Index Modulation in Backscatter Communication for IoT-Sensor-Based Applications: A Review

The Internet of Things (IoT), a key enabler of Agriculture 4.0, has numerous devices and sensors connected to the Internet. Most devices and sensors being powered by batteries with finite capacities may suffer from a limited lifetime. Furthermore, passive devices, such as radio frequency identification (RFID) tags, are expected to be connected. To this end, backscatter communication (BackCom) can play a crucial role in extending the lifetime of devices with limited power sources or supporting the connectivity to passive devices. In this article, we review the application of index modulation (IM) to BackCom. In particular, we discuss the different energy harvesting mechanisms, reliable detection, and security schemes suitable for a low-power wireless communication paradigm. In addition, a detailed review and comparison of existing techniques from recent literature are presented. After reviewing the key potential features of BackCom to support future wireless communication, this article discusses the opportunities of using IM in BackCom. Its focus is mainly on the various existing work that implements IM technologies to reduce energy consumption and enhance spectral and energy efficiencies. Finally, the potential challenges and future research direction in implementing IM for low-power wireless communication systems are presented.