Phase Detection and Modulation Improvement for Active Load Modulation during Continuous Transmission.

Nejc Suhadolnik,Jernej Rozman,Anton Pleteršek,Tilen Svete,Maja Atanasijević-Kunc,Žiga Korošak

doi:10.3390/s21186155

Abstract

The paper covers one of the communication technologies used in wireless sensor networks. We have presented improvements in existing radio frequency identification (RFID) systems to address the problem of the phase selection in active load modulation (ALM). The phase selection affects the interoperability of communication devices and has to be addressed in the design phase of a new tag. A novel transmission method is presented to make the phase selection irrelevant for device interoperability. A second solution is shown to improve the existing system synchronization, which allows operation with arbitrary selected phase. A mathematical analysis of signals present on the antenna was used together with the reference reader model to perform an analysis of proposed improvements. We proved that the proposed transmission method is less affected by phase selection. Furthermore, we demonstrated that existing system improvement allows synchronization and operation at an arbitrarily selected phase despite the continuous transmission and large signal-to-interference ratio.

Highlights

An overview of existing active load modulation (ALM) solutions was given in the paper, focusing on signal synchronization between the received reader signal and the transmitted tag signal
The emphasis was placed on the limitation of the existing solution, which is able to synchronize during the continuous transmission without pauses for synchronization
The limitation of the existing system was identified as the phase detector, which has a limited input phase range

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Usage of wireless sensor networks (WSNs) has increased over the last decade, with multiple implementation options. WSNs differ in communication distance, network topology, device complexity and several other parameters. Each topology and technology used has their own advantages and disadvantages, which need to be taken into consideration when designing a WSN for a specific application. One of the studied communication technologies for WSNs is radio frequency identification (RFID) in the high-frequency (HF)

Methods

Results

Discussion

Conclusion