In this paper, we investigate a two-way backscatter communication system assisted by a dual-sided reconfigurable intelligent surface (RIS) which consists of active or passive elements. By altering the switch status within each RIS element, different transmission and reflection coefficients can be achieved, thus enabling a binary backscatter modulation. To begin with, we propose a maximum likelihood (ML) detector and a maximal-ratio-combining (MRC)-based detector for the proposed dual-sided RIS-assisted two-way communication system to decode the backscatter signal as well as the end-users’ respective signal. Moreover, we compare the underlying system with and without backscatter modulation at the dual-sided RIS. Subsequently, we analyze the corresponding symbol error rate (SER) and throughput to highlight the performance differences of the various communication modes under perfect channel state information (CSI) and imperfect CSI. Finally, numerical results reveal that: (1) the ML detector significantly outperforms the MRC-based detector in terms of SER and throughput; (2) the throughput performance can be significantly improved by adopting a backscatter modulation, especially in the medium and high signal-to-noise ratio regimes; (3) the phase shift of the dual-sided RIS element should be aligned with the signal to be decoded first, to guarantee an improvement in the SER performance.

Existing reconfigurable intelligent surface (RIS)-enabled symbiotic systems generally rely on a dynamic adjustment of the amplitude of the RIS’s reflection coefficient to continuously change from 0 to 1 to support the underlying symbiotic trans-missions, which is however infeasible for practical RIS hardware. To address this, we propose a novel on-off digitalized symbiotic backscatter non-orthogonal multiple access (NOMA) system that employs an on-off mechanism of the RIS’s reflecting elements. In particular, the adjustment of the on-off state of reflecting elements in batches is adaptively invoked to control the power gain of the backscatter channel, thereby changing the amplitude of backscatter signals to establish symbiotic transmissions. In order to evaluate the practicability of the proposed on-off symbiotic mechanism, an analytical expression of coexistence outage probability at high SNR has been derived. Moreover, the adjustment of RIS’s elements on-off state is discussed and extended to the scenarios of one-shot and one-by-one activation modes. Finally, representative numerical results show that when a sufficient number of reflecting elements is deployed on the RIS, our proposed on-off mechanism can fully support the symbiotic transmissions of the underlying systems.

In this paper, we propose a two-way backscatter communication system assisted by an active and passive dualsided reconfigurable intelligent surface (RIS) where the active RIS element contains an amplifier while the passive one does not. By altering the switch status within each RIS element, different transmission and reflection coefficients can be achieved, enabling a binary backscatter modulation. Moreover, a maximal-ratio-combining (MRC)-based detector is proposed to decode the backscatter signal and the end-user's signal, and the corresponding symbol error rate (SER) and throughput are subsequently analyzed. Numerical results show that by avoiding the additive thermal noise within each RIS element, passive dual-sided RISenabled communications outperform the active dual-sided RISenabled communications in terms of SER, and it is also revealed that the throughput can be significantly improved through backscatter modulation.

With the advancement of intelligence and networked automotive, the domain-centralized architecture, which employs time sensitive networking (TSN) as the inter-domain backbone network and control area network with flexible data rate (CAN-FD) as the intra-domain network, has garnered significant attention. However, cross-domain end-to-end communication involves multiple components, and significant disparities between TSN and CAN-FD render response time analysis within domain-centralized architecture for mixed-critical traffic exceptionally complex. In this paper, we develop a cross-domain with TSN and CAN-FD end-to-end response time evaluation tool, which analyzes the response time of mixed-critical traffic under different design options segment by segment. We specifically analyze the waiting times of different messages in the domain control unit when faced with the design options of one-to-one and multi-to-one conversion of CAN-FD and TSN frames. The proposed evaluation tool can be easily extended to different design options to support more application scenarios. Theoretical computational analysis and real hardware measurements show the effectiveness of our tool.

In this paper an intelligent computer-aided instruction system for teaching normal form determination is described.The general architecture of intelligent tutoring systems is also discussed, as are the results of experience using the tool in an undergraduate database course.