153 research outputs found
A comprehensive survey of wireless body area networks on PHY, MAC, and network layers solutions
Recent advances in microelectronics and integrated circuits, system-on-chip design, wireless communication and intelligent low-power sensors have allowed the realization of a Wireless Body Area Network (WBAN). A WBAN is a collection of low-power, miniaturized, invasive/non-invasive lightweight wireless sensor nodes that monitor the human body functions and the surrounding environment. In addition, it supports a number of innovative and interesting applications such as ubiquitous healthcare, entertainment, interactive gaming, and military applications. In this paper, the fundamental mechanisms of WBAN including architecture and topology, wireless implant communication, low-power Medium Access Control (MAC) and routing protocols are reviewed. A comprehensive study of the proposed technologies for WBAN at Physical (PHY), MAC, and Network layers is presented and many useful solutions are discussed for each layer. Finally, numerous WBAN applications are highlighted
Wireless body sensor networks for health-monitoring applications
This is an author-created, un-copyedited version of an article accepted for publication in
Physiological Measurement. The publisher is
not responsible for any errors or omissions in this version of the manuscript or any version
derived from it. The Version of Record is available online at http://dx.doi.org/10.1088/0967-3334/29/11/R01
A MAC protocol for quality of service provisioning in adaptive biomedical wireless sensor networks
Doctorate program on Electronics and Computer EngineeringNew healthcare solutions are being explored to improve the quality of care and the
quality of life of patients, as well as the sustainability and efficiency of the healthcare
services. In this context, wireless sensor networks (WSNs) constitute a key technology
for closing the loop between patients and healthcare providers, as WSNs provide
sensing ability, as well as mobility and portability, essential characteristics for wide
acceptance of wireless healthcare technology.
Despite the recent advances in the field, the wide adoption of healthcare WSNs is still
conditioned by quality of service (QoS) issues, namely at the medium access control
(MAC) level. MAC protocols currently available for WSNs are not able to provide the
required QoS to healthcare applications in scenarios of medical emergency or intensive
medical care. To cover this shortage, the present work introduces a MAC protocol with
novel concepts to assure the required QoS regarding the data transmission robustness,
packet delivery deadline, bandwidth efficiency, and energy preservation. The proposed
MAC protocol provides a new and efficient dynamic reconfiguration mechanism, so
that relevant operational parameters may be redefined dynamically in accordance with
the patientsâ clinical state. The protocol also provides a channel switching mechanism
and the capacity of forwarding frames in two-tier network structures.
To test the performance of the proposed MAC protocol and compare it with other
MAC protocols, a simulation platform was implemented. In order to validate the
simulation results, a physical testbed was implemented to replicate the tests and verify
the results. Sensor nodes were specifically designed and assembled to implement this
physical testbed. New healthcare solutions are being explored to improve the quality of care and the
quality of life of patients, as well as the sustainability and efficiency of the healthcare
services. In this context, wireless sensor networks (WSNs) constitute a key technology
for closing the loop between patients and healthcare providers, as WSNs provide
sensing ability, as well as mobility and portability, essential characteristics for wide
acceptance of wireless healthcare technology.
Despite the recent advances in the field, the wide adoption of healthcare WSNs is still
conditioned by quality of service (QoS) issues, namely at the medium access control
(MAC) level. MAC protocols currently available for WSNs are not able to provide the
required QoS to healthcare applications in scenarios of medical emergency or intensive
medical care. To cover this shortage, the present work introduces a MAC protocol with
novel concepts to assure the required QoS regarding the data transmission robustness,
packet delivery deadline, bandwidth efficiency, and energy preservation. The proposed
MAC protocol provides a new and efficient dynamic reconfiguration mechanism, so
that relevant operational parameters may be redefined dynamically in accordance with
the patientsâ clinical state. The protocol also provides a channel switching mechanism
and the capacity of forwarding frames in two-tier network structures.
To test the performance of the proposed MAC protocol and compare it with other
MAC protocols, a simulation platform was implemented. In order to validate the
simulation results, a physical testbed was implemented to replicate the tests and verify
the results. Sensor nodes were specifically designed and assembled to implement this
physical testbed. Preliminary tests using the simulation and physical platforms showed that simulation
results diverge significantly from reality, if the performance of the WSN software
components is not considered. Therefore, a parametric model was developed to reflect
the impact of this aspect on a physical WSN. Simulation tests using the parametric
model revealed that the results match satisfactorily those obtained in reality.
