One of the most rapidly growing technology areas is the advances in sensing, networking, and miniaturization in medical domain, which enables innovative new applications. This is especially apparent in e-Health and telemedicine. There is an enormous demand for innovation in wireless sensor networking, body area networks, network security and routing, and many other areas, attracting the attention of numerous researchers. With all the advances it can be challenging to identify trends and areas with opportunities for research engagement. In this paper, the authors therefore review the state-of-the-art in wireless communication used in telemedicine and e-Health applications – ranging from the Wide Area Networks to Body Area Networks – and discuss the studies and literature that employ these technologies for e-Health applications. Moreover, recent routing protocols and techniques that are used for Body Area Networks are investigated. One key challenge for e-Health applications, particularly for mobile or patient-worn devices, is energy consumption and supply. One possible solution is found in energy harvesting, and our survey encompasses current challenges and accomplishments in its application to e-Health and discuss various promising techniques.
Top1. Introduction
Wireless communication technologies and standards have seen a steadily accelerating growth, especially over the last decade. This allows them to be applied to various domains that were previously not feasible. E-Health and telemedicine are two areas at the forefront of this development that take full advantage of current wireless communication technologies to provide emergency and on-demand medical services, enable outpatient monitoring and treatment, aid in patient recovery, directly connect doctors and nursing staff with patients, and much more.
Employing diverse wireless communication standards in healthcare contributes to patient monitoring and diagnosis of the health concerns remotely, and in real-time. This provides the means to revolutionize the speed and accuracy of offering healthcare services in all aspects of our lives, especially when medical personnel are not locally available. The overall view of the end-to-end e-Health wireless technologies are presented in Figure 1.
Figure 1. End-to-end view of a typical e-health topology
The contribution of the wireless communication standards in e-Health currently culminates with Body Area Networks, enabled through advances in device miniaturization, drastic improvements in energy efficiency in hardware and optimization in software, as well as novel communication technologies. Body Area Networks (BAN) leverage support for ultra-low power short-range communication of sensor nodes placed in different locations of a patient’s body. These sensors collect biosignals, defined as the collection of all measurable data from a biological being. These biosignals are delivered to medium-range gateways via Local Area Network technologies that interface with the Body Area Network to collect the information from the sensor nodes and transfer it to local monitoring centers. This information can then further be relayed to medical centers or hospitals via Wide Area Networks.
With the rapid advances in healthcare technology we can observe a corresponding exponential growth in data volume produced by a plethora of medical sensors such as high-resolution Magnetic Resonance Imaging (MRI) or Computed Tomography (CT) scans, live multi-lead Electrocardiogram (ECG) data, and more. Therefore, the wireless communication standards that are involved in e-Health and telemedicine applications need to support increasingly higher data rates, as well as low latency data transmission. The reliability and robustness of the wireless link is also an important aspect, particularly for real time and emergency healthcare services.
This results in the demand for advanced routing techniques and protocols in Body Area Networks, in order to be able to reliably and expediently acquire and deliver critical information from the patient’s body. In fact, reliable routing techniques are among the most critical demands in e-Health applications due to the fact that erroneous or missing biosignals and medical data can lead to mis-diagnosed ailments, which can potentially lead to the loss of a patient’s life.
However, many approaches that successfully address the demand for reliable routing in turn suffer from an increase in energy consumption and thus degradation in network lifetime. Owing to the fact that sensor nodes in body area networks are placed on a patient’s body, the utilization of large batteries for energy storage is simply not feasible. These leads to critical research in both improving energy efficiency of hardware and software, as well as the innovative application of energy harvesting to replenish power reserves over time from the environment.