A survey of symbiotic radio: Methodologies, applications, and future directions

The sixth generation (6G) wireless technology aims to achieve global connectivity with environmentally sustainable networks to improve the overall quality of life. The driving force behind these networks is the rapid evolution of the Internet of Things (IoT), which has led to a proliferation of wireless applications across various domains through the massive deployment of IoT devices. The major challenge is to support these devices with limited radio spectrum and energy-efficient communication. Symbiotic radio (SRad) technology is a promising solution that enables cooperative resource-sharing among radio systems through symbiotic relationships. By fostering mutualistic and competitive resource sharing, SRad technology enables the achievement of both common and individual objectives among the different systems. It is a cutting-edge approach that allows for the creation of new paradigms and efficient resource sharing and management. In this article, we present a detailed survey of SRad with the goal of offering valuable insights for future research and applications. To achieve this, we delve into the fundamental concepts of SRad technology, including radio symbiosis and its symbiotic relationships for coexistence and resource sharing among radio systems. We then review the state-of-the-art methodologies in-depth and introduce potential applications. Finally, we identify and discuss the open challenges and future research directions in this field

Beam selection for ambient backscatter communication in beamspace mmWave symbiotic radio

The Internet of Things revolution has profoundly impacted wireless communication systems. Access to high data rates is now just as important as low power operation. The use of incident millimeter-wave (mmWave) signals for ambient backscatter communication (AmBC) has shown significant promise for delivering high data rates. However, due to channel sparsity, incident signal availability to backscatter devices (BDs) at mmWave is erratic. In order to address the incident signal inaccessibility problem and enable high data-rate AmBC, this paper presents an efficient beam selection method in the beamspace millimeter-wave symbiotic radio system. The proposed method improves the overall system’s sum-rate performance by up to 30% while ensuring signal accessibility to BDs

Population Attributable Risk of Unintentional Childhood Poisoning in Karachi Pakistan

Background: The percentage of unintentional childhood poisoning cases in a given population attributable to specific risk factors (i.e., the population attributable risk) which can be calculated, determination of such risk factors associated with potentially modifiable risk factors, are necessary to focus on the prevention strategies. Methods: We calculated PARs, using 120 cases with unintentional poisoning and 360 controls in a hospital based matched case- control study. The risk factors were accessibility to hazardous chemicals and medicines due to unsafe storage, child behavior reported as hyperactive, storage of kerosene and petroleum in soft drink bottles, low socioeconomic class, less education of the mother and the history of previous poisoning. Results: The Following Attrubuted Risks Were Observed: 12% (95% confidence interval [CI] = 8%-16%) for both chemicals and medicines stored unsafe, 19% (15%-23%) for child reported as hyperactive, 40% (38%-42%) for storage of kerosene and petroleum in soft drink bottles, 48% (42%-54%) for low socioeconomic status, 38% (32%-42%) for no formal mothers education and 5.8% (2%-10%) for history of previous poisoning. 48% of cases for overall study population which could be attributed to at least one of the six risk factors. Among girls, this proportion was 23% and 43% among boys. About half of the unintentional childhood poisoning cases in this Pakistani population could be avoided. Conclusion: Exposure to potentially modifiable risk indicators explained about half of the cases of unintentional poisoning among children under five years of age in this Pakistani population, indicating the theoretical scope for prevention of the disease

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

A Survey of Symbiotic Radio: Methodologies, Applications, and Future Directions

The sixth generation (6G) wireless technology aims to achieve global connectivity with environmentally sustainable networks to improve the overall quality of life. The driving force behind these networks is the rapid evolution of the Internet of Things (IoT), which has led to a proliferation of wireless applications across various domains through the massive deployment of IoT devices. The major challenge is to support these devices with limited radio spectrum and energy-efficient communication. Symbiotic radio (SRad) technology is a promising solution that enables cooperative resource-sharing among radio systems through symbiotic relationships. By fostering mutualistic and competitive resource sharing, SRad technology enables the achievement of both common and individual objectives among the different systems. It is a cutting-edge approach that allows for the creation of new paradigms and efficient resource sharing and management. In this article, we present a detailed survey of SRad with the goal of offering valuable insights for future research and applications. To achieve this, we delve into the fundamental concepts of SRad technology, including radio symbiosis and its symbiotic relationships for coexistence and resource sharing among radio systems. We then review the state-of-the-art methodologies in-depth and introduce potential applications. Finally, we identify and discuss the open challenges and future research directions in this field

Exchange bias in magnetic thin films and nanoparticles : study of spin glass, spin dynamics and anisotropy

