Low-cost indoor localization system combining multilateration and Kalman filter

Indoor localization systems play an important role to track objects during their life-cycle in indoor environments, e.g., related to retail, logistics and mobile robotics. These positioning systems use several techniques and technologies to estimate the position of each object, and face several requirements such as position accuracy, security, range of coverage, energy consumption and cost. This paper describes a practical implementation of a BLE (Bluetooth Low Energy) based localization system that combines multilateration and Kalman filter techniques to achieve a low cost solution, maintaining a good position accuracy. The proposed approach was experimentally tested in an indoor environment, with the achieved results showing a clear low cost system presenting an increase of the estimated position accuracy by 10% for an average error of 2.33 metersThis work has been supported by FCT – Fundação para a Ciência e Tecnologia within the Project Scope UIDB/05757/2020.info:eu-repo/semantics/publishedVersio

Energy efficiency-spectral efficiency trade-off of transmit antenna selection

We investigate the energy efficiency-spectral efficiency (EE-SE) trade-off of transmit antenna selection/maximum ratio combining (TAS) scheme. A realistic power consumption model (PCM) is considered, and it is shown that using TAS can provide significant energy savings when compared to multiple-input multiple-output (MIMO) in the low to medium SE region, regardless the number of antennas, as well as outperform transmit beamforming scheme (MRT) for the entire SE range. For a fixed number of receive antennas, our results also show that the EE gain of TAS over MIMO becomes even greater as the number of transmit antennas increases. The optimal value of SE that maximizes the EE is obtained analytically, and confirmed by numerical results. Moreover, the influence of receiver correlation is also evaluated and it is shown that considering a non-realistic PCM can lead to mistakes when comparing TAS and MIMO

On the Area Energy Efficiency of Multiple Transmit Antenna Small Base Stations

We analyze the area energy efficiency (AEE) of spatial multiplexing (SM) and transmit antenna selection (TAS), considering a realistic power consumption model for small base stations (BSs), which includes the power consumed by the backhaul as well as different interference attenuation levels. Our results show an optimum number of BSs for each technique that maximizes the AEE. Moreover, we also show that TAS has a larger AEE than SM when the demand for system capacity is low, while SM becomes more energy efficient when the demanded capacity is larger. Additionally, when the capacity demand and the area to be covered are fixed, the number of BSs needed to be deployed is smaller for SM than for the other techniques. Finally, the system performance in terms of AEE is shown to be strongly dependent on the amount of interference, which in turn depends on the employed interference-mitigation scheme, and on the employed power consumption model

Energy efficiency of multiple antenna cellular networks considering a realistic power consumption model

We analyze the area energy efficiency (AEE) of a cellular network employing spatial multiplexing (SM), maximal ratio transmission (MRT) and transmit antenna selection (TAS) schemes. Moreover, we consider a realistic power consumption model for small base stations (BSs), which includes the power consumed by the backhaul as well as different interference attenuation levels. Our goal is to maximize the AEE by deploying the optimal number of BSs given some requirements, such as demanded network capacity, amount of interference and employed MIMO scheme. Results show that TAS performs better in terms of AEE when the interference is not fully canceled and for no interference cancellation when the demand for system capacity is lower, while SM becomes more energy efficient when the demanded capacity is higher. Additionally, when the capacity demand and the area to be covered are fixed, we show that although achieving the highest AEE, TAS also demands more small BSs than SM. The system performance in terms of AEE is shown to be strongly dependent on the amount of interference, which in turn depends on the employed interference-mitigation scheme and on the power consumption model

Relação de troca entre eficiência energética e eficiência espectral em redes de comunicação sem fio com múltiplas antenas

