Abstract
Biomedical wireless sensor networks enable the development of real time patient monitoring systems, either to monitor chronically ill persons in their homes or to monitor patients in step-down hospital units. However, due to the critical nature of medical data, these networks have to meet demanding quality of service requirements, ensuring high levels of confidence to their users. These goals depend on several factors, such as the characteristics of the network deployment area or the network topology. In such context, this chapter surveys the main applications of biomedical wireless sensor networks, taking into account the key quality of service requirements of each one of them. Finally, it presents an analytic method, and its experimental validation, to help engineers managing the radio power of the network nodes in order to improve the communications and the quality of service provided by the network while minimising the energy consumption and, thus, maximising the network lifetime.
TopIntroduction
Healthcare providers and professionals broadly use information and communication technologies in their daily practice. Indeed, it is practically impossible to find a healthcare service that does not use any kind of computer-based technology. The information and communication technologies become almost completely pervasive and ubiquitous. The last frontier envisioned by the research community concerns closed-loop real-time and continuous monitoring of each person’s health in every aspect of its daily life, using non-intrusive and ubiquitous technologies. Although this futuristic vision is still far from reality, some big steps are being taken in that direction. It is expected that pervasive and ubiquitous healthcare (u-health) systems, combined with wireless sensing systems like Biomedical Wireless Sensor Networks (BWSNs) and Body Sensor Networks (BSNs), contribute to change the actual healthcare practice centred in the episodic evaluation of the patients, to the continuous patient assessment, based on real-time and long-term monitoring.
BWSNs are small-sized Wireless Sensor Networks (WSNs) equipped with biomedical sensors, designed for medical applications or healthcare services. Typical applications of BWSNs include catastrophe and emergency response, Ambient Assisted Living (AAL) applications to monitor and assist disabled or elderly people, and patient monitoring systems for chronically ill persons. Among these application fields, this chapter will focus on the aspects related to the Quality of Service (QoS) guarantees requested to BWSNs by patient monitoring systems used to collect vital and physiological signs of patients in step-down hospital units of nursing homes.
Typical patient monitoring applications, supported by BWSNs, are used to collect vital or physiological signs, such as respiratory rate, pulse rate, temperature, blood pressure, and blood oxygen saturation in order to complement the measurements performed manually by nursing professionals a few times a day and thus, enhancing the quality of the health care provided to patients. The sensed data are then sent to a local or remote database to be used to support healthcare professionals in their medical practice. As an abstraction, BWSNs can be seen as a physical layer for Healthcare Information System (HIS), collecting data to support healthcare professionals in their decisions and medical diagnosis, see Figure 1.
Figure 1.
Typical applications of biomedical wireless sensor networks and their architecture
Such patient monitoring systems present several benefits to both the healthcare professionals and, mainly, the patients. They enable continuous and real-time patient monitoring, even from a remote location, facilitating the identification of emergency or dangerous situations. For those with some degree of cognitive or physical disability, these systems propel a more independent, secure and easy life, reducing the dependency on carers. Despite such benefits, BWSNs have a long way to go in order to be completely accepted by both the healthcare professionals and the patients.
In summary, BWSNs enable the development of new applications and services, bringing several benefits to the healthcare professionals and to the patients. However, to make this vision a reality they must guarantee high standards of QoS.
TopBackground
Since its beginnings, computer technologies have always been used in healthcare. They have allowed the development of novel instruments and information systems, assisting healthcare providers evaluating and tracking the health condition of their patients. More recently, wireless technologies together with small and smart sensors bring the possibility to develop distributed patient monitoring systems. Nevertheless, to be fully accepted by the healthcare stakeholders, BWSN-based patient monitoring systems must guarantee stringent QoS requirements in terms of system reliability and robustness, on-time data delivery, privacy, and security.
Key Terms in this Chapter
Wireless Sensor Network: Is a self-organised, infrastructure-less and distributed wireless network of small and very limited electronic devices called sensor nodes.
Scalability: Refers to the ability of a system to adapt itself in order to handle dynamic changes on its workload in an efficient way ( Marron et al., 2011 ).
Reliability: Is the ability of a system to perform as required under predefined conditions during a specific period.
Quality of Service: Concerns with the ability of a network to provide a data transmission service according to the client requirements.
Robustness: Refers to the capability of a system to perform as required not only under its design conditions, but also under adverse circumstances unpredicted by its designers.
Timeliness: Refers to the timing behaviour of a system.
Biomedical Wireless Sensor Network: Is a wireless sensor network equipped with biomedical sensors, designed for medical applications or healthcare services.