## 1 Introduction  
In the current era, health is the primary factor of concern for every person [1]. A large number of doctors are serving the patients day and night. Now, due to unhygienic food and polluted environment, diseases become very common [2]. Patients suffering from primary diseases such as diabetes, heart stock, high blood pressure, etc., require periodic monitoring for their health status, and this results in a splurge of money [3]. As the number of patients increase, a large number of doctors, hospitals, along with other medical personnel required for attending patients may also need to increase [3]. Moreover, the patients will require physical mobility, which could be difficult, and due to daily life activity, the patient is no more force to stay in a hospital. As the health factor is the primary concern for everyone; therefore, many healthcare organizations emphasize the use of Wireless Body Area Network (WBAN), e.g., World Health Organization (WHO) [4]. According to WHO, the main reason for deaths in the world by 2030 will be due to cardiovascular disease, heart diseases, and diabetes. The current survey describes the currently providing healthcare services to the patient with chronic diseases and patients with multiple health difficulties are rapidly increasing the cost of healthcare system [5]. Health care organizations make use of advanced information technology techniques and communication gadgets to overcome complex medical issues to reduce errors and minimize the overall cost, as per WHO providing healthcare services with advanced technologies for the exchange of sensitive information to overcome complex medical problems (e.g., data security and sharing etc.) to reduce error and for the continuity of healthcare providers [6]. It is, however, possible to utilize the latest technology for early identification and precaution of potential diseases that may take place later in the lives of people, e.g., telemedicine and e-health, etc. Telemedicine is the use of advanced information technology and telecommunication that provide several healthcare services to patients [7]. Telemedicine enables remote treatment and helps to eliminate the distance barriers which improve medical access to distant rural communities. The current advancement in wireless communication and microchip technology brings the emergence of small, intelligent, wearable sensors able to use on the human body [8]. In WBAN, the implanted sensors required energy to communicate with each other; therefore, every sensor is equipped with a small battery. These sensors are utilized to measure the variation in patient vital signs and send data to the central node, which is responsible for coordinating nodes and send data to medical personnel for analyzing and real-time diagnosis. However, the security and privacy of medical data while sharing medical information is a challenging task in WBAN [9]. The current healthcare system does not meet the advanced systems requirements for an optimal operation because these systems have no reliable and consistent structure in terms of data sharing, security, and access control techniques. Hence, it is mandatory to design a secure wireless system to improve the data-access operation under the security and privacy of government regulations to assure accountability for monitoring and analyzing patient vital signs. Blockchain is a distributed ledger technology, which holds the secure log of translations [10]. The new technology blockchain revolutionized the existing healthcare platforms by adding its security, privacy, and data interoperability features. Blockchain technology replaces the current design approaches for data transmission between the user of the network and distributed ledger technology that support complete, immutable logs of transactions [11]. The blocks in blockchain consist of records that contain transaction details between the system and users. Blockchain technology can be beneficial in improving the telemedicine results in terms of security, transparency, audit, and trust.