After validating the simulation platform, comparative tests against IEEE 802.15.4, a
prominent standard used in many wireless healthcare systems, showed that the proposed
MAC protocol leads to a performance increase regarding diverse QoS metrics, such as
packet loss and bandwidth efficiency, as well as scalability, adaptability, and power
consumption. In this way, AR-MAC is a valuable contribution to the deployment of
wireless e-health technology and related applications.Novas soluçÔes de cuidados de saĂșde estĂŁo a ser exploradas para melhorar a qualidade
de tratamento e a qualidade de vida dos pacientes, assim como a sustentabilidade e
eficiĂȘncia dos serviços de cuidado de saĂșde. Neste contexto, as redes de sensores sem
fios (wireless sensor networks - WSN) sĂŁo uma tecnologia chave para fecharem o ciclo
entre os pacientes e os prestadores de cuidados de saĂșde, uma vez que as WSNs
proporcionam não só capacidade sensorial mas também mobilidade e portabilidade,
caracteristicas essenciais para a aceitação à larga escala da tecnologia dos cuidados de
saĂșde sem fios.
Apesar dos avanços recentes na årea, a aceitação genérica das WSNs de cuidados de
saĂșde ainda estĂĄ condicionada por aspectos relacionados com a qualidade de serviço
(quality of service - QoS), nomeadamente ao nĂvel do controlo de acesso ao meio
(medium access control - MAC). Os protocolos MAC actualmente disponĂveis para
WSNs são incapazes de fornecer a QoS desejada pelas aplicaçÔes médicas em cenårios
de emergĂȘncia ou cuidados mĂ©dicos intensivos. Para suprimir esta carĂȘncia, o presente
trabalho apresenta um protocolo MAC com novos conceitos a fim de assegurar a QoS
respeitante Ă robustez de transmissĂŁo de dados, ao limite temporal da entrega de
pacotes, à utilização da largura de banda e à preservação da energia eléctrica. O
protocolo MAC proposto dispÔe de um novo e eficiente mecanismo de reconfiguração
para que os parĂąmetros operacionais relevantes possam ser redefinidos dinamicamente
de acordo com o estado de saĂșde do paciente. O protocolo tambĂ©m oferece um
mecanismo autónomo de comutação de canal, bem como a capacidade de encaminhar
pacotes em redes de duas camadas.
Para testar o desempenho do protocolo MAC proposto e comparĂĄ-lo com outros
protocolos MAC foi implementada uma plataforma de simulação. A fim de validar os
resultados da simulação foi tambĂ©m implementada uma plataforma fĂsica para permitir
replicar os testes e verificar os resultados. Esta plataforma fĂsica inclui nĂłs sensoriais
concebidos e construĂdos de raiz para o efeito. Testes preliminares usando as plataformas de simulação e fĂsica mostraram que os
resultados de simulação divergem significativamente da realidade, caso o desempenho
dos componentes do software presentes nos componentes da WSN nĂŁo seja
considerado. Por conseguinte, desenvolveu-se um modelo paramétrico para reflectir o
impacto deste aspecto numa WSN real. Testes de simulação efectuados com o modelo
paramétrico apresentaram resultados muito satisfatórios quando comparados com os
obtidos na realidade.
Uma vez validada a plataforma de simulação, efectuaram-se testes comparativos com
a norma IEEE 802.15.4, proeminentemente usada em projectos académicos de cuidados
de saĂșde sem fios. Os resultados mostraram que o protocolo MAC conduz a um
desempenho superior no tocante a diversas métricas QoS, tais como perdas de pacotes e
utilização de largura de banda, bem como no respeitante à escalabilidade,
adaptabilidade e consumo de energia eléctrica. Assim sendo, o protocolo MAC proposto
representa um valioso contributo para a concretização efectiva dos cuidados de saĂșde
sem fios e suas aplicaçÔes
A Speculative Study on 6G
While 5G is being tested worldwide and anticipated to be rolled out gradually
in 2019, researchers around the world are beginning to turn their attention to
what 6G might be in 10+ years time, and there are already initiatives in
various countries focusing on the research of possible 6G technologies. This
article aims to extend the vision of 5G to more ambitious scenarios in a more
distant future and speculates on the visionary technologies that could provide
the step changes needed for enabling 6G.Comment: This work has been submitted to the IEEE for possible publication.
Copyright may be transferred without notice, after which this version mayno
longer be accessibl
Innovative energy-efficient wireless sensor network applications and MAC sub-layer protocols employing RTS-CTS with packet concatenation
of energy-efficiency as well as the number of available applications. As a consequence there
are challenges that need to be tackled for the future generation of WSNs. The research work
from this Ph.D. thesis has involved the actual development of innovative WSN applications contributing
to different research projects. In the Smart-Clothing project contributions have been
given in the development of a Wireless Body Area Network (WBAN) to monitor the foetal movements
of a pregnant woman in the last four weeks of pregnancy. The creation of an automatic
wireless measurement system for remotely monitoring concrete structures was an contribution
for the INSYSM project. This was accomplished by using an IEEE 802.15.4 network enabling for
remotely monitoring the temperature and humidity within civil engineering structures. In the
framework of the PROENEGY-WSN project contributions have been given in the identification
the spectrum opportunities for Radio Frequency (RF) energy harvesting through power density
measurements from 350 MHz to 3 GHz. The design of the circuits to harvest RF energy
and the requirements needed for creating a WBAN with electromagnetic energy harvesting and
Cognitive Radio (CR) capabilities have also been addressed. A performance evaluation of the
state-of-the art of the hardware WSN platforms has also been addressed. This is explained by
the fact that, even by using optimized Medium Access Control (MAC) protocols, if the WSNs
platforms do not allow for minimizing the energy consumption in the idle and sleeping states,
energy efficiency and long network lifetime will not be achieved.
