FD Systems Research Articles

Exploring Design Tradeoffs and Rate Gain Regions in Full-Duplex Wireless Communications

Conventional HD wireless networks operated by using distinct time slots or frequency (freq.) sub-bands for transmission and reception within the same family. Therefore, the wireless research community aims to develop FD operation to enable simultaneous transmission along with reception inside a single time/ freq. channel. This research aims to conduct an analytical investigation of the conditions under which real FD systems may attain higher data rates compared to analogous HD systems. The primary obstacle in real FD systems is to the uncancelled self-interference (SI) signal, which arises due to a confluence of hardware along with implementation defects. First, provide a signal model that encompasses the impact of notable impairments, including oscillator phase noise (PN), along with low-noise amplifier (LNA) noise figure, along with mixer noise, along with analog-to-digital converter quantization noise. The rate gain area (RGA) is examined in this research using the comprehensive signal model. A~1.2x to ~1.4x that of HD systems for short-range applications like class-3 Bluetooth. To get the same rate gain with Class-1 Bluetooth, −70dB in-band PN must be paired with 50dB passive SI suppression.

Impacts of dyke systems on the distribution of benthic invertebrate communities and physicochemical characteristics of surface water in An Giang, Vietnam.

The dyke system plays a vital role in cultivating rice intensively in the Vietnamese Mekong Delta, which protects rice paddy fields from annual floods. This study aimed to examine whether the full-dyke system (FD, which restricts water exchange for a long time) can cause degradation of surface water quality and reduction in benthic invertebrate biodiversity. The surface water quality and benthic invertebrate community were compared between the FD and semi-dyke systems (SD, which permits water exchange during flooding season) using a large number of samples collected seasonally in 2019. The results showed that the surface water quality within the FD system had significantly higher concentrations of TSS, COD, BOD5, N-NO3-, N-TKN, P-PO43-, and TP than compared to the SD system (p < 0.05), indicating greater pollution levels. The benthic invertebrate community was less diverse in the FD system than in the SD system. Only 17 species (belonging to 4 families) were detected in the FD system, and 30 species (belonging to 5 families) were detected in the SD system. The benthic invertebrate community structure changes and biodiversity loss were associated with degraded water quality. The P-PO43- and TP parameters were negatively correlated with the number of species, density, and biomass in the FD system and with the Shannon-Wiener (H') index in the SD system. In conclusion, the FD system has been degrading water quality and causing biodiversity loss.

Timing Analysis of CAN FD for Security-Aware Automotive Cyber-Physical Systems

The CAN FD emerges as a promising CAN technology inside the ACPS due to its advantages of high data-phase bit-rate and message payload. HSM based security solution is recommended by auto industry to protect CAN FD from potential security attacks, but it induces new challenges on timing analysis of CAN FD messages, which is left open in the literature. This paper develops the first security-aware system model to describe the processing of CAN FD messages, and presents a new WCRT analysis to bound the interference induced by security-critical messages. We give the theoretical proof that our WCRT analysis can upper bound the response time of CAN FD messages. Using a small message set, we show that the WCRT computed by our new analysis is only 14&#x0025; percent higher than the true WCRT obtained from an exhaustive search based simulator. By comparing with existing method, the number of impacted messages increases along with the increasing number of security critical messages, and for the two typical CAN FD systems, the percentage of WCRT increase varies from 12.43&#x0025; to 14.57&#x0025; and 7.0&#x0025; to 10.89&#x0025;, respectively; the percentage of WCRT decrease varies from 3.29&#x0025; to 6.04&#x0025; and 4.13&#x0025; to 7.93&#x0025;, respectively.

Deep Reinforcement Learning for RIS-Assisted FD Systems: Single or Distributed RIS?

This paper investigates reconfigurable intelligent surface (RIS)-assisted full-duplex multiple-input single-output wireless system, where the beamforming and RIS phase shifts are optimized to maximize the sum-rate for both single and distributed RIS deployment schemes. The preference of using the single or distributed RIS deployment scheme is investigated through three practical scenarios based on the links' quality. The closed-form solution is derived to optimize the beamforming vectors and a novel deep reinforcement learning (DRL) algorithm is proposed to optimize the RIS phase shifts. Simulation results illustrate that the choice of the deployment scheme depends on the scenario and the links' quality. It is further shown that the proposed algorithm significantly improves the sum-rate compared to the non-optimized scenario in both single and distributed RIS deployment schemes. Besides, the proposed beamforming derivation achieves a remarkable improvement compared to the approximated derivation in previous works. Finally, the complexity analysis confirms that the proposed DRL algorithm reduces the computation complexity compared to the DRL algorithm in the literature.

