Where this book is exceptional is that the reader will not just learn how LTE works but why it works Adrian Scrase, ETSI Vice-President, International Partnership Projects LTE - The UMTS Long Term Evolution: From Theory to Practice provides the reader with a comprehensive system-level understanding of LTE, built on explanations of the theories which underlie it. The book is the product of a collaborative effort of key experts representing a wide range of companies actively participating in the development of LTE, as well as academia. This gives the book a broad, balanced and reliable perspective on this important technology. Lucid yet thorough, the book devotes particular effort to explaining the theoretical concepts in an accessible way, while retaining scientific rigour. It highlights practical implications and draws comparisons with the well-known WCDMA/HSPA standards. The authors not only pay special attention to the physical layer, giving insight into the fundamental concepts of OFDMA, SC-FDMA and MIMO, but also cover the higher protocol layers and system architecture to enable the reader to gain an overall understanding of the system. Key Features: Draws on the breadth of experience of a wide range of key experts from both industry and academia, giving the book a balanced and broad perspective on LTE Provides a detailed description and analysis of the complete LTE system, especially the ground-breaking new physical layer Offers a solid treatment of the underlying advances in fundamental communications and information theory on which LTE is based Addresses practical issues and implementation challenges related to the deployment of LTE as a cellular system Includes an accompanying website containing a complete list of acronyms related to LTE, with a brief description of each (http://www.wiley.com/go/sesia_theumts) This book is an invaluable reference for all research and development engineers involved in LTE implementation, as well as graduate and PhD students in wireless communications. Network operators, service providers and R&D managers will also find this book insightful.
This Account provides perspective on the evolution of the rechargeable battery and summarizes innovations in the development of these devices. Initially, I describe the components of a conventional rechargeable battery along with the engineering parameters that define the figures of merit for a single cell. In 1967, researchers discovered fast Na(+) conduction at 300 K in Na β,β''-alumina. Since then battery technology has evolved from a strongly acidic or alkaline aqueous electrolyte with protons as the working ion to an organic liquid-carbonate electrolyte with Li(+) as the working ion in a Li-ion battery. The invention of the sodium-sulfur and Zebra batteries stimulated consideration of framework structures as crystalline hosts for mobile guest alkali ions, and the jump in oil prices in the early 1970s prompted researchers to consider alternative room-temperature batteries with aprotic liquid electrolytes. With the existence of Li primary cells and ongoing research on the chemistry of reversible Li intercalation into layered chalcogenides, industry invested in the production of a Li/TiS2 rechargeable cell. However, on repeated recharge, dendrites grew across the electrolyte from the anode to the cathode, leading to dangerous short-circuits in the cell in the presence of the flammable organic liquid electrolyte. Because lowering the voltage of the anode would prevent cells with layered-chalcogenide cathodes from competing with cells that had an aqueous electrolyte, researchers quickly abandoned this effort. However, once it was realized that an oxide cathode could offer a larger voltage versus lithium, researchers considered the extraction of Li from the layered LiMO2 oxides with M = Co or Ni. These oxide cathodes were fabricated in a discharged state, and battery manufacturers could not conceive of assembling a cell with a discharged cathode. Meanwhile, exploration of Li intercalation into graphite showed that reversible Li insertion into carbon occurred without dendrite formation. The SONY corporation used the LiCoO2/carbon battery to power their initial cellular telephone and launched the wireless revolution. As researchers developed 3D transition-metal hosts, manufacturers introduced spinel and olivine hosts in the Lix[Mn2]O4 and LiFe(PO4) cathodes. However, current Li-ion batteries fall short of the desired specifications for electric-powered automobiles and the storage of electrical energy generated by wind and solar power. These demands are stimulating new strategies for electrochemical cells that can safely and affordably meet those challenges.
Background Tobacco smoking is the cause of many preventable diseases and premature deaths in the UK and around the world. It poses enormous health- and non-health-related costs to the affected individuals, employers, and the society at large. The World Health Organization (WHO) estimates that, globally, smoking causes over US$500 billion in economic damage each year. Objectives This paper examines global and UK evidence on the economic impact of smoking prevalence and evaluates the effectiveness and cost effectiveness of smoking cessation measures. Study Selection Search Methods We used two major health care/economic research databases, namely PubMed and the National Institute for Health Research (NIHR) database that contains the British National Health Service (NHS) Economic Evaluation Database; Cochrane Library of systematic reviews in health care and health policy; and other health-care-related bibliographic sources. We also performed hand searching of relevant articles, health reports, and white papers issued by government bodies, international health organizations, and health intervention campaign agencies. Selection Criteria The paper includes cost-effectiveness studies from medical journals, health reports, and white papers published between 1992 and July 2014, but included only eight relevant studies before 1992. Most of the papers reviewed reported outcomes on smoking prevalence, as well as the direct and indirect costs of smoking and the costs and benefits of smoking cessation interventions. We excluded papers that merely described the effectiveness of an intervention without including economic or cost considerations. We also excluded papers that combine smoking cessation with the reduction in the risk of other diseases. Data Collection and Analysis The included studies were assessed against criteria indicated in the Cochrane Reviewers Handbook version 5.0.0. Outcomes Assessed in the Review Primary outcomes of the selected studies are smoking prevalence, direct and indirect costs of smoking, and the costs and benefits of smoking cessation interventions (eg, “cost per quitter”, “cost per life year saved”, “cost per quality-adjusted life year gained,” “present value” or “net benefits” from smoking cessation, and “cost savings” from personal health care expenditure). Main Results The main findings of this study are as follows: 1. The costs of smoking can be classified into direct, indirect, and intangible costs. About 15% of the aggregate health care expenditure in high-income countries can be attributed to smoking. In the US, the proportion of health care expenditure attributable to smoking ranges between 6% and 18% across different states. In the UK, the direct costs of smoking to the NHS have been estimated at between £2.7 billion and £5.2 billion, which is equivalent to around 5% of the total NHS budget each year. The economic burden of smoking estimated in terms of GDP reveals that smoking accounts for approximately 0.7% of China's GDP and approximately 1% of US GDP. As part of the indirect (non-health-related) costs of smoking, the total productivity losses caused by smoking each year in the US have been estimated at US$151 billion. 2. The costs of smoking notwithstanding, it produces some potential economic benefits. The economic activities generated from the production and consumption of tobacco provides economic stimulus. It also produces huge tax revenues for most governments, especially in high-income countries, as well as employment in the tobacco industry. Income from the tobacco industry accounts for up to 7.4% of centrally collected government revenue in China. Smoking also yields cost savings in pension payments from the premature death of smokers. 3. Smoking cessation measures could range from pharmacological treatment interventions to policy-based measures, community-based interventions, telecoms, media, and technology (TMT)-based interventions, school-based interventions, and workplace interventions. 4. The cost per life year saved from the use of pharmacological treatment interventions ranged between US$128 and US$1,450 and up to US$4,400 per quality-adjusted life years (QALYs) saved. The use of pharmacotherapies such as varenicline, NRT, and Bupropion, when combined with GP counseling or other behavioral treatment interventions (such as proactive telephone counseling and Web-based delivery), is both clinically effective and cost effective to primary health care providers. 5. Price-based policy measures such as increase in tobacco taxes are unarguably the most effective means of reducing the consumption of tobacco. A 10% tax-induced cigarette price increase anywhere in the world reduces smoking prevalence by between 4% and 8%. Net public benefits from tobacco tax, however, remain positive only when tax rates are between 42.9% and 91.1%. The cost effectiveness ratio of implementing non-price-based smoking cessation legislations (such as smoking restrictions in work places, public places, bans on tobacco advertisement, and raising the legal age of smokers) range from US$2 to US$112 per life year gained (LYG) while reducing smoking prevalence by up to 30%–82% in the long term (over a 50-year period). 6. Smoking cessation classes are known to be most effective among community-based measures, as they could lead to a quit rate of up to 35%, but they usually incur higher costs than other measures such as self-help quit-smoking kits. On average, community pharmacist-based smoking cessation programs yield cost savings to the health system of between US$500 and US$614 per LYG. 7. Advertising media, telecommunications, and other technology-based interventions (such as TV, radio, print, telephone, the Internet, PC, and other electronic media) usually have positive synergistic effects in reducing smoking prevalence especially when combined to deliver smoking cessation messages and counseling support. However, the outcomes on the cost effectiveness of TMT-based measures have been inconsistent, and this made it difficult to attribute results to specific media. The differences in reported cost effectiveness may be partly attributed to varying methodological approaches including varying parametric inputs, differences in national contexts, differences in advertising campaigns tested on different media, and disparate levels of resourcing between campaigns. Due to its universal reach and low implementation costs, online campaign appears to be substantially more cost effective than other media, though it may not be as effective in reducing smoking prevalence. 8. School-based smoking prevalence programs tend to reduce short-term smoking prevalence by between 30% and 70%. Total intervention costs could range from US$16,400 to US$580,000 depending on the scale and scope of intervention. The cost effectiveness of school-based programs show that one could expect a saving of approximately between US$2,000 and US$20,000 per QALY saved due to averted smoking after 2–4 years of follow-up. 9. Workplace-based interventions could represent a sound economic investment to both employers and the society at large, achieving a benefit–cost ratio of up to 8.75 and generating 12-month employer cost savings of between $150 and $540 per nonsmoking employee. Implementing smoke-free workplaces would also produce myriads of new quitters and reduce the amount of cigarette consumption, leading to cost savings in direct medical costs to primary health care providers. Workplace interventions are, however, likely to yield far greater economic benefits over the long term, as reduced prevalence will lead to a healthier and more productive workforce. Conclusions We conclude that the direct costs and externalities to society of smoking far outweigh any benefits that might be accruable at least when considered from the perspective of socially desirable outcomes (ie, in terms of a healthy population and a productive workforce). There are enormous differences in the application and economic measurement of smoking cessation measures across various types of interventions, methodologies, countries, economic settings, and health care systems, and these may have affected the comparability of the results of the studies reviewed. However, on the balance of probabilities, most of the cessation measures reviewed have not only proved effective but also cost effective in delivering the much desired cost savings and net gains to individuals and primary health care providers.
Background Online appointment booking is a commonly used tool in several industries. There is limited evidence about the benefits and challenges of using online appointment booking in health care settings. Potential benefits include convenience and the ability to track appointments, although some groups of patients may find it harder to engage with online appointment booking. We sought to understand how patients in England used and experienced online appointment booking. Objective This study aims to describe and compare the characteristics of patients in relation to their use of online appointment booking in general practice and investigate patients’ views regarding online appointment booking arrangements. Methods This was a mixed methods study set in English general practice comprising a retrospective analysis of the General Practice Patient Survey (GPPS) and semistructured interviews with patients. Data used in the retrospective analysis comprised responses to the 2018 and 2019 GPPS analyzed using mixed-effects logistic regression. Semistructured interviews with purposively sampled patients from 11 general practices in England explored experiences of and views on online appointment booking. Framework analysis was used to allow for comparison with the findings of the retrospective analysis. Results The retrospective analysis included 1,327,693 GPPS responders (2018-2019 combined). We conducted 43 interviews with patients with a variety of experiences and awareness of online appointment booking; of these 43 patients, 6 (14%) were from ethnic minority groups. In the retrospective analysis, more patients were aware that online appointment booking was available (581,224/1,288,341, 45.11%) than had experience using it (203,184/1,301,694, 15.61%). There were deprivation gradients for awareness and use and a substantial decline in both awareness and use in patients aged >75 years. For interview participants, age and life stage were factors influencing experiences and perceptions, working patients valued convenience, and older patients preferred to use the telephone. Patients with long-term conditions were more aware of (odds ratio [OR] 1.43, 95% CI 1.41-1.44) and more likely to use (OR 1.65, 95% CI 1.63-1.67) online appointment booking. Interview participants with long-term conditions described online appointment booking as useful for routine nonurgent appointments. Patients in deprived areas were clustered in practices with low awareness and use of online appointment booking among GPPS respondents (OR for use 0.65, 95% CI 0.64-0.67). Other key findings included the influence of the availability of appointments online and differences in the registration process for accessing online booking. Conclusions Whether and how patients engage with online appointment booking is influenced by the practice with which they are registered, whether they live with long-term conditions, and their deprivation status. These factors should be considered in designing and implementing online appointment booking and have implications for patient engagement with the wider range of online services offered in general practice.
In this design, a novel inverted F antenna with a low profile feed structure is proposed for millimeter-wave (mmW) applications. The array element consists of a printed inverted F antenna and a L-shaped parasitic deflector, approximately forming a structure similar to the Yagi-Uda antenna. The gain could be increased and the impedance bandwidth could be broadened by the structure. And, it is important to realize the miniaturization of the antenna element by bending the parasitic deflector based on the traditional deflector without affecting the performance. The proposed antenna has a low feed substrate height (0.254 mm∼0.02λ0), which makes it easy to integrate with planar circuits. As proof, a 1 × 4 array model with an impedance bandwidth of 20.5% (23.0–28.3 GHz) is designed and measured. The inverted F array demonstrated is an important candidate for mmW applications due to its wide bandwidth, miniaturization, ease of integration with planar circuits, and low manufacturing cost.
The antenna end of the tethered balloon-type high-power VLF communication system will be exposed to an extremely strong alternating electric field environment when it is in operation. Due to dielectric loss, an abnormal temperature rise may occur at the antenna end, which may lead to an antenna fracture in serious cases. It is an effective measure to install a corona ring at the end of the antenna to prevent such accidents. In this paper, the structural parameters of the corona ring, including ring radius, tube radius, and ring depth, are optimized based on intelligent optimization algorithm to significantly improve the electric field distribution and restrain the temperature rise to the maximum extent. The effectiveness of the optimization results is verified by simulation.
The work presented in this paper concerns a method for the miniaturized frequency selective surface (FSS) based on the meander lines. A miniaturized dual-bandstop FSS structure based on meander lines with spiral-shape is proposed and simulated. The equivalent circuit and current distributions are introduced to explain the FSