Comprehensive Survey of Routing Protocols for Wireless Body Area Networks (WBANs)

Introduction

The wireless technology has evolved over the years, today most of the electronic appliances and gadgets at home and offices are wirelessly operated. The group of devices that record data subjected to the application and transmit the recorded data wirelessly to the base station is called wireless sensor networks (WSNs). Initially, the scope of WSNs was limited to military, science and engineering experiments. However, today WSNs are applicable to various other fields such as water monitoring systems for managing river water level, fire monitoring system for protecting the forest from disasters, earthquake monitoring, habitat monitoring, military, etc. Although the sensor nodes are not rich in resource possession such as memory and processing capabilities, the large-scale deployment of these sensor nodes over an unattended area helps to monitor a larger geographical area. Similarly, Healthcare applications of WSNs have witnessed revolutionary changes and have got a significant acceptance in the recent past. The low cost, hazardless and extremely small size invasive and non-invasive sensor nodes are capable to indicate any abnormal health condition instantly to the patient himself, hospital management system or in some cases directly to the physician.

The network of these tiny biosensor sensor nodes placed on, around and inside the human body is called wireless body area networks (WBANs). The prime objective of WBANs is to provide health management facilitations to the patients/elderly peoples at low cost and ease. However, sensor nodes in WBANs have limited resources in terms of memory, processing power, battery storage, communication range, etc. Therefore, WBANs are considered quite different from traditional resource-efficient WSNs in terms of scalability, reliability, deployment, etc. The WSN is typically a standalone network in which sensor nodes are capable to adjust themselves to the condition. The homogeneous sensor nodes are deployed at a large scale to cover a significant geographical area and data rate is mostly application dependent, whereas nodes in a WBAN are of heterogeneous nature, the deployment of nodes is limited to the size of the human body and most of the time high data rate is required to monitor physiological characteristics like ECG and Blood pressure (Kumar & Lee, 2012). To better understand the difference between the two technologies, a brief comparison is presented in the following sub-section that highlights the key features of WBANs and their associated constraints before formally adopting WBANs for the betterment of human life. As nodes in a WBAN, are required to transmit the patient’s data to the destination node in a cooperative manner using a multi-hop environment. Therefore, routing protocols play a key role in the extended network lifetime. Various routing protocols can be found in WSNs that routes data efficiently. However, these routing protocols in their original form cannot be applied in WBANs for patients’ data transmission. The comparison between WSN and WBAN will unfold various characteristics of WBAN that demands to develop entirely new efficient routing protocols for WBANs.