In this dissertation, we investigate the Energy Efficiency-Spectral Efficiency (EE-SE) trade- off of a multiple antenna wireless communication system employing Transmit Antenna Selection/Maximum Ratio Combining (TAS) scheme. A realistic power consumption model (PCM) is considered, and it is shown that the use of TAS/MRC can provide significant energy savings when compared to Multiple-Input Multiple-Output (MIMO) in the low to medium spectral efficiency region, regardless the number of antennas, as well as outperform transmit beamforming scheme (MRT) for the entire spectral efficiency range. For a fixed number of receive antennas, our results also show that the energy efficiency gain of TAS over MIMO becomes even greater as the number of transmit antennas increases. The optimal value of spectral efficiency that maximizes the energy efficiency is obtained analytically, and confirmed by numerical results. Expressions that evaluate the capacity and the EE-SE trade-off for TAS under the influence of receiver correlation are obtained and it is shown that considering a non- realistic power consumption model can lead to mistakes when comparing TAS and MIMO.CAPESNesta tese, a relação de troca entre Eficiência Espectral e Eficiência Energética (EE-SE, do inglês Energy Efficiency-Spectral Efficiency) de um sistema de comunicação sem fio com múltiplas antenas empregando Seleção de Antena de Transmissão/Combinação de Máxima Razão (TAS/MRC, do inglês Transmit Antenna Selection/Maximum Ratio Combining) é investigada. Um modelo de consumo (PCM, do inglês Power Consumption Model) realista é considerado e demonstra-se que utilizar o esquema TAS/MRC pode promover economia de energia significativa quando comparada ao esquema Múltiplas Antenas de Transmissão/Recepção (MIMO, do inglês Multiple-Input Multiple-Output) na região de baixa para média eficiência espectral, independentemente do número de antenas, assim como possuir melhor desempenho energético em relação à utilização do esquema Combinação de Máxima Razão na Transmissão (MRT, do inglês Maximum Ratio Transmission) para qualquer valor de eficiência espectral. Para um número fixo de antenas, resultados obtidos demonstram que o ganho em eficiência energética do TAS/MRC sobre o MIMO se torna ainda maior com o aumento do número de antenas transmissoras. O valor ótimo de eficiência espectral que maximiza a eficiência energética é obtido analiticamente e comprovado por resultados numéricos. Expressões para avaliar a capacidade e a relação EE-SE do TAS sob a influência de correlação entre as antenas do receptor são obtidas e se demonstra que considerar um modelo de consumo não realista pode levar a equívocos na comparação entre TAS/MRC e MIMO

Análise da eficiência energética de codificação de rede aplicada a redes cooperativas

In this dissertation, an energy efficiency analysis of wireless systems is performed, comparing several schemes, from the direct transmission between two nodes, going through cooperative networks, where multiple nodes have independent information to send to a common destination, and getting to the most advanced network-coded cooperative systems. It is intended to evaluate the gain generated by the error rate reduction (caused by the network coding) and by the increase in the diversity order (provided by the cooperation between the nodes) in terms of the energy consumption reduction when transmitting the same amount of information. The analysis is performed considering Nakagami-m block fading, so the influence of some line-of-sight is also evaluated. Through the outage probability equations and a hardware model, energy consumption expressions for each scenario were obtained. Furthermore, through the graphical analysis of the numeric results, it was possible to notice that exists an optimal number of nodes that minimizes the energy consumption of the Generalized Dynamic Network Coding (GDNC) scheme for a given distance. An expression that represents this number was also obtained, and is the great contribution of this work, since if in the network project smaller sets containing the optimal number of nodes (called cooperation clusters) are organized, the energy consumption will be minimized. These results are also presented, and for the considered configuration, the energy saving can reach 10x.Nesta dissertação, uma análise da eficiência energética de transmissão de dados sem fio é efetuada, comparando desde a simples transmissão direta entre dois nós, passando por redes cooperativas, onde múltiplos nós possuem informações independentes para enviar para um destino em comum, chegando aos mais avançados esquemas de cooperação com codificação de rede. O objetivo é verificar os benefícios gerados pela diminuição da taxa de erro (ocasionada pela codificação de rede) e do aumento da ordem de diversidade (proporcionado pela cooperação entre os nós) em termos de diminuição do consumo energético para transmissão de uma mesma quantidade de informação. A análise é realizada considerando desvanecimento em bloco Nakagami-m, de forma que o efeito da presença de linha de visada também possa ser avaliado. Através das equações de probabilidade de outage e de um modelo de hardware, expressões que representam o consumo energético de cada cenário foram obtidas. Além disto, a partir da análise gráfica dos resultados obtidos, foi possível perceber que existe um número ótimo de nós que minimiza o consumo energético da Codificação de Rede Dinâmica Generalizada (GDNC) para uma dada distância. Uma expressão que representa esse número foi obtida, e é a maior contribuição deste trabalho, pois se no projeto da rede sem fio cooperativa conjuntos menores contendo o número ótimo de nós (chamados de clusters de cooperação) forem organizados, o consumo energético da rede será minimizado. Estes resultados também são apresentados e, para as configurações utilizadas, a economia de energia pode ser de até 10x