# A QoS Optimization Approach in Cognitive Body Area Networks for Healthcare Applications
## 2 Related Works  
WBANs have become a popular research topic in the last few years. Despite WBANs' potential uses in many fields of human life, they are not yet widely adopted and further research and development are still needed. There are many open research questions and challenges that remain to be addressed. The authors of [9] have presented a comprehensive overview of WBANs. They discussed the network architecture, sensor hardware, 802.15.6 IEEE standard layers [10] and emerging radio technologies available for WBAN applications. They also presented a taxonomy of proposed WBAN projects. They highlighted various open research challenges related to the bandwidth and energy efficient protocols, issues arising from the co-existence of WBANs with other wireless technologies and WBANs' successful integration into society. The authors in [11] have presented an overview of WBAN applications related to healthcare. They recommended various wireless technologies for WBAN medical applications; however, the non-medical aspects of WBANs were not considered and no specific details for designing a WBAN application were presented. In [12], the authors described the prospective usage of WBANs in the future health care system. In [2; 13; 12], the authors have provided extensive overviews of generic WBANs and their applications, but they fall short in addressing specific research challenges. Like with any other wireless network, interference is a major hindrance in WBANs. Interference occurs commonly if multiple WBANs are deployed next to each other in a given physical location. Inter-network interference can seriously diminish the performance of WBANs if proper interference avoidance methods are not considered. In [14], the authors presented an approach towards inter-network inference mitigation while considering the energy efficiency of WBANs. A power control algorithm was presented for interference mitigation and avoidance. The authors presented simulation results to prove their hypothesis. WBANs are like cognitive radios in the sense that they share the spectrum with other existing technologies such as Bluetooth, ZigBee, Wi-Fi, etc., [12]. In [14], the authors did not mention any interactions, either positive or negative, with other technologies which share the spectrum bands with WBANs. In [15], the authors described the convergence of cognitive radios (CR) and internet of things (IoT), i.e., an overview of how CR technology can be beneficial for various sensor network fields. There may be possibilities for WBANs to also interact with the internet directly at some tier of the communication stack. However, that paper did not present any specific system design or implementation suggestions. In addition to the internet, WBANs may also interact with other existing wireless communication technologies and standards. In [16; 17], the authors described the integration of health care system WBANs with other communication technology standards and protocols and they reviewed their aspects. The authors in [16] proposed a unified networking model for hospital scenarios combing various networking technologies. They have analyzed the basic requirements for such systems. Each networking system relies on a wired backbone network and a detailed analysis highlights how combining wired and wireless network would really give the future hospital network designers a clear picture. The authors in [17] proposed a hybrid model of WBAN data transmission and sharing. Their proposed architecture combines WBAN communication tiers with the cloud for data sharing and delivery in healthcare applications. However, including the cloud may pose some data security challenges that are now being acknowledged by this research community as a critical issue. Since WBANs operate in a traffic changing and interfering environment, many distributed WBANs can be located in the same vicinity and there could be other communication technologies (e.g., Bluetooth, ZigBee, etc.) communicating in the same spectrum bands.