# A QoS Optimization Approach in Cognitive Body Area Networks for Healthcare Applications
## 1 Introduction  
Recent advances in electronics and system on chip design have given birth to a new era of wireless communication systems. Intelligent and low powered devices enable building small and miniaturized wireless networks to help and improve human life, including among other things, wireless body area networks (WBANs). A WBAN is a combination of ultra-low powered, programmable miniaturized sensor nodes combined with wireless radio communication capabilities used to monitor the human body and its physiological features, e.g., heart rate, blood pressure, temperature, etc., using either invasive, or preferably, non-invasive sensors [1; 2; 3]. WBANs are touted as one of the key technologies foreseen to help dealing with the challenges found in many healthcare systems around the world. Indeed, current healthcare facilities are facing huge challenges from the growing elderly population and limited human and financial resources. In the USA alone, from 1960 to 2010, life expectancy increased on average by 13.5% [4]. The population aged 60-80 years will have doubled by 2050 (from 33 million to 81 million people) [5]. It is expected that this huge increase will overload the healthcare system and overall quality of life will be affected. Let us consider a patient who has to visit a doctor for a routine blood pressure and temperature check; for this, he/she has to travel to the health facilities. This is costly in terms of time and money and overloads the healthcare system; there are more urgent health issues and cases that must be taken care of by health practitioners. To avoid such situations, a remote system can enable the persons to send information about their health status to health care givens from their homes and thus they do not needto get out from their comfort zone just to do routine monitoring. This will both greatly benefit the overall health care system and quality of life in general. A WBAN allows the integration of intelligent small sensor nodes in, on, or around the human body to monitor the human vital signs. The miniature devices are basically small radios that can collect data through their sensors and transmit them to a central node or a master node. This central node can be linked to a backend network where, upon reception, the patients' data can be analyzed for diagnosis and prescriptions. Generally, a WBAN can consist of in-body and/or on-body area networks. An in-body area network allows communication between invasive or implanted sensor nodes to a base station. An on-body area network, on the other hand, allows communication between a non-invasive or wearable sensory device to a base station. Since human tissues are being monitored, the devices used in WBAN have to build upon ultra-low power radio transmitters so as to avoid any adverse effects on the human health. In this paper, we focus solely on on-body area networks where single or multiple sensors are attached or fitted to a person. A key idea is that instead of having all the on-body sensors transmitting to the base station individually, a central on-body node is used as an intermediate hub and receives all the sensors' data and transmit them to the base station. From here onwards, we will refer to such a sensing device as the node which is routing all the sensors' data to the base station. The base station itself will be referred to as gateway from here onwards. Although wireless sensor networks in general are not new per se, their design and capabilities are continuously evolving, including the adoption (and adaptation) of certain cognitive elements previously developed for cognitive radios [6; 7] either for resource allocation (frequency, power, etc.) and/or signal processing and data analytics. Cognitive capabilities can be exploited in smart routing and provide the ability to foresee any changes in the routing path [8]. Such a trend is also being applied to WBANs and result in what we term cognitive body area network (C-BAN).