###### Abstract  
Wireless body area sensor networks (WBASNs) have received growing attention from industry and academia due to their exceptional potential for patient monitoring systems that are equipped with low-power wearable and implantable biomedical sensors under communications standards such as IEEE 802.15.4-2015 and IEEE 802.15.6-2012. The goal of WBASNs is to enhance the capabilities of wireless patient monitoring systems in terms of data accuracy, reliability, routing, channel access, and the data communication of sensors within, on and around the human body. The huge scope of challenges related to WBASNs has led to various research publications and industrial experiments. In this paper, a survey is conducted for the recent state-of-art in the context of medium access control (MAC) and routing protocols by considering the application requirements of patient monitoring systems. Moreover, we discuss the open issues, lessons learned, and challenges for these layers to provide a source of motivation for the upcoming design and development in the domain of WBASNs. This survey will be highly useful for the 6 th generation (6G) networks; it is expected that 6G will provide efficient and ubiquitous connectivity to a huge number of IoT devices, and most of them will be sensor-based. This survey will further clarify the QoS requirement part of the 6G networks in terms of sensor-based IoT. WABAN; patient monitoring systems; IoTs; RSSI; LQI; link quality; routing; IEEE 802.15.4; IEEE 802.15.6  
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is not considered an optimal design approach unless they are designed by considering the lifetime of sensor nodes. Despite the limited battery power of body sensors, some devices are required to work unobtrusively for months or even years. Further, in MAC protocols, energy waste is due to idle listening, collision, packet overhead, and overhearing. WBASNs consist of multiple physiological sensors that require different data rates, as shown in Table 1. Therefore, the selection of an appropriate radio frequency (RF) is a crucial part of deploying patient monitoring systems. The heterogeneous nature of biomedical sensors in terms of sensing and transmitting data make the required QoS more complex for the MAC layer as it may now need to send some data with high priority, such as electrocardiography (ECG) data in an emergency scenario. For such communication, using the wired solution will be expensive. However, the use of wireless infrastructure is more cost-efficient and easily deployable. Wireless patient monitoring provides flexibility in terms of mobility; further, it helps to remotely monitor elderly people. Every year, millions of people suffer from diseases, including cardiovascular, blood pressure, asthma, diabetes, etc. Research has revealed that most of these diseases can be avoided if they are identified early. In this context, patient monitoring systems [10; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22; 23; 24] could be very useful in providing quality of life without disrupting the patients' daily routines. WBASNs integrate with other communication technologies, including ZigBee, Bluetooth, wireless local area networks (WLANs) and wireless personal area networks (WPANs). Usually, for communications at the MAC and physical layers, WBASNs use IEEE 802.15.4 low-rate wireless personal area networks (LR-WPANs) and IEEE 802.15.6 wireless \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Sensor Nodes** & **Data Generation Interval** & **Required Data Rate (Kbps)** & **Delay Requirement** \\ \hline ECG & 4 ms & 34 & \textless{}125 ms \\ \hline EMG & 6 ms & 19.6 & \textless{}125 ms \\ \hline EEG & 4 ms & 19.6 & \textless{}125 ms \\ \hline SpO2 (Pulse Oximeter) & 10 ms & 13.2 & \textless{}250 ms \\ \hline BP & 10 ms & 13.2 & \textless{}250 ms \\ \hline Respiration & 40 ms & 3.2 & \textless{}250 ms \\ \hline Skin temperature & 60 s & 2.27 & \textless{}250 ms \\ \hline Glucose sensor & 250 s & 0.528 & \textless{}250 ms \\ \hline \hline \end{tabular}
\end{table}