Primary Receiver Research Articles

Credit spread drivers and cross-country connectedness: a study of emerging economies in Asia

PurposeWhile the existing literature lacks a holistic approach to determining credit spreads and is limited to mostly developed countries, this study investigates credit spread determinants and their cross-country connectedness in the context of four emerging economies in Asia by incorporating bonds, market risk, macroeconomic and global factors.Design/methodology/approachThis study utilizes principal component analysis for dimensionality reduction and variable representation. Furthermore, we employ the dynamic conditional correlation–generalized autoregressive conditional heteroskedasticity model to capture the cross-country credit spread connectedness between the variables.FindingsThe findings indicate that market volatilities are the most significant drivers of credit spreads, while global factors play a moderating role. Furthermore, the results provide compelling evidence of cross-country credit spread connectedness, with China as the primary transmitter and Malaysia as the primary receiver among the selected emerging economies.Originality/valueThis study addresses the limitations of previous research by extending the analysis beyond the commonly studied developed economies and focusing on emerging economies in Asia. It also employs a comprehensive approach to determine credit spread and explores cross-country credit spread connectedness in developing economies, thereby shedding light on financial risks and vulnerabilities within interconnected global financial systems.

Unified and Scalable Deep Image Compression Framework for Human and Machine

Image compression aims to minimize the amount of data in image representation while maintaining a certain visual quality for humans, which is an essential technique for storage and transmission. Recently, along with the development of computer vision, machines have become another primary receiver for images and require compressed images at a certain quality level, which may be different from that of human vision. In many scenarios, compressed images should serve both human and machine vision tasks, but few compression methods are designed for both goals simultaneously. In this paper, we propose a unified and scalable deep image compression (USDIC) framework that jointly optimizes the image quality according to human and machine vision in an end-to-end style. For the encoder, we propose an information splitting mechanism (ISM) to separate images into semantic and visual features, which mainly aims at machine analysis and human viewing tasks. For the decoder, we design a scalable decoding architecture. The encoded semantic feature is first decoded for machine analysis tasks, and the image is decoded and reconstructed further by leveraging the decoded semantic features. Herein, to further remove the redundancy between the semantic and visual features of images, we propose a scalable entropy model (SEM) with a joint optimization strategy to reconstruct the image using the two kinds of decoded features. Extensive experimental results show that the proposed USDIC achieves much better performance on the image analysis task while maintaining competitive performance on the traditional image reconstruction task compared with popular image compression methods.

Outage and throughput performance analysis of incremental relaying‐based underlay cognitive nonorthogonal multiple access networks with maximal ratio combining

SummaryIn this paper, we investigate the effectiveness of incremental relaying (IR)‐based underlay cognitive nonorthogonal multiple access (CNOMA) system with maximal ratio combining (MRC). Considering imperfect successive interference cancelation (i‐SIC), we derive analytical expressions for the outage probabilities experienced by the secondary users (SUs) and the system outage probability of the IR‐CNOMA system. We also derive the analytical expression for the outage probability of far SUs by considering IR‐CNOMA system with MRC. The maximum transmit power constraint of the secondary nodes and the interference threshold constraint of the primary receiver are considered in the analysis. We also evaluate the system throughput of IR‐CNOMA network. We also derive outage and throughput expression for the traditional cooperative relaying‐based CNOMA system (CR‐CNOMA) for the purpose of comparison. We derive analytical expression for the asymptotic outage probability and the asymptotic system outage probabilities of the SUs of IR‐CNOMA system. Further, we derive expressions for the optimal power allocation (OPA) factor at the secondary source that minimizes the asymptotic system outage probability of the IR‐CNOMA system. Through numerical and simulation investigations, we demonstrate that the system outage probability significantly lowers when the OPA factor is selected based on the criteria outlined in this work. It can be observed from the results that the IR‐CNOMA system outperforms the conventional CR‐CNOMA system in terms of outage probabilities and throughput. The outage probability is further reduced when IR‐CNOMA system with MRC is considered for the far SUs.

Sum rate maximization for RIS-assisted NOMA-enabled underlay AmBC-CR networks

Ambient backscatter communications (AmBC) have introduced a revolutionary approach to wireless communication that utilizes ambient radio frequency (RF) signals in contrast to self-generated RF signals. This makes AmBC a compelling candidate for future Internet-of-Things (IoT) applications, particularly considering the constraints of energy and spectrum resources. In this work, we investigate a cognitive radio (CR) based underlay network of backscatter devices (BDs) that communicate with the backscatter receiver (BR) by utilizing non-orthogonal multiple access (NOMA). Due to the dual fading effect in backscatter networks, the backscatter link is weakened which degrades the achievable performance. In order to tackle this issue, reconfigurable intelligent surface (RIS) is exploited in such networks. Therefore, to maximize the sum rate of the RIS-assisted NOMA-enabled underlay AmBC-CR (RIS-NUAC) network, subject to individual BDs’ data rate constraint and primary receiver (PR) interference threshold constraint, we jointly optimize the phase shift matrix (PSM) at the RIS and the power reflection coefficients (PRCs) at the BDs. To solve the resultant non-convex optimization problem, we propose a sub-optimal solution based on an alternating optimization (AO) algorithm by applying semidefinite relaxation (SDR) and rank one approximation. Based on simulation results, the proposed scheme demonstrates superior performance over baseline schemes, including NOMA with random phases, NOMA without RIS, orthogonal multiple access (OMA) with optimal phases, and OMA without RIS.

Towards sustainable development: Exploring the spillover effects of green technology innovation on energy markets and economic cycles

With the proposal of sustainable development goals, the world has placed increasing emphasis on energy transition and green, low-carbon initiatives, leading to the emergence of green technology. This article explores the spillover effects among green technology innovation (GTI), oil prices (OP), clean energy (CE), sustainable development (SD), and economic cycles (EC) with the time-varying parameter vector autoregression (TVP-VAR) connectedness method. The empirical results demonstrate that, in static analysis, the short-term connectedness is significantly stronger than that in the long term. SD serves as the main transmitter, while EC acts as the primary receiver. Furthermore, dynamic analysis suggests that spillover effects fluctuate with time and frequency. Finally, the net direction and net pairwise connectedness reveal that GTI is favorable for mitigating OP shocks and accelerating EC in the long term, while it is driven by CE and SD in the short term. The contribution of this paper lies in its incorporation of GTI, energy markets, economic cycles, and SD into a unified framework, and its detailed analysis of the channels of influence. Also, based on a time-frequency domain perspective, the paper dynamically examines the different performances of specific markets in the short or long term. Finally, the paper proposes some policy recommendations, including the strengthening of green technology innovation and the acceleration of energy transition.

Joint resource allocation and beamforming design for RIS-aided symbiotic radio networks: A DRL approach

In this paper, we investigate a Reconfigurable Intelligent Surface (RIS)-assisted secure Symbiosis Radio (SR) network to address the information leakage of the primary transmitter (PTx) to potential eavesdroppers. Specifically, the RIS serves as a secondary transmitter in the SR network to ensure the security of the communication between the PTx and the Primary Receiver (PRx), and simultaneously transmits its information to the PTx concurrently by configuring the phase shifts. Considering the presence of multiple eavesdroppers and uncertain channels in practical scenarios, we jointly optimize the active beamforming of PTx and the phase shifts of RIS to maximize the secrecy energy efficiency of RIS-supported SR networks while satisfying the quality of service requirement and the secure communication rate. To solve this complicated non-convex stochastic optimization problem, we propose a secure beamforming method based on Proximal Policy Optimization (PPO), which is an efficient deep reinforcement learning algorithm, to find the optimal beamforming strategy against eavesdroppers. Simulation results show that the proposed PPO-based method is able to achieve fast convergence and realize the secrecy energy efficiency gain by up to 22% when compared to the considered benchmarks.

Secrecy and Throughput Performance of Cooperative Cognitive Decode-and-Forward Relaying Vehicular Networks with Direct Links and Poisson Distributed Eavesdroppers

Cooperative communication and cognitive radio can effectively improve spectrum utilization, coverage range, and system throughput of vehicular networks, whereas they also incur several security issues and wiretapping attacks. Thus, security and threat detection are vitally important for such networks. This paper investigates the secrecy and throughput performance of an underlay cooperative cognitive vehicular network, where a pair of secondary vehicles communicate through a direct link and the assistance of a decode-and-forward (DF) secondary relay in the presence of Poisson-distributed colluding eavesdroppers and under an interference constraint set by the primary receiver. Considering mixed Rayleigh and double-Rayleigh fading channels, we design a realistic relaying transmission scheme and derive the closed-form expressions of secrecy and throughput performance, such as the secrecy outage probability (SOP), the connection outage probability (COP), the secrecy and connection outage probability (SCOP), and the overall secrecy throughput, for traditional and proposed schemes, respectively. An asymptotic analysis is further presented in the high signal-to-noise ratio (SNR) regime. Numerical results illustrate the impacts of network parameters on secrecy and throughput and reveal that the advantages of the proposed scheme are closely related to the channel gain of the relay link compared to the direct link.

Physical layer security‐oriented energy‐efficient resource allocation and trajectory design for UAV jammer over 5G millimeter wave cognitive relay system

AbstractThis work focuses on the optimal trajectory of a rotary‐wing unmanned aerial vehicle (UAV) jammer and the system power allocation with the objective of maximizing the total secure energy efficiency (EE) of a slotted relay‐assisted millimeter wave (mm‐Wave) cognitive radio system. The UAV flies from starting location to final one in a round of communication mission that is overheard by a malicious eavesdropper. The network terminals are equipped with multiple‐input multiple‐output (MIMO) antenna array. This work first develops a practical approximation propagation model by addressing three key challenges: path loss, small‐scale Nakagami‐m fading channel gains, and transceiver antenna beamforming gains. By using the approximate model, the upper and lower bounds of the ergodic rate of each communication link are derived. Second, with the objective of maximizing secure EE, the optimal UAV trajectory and system resource allocation framework is established by considering the constraints of interference at primary receiver (PR), information‐causality relationship, rotary‐wing UAV propulsion energy and so forth. The optimal framework is solved with a tractable CVX tool by using the derived upper and lower bounds and successive convex approximation. Finally, an iterative optimizing algorithm is established by using Dinkelbach's method. In the simulation, the work presents the comparison of UAV trajectories, secure rates, and secure EEs of three schemes, that is, the proposed EE scheme, the non‐EE scheme where only the optimal secure rate is considered, and the EE scheme with the consideration of all communication‐related energy consumption. The simulations show that the EE schemes achieve smoother UAV trajectory than non‐EE, but the non‐EE scheme has higher secure rate. The impact of communication energy consumption is negligible. In addition, the effect of MIMO antenna array and mm‐Wave on system performance is exploited.

Intelligent-Reflecting-Surface-Enhanced Cell-Free Symbiotic Radio Systems

This paper considers a novel intelligent reflecting surface (IRS) assisted cell-free symbiotic radio (SR) system, where an IRS is employed to facilitate the transmission from all the base stations (BSs) to the primary receivers (PRs), i.e., the primary transmission, and simultaneously, to send messages to the Internet-of-Things (IoT) devices, i.e., the secondary transmission. We aim to minimize the bit error rate (BER) of the IRS symbols by jointly optimizing the transmit beamformers at all the BSs and the IRS phase shifts. To solve this non-convex problem, we propose a plenty-based algorithm by using the multidimensional complex quadratic transform (MCQT) and the consensus alternative direction method of multipliers (ADMM) methods, and obtain a high-performance solution. Besides, the convergence of the proposed algorithm is analyzed. Simulation results demonstrate the effectiveness of the proposed algorithm and show that the proposed algorithm outperforms two baselines under different setups.

Joint Beamforming and Backscatter Communication Design for Symbiotic Radio Networks

Symbiotic radio (SR) is a promising energy-, spectrum-and cost-efficient communication technology for Internet of Things. This paper considers an SR network (SRN) in which backscatter devices (BDs) communicate with a primary receiver (PR) by riding on ambient radio frequency carriers from a primary transmitter (PT). First, both the achievable primary rate and backscatter-link sum rate are derived for BDs adopting spatial-division-multiple-access (SDMA) scheme and dynamic time-division-multiple-access (TDMA) scheme, respectively. Then, two optimization problems are formulated to maximize the BDs’ sum rate, by jointly optimizing the PT’s beamforming matrix, and the BDs’ power reflection coefficients as well as the backscatter time allocation. For the single-antenna PR case, the optimal beamforming is obtained in semi-closed forms. For the multi-antenna PR case, to solve the non-convex problems with coupled variables, efficient iterative algorithms are proposed based on block coordinate descent and sequential convex approximation techniques. Finally, numerical results show that the proposed design enhances the SRN’s throughput significantly, and give useful insights on the BDs’ multiple-access schemes.

Cooperative NOMA-Based Spectrum Leasing With Multiple Secondary Users

This paper proposes a new cooperative nonorthogonal multiple access-based spectrum leasing (CNOMA-SL) framework for enhanced network performance. Herein, the system is comprised of a primary network and a secondary network with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$n$</tex-math></inline-formula> -transmitting users. Primary and secondary users exploit an underlay spectrum leasing scheme to transmit signals to a relay station (RS), which forwards the signals to the corresponding receivers. Two phases of data transmission are assumed. In Phase I, the secondary transmitters employ uplink NOMA to transmit the symbols. The RS then uses downlink NOMA to broadcast the received symbols in Phase II. We employ the maximum ratio combining decoding scheme and propose a successive-interference-cancellation concept with ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$n+1$</tex-math></inline-formula> ) stages to decode the symbols at the primary and secondary receiving ends, respectively. Considering a transmission power constraint imposed at the secondary transmitters, we derive the closed-form expressions for achievable rate and outage probability for both primary and secondary users. Simulation results manifest that, compared with the conventional cooperative orthogonal multiple access-based spectrum leasing scheme, the proposed CNOMA-SL exhibits improved performance in terms of both achievable rate and outage probability. It is also revealed that the system performs better when the RS takes the lease of the whole spectrum. Furthermore, if more interference power is allowed to the primary receiver, the secondary users reach higher achievable rates.

Symbiotic Backscatter Communication Underlying a Cell-Free Massive MIMO System

In ambient backscatter communications, backscatter devices (BDs) utilize ambient “legacy” radio signals as both a harvested energy source and a carrier on which to modulate data. Symbiotic radio, a subtype in which the legacy system assists both its own users and underlaid BDs, has attracted much research interest recently. Furthermore, cell-free massive multiple-input multiple-output (CF mMIMO) systems are promising for beyond-5G networks from both spectral and energy efficiency perspectives. To reap the benefits of both, we consider a primary CF mMIMO system where the access points (APs) aid an underlaid BD layer to both harvest energy and reflect information toward the primary receivers (which receive data from both layers). To acquire separate channel state information (CSI) of the direct and backscattered channels at the APs, a two-phase uplink pilot training method is proposed, with the effects of pilot contamination and spatial correlation between antennas accounted for. However, the receivers are assumed to only have partial CSI (statistical knowledge plus instantaneous phase information for partially-coherent reception). Assuming uplink/downlink radio channel reciprocity, the CSI is used to design downlink precoding vectors for the APs such that channel hardening is enhanced and both primary receivers and BDs benefit. We derive expressions for the average signal-to-interference-plus-noise ratios of both primary and backscatter signals, accounting for the effects of imperfect CSI, spatial correlation, pilot contamination, and channel hardening. Furthermore, the average power harvested in the BDs is derived. Simulation results demonstrate that the performance of the proposed scheme is much more uniform across all devices with CF mMIMO than with conventional co-located mMIMO. The use of CF mMIMO also largely removes the need for special consideration of the BD layer in the symbiotic system, which is not the case with co-located mMIMO.

Online Extremism, Cognitive Dissonance and Students’ Agitation Rallies: Analyzing perception of Facebook users in Pakistan

With the emergence of social media hot trends, deliberate acts of getting masses involved in agitation movements got popular from political or ideological groups in Pakistan. Youth, as the primary receiver of social media inciting emotionalism campaigns has been the major stakeholder in this regard. An emerging concern has been observed in the form of student unions’ demonstrations staged in the favor of restoration of student unions banned by President Zia-ul-Haq in 80s. These unions under the banner of Student Action Committee have taken to the street to pressurize the government to fulfill their charter of demands including restoration of students unions, freezing fee hikes, polices on sexual harassment and representation of students’ decision making in campuses. Thus the demonstrations resulted in the heavily bombardment of extremist narratives on social media regarding student solidarity march. Due to the series of events, the student solidarity march has gathered different opinions aiming at creating conflict among people of different school of thoughts. The diversity of opinion among various segments of society may create a perception of this march as political, ethnic or educational movement or involving the participants in a constant state of dissonance as participating in demonstrations without having clarity about the purpose, objectives and agenda of such processions. Drawing upon the theoretical perspective of Cognitive Dissonance, the study tends to investigate the FB users' reaction towards the students solidarity march. For this purpose, 150 Facebook respondents are selected by using purposive sampling and surveyed. The findings suggested that all the hypotheses are proven on finding P value 0.000 using Spearman correlation as more exposure to the student agitation movement is negatively correlated with more dissonance in the minds of audience and exaggerated coverage of student movement is also positively correlated with the conflict of thoughts among the audience. Moreover, it is also found that student agitation movement is catering political agenda under the name of education.

Computational-Intelligence-Based Spectrum-Sharing Scheme for NOMA-Based Cognitive Radio Networks

The integration of non-orthogonal multiple access (NOMA) technology and cognitive radio networks (CRNs) promises to enhance the spectrum utilization efficiency of 5G and beyond-5G (B5G) mobile communication systems. In this article, a NOMA-based spectrum-sharing scheme is proposed for dual-hop CRNs in which a primary transmitter separated by a long distance from the primary receiver communicates via NOMA-based CRN. In this scenario, we mathematically formulate a constrained optimization problem to maximize the sum rate of all secondary users (SUs) while maintaining the total transmit power of the system. Inspired by the effectiveness of computational intelligence (CI) tools in solving non-linear optimization problems, this article proposes three CI-based solutions to the given problem aiming to guarantee quality of service (QoS) for all users. In addition, an enhanced version of the classic artificial bee colony (ABC) algorithm, referred to here as the enhanced-artificial-bee-colony (EABC)-based power allocation scheme, is proposed to overcome the limitations of classic ABC. The comparison of different CI approaches illustrates that the minimum power required by the secondary NOMA relay to satisfy the primary rate threshold of 5 bit/s/Hz is 20 mW for EABC, while ABC, PSO and GA achieve the same target at 23 mW, 27 mW and 32 mW, respectively. Thus, EABC reduces power consumption by 13.95% compared to ABC, while 29.78% and 46.15% power-saving is achieved compared to PSO and GA, respectively.

Physical Layer Security Performance Analysis of IRS-Aided Cognitive Radio Networks

Cognitive radio (CR) acts as a significant player in enhancing the spectral efficiency (SE) of wireless telecommunications; simultaneously, the intelligent reflecting surface (IRS) technique is a valid technique for increasing the confidentiality properties of wireless telecommunications systems through the modulation of the amplitude and phase shift of the channel. Therefore, we take into consideration an IRS-assisted multiple-input single-output (MISO) CR system to raise the confidentiality rate, which is composed of a primary network with a primary receiver (PR) and an eavesdropping link, as well as a secondary network with a secondary receiver (SR) and SR transmitter (SR-TX). In particular, we minimize the SR’s transmit power under the interference temperature (IT) and confidentiality capacity constraints via the joint optimization of the beamforming vector and artificial noise (AN) constraint matrix at SR-TX together with the phase shift matrix of IRS. Numerical outcomes indicate that various transmit antenna values and the IRS element numbers at SR-TX can greatly reduce transmit power while assuring secure communication.

Maximizing the Sum-Rate of Secondary Cognitive Radio Networks by Jointly Optimizing Beamforming and Energy Harvesting Time

In this paper, we consider an energy harvesting (EH) cooperative cognitive radio network (CCRN) framework, in which the primary network (consisting of a transmitter-receiver pair) shares both energy and spectrum with the secondary network (consisting of two transceivers and multiple amplify-and-forward (AF)-based relays). Since the relays have no power source, they periodically switch between the EH and information transmission (IT) tasks. In particular, we apply a sum-rate maximization strategy to jointly obtain the optimal EH time allocation factor and distributed beamforming coefficients that achieve the best system performance for the secondary network under the individual EH power constraints at relays and an interference power constraint at the primary receiver. Although the formulated optimization problem is non-convex and complicated, we devise an efficient iterative scheme by applying the semi-definite relaxation (SDR) technique followed by the successive upper-bound minimization (SUM) strategy. Our simulation results confirm that the proposed method is spectrally and energy efficient.

On the outage probability of energy harvested cooperative multiuser cognitive NOMA network

AbstractThis paper investigates a multiple users cooperative cognitive non‐orthogonal multiple access (NOMA) network with energy harvesting. Primary transmitter and secondary sources serving as energy‐constrained nodes harvest energy from the power beacon PBS. In primary network, primary transmitter sends signals towards primary receiver. In order to make full use of spectrum resources, the secondary network access the licensed spectrum of primary network with overlay mode, where the best secondary source with maximum transmission signal‐to‐noise ratio between primary transmitter and secondary sources act as relays to forward signal via NOMA principle. In this context, two cooperative transmission protocols, namely, traditional NOMA cooperative transmission and adaptive NOMA cooperative transmission are proposed. For NOMA cooperative transmission, relays use NOMA to forward the superimposed signal of primary signal and secondary signal without any constrain. However, for adaptive NOMA cooperative transmission, relays use NOMA by judging whether the transmission between primary transmitter and primary receiver is successful or not. Primary receiver merges signals received from two transmission slots by selection combining. Finally, exact and asymptotic outage probability of primary network and secondary network with two cooperative transmissions are derived and simulated. It is shown that outage performance is improved for the proposed adaptive NOMA cooperative transmission.

Licenced to Play: Espionage Role-Playing Games in the Late Cold War Era

Hoping to tap into the massive success of the Tactical Studies Rules (TSR) Dungeons and Dragons (D&amp;D) role-playing game, strategy-game producer Victory Games released James Bond 007: Role-Playing in Her Majesty's Secret Service in 1983. Like D&amp;D, James Bond 007 allowed players to indulge in a world of fantasy and adventure. Unlike D&amp;D, however, the game was set in the contemporary world and offered players a chance to find that adventure in the Cold War era. Using sociologist Wendy Griswold’s “Cultural Diamond” as a theoretical tool, this paper analyses how TSR’s Top Secret and James Bond 007 were part of a more extensive culture system of the early 1980s, especially youth culture (Griswold 2013). In this system, cultural meaning was constructed through the intersection of four main components: the Social World, Cultural Objects, Producers, and Receivers. The Social World component is life during the Cold War, especially throughout the early 1980s, emphasising how the primary receivers, young consumers, viewed this world. The Cultural Object is the James Bond 007 game and other espionage role-playing games, especially TSR’s Top Secret. The Producers of the Cultural Object include the writers and publishers, and the Receivers are the young players and the game administrators.

Abstract 134: A Single-cell Atlas Of Human Skeletal Muscle Tissue In Chronic Limb-threatening Ischemia

Introduction: Chronic limb-threatening ischemia (CLTI) represents end-stage peripheral arterial disease (PAD) and is a significant cause of limb amputation and mortality. Evidence supports the importance of skeletal muscle responses in the pathobiology of CLTI. Skeletal muscle regeneration depends on the coordinated activity of muscle stem cells (MuSCs) and an array of non-myogenic cells, including immune cells and fibroadipogenic progenitors (FAPs). The mechanisms underlying failed muscle regeneration in the CLTI limb are unknown. Single-cell RNA sequencing (scRNA-seq) facilitates the deconvolution of multicellular tissues in homeostatic and pathologic conditions. Herein, we profiled the transcriptomes of 135,203 cells from lower extremity skeletal muscle of PAD patients to construct a cellular atlas of CLTI. Methods: We recruited 12 PAD patients undergoing major limb amputation for CLTI. We obtained proximal (non-ischemic) and distal (ischemic) muscle samples from each patient and used scRNA-seq to profile the transcriptomes of 1,700 – 20,000 cells per sample. Results: We observed 10 distinct cellular populations in the CLTI limb. The predominant cell types were MuSCs, FAPs, and immune cells. There was significant transcriptional heterogeneity in each population; we defined a range of MuSC, FAP, and macrophage sub-populations and identified specific FAPs and macrophages associated with tissue ischemia. Using CellChat analysis, we found differential cell-cell signaling probabilities in ischemic vs. non-ischemic muscle. In ischemic muscle, FAPs are the primary source of outgoing signals, while macrophages are the primary receiver. Conclusions: Our single-cell atlas highlights the transcriptional heterogeneity of cellular responses in the CLTI limb. This atlas will serve as a resource for future studies of the molecular underpinnings of CLTI, advance our understanding of its pathogenesis, and support the development of novel therapies.

Robust Beamformer Design in Active RIS-Assisted Multiuser MIMO Cognitive Radio Networks

In this work, we address the problem of a joint robust transmission, reflection and reception strategy design at an active reconfigurable intelligent surface (RIS)-assisted underlay multiple input multiple output (MIMO) cognitive radio networks in which a secondary transmitter serves multiple secondary receivers simultaneously. As such, we study the impact of imperfection in channel state information (CSI) at the secondary transmitter following a norm-bounded error model. A sum mean squared error (MSE) minimization problem is formulated by jointly optimizing the transmit beamforming matrix (BFM) at the secondary transmitter, the linear reception filters (LRF) at the secondary receivers and the reflection coefficient matrix (RCM) at the RIS subject to the constraints of available transmission power at the secondary transmitter, maximum allowed interference power towards the primary receiver and the permissible amplification range at each RIS element. Due to the coupled nature of the BFM, LRF and RCM variables, the formulated problem is non-convex and, thus, cannot be solved using conventional optimization methods. As a result, we propose an alternating optimization (AO) based iterative algorithm that determines the optimal BFM, LRF and RCM using semidefinite programming and inner approximation methods with guaranteed convergence. We also discuss the impact of the limited power budget at active RIS on the performance of the considered network. We present simulation-based numerical results to validate the efficacy and robustness of the proposed algorithm. Moreover, we also highlight the superiority of the use of the active RIS over passive RIS in the considered communication network.