Digital Self-interference cancellation in the era of machine learning: A comprehensive review

In-band full-duplex (IBFD) transmission has been identified as a promising solution to improve spectral efficiency as compared to half-duplex (HD) systems. One of the major challenges of FD systems is to effectively manage the self-interference (SI) produced by the transmitter antenna to the local receiver antenna. In this survey paper, we first review and discuss the preliminaries related to SI cancellation (SIC). Furthermore, this survey presents the advancements to the date of digital SIC approaches and highlights the advantages and limitations of each approach. The survey also summarizes different hardware platforms used for SIC along with their key features. Additionally, we also survey and compare different FD techniques for their SIC performances. Finally, this paper identifies a variety of new research areas in the era of machine learning and deep learning for digital SIC.

Reliability and Confidentiality Co-Verification for Parallel Applications in Distributed Systems

Co-verification of reliability and confidentiality is a necessary process for safety- and security-critical applications. While these two objectives are conflicting, preassignment has emerged as an effective and efficient verification solution. In this article, we propose two preassignment-based co-verification techniques, namely, Blocks-based Vulnerability Preassignment (BVP) and Reversed Blocks-based Time Preassignment (RBTP) for a parallel application in distributed CAN FD systems. BVP can significantly improve reliability under a vulnerability bound, while RBTP can reduce vulnerability over a reliability goal. Real case study with the parallel automotive application and parallelism study with two structures of high-parallelism and low-parallelism applications are demonstrated; the proposed BVP and RBTP can improve the verification acceptance ratio by 19 and 10 percent compared to the state-of-the-art Average Vulnerability Preassignment (AVP) and Average Time Preassignment (ATP) techniques, respectively.

RGD-presenting peptides in amphiphilic and anionic β-sheet hydrogels for improved interactions with cells.

The interest in developing functional biomaterials based on designed peptides has been increasing in recent years. The amphiphilic and anionic β-sheet peptide Pro-Asp-(Phe-Asp)5-Pro, denoted FD, was previously shown to assemble into a hydrogel that induces adsorption of calcium and phosphate ions and formation of the bone mineral hydroxyapatite. In this study the integrin binding peptide, Arg-Gly-Asp (RGD), was incorporated into the hydrogel to assess its influence on an osteoblast culture. In solutions and in hydrogels FD fibrils dominated the assembly structures for up to 25 mol% FD-RGD incorporation. The cellular density of osteoblasts cultured in hydrogels composed of 25 mol% FD-RGD in FD was higher than that of only FD hydrogel cultures. These results demonstrate that RGD and possibly other cell binding motifs can be combined into amphiphilic and anionic β-sheet hydrogels, using the design principles of FD and FD-RGD systems, to enhance interactions with cells.

Nonlinear Transceiver Designs for Full-Duplex MIMO Relay Systems

This paper investigates nonlinear transceiver design for full-duplex multiple-input multiple-output (FD-MIMO) relay systems. A dual-hop amplify-and-forward relaying protocol is considered. At the destination, nonlinear successive-interference-cancellation (SIC) is used for signal detection. The goal is to find the source and relay precoders such that the symbol-vector error rate (SVER) can be minimized. Due to the loop interference (LI), optimizing the relay precoder in FD systems is much more involved. In this paper, we propose novel designs to solve this problem. Starting from the QR-SIC receiver, we theoretically show that the relay precoder can be solved with a closed-form expression even when the system incurs LI. Then, we consider the system with a minimum mean-squared-error SIC receiver, where the relay precoder design entails a different problem formulation and introduces new challenges. We propose a novel iterative method, with closed-form solutions in each iteration, to solve this problem. Simulations show that our designs can significantly improve the SVER performance for FD-MIMO relay systems.

On the Performance of Full-Duplex Multi-Relay Channels With DF Relays

In this paper, we consider a two-hop full-duplex multi-relay channel (FD-MRC) for exploiting the high spectral efficiency of FD systems and the diversity gains of multi-relay systems. Employing a decode-and-forward (DF) relaying protocol, the single best relay is selected from those relays that have successfully decoded the source message, which then helps forward the source message to the destination. Meanwhile, a new message is broadcast by the source, and all the $N$ relays, including the selected best one, attempt to decode this new message. In view of the effect of both inter-relay interference and self-interference, a one-step correlation exists between the relay decoding results in successive time slots. Then, a Markov chain-based analytical model is utilized for analyzing the exact outage probability of FD-MRC. Furthermore, a close-to-full diversity order of $(N-1+\mu)$ is analytically proved to be attainable for FD-MRC, where $\mu$ is a factor characterizing the efficiency of SI mitigation.

