## 1 Introduction  
The development of Wireless Body Area Network (WBAN) technology made the sensing and communication of various medical and non-medical signal applications easier, as shown in Figure 1. The authors [1] have initiated the need for an inexpensive monitoring device and a secure communication system for monitoring at the doctor's end. Devices such as wearable Electro Cardi Gram (ECG), Electromyography (EMG), Electroencephalography (EEG), Blood Pressure (BP),Oxygen Saturation (SpO2), and temperature monitor the subject and collect the data. This vital information is communicated through an open wireless channel to the doctor's programming device on demand or on a daily basis. The communication of these signals is made through dedicated frequencies such as Wireless Medical Telemetry Services (WMTS), unlicensed Industrial Scientific and Medical (ISM) Band, Ultra-Wide Band, and Medical Implanted Communication services (MICS) band for bio-medical signal transmission. These Implantable Medical Devices (IMDs) are invasive to the human body, requiring a miniature structure. The Body Network Controller (BNC) consists of a wireless module, a small processor, and a miniature battery. Therefore, it becomes mandatory to design with a light weight security algorithm to protect the data and device from an attacker. The IMD placed in the human body is connected to another reliable node or to an IMD programmer through a wireless telemetry interface. The wireless communication between devices is not an authenticated channel, and information transmitted is unencrypted. This Physiological Value (PV) has more valuable information, and when hacked during communication, it can result in false treatment, leading to life-threatening situations. Security issues of data privacy and device authentication are discussed with the energy constrains of the device. To address the spectrum scarcity, the next-generation promising wireless technology has evolved, which is known as Cognitive Radio (CR). The CR technology has two band users: Primary Users (PUs) and Secondary Users (SUs). Whenever the licensed PUs are idle, the SUs can access the underutilized licensed (PUs) spectrum opportunistically [2]. In the working spectrum, PUs has first priority to access the channels ahead of SUs. In order to efficiently improve the spectrum usage, the SUs utilizes both licensed and unlicensed bands. The health-care sector (or Hospital) is the best example of how CR techniques can be engaged to improve the utility, scalability, and robustness of IMDs. The WBAN standardization working group (IEEE 802.15.6) had drafted a document requiring the Physical (PHY) and Medium Access Control (MAC) layer characteristics for WBAN applications [3; 4]. The wide range of power with the data rate of a WBAN is shown below in Figure 2. In order to reduce or eliminate the Electro Magnetic Interferences (EMI) to the Medical Devices (MDs), the CR can be applied to reduce the interference. Reducing the EMI effect to the WBAN devices can considerably improve the level of Quality of Service (QoS) and precision of the MDs. Table 1 gives the medical and non-medical devices available in the market with their operating range [5; 6; 7]. Figure 1: Wireless Body Area Network (WBAN) Applications. Irrespective of the different spectrum regulatory limitations across the world, several bands designated for medical applications are available on a license band [2]. The United States and Europe have regulated the spectrum that can be used by Ultra-Wide Band (UWB) on a license-exempt basis. The band made available in the United States corresponds to 3.1-10.6 GHz, whereas in Europe, two spectrum sections have been defined, 3.4-4.8 GHz and 6-8.5 GHz, as shown in detail in Figure 3.  
The Enhanced Flower Pollination-based Optimized Channel selection (EFPOC) algorithm is assigned with the following modulation techniques between the node and BNC with impulse radio UWB frequency.