## 1 Introduction  
Thanks to Moore's law, the continuous decrease in size while growing capacity increase of electronic devices has made it inevitable for the development of tiny and portable devices that can communicate with each other around the human body. This substantial development creates growing interest amongst researchers, system designers and application developers on a new type of network architecture generally known as a Wireless Body Area Network (WBAN). A WBAN is thus a special type of network that integrates miniaturized, intelligent, low-power sensor nodes in, on or around a human body that continuously monitor the body functions and surrounding environment [1]. WBAN is equipped with nodes that are wearable and/or implanted, and capable of wireless communication to transmit data to a nearby coordinator known as the Body Coordinator (BC). An implanted sensor node, also known as an _in-vivo_ node is a special type of sensor which detects and collects the desired biometric data of a certain physiological change inside the body, and transmits the data to the BC. One of the major problems caused by continuous sensing of _in-vivo_ sensor node is the heat produced due to wireless communication and the power dissipation by the sensor circuitry [2,3]. The increased heat causes thermal damage to the human tissue inside the body if the communication is prolonged for a long time which might be a threat to the human life [4]. Hence, temperature rise in one the significant issues to be considered in designing communication protocols for WBAN having _in-vivo_ nodes. Because of the high potential in e-healthcare, WBAN has been facilitated nowadays with wider range of applications [5] having distinct Quality of Service (QoS) demands in terms of delay, reliability, throughput _etc_. Moreover, a patient can be equipped with diverse _in-vivo_ sensors with various QoS requirements. For instance, electroencephalogram (EEG), electrocardiogram (ECG) and Electromyography (EMG) _etc_. require higher reliability with real time delivery. However, the traffic from respiration monitoring, pH-level monitoring sensors demand higher reliability but can tolerate delay to some extent. Thus, addressing traffic heterogeneity satisfying respective QoS requirements is another considerable challenging issue for the design of WBAN communication protocols. Although a number of implementations generally use a single-hop communication architecture for a WBAN to connect all sensors to a central sink node, recent researchers [6, 7, 8, 9, 10] pointed out that the multihop communication paradigm is more energy-efficient and even necessary when applied inside the human body with innate severe propagation loss. Considering the temperature rise as a striking metric, a number of studies presented thermal-aware communication protocols exploiting the multi-hop communication paradigm for WBAN having _in-vivo_ nodes. These protocols mainly aim to minimize the temperature rise in route selection procedure and ignore the QoS issues. There are also few researches found in the literature considering QoS provisioning in WBAN but these studies neglect the thermal effect [11, 12, 13]. Considering the thermal-awareness as well as QoS provisioning with the support of traffic heterogeneity of implanted WBAN, recently TMQoS [14] has been proposed. TMQoS employs a cross-layer proactive routing framework that maintains an ongoing routing table containing end-to-end routes for all traffic types. Thus, this protocol requires not only local knowledge, but also the knowledge of end-to-end network information for the route selection towards the \(BC\). Although TMQoS selects the best end-to-end route satisfying certain QoS parameters, but it has some drawbacks in the context of WBAN. First, this overhead to too high to scale the network to a good number of nodes. Secondly, the wireless environment inside the human body is highly dynamic due to its variability in path loss [15].