-based algorithms such as Multiple Signal Classification (MUSIC) suffer from sensitivity to array calibration errors coming from hardware imperfections. A detailed experimental implementation is performed using a Software Defined Radio (SDR) platform to precisely evaluate the accuracy of AoA measurements. For this purpose, a new Over-the-Air (OTA) calibration method is proposed and the array calibration error is investigated. The experimental results are compared with the theoretical analysis. These results show that array calibration errors can cause some degrees of uncertainty in AoA estimation. Moreover, we propose iterative positioning algorithms based on AoA measurements for low capacity IoT sensors with high accuracy and fair computational complexity. Efficient positioning accuracy is obtained by iterating between the angle and position estimation steps. We first develop a Data-Aided Maximum a Posteriori (DA- MAP) estimator based on the preamble of the transmitted signal. DA-MAP estimator relies on the knowledge of the transmitted signal which makes it impractical for narrowband communications where the preamble is short. For this reason, a Non-Data- Aided Maximum a Posteriori (NDA-MAP) estimator is developed to improve the AoA accuracy. The iterative positioning algorithms are therefore classified as Data-Aided Iterative (DA-It) and Non-Data-Aided Iterative (NDA-It) depending on the knowledge of the transmitted signal that is used for estimation. Both numerical and experimental analyses are carried out to evaluate the performance of the proposed algorithms. The results show that DA-MAP and NDA-MAP estimators are more accurate than MUSIC. The results also show that DA-It comes very close to the performance of the optimal approach that directly estimates the position based on the observation of the received signal, known as Direct Position Estimation (DPE). Furthermore, the NDA-It algorithm significantly outperforms the DA-It because it can use a much higher number of samples; however, it needs more iterations to converge. In addition, we evaluate the computational savings achieved by the iterative schemes compared to DPE through a detailed complexity analysis. Finally, we investigate the performance degradation of the proposed iterative algorithms due to the impact of multipath and NLOS propagation in indoor environments. Therefore, we develop an enhanced iterative positioning algorithm with an anchor selection method in order to identify and exclude NLOS anchors. The numerical results show that applying the anchor selection strategy significantly improves the positioning accuracy in indoor environments. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished

Les systèmes de localisations existants présentent des insuffisances au niveau desapplications en environnement indoor. Ces insuffisances se traduisent soit par la non-disponibilité des signaux (le GPS) dans ce type d’environnement, soit par leur manque de précision quand ils sont prévus à cet effet. Ces limites ont motivé la recherche de nouvelles techniques. Les transmissions Ultra-Large Bande (ULB) de par leur singularité en matière de précision et de faible puissance d’émission, s’avèrent être la meilleure réponse à la problématique ci-dessus. Nous avons donc choisi cette technique pour mettre au point un procédé de localisation endogène permettant d’assurer, avec précision, la continuité des services de localisation dans les environnements indoor. Ce procédé s’appuie sur la localisation en trois dimensions (3-D). Il utilise la technique temporelle de différenciation du temps d’arrivée (TDOA). Cette technique permet de mieux tirer profit de la bonne résolution temporelle de l’ULB et de pallier au problème de synchronisation entre l’émetteur et le récepteur. Deux techniques de transmission ULB ont été étudiées : la technique d’accès multiples par séquence directe (DS-CDMA) et la technique d’accès multiples par sauts temporels (TH-CDMA). Une autre étape importante de notre étude a été de développer un algorithme non-itératif de localisation en 3-D pour réduire le temps de calcul. En effet, l’utilisation d’un algorithme non-itératif permet d’optimiser les performances du système en termes de temps de calcul voire de coûts de consommation énergétique. Après l’étude théorique des différents blocs du système, le système a été tout d’abord simulé dans le canal Gaussien (AWGN) et les canaux IEEE.802.15.4a indoor. Il a été ensuite testé dans différents environnements réels de types laboratoires. Les résultats obtenus démontrent que l’utilisation des techniques de transmission basées sur la technologie radio impulsionnelle ULB permet d’obtenir un système de localisation en 3-D avec une précision centimétrique pour les applications indoor. / Existing positioning systems have deficiencies in applications indoor environment. These deficiencies result is the non-availability of signals (GPS) in this type of environment, either by their lack of precision when they are provided for this purpose. These limitations have led to research for novel techniques. Ultra-Wide Band (UWB) transmission techniques due to their uniqueness in terms of fine resolution and low power emission, prove to be the best answer to this problem. So we choose this technique to develop a process to ensure self location, with accuracy, continuity of location services in indoor environments. This method is based on the location in three dimensions (3-D). It uses the Time Difference Of Arrival (TDOA) technique. This technique allows to better take advantage of the high time resolution of the ULB and overcome the problem of synchronization between the transmitter and the receiver. Two UWB transmission techniques were studied: the Direct Sequence multiple access technique (DS-CDMA) and Time Hopping (TH-CDMA) multiple access technique. Another important step in our study was to develop a non-iterative positioning algorithm in 3-D to reduce the computation time. Indeed, using a non-iterative algorithm optimizes system performance in terms of computing time or cost of energy consumption. After the theoretical study of the system, the proposed positioning system was firstly simulated in Additive White Gaussian Noise (AWGN) channel and indoor IEEE.802.15.4a channels. It was then tested in various real environments types laboratories. The results obtained show that using UWB impulse radio technology transmission techniques allows to achieve a high accuracy 3-D location system in order of centimeter for applications in indoor environments.