The spin valve structure has important applications in the hard disk drives, magnetic sensors, magnetoresistive random-access memory, etc. and consequently is actively researched. The materials having perpendicular magnetic anisotropy are in high demand for perpendicular magnetic recording and heat-assisted magnetic recording. Other than the magnetic thin films, the magnetic nanoparticles have strong contribution in the emerging technologies, such as, drug delivery, tagging or labeling of the desired biological entity and magnetic resonance imaging. The goal of this thesis is to explore different magnetic behaviours in the magnetic thin films and nanoparticles, i.e., exchange bias (EB), perpendicular magnetic anisotropy (PMA), spin glass (SG) phases, spin dynamics, magnetic interactions in the magnetic thin films and nanoparticles. Moreover, this thesis includes some new magnetic behaviours which have not been yet reported after the acreful literature survey. The PMA is studied in the thin films of CoPd alloy. Perpendicular EB is developed by using IrMn as an antiferromagnet. A transition in the EB is observed at low temperatures, where the in-plane (IP) EB field becomes larger than the out-of-plane (OP) EB field. It is found that with decreasing temperature there is a spin structure transition in the IrMn (111) layer related to a 3Q (favors OP spins component) to 2Q transition (favors IP spins component) in the bulk. This transition is responsible for the increase in the IP EB at low temperatures and has not been reported before. A spin reorientation transition from OP to IP (at higher temperatures) is also observed in the CoPd alloy, but is too weak to perturb the spin structure transition of IrMn, which dominates the temperature dependence of EB. The most interesting result is an increase in PMA of CoPd/IrMn with decreasing the thickness of CoPd layer, which is contrary to bare CoPd alloy. The bulk 3Q spin structure of IrMn and the angle between the CoPd and IrMn moments at the interface are the reasons of this discrepancy. Memory effect, aging, Morin transition and EB effect are studied in the agglomerated hematite nanoparticles of different shapes from spherical to spindle. The super spin glass (SSG) and surface SG phases are found in these nanoparticles generating EB field. The interesting behaviour is the sign change in the EB field along with Morin transition, where the rotation of Fe ions in the core changes the exchange coupling at interface resulting in positive EB field. Morin transition is diminished with increasing the aspect ratio of nanoparticles due to the enhanced lattice strain and surface defects. In order to eliminate agglomeration, silica coating is used around the nanoparticles. The silica coating enhances the surface disorder, decreases magnetization and depletes Morin transition. The sign of the EB field is changed to negative as compared to uncoated ones. Co1-xMgxFe2O4 nanoparticles are studied in quasi-free state and semi-compressed form. Spontaneous exchange bias (SEB) is observed along with conventional exchange bias (CEB) in the both states of nanoparticles. In the quasi-free state of nanoparticles, SEB is larger than CEB, while SEB becomes weak in semi-compressed form. The initial magnetic state has strong influence on SEB, where strong randomness contributes to the volume fraction of SG phase. The frustration and smooth movement of nanoparticles enhance SEB in quasi-free state of nanoparticles. The metastable domain states are developed in the system due to strain and dilution which perturbed by the rotation of the ferrimagnetic core moments with increasing temperature.The temperature driven sign reversal in Fe/Cr bilayers is studied and explained by the formation of interface alloying. The FeCr alloy at the interface transforms into SG phase during cooling. At low temperatures, the ferromagnetic interactions between frozen Fe clusters in alloy and adjacent Fe layer, results into enhanced negative EB field. The Cr rich alloy favours re-entrant SG to antiferromagnetic phase transition in alloy with increase in temperature. This phase transition changes the ferromagnetic coupling to antiferromagnetic between uncompensated Cr moments and Fe layer at interface resulting into positive EB.The novel results in the EB in different magnetic systems certainly encourage further probe into it by changing the thickness of IrMn layer for CoPd/IrMn system and the interparticle interactions

Improving connectivity via multi-user scheduling in 5G and beyond networks

In this paper, a novel, yet efficient, multi-user scheduling scheme based on mode selection and power allocation is presented for 5G and beyond networks. The proposed scheme schedules the users in co-existence (CE) and non coexistence (NCE) modes to maximize the connectivity under signal separability and reliability constraints. In addition, two multi-user scheduling mechanisms; check requirements before scheduling (CRBS) and check requirements after scheduling (CRAS), are proposed for practical scenarios to study the impact of quality of service (QoS) on multi-user scheduling in terms of users' reliability requirements. Analytical results show that CRBS outperforms CRAS and orthogonal multiple access (OMA) schemes in terms of connectivity and system throughput with a complexity trade-off

User pairing and power allocation strategies for 3D VLC-NOMA systems

In this letter, we propose two novel, yet efficient, user pairing schemes for non-orthogonal multiple access (NOMA) in 3D visible light communication (VLC). Our analysis is carried out assuming different heights for the users & x2019; location as well as two dynamic power allocation strategies. Performance gains are attained when compared the proposed schemes with NOMA without user pairing and with orthogonal multiple access (OMA). The effects of the key system parameters on the overall performance are investigated and insightful discussions are drawn