Multi-Antenna Beamforming Techniques in Full-Duplex and Self-Energy Recycling Systems: Opportunities and Challenges

Full-duplex technique is considered as an essential component of the coming 5G wireless systems. Since the SI from its transmit antennas dominates over the signal received from remote sites, the suppression of SI is the first priority challenge in the design of FD systems, and thus combinations of analog SI cancellation with radio frequency domain approaches are considered. Applying BF techniques with multiple antennas on top of these combined approaches can further strengthen the SI suppression capability so that wireless systems can enjoy the benefit from FD operation without much concern on SI. However, various factors affect the design of BF in FD networks, and hence they provide a set of research challenges. Also, S-ER is an alternative way of utilizing SI in FD networks, where the RF radiation from a node is reused as an energy source. In this article, we go through these opportunities and challenges along with a survey of technical results developed so far in regard to the BF for handling the SI of FD systems. We look at various network models, the strategies for handling the SI, relay protocols, and antenna structure to see how these provide technical challenges for the BF design.

Game-theoretic resource allocation for full-duplex communications

The recent significant progress in realizing FD systems has opened up a promising avenue for increasing the capacity of future wireless networks. In addition to hardware design and signal processing techniques, radio resource management is essential in the design and implementation of practical FD communication networks. FD communications introduce additional dimensions of network resources requiring the development of new resource allocation algorithms. In this article we concentrate on distributed radio resource allocation, and show how game-theoretic models can be used to effectively solve the optimization problems in FD communication systems. Finally, we outline several key open research directions in this emerging area.

Effect of fluoroscopic X-ray beam spectrum on air-kerma measurement accuracy: implications for establishing correction coefficients on interventional fluoroscopes with KAP meters.

The first goal of this study was to investigate the accuracy of the displayed reference plane air kerma (Ka,r) or air kerma‐area product (Pk,a) over a broad spectrum of X‐ray beam qualities on clinically used interventional fluoroscopes incorporating air kerma‐area product meters (KAP meters) to measure X‐ray output. The second goal was to investigate the accuracy of a correction coefficient (CC) determined at a single beam quality and applied to the measured Ka,r over a broad spectrum of beam qualities. Eleven state‐of‐the‐art interventional fluoroscopes were evaluated, consisting of eight Siemens Artis zee and Artis Q systems and three Philips Allura FD systems. A separate calibrated 60 cc ionization chamber (external chamber) was used to determine the accuracy of the KAP meter over a broad range of clinically used beam qualities. For typical adult beam qualities, applying a single CC determined at 100 kVp with copper (Cu) in the beam resulted in a deviation of <5% due to beam quality variation. This result indicates that applying a CC determined using The American Association of Physicists in Medicine Task Group 190 protocol or a similar protocol provides very good accuracy as compared to the allowed ±35% deviation of the KAP meter in this limited beam quality range. For interventional fluoroscopes dedicated to or routinely used to perform pediatric interventions, using a CC established with a low kVp (∼55−60 kVp) and large amount of Cu filtration (∼0.6−0.9 mm) may result in greater accuracy as compared to using the 100 kVp values. KAP meter responses indicate that fluoroscope vendors are likely normalizing or otherwise influencing the KAP meter output data. Although this may provide improved accuracy in some instances, there is the potential for large discrete errors to occur, and these errors may be difficult to identify.PACS number(s): 87.59.C‐, 87.59.cf, 87.53.Bn

An extension of ab initio molecular orbital theory to nuclear motion

We propose an extension of the quantum chemical molecular orbital (MO) method to describe the nuclear motion. Both electronic and nuclear wavefunctions are simultaneously solved with the full variational MO method, by which exponents and centers of gaussian-type function (GTF) basis sets are optimized as well as the linear combination of GTF coefficients. Applications of the method to [F −; e +], FH and FD systems are carried out. The calculated bond lengths and harmonic frequencies agree well with the experimental values.

An algebraic point of view of the data structures of database systems

We present a formalization of certain data structures involved in the design of database management systems starting from abstractizations of the notions of functional and multivalued dependencies in relational database systems (referred to as FD and MVD systems, respectively). The advantage of this abstract approach is a clarification of the essential properties of these data structures. Also, by identifying other objects which fit into the abstract concept we manage to transfer a number of intractable problems originating in graph theory and combinatorial set theory to the realm of relational databases.