727 research outputs found
Evaluation, Modeling and Optimization of Coverage Enhancement Methods of NB-IoT
Narrowband Internet of Things (NB-IoT) is a new Low Power Wide Area Network
(LPWAN) technology released by 3GPP. The primary goals of NB-IoT are improved
coverage, massive capacity, low cost, and long battery life. In order to
improve coverage, NB-IoT has promising solutions, such as increasing
transmission repetitions, decreasing bandwidth, and adapting the Modulation and
Coding Scheme (MCS). In this paper, we present an implementation of coverage
enhancement features of NB-IoT in NS-3, an end-to-end network simulator. The
resource allocation and link adaptation in NS-3 are modified to comply with the
new features of NB-IoT. Using the developed simulation framework, the influence
of the new features on network reliability and latency is evaluated.
Furthermore, an optimal hybrid link adaptation strategy based on all three
features is proposed. To achieve this, we formulate an optimization problem
that has an objective function based on latency, and constraint based on the
Signal to Noise Ratio (SNR). Then, we propose several algorithms to minimize
latency and compare them with respect to accuracy and speed. The best hybrid
solution is chosen and implemented in the NS-3 simulator by which the latency
formulation is verified. The numerical results show that the proposed
optimization algorithm for hybrid link adaptation is eight times faster than
the exhaustive search approach and yields similar latency
Efficient vertical handover in heterogeneous low-power wide-area networks
As the Internet of Things (IoT) continues to expand, the need to combine communication technologies to cope with the limitations of one another and to support more diverse requirements will proceed to increase. Consequently, we started to see IoT devices being equipped with multiple radio technologies to connect to different networks over time. However, the detection of the available radio technologies in an energy-efficient way for devices with limited battery capacity and processing power has not yet been investigated. As this is not a straightforward task, a novel approach in such heterogeneous networks is required. This article analyzes different low-power wide-area network technologies and how they can be integrated in such a heterogeneous system. Our contributions are threefold. First, an optimal protocol stack for a constrained device with access to multiple communication technologies is put forward to hide the underlying complexity for the application layer. Next, the architecture to hide the complexity of a heterogeneous network is presented. Finally, it is demonstrated how devices with limited processing power and battery capacity can have access to higher bandwidth networks combined with longer range networks and on top are able to save energy compared to their homogeneous counterparts, by measuring the impact of the novel vertical handover algorithm
On the Fundamental Limits of Random Non-orthogonal Multiple Access in Cellular Massive IoT
Machine-to-machine (M2M) constitutes the communication paradigm at the basis
of Internet of Things (IoT) vision. M2M solutions allow billions of multi-role
devices to communicate with each other or with the underlying data transport
infrastructure without, or with minimal, human intervention. Current solutions
for wireless transmissions originally designed for human-based applications
thus require a substantial shift to cope with the capacity issues in managing a
huge amount of M2M devices. In this paper, we consider the multiple access
techniques as promising solutions to support a large number of devices in
cellular systems with limited radio resources. We focus on non-orthogonal
multiple access (NOMA) where, with the aim to increase the channel efficiency,
the devices share the same radio resources for their data transmission. This
has been shown to provide optimal throughput from an information theoretic
point of view.We consider a realistic system model and characterise the system
performance in terms of throughput and energy efficiency in a NOMA scenario
with a random packet arrival model, where we also derive the stability
condition for the system to guarantee the performance.Comment: To appear in IEEE JSAC Special Issue on Non-Orthogonal Multiple
Access for 5G System
Modeling and Analysis of Data Trading on Blockchain-based Market in IoT Networks
Mobile devices with embedded sensors for data collection and environmental
sensing create a basis for a cost-effective approach for data trading. For
example, these data can be related to pollution and gas emissions, which can be
used to check the compliance with national and international regulations. The
current approach for IoT data trading relies on a centralized third-party
entity to negotiate between data consumers and data providers, which is
inefficient and insecure on a large scale. In comparison, a decentralized
approach based on distributed ledger technologies (DLT) enables data trading
while ensuring trust, security, and privacy. However, due to the lack of
understanding of the communication efficiency between sellers and buyers, there
is still a significant gap in benchmarking the data trading protocols in IoT
environments. Motivated by this knowledge gap, we introduce a model for
DLT-based IoT data trading over the Narrowband Internet of Things (NB-IoT)
system, intended to support massive environmental sensing. We characterize the
communication efficiency of three basic DLT-based IoT data trading protocols
via NB-IoT connectivity in terms of latency and energy consumption. The model
and analyses of these protocols provide a benchmark for IoT data trading
applications.Comment: 10 pages, 8 figures, Accepted at IEEE Internet of Things Journa
A Modelling and Experimental Framework for Battery Lifetime Estimation in NB-IoT and LTE-M
To enable large-scale Internet of Things (IoT) deployment, Low-power
wide-area networking (LPWAN) has attracted a lot of research attention with the
design objectives of low-power consumption, wide-area coverage, and low cost.
In particular, long battery lifetime is central to these technologies since
many of the IoT devices will be deployed in hard-toaccess locations. Prediction
of the battery lifetime depends on the accurate modelling of power consumption.
This paper presents detailed power consumption models for two cellular IoT
technologies: Narrowband Internet of Things (NB-IoT) and Long Term Evolution
for Machines (LTE-M). A comprehensive power consumption model based on User
Equipment (UE) states and procedures for device battery lifetime estimation is
presented. An IoT device power measurement testbed has been setup and the
proposed model has been validated via measurements with different coverage
scenarios and traffic configurations, achieving the modelling inaccuracy within
5%. The resulting estimated battery lifetime is promising, showing that the
10-year battery lifetime requirement specified by 3GPP can be met with proper
configuration of traffic profile, transmission, and network parameters.Comment: submitted to IEEE Internet of Things Journal, 12 pages, 10 figure
Modelaçcão comportamental da camada física NB-IoT - Uplink
Mestrado em Engenharia Eletrónica e TelecomunicaçõesA Internet das Coisas (IoT) consiste numa rede sem fios de sensores/atuadores
ligados entre si e que têm a capacidade de recolher dados. Devido
ao crescimento rápido do mercado IoT, as redes de longa distância e baixa
potência (LPWAN) tornaram-se populares. O NarrowBand-IoT (NB-IoT),
desenvolvido pela 3rd Generation Partnership Project (3GPP), é um desses
protocolos.
O principal objectivo desta dissertação é a implementação de uma simulação
comportamental em MATLAB do NB-IoT no uplink, que será disponibilizada
abertamente. Esta será focada, primariamente, na camada física e nas
suas respetivas funcionalidades, nomeadamente turbo coding, modulação
SC-FDMA, modelos de simulação de canal, desmodulação SC-FDMA, estimação de canal, equalizador e turbo decoding. A estimação de canal é
feita usando símbolos piloto previamente conhecidos. Os modelos de canal
utilizados são baseados nas especificações oficiais da 3GPP.
A taxa de bits errados (BER) é calculada e usada de forma a avaliar a performance
do turbo encoder e do equalizador zero forcing (ZF). Serve também
como comparação quando a implementação usa esquemas de modulação
diferentes (Binary Phase-Shift Keying (BPSK) e Quadrature Phase-Shift
Keying (QPSK)). Além disso, os sinais gerados em MATLAB são transmitidos
usando como front-end de radio-frequência (RF) uma Universal
Software Radio Peripheral (USRP). Posteriormente, são recebidos, desmodulados
e descodificados. Finalmente, é obtida a constelação do sinal, a BER
é calculada e os resultados são analisados.The Internet of Things (IoT) refers to a wireless network of interconnected
sensors/actuators with data-collecting technologies. Low Power Wide Area
Networks (LPWAN) have become popular due to the rapid growth of the
IoT market. Narrowband-IoT (NB-IoT), developed by 3rd Generation Partnership
Project (3GPP), is one of these protocols.
The main objective of this thesis is the implementation of an open-source uplink
behavioral simulator based on MATLAB. Its focus is primarily on Layer 1
(physical layer) relevant functionalities, namely turbo coding, Single-Carrier
Frequency-Division Multiple Access (SC-FDMA) modulation, channel modeling,
SC-FDMA demodulation, channel estimation, equalization and turbo
decoding. Channel estimation is performed using known pilot symbols. The
used channel models are based on the 3GPP o cial release specs.
The Bit Error Rate (BER) is calculated in order to evaluate the turbo encoder
and the Zero Forcing (ZF) equalizer performance, and to compare
Binary Phase-Shift Keying (BPSK) and Quadrature Phase-Shift Keying
(QPSK) implementations. Furthermore, the MATLAB generated signal is
transmitted using a radio-frequency (RF) front-end consisting of an Universal
Software Radio Peripheral (USRP). Afterwards, the signal is received,
demodulated and decoded. A constellation is obtained, the BER is calculated
and the results are analyzed
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