## 1 Introduction  
Wireless sensor networks (WSNs) are composed of tiny, low-powered sensors capable of detecting many types of urgent information from their surroundings, and have the primary features of robustness, scalability, and large-scale deployment capability [1, 2]. These miniature devices can sense and extract information from the environment and are often referred to as sensor nodes. These nodes are capable of storing physical data, performing computational tasks, and forwarding the gathered information to a specific point [3, 4]. They are used for a wide range of applications, including healthcare, residential, smart homes, industrial, military, and other commercial purposes [5, 6, 7]. Sensor nodes in WSN have finite battery life and it is challenging to replace and recharge the battery in a timely manner [8]. This becomes prohibitively expensive when a large number of nodes are spread out across a vast area [9]. When it comes to ensuring effective communications in WSNs, Medium Access Control (MAC) protocol plays an important role. When the MAC protocol is well designed, it allows the sensor nodes to access the medium to improve energy efficiency while minimizing latency [10]. The Quality of Service (QoS) plays a vital role and refers to the capability to assign alternative priority to data packets depending on the requirements of the user [11]. End-to-end latency, energy efficiency, network throughput, and packet delivery ratio are essential QoS characteristics. Sensor nodes should provide data packets with varying levels of urgency or priority, for example, fire alerts have a higher priority than temperature monitoring [12; 13]. Routing's function is to find the best way to get data from one place to another. The network layer is extensively utilized in WSNs to handle the routing of incoming data, and the routing protocol is a significant aspect of the architecture of a communication stack [14]. In multi-hop networks, intermediate sensor nodes are responsible for relaying packets to the base station. Therefore, there must be several paths for data to go from source to the destination that guarantees reliability. Furthermore, due to the limited battery life, energy conservation is a critical design consideration in WSNs [15]. Researchers have done extensive work in the past to save energy, focusing primarily on optimizing MAC protocols [16], routing protocols [17], data acquisition [18], and cross-layer optimization approaches [19]. However, most of the energy is used at the MAC layer in sensing the channel, idle listening, packet transmission, packet reception as well as overhearing, and data collisions [20; 21]. It is also important to note that the routing protocols in WSNs are application-specific and energy-efficient [22]. A good routing protocol must be simple, energy-aware, adaptable, and scalable [23; 24]. A typical deployment of many sensor nodes has brought various design and management issues for sensor networks. Because of the unbalanced traffic, the sensor node's energy is depleted far sooner than it should be. The primary design purpose of WSNs is to facilitate data transmission while attempting to extend the network's life [25]. In WSNs, an essential performance parameter is the network lifetime, which is defined as the amount of time until the energy in the first sensor node runs out [26]. Considerable enhancements have been made to many QoS-aware MAC protocols [27] to improve energy efficiency, network lifetime, support packets' priority in the network and so on. Some of the prominent MAC protocols that consider QoS characteristics are EAMP-AIDC [28], AQSen-MAC [29], MPQ-MAC [30], QAEE-MAC [31], PMME-MAC [32], RMP-MAC [33] and our previously proposed the TMPQ-MAC protocol [34]. However, all these protocols lack the multi-hop routing feature, which limits the deployment area to the transmission range. On the other hand, MAC protocols with multi-hop routing have also been proposed, such as MDA-SMAC [35], SPEECH-MAC [36], EDS-MAC [37], and DCD-MAC [38].