Near-Field Image Transmission and Evm Measurements in Rich Scattering Environment in Metal Enclosure

Abstract

In this work we present near-field image transmission and error vector magnitude measurement in rich scattering environment in metal enclosure. We check the effect of loading metal enclosure on the performance of SDR based near-field communication link. We focus on the key communication receiver parameters to observe the effect of near-field link in presence of richscattering and in presence of loading with RF absorber cones. The near-field performance is measured by transmitting wideband OFDM-modulated packets containing image information. Our finding suggests that the performance of OFDM based wideband near-field communication improves when metal enclosure is loaded with RF absorbers. Near-field EVM improves when the enclosure is loaded with RF absorber cones. Loading of the metal enclosure has the effect of increased coherence bandwidth. Frequency selectivity was observed in an empty enclosure which suggests coherence bandwidth less than the signal bandwidth. 1. INTRODUCTION Data transmission in the near-field in rich scattering environment for applications like wireless chip-tochip communication and wireless network-on-chip (WNoC) communication has become important [1-3]. Near-field communication is traditionally used for low-rate and short-range communication that takes place using magnetic induction (MI) communication links. Magnetic induction communication depends on near-field component of magnetic dipole which decays as 1/r 3 from the dipole. Hence, it may be suitable for low-rate information and power transfer [4]. It has also been used for wireless underground sensor networks [5, 6] and underwater communication [7, 8]. Because of limited range, it may offer frequency reuse and secure communication link. Hence, the receiver design for MI communication should be simple as there are no interfering components involved. However, it is not a suitable technology for scalable and high-data rate applications like wireless chip-to-chip communication. Additionally, the performance of MI links is subject to ambient effects, and any misalignment between transmitter and receiver degrades the performance. Authors in [9] have shown near-field magnetically coupled communication using loop antennas; however, the performance of real-world communication receiver in the near-field is not investigated. Authors in [10] have proposed an inductively coupled RF transceiver for wireless-chip-chip communication; however, the work has not introduced any signal quality based and end-to-end system performance analysis. There are a few more studies on metal enclosure at high frequencies for wireless chip-to-chip communication such as [11-13], but they are limited to transfer function measurements, and digital receiver design part is not investigated. The complexity of communication receiver design in the near-field has been highlighted by the author in [14], and we link near-field effects on the communication signal quality. We have organized our paper into five sections. Section 1 is an introduction that highlights the importance of...

OTA testing of near‐field and far‐field communication links

“…However, after at a certain Rx gain (47 dB) RMS EVM increases significantly to a very high level. The RMS EVM varies between 1.85% and 82.75%, with the minimum RMS EVM reached at −5 dB Tx gain and 42 dB Rx gain, which is lower than the minimum total system EVM (3.90%) [10, 11] and RMS EVM in the empty metal enclosure case (5.8%) [13]. The reason for the EVM bathtub curve is noise affecting EVM performance at low power levels, while overdriving the amplifier causes signal distortion and out‐of‐band spurious emissions, degrading EVM performance at high power levels.…”

“…They also investigated the effects of modulation type and the position of RF absorbers on BER and EVM levels during image transmission in ref. [13]. The assessment of simulation-based techniques for characterizing a reconfigurable intelligent surface (RIS)-assisted vehicle-to-vehicle (V2V) propagation environment involved the evaluation of both near-field conditions [14] and the hybrid combination of far-field and near-field scenarios [15].…”

Compact MIMO System Performances in Metallic Enclosures

“…Wireless communication system deployment in highly reflective and complex propagation environments, such as in a metal enclosure or a compact box environment, is extremely challenging [1,2]. Near-field MIMO for high-data-rate communication is important for applications, such as wireless chip-to-chip communications and wireless network-on-chip (WNoC) [2][3][4][5][6][7].…”

“…We previously presented over-the-air (OTA) testing of a QPSK receiver for the performance of baseband receiver design stages and the measurements were performed in a metal enclosure with all baseband receiver design stages [2]. In [1], we conducted near-field EVM measurements in a metal enclosure using a single transmit and a single receive antenna. We transmitted non-high throughput (nonHT) IEEE 802.11a OFDM packets for all modulation and coding techniques (MCS0-MCS7) in metal enclosures in different loading conditions.…”