Wi-Fi Coexistence with Duty Cycled LTE-U

Coexistence of Wi-Fi and LTE-Unlicensed (LTE-U) technologies has drawn significant concern in industry. In this paper, we investigate the Wi-Fi performance in the presence of duty cycle based LTE-U transmission on the same channel. More specifically, one LTE-U cell and one Wi-Fi basic service set (BSS) coexist by allowing LTE-U devices transmit their signals only in predetermined duty cycles. Wi-Fi stations, on the other hand, simply contend the shared channel using the distributed coordination function (DCF) protocol without cooperation with the LTE-U system or prior knowledge about the duty cycle period or duty cycle of LTE-U transmission. We define the fairness of the above scheme as the difference between Wi-Fi performance loss ratio (considering a defined reference performance) and the LTE-U duty cycle (or function of LTE-U duty cycle). Depending on the interference to noise ratio (INR) being above or below -62dbm, we classify the LTE-U interference as strong or weak and establish mathematical models accordingly. The average throughput and average service time of Wi-Fi are both formulated as functions of Wi-Fi and LTE-U system parameters using probability theory. Lastly, we use the Monte Carlo analysis to demonstrate the fairness of Wi-Fi and LTE-U air time sharing

Capacity Approximations of Mimo Interference Channels: Beyond Degrees of Freedom

Spectrum sharing allows the coexistence of heterogeneous wireless networks on the same frequency band. Managing the interference between such networks is critically important to ensure high spectrum efficiency, thus motivating the study of multiple-input-multiple-output (MIMO) interference channels (IC) in information theory. This dissertation studies three classes of such interference channels, namely, the MIMO one-to-three IC, the MIMO IC-ZIC, and the MIMO MAC-IC-MAC.The MIMO one-to-three IC is a partially connected three-user IC with multiple antenna terminals, where one transmitter that causes interference is heard at all three receivers, whereas the other two transmitters are heard only by their intended receivers. We present inner and outer bounds on the capacity region of the MIMO one-to-three IC, quantify the gap between the two bounds, and show that the gap is independent of the channel signal-to-noise ratios (SNRs) and interference-to-noise ratios (INRs). In particular, the achievable scheme at the interfering transmitter involves three-level superposition coding with linear precoding based on the generalized singular value decomposition (GSVD) whereas the non-interfering transmitters perform single-user coding with Gaussian codebooks and scaled identity covariances. The outer bound is obtained using genie-aided arguments with various combinations of genie information provided to the receivers. The generalized degrees of freedom (GDoF) region, which can be seen as a high SNR approximation of the capacity region, of the MIMO one-to-three IC is then fully characterized. We study the achievability of the GDoF region and the sum GDoF curve using an analysis tool developed in this dissertation, which we refer to as multidimensional signal-level partitioning. This tool is tailored for demonstrating the achievability of GDoF-tuples of a MIMO network that can be achieved via multi-level superposition coding.The MIMO IC-ZIC is also a partially connected three-user IC consisting of three transmitter-receiver pairs. In the IC-ZIC, the first and second pairs form a two-user IC, the first and third pairs form a one-sided or Z interference channel (ZIC) and the second and third transmitter-receiver pairs taken by themselves are two non-interfering point-to-point links. In this thesis, an explicit inner bound is obtained via a coding scheme is proposed in which the first transmitter employs three-level superposition coding (as in the MIMO one-to-three IC), the second one employs the previously proposed and well-known Karmakar-Varanasi coding scheme (which achieves a constant-gap-to-capacity region of the two-user MIMO IC), and the third transmitter employs single-user coding with a Gaussian codebook (with scaled identity covariance). An explicit single region outer bound based on genie-aided arguments is then obtained. The gap between the inner and outer bounds is then shown to be within a quantifiable gap to the capacity region and the gap is independent of channel SNRs and INRs. The GDoF region is then characterized and analyzed in a variety of channel settings. The difficulty in this part of the research lies in the quantification of the gap between the 28-inequality inner bound and the 33-inequality outer bound, which is characterized via a series of supporting lemmas that reveal the relationship between the entropy terms in the inner and outer bounds.The MIMO MAC-IC-MAC consists of two interfering MACs in which there is interference only from one transmitter of each MAC to the receiver of the other MAC. Two achievable rate regions that are within a quantifiable gap of the capacity region for the discrete-memoryless semi-deterministic MAC-IC-MAC were obtained in a previous published work by Pang and Varanasi using inner and outer bounds that are unions of polytopes. In the dissertation, we obtain single region inner and outer bounds that characterize a constant-gap-to-capacity region of the MIMO MAC-IC-