The research also involved the development of new innovative mechanisms that tries and solves
overhead, one of the fundamental reasons for the IEEE 802.15.4 standard MAC inefficiency. In
particular, this Ph.D. thesis proposes an IEEE 802.15.4 MAC layer performance enhancement by
employing RTS/CTS combined with packet concatenation. The results have shown that the use
of the RTS/CTS mechanism improves channel efficiency by decreasing the deferral time before
transmitting a data packet. In addition, the Sensor Block Acknowledgment MAC (SBACK-MAC)
protocol has been proposed that allows the aggregation of several acknowledgment responses
in one special Block Acknowledgment (BACK) Response packet. Two different solutions are
considered. The first one considers the SBACK-MAC protocol in the presence of BACK Request
(concatenation) while the second one considers the SBACK-MAC in the absence of BACK Request
(piggyback). The proposed solutions address a distributed scenario with single-destination and
single-rate frame aggregation. The throughput and delay performance is mathematically derived
under both ideal conditions (a channel environment with no transmission errors) and non
ideal conditions (a channel environment with transmission errors). An analytical model is proposed,
capable of taking into account the retransmission delays and the maximum number of
backoff stages. The simulation results successfully validate our analytical model. For more
than 7 TX (aggregated packets) all the MAC sub-layer protocols employing RTS/CTS with packet
concatenation allows for the optimization of channel use in WSNs, v8-48 % improvement in the
maximum average throughput and minimum average delay, and decrease energy consumption
Experimental Demonstration of Coexistence of Microwave Wireless Communication and Power Transfer Technologies for Battery-Free Sensor Network Systems
This paper describes experimental demonstrations of a wireless power transfer system equipped with a microwave band communication function. Battery charging using the system is described to evaluate the possibility of the coexistence of both wireless power transfer and communication functions in the C-band. A battery-free wireless sensor network system is demonstrated, and a high-power rectifier for the system is also designed and evaluated in the S-band. We have confirmed that microwave wireless power transfer can coexist with communication function
Wireless sensor network for health monitoring
Wireless Sensor Network (WSN) is becoming a significant enabling technology for a wide variety of applications. Recent advances in WSN have facilitated the realization of pervasive health monitoring for both homecare and hospital environments. Current technological advances in sensors, power-efficient integrated circuits, and wireless communication have allowed the development of miniature, lightweight, low-cost, and smart physiological sensor nodes. These nodes are capable of sensing, processing, and communicating one or more vital signs. Furthermore, they can be used in wireless personal area networks (WPANs) or wireless body sensor networks (WBSNs) for health monitoring. Many studies were performed and/or are under way in order to develop flexible, reliable, secure, real-time, and power-efficient WBSNs suitable for healthcare applications. To efficiently control and monitor a patientâs status as well as to reduce the cost of power and maintenance, IEEE 802.15.4/ZigBee, a communication standard for low-power wireless communication, is developed as a new efficient technology in health monitoring systems. The main contribution of this dissertation is to provide a modeling, analysis, and design framework for WSN health monitoring systems. This dissertation describes the applications of wireless sensor networks in the healthcare area and discusses the related issues and challenges. The main goal of this study is to evaluate the acceptance of the current wireless standard for enabling WSNs for healthcare monitoring in real environment. Its focus is on IEEE 802.15.4/ZigBee protocols combined with hardware and software platforms. Especially, it focuses on Carrier Sense Multiple Access with Collision Avoidance mechanism (CSMA/CA) algorithms for reliable communication in multiple accessing networks. The performance analysis metrics are established through measured data and mathematical analysis.
This dissertation evaluates the network performance of the IEEE 802.15.4 unslotted CSMA/CA mechanism for different parameter settings through analytical modeling and simulation. For this protocol, a Markov chain model is used to derive the analytical expression of normalized packet transmission, reliability, channel access delay, and energy consumption. This model is used to describe the stochastic behavior of random access and deterministic behavior of IEEE 802.15.4 CSMA/CA. By using it, the different aspects of health monitoring can be analyzed. The sound transmission of heart beat with other smaller data packet transmission is studied. The obtained theoretical analysis and simulation results can be used to estimate and design the high performance health monitoring systems
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