The life critical and real time medical application of Wireless Body Sensor Networks (WBSNs) requires the assurance of the demanded Quality of Service (QoS)  In WBSN -used for contineouse and remote healthcare monitoring [1], the tiny, lightweight, cost effective and low-power Bio-Medical Sensor Devices (BMSDs) are deployed on and/or inside the human body to sense and analyze the vital sign data of the human body. It It has a three-tiered architecture in order to send the sensory data to the final destination [2],[3]. In the first tier i.e. Intra-WBSN, the tiny BMSDs send the vital sign data to on-body base station called as Body Coordinator (BC). In the second tier i.e. Inter WBSN, the BCs are responsible to forward the received vital-sign data towards the sink(s) using other BCs and/or regular infrastructure like wireless local area network. Finally, in the third tier, it's the responsibility of the sink(s) to send the received vital-sign data to the final destination which could be a physician, health-care sever and/or emergency control room, using regular infrastructure such as internet. As WBSN deals with the human body and due to structure, nature and behavior of the human body, it faces some unique challenges along with the traditional constraints of Wireless Sensor Networks (WSNs). A range of BMSDs, like blood pressure, Electroencephalography (EEG), temperature, Electrocardiography (ECG) and many more, are deployed for different applications, which make WBSN heterogeneous in nature. Due to its heterogeneous nature it generates different categories of data, where different QoS parameters are among the key requirements. Similarly, due to saline-water nature, the human tissues absorb the electromagnetic waves carrying the information in wireless communications. This electromagnetic waves absorption along with the energy consumption during the operations of the BMSDs result in temperature rise of the BMSDs. In case of the implanted BMSDs, this temperature rise might affect and/or damage the human tissues if remain for long time [4], [5] . In addition to these, the postural movement of the human body along with the electromagnetic waves absorption results in dynamic and high path loss while exchanging information with other implanted BMSDs and/or BC. Due to this high and dynamic path loss the conventional path loss models of wireless communication are not applicable for intra WBSNs. Different people have tried to address these challenges of WBSNs and proposed various routing protocols. . The high and dynamic path loss issue of intra WBSN due to postural movement of human body has been addressed in [6]-[9]. In [6] Quwaider and Biswas have proposed a routing scheme by partitioning the sensor field into different partitions and uses store and flood mechanism to route the sensory data towards BCl While in [7] the same authors
Authors in REF proposed a routing scheme focused on efficient and reliable delivery of critical data in the specified duration.
Critical data routing (CDR) for Intra Wireless Body Sensor Networks
TELKOMNIKA Telecommunication Computing Electronics and Control
Engineering