Characterization and Identification of Lactic Acid Bacteria Isolated from Silage Prepared in Lao PDR

Silage is now the most common preserved cattle feed in many countries and lactic acid bacteria (LAB) play an important role during silage fermentation process. In order to establish an animal feed production system to cover the shortage of animal feed in the dry season of Lao PDR, silage fermentation technology is needed that has potential application in poor villages. Therefore, the characterization of LAB in various forage crops and their species identification requires further study. In the present study, the characterization of LAB species isolated from forage crops in Lao PDR was examined. In order to determine their taxonomic status, these strains were also studied by 16S rRNA sequence analysis

Real-World Image Super Resolution via Unsupervised Bi-directional Cycle Domain Transfer Learning based Generative Adversarial Network

Deep Convolutional Neural Networks (DCNNs) have exhibited impressive performance on image super-resolution tasks. However, these deep learning-based super-resolution methods perform poorly in real-world super-resolution tasks, where the paired high-resolution and low-resolution images are unavailable and the low-resolution images are degraded by complicated and unknown kernels. To break these limitations, we propose the Unsupervised Bi-directional Cycle Domain Transfer Learning-based Generative Adversarial Network (UBCDTL-GAN), which consists of an Unsupervised Bi-directional Cycle Domain Transfer Network (UBCDTN) and the Semantic Encoder guided Super Resolution Network (SESRN). First, the UBCDTN is able to produce an approximated real-like LR image through transferring the LR image from an artificially degraded domain to the real-world LR image domain. Second, the SESRN has the ability to super-resolve the approximated real-like LR image to a photo-realistic HR image. Extensive experiments on unpaired real-world image benchmark datasets demonstrate that the proposed method achieves superior performance compared to state-of-the-art methods.Comment: 12 pages, 5 figures,3 tables. This work is submitted to IEEE Transactions on Systems, Man, and Cybernetics: Systems (2022). It's under review by IEEE Transactions on Systems, Man, and Cybernetics: Systems for no

Risk of venous thromboembolism with janus kinase inhibitors in inflammatory immune diseases: a systematic review and meta-analysis

Objectives: This study aimed to evaluate the risk of venous thrombosis (VTE) associated with Janus kinase (JAK) inhibitors in patients diagnosed with immune-mediated inflammatory diseases.Methods: We conducted a comprehensive search of PUBMED, Cochrane, and Embase databases for randomized controlled trials evaluating venous thromboembolic incidence after administering JAK inhibitors in patients with immune-mediated inflammatory diseases. The studies were screened according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and a meta-analysis was performed.Results: A total of 16 studies, enrolling 17,242 participants, were included in this review. Four approved doses of JAK inhibitors were administered in the included studies. The meta-analysis revealed no significant difference in the incidence of VTE between patients receiving JAK inhibitors, a placebo, or tumor necrosis factor (TNF) inhibitors (RR 0.72, 95% CI (0.33-1.55); RR 0.94, 95%CI (0.33-2.69)). Subgroup analysis showed a lower risk of VTE with lower doses of JAK inhibitors [RR 0.56, 95%CI (0.36-0.88)]. Compared with the higher dose of tofacitinib, the lower dose was associated with a lower risk of pulmonary embolism [RR 0.37, 95%CI (0.18-0.78)].Conclusion: Our meta-analysis of randomized controlled trials observed a potential increase in the risk of VTE in patients with immune-mediated inflammatory diseases treated with JAK inhibitors compared to placebo or tumor necrosis factor inhibitors, though statistical significance was not attained. Notably, a higher risk of pulmonary embolism was observed with high doses of tofacitinib. Our findings provide valuable insights for physicians when evaluating the use of JAK inhibitors for patients with immune-mediated inflammatory diseases.Systematic Review Registration:https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023382544, identifier CRD4202338254

Al-based Nano-sized Composite Energetic Materials (Nano-CEMs): Preparation, Characterization and Performance

As one of the new types of functional materials, nano-sized composite energetic materials (nano-CEMs) possess many advantages and broad application prospects in the research field of explosives and propellants. The recent progress in the preparation and performance characterization of Al-based nano-CEMs has been reviewed. The preparation methods and properties of Al-based nano-CEMs are emphatically analyzed. Special emphasis is focused on the improved performances of Al-based nano-CEMs, which are different from those of conventional micro-sized composite energetic materials (micro-CEMs), such as thermal decomposition and hazardous properties. The existing problems and challenges for the future work on Al-based nano-CEMs are discussed