Subsampling OFDM-Based Ultrasonic Data Communication Through Metallic Channels for Monitoring of Cargo Containers

Abstract

An enhanced ultrasonic communication system based on piezoelectric transducers for monitoring of goods in cargo containers is presented. The proposed system consists of several sensors placed inside the container, whose data are collected and transmitted outside it. Data transmission is carried out by an ultrasonic communication channel, in order to avoid drilling the wall of the container. The proposed data communication system is based on the transmission of a 128-OFDM signal. This modulation has been chosen due to its robustness to channels with frequency-selective fading and its spectrum efficiency. In order to increase the signal bandwidth and to reduce the power consumption at the internal node (transmitter), the proposed system exploits the non-linearity of the metallic channel to transmit at higher resonance frequencies. Moreover, power consumption at the external node (receiver) is reduced by using a subsampling based receiver, which allows its implementation by low-cost electronics.

Ultrasonic Through-Metal Communication Based on Deep-Learning-Assisted Echo Cancellation

“…The OFDM technique divides the frequencyselective channel into orthogonal flat fading bands, allowing for a marked increase in data rate without using highly complex equalizers to correct signal fading. Previous literature indicated that OFDM-based communications could accomplish high-data-rate transmission through metal barriers [20][21][22]; however, one shortcoming of OFDM is that it will result in a high peak-to-average power ratio (PAPR). High PAPR means that the system should consume high power and employ a power amplifier with a broad linear range for the transmitter.…”