Abstract
To reduce healthcare costs and improve human well-being, a promising technology known as wireless body area networks (WBANs) has recently emerged. It is comprised of various on-body as well as implanted sensors which seamlessly monitor the physiological characteristics of the human body. The information is heterogeneous in nature, requires different QoS factors. The information may be classified as delay-sensitive, reliability-sensitive, critical, and routine. On-time delivery and minimum losses are the main QoS-factors required to transmit the captured information. Various researchers have work to provide the required QoS, and some have also considered the other constraints due to the characteristics and texture of the human body. In this research work, we have discussed the communication architecture of WBANS along with the various challenges of WBANS. Furthermore, we have classified and discussed the existing QoS-aware data dissemination mechanisms. In the end, a comparative study of existing QoS-aware data dissemination mechanisms highlights the pros and cons of each mechanism.
Top1. Introduction
Rapid increase in population of elderly people living with chronic diseases is inevitable in years to come which requires round the clock monitoring of such patients (Movassaghi et al., 2013). According to World Population Ageing 2017, the worldwide elderly population (60+ aged people) is predictable to be increased from 962 million to 2100 million between 2017 & 2050 and 3100 million in 2100 (World Population Ageing, 2017). Similarly, as per report of World Health Organization (WHO), the world’s population of 60+ aged people between 2015 and 2050 will be almost doubled (12% - 22%) (World Health Organization (WHO) - Ageing and Health, 2017). Besides the people suffering from chronic diseases, the patients inside the hospital also require different level of monitoring ranging from a couple of times a day to continuous monitoring. The continuous and on-and-off health monitoring requires a huge amount of additional medical and health-care cost (World Health Organization (WHO) - Gobal Health Observatory, 2018). The aforementioned statistics ask for major change towards proactive and more affordable management to prevent or detect the diseases at an early stage (Movassaghi et al., 2014). The merger of pervasive computing, wireless sensor technologies and bio-medical engineering has led to the emergence of a promising technology called as Wireless Body Area Networks (WBANs), as shown in Figure 1. WBANs provide continuous and unsupervised vital-signs monitoring of human body. It can be utilized in various monitoring applications, such as medical assistance and health-care, sports, entertainments and rehabilitation systems.
WBANs offer the paradigm change towards proactive arrangements and early detection of the different diseases. In WBANs, with the help of various on-body, on-cloths (wearable) and/or implanted sensors (Ullah et al., 2010) like temperature1, heartbeat2, electromyography (EMG)3, pH-level4, blood pressure5, electrocardiogram (ECG)6, electroencephalogram (EEG)7, respiration rate7 data collection and analysis is performed thereby reducing the health-care cost. Such sensors are commonly known as Bio-Medical Sensor Nodes (BMSNs). Different BMSNs are shown in Figure 2 where upon sensing and locally processing, the vital signs information is further reported to a Body Coordinator (BC), located locally near the human body or on the human body.
Figure 2. (a) Wearable BMSNs (b) Implanted BMSNs and (c) Deep brain stimulator
Key Terms in this Chapter
QoS: Heterogeneous natured sensor nodes generate various kinds of data packets containing the vital-signs information and require different QoS provisions.
Temperature-Rise: Energy consumption of sensor node’s circuitry and absorption of antenna radiation are the two main factors contribute to the temperature rise issue of BMSNs fixed inside the body. This temperature rise will affect the human tissues, which are heat sensitive organs and may cause some damage to the tissues if continued for long period of time.
Inter-WBAN: It is the segment of the network where different BCs process, aggregate and forward the received vital-signs information towards the sink(s).
Data Dissemination: Data dissemination is procedure that how the generated or received data packets can be forwarded towards the destination.
Vital Signs: It the measurement of the basic functions through which the status of the human body can be evaluated such as temperature, heartbeat, electromyography (EMG), pH-level, blood pressure, electrocardiogram (ECG), electroencephalogram (EEG), respiration rate.
Routing: Routing refers to the procedure of choosing the next hop node while forwards data from one BMSN to another or sink.
Delay: Delay of a data packet is time calculated by taking the difference between the time once it is generated at the source BMSN and the time it delivered to the BC.
Path Loss: WBANs implies higher and dynamic on and in-body path loss. The reasons behind the dynamic and high path loss in WBANs are the human body’s postural movements and the in-body wireless communication (in case of implanted BMSNs).
Reliability: Reliability is the ratio of the number of data packets delivered to BC to number of data packets transmitted by the source BMSNs.
BMSNs: Bio-Medical Sensor Nodes (BMSNs) are the sensor nodes, which are fixed either with the body or inside the body.
WBANs: The merger of pervasive computing, wireless sensor technologies and bio-medical engineering has led to the emergence of a promising technology known as Wireless Body Area Networks (WBANs).
Intra-WBAN: It is the local body area network of various BMSNs where they report the sensory data of patients to the Body Coordinator (BC) which is the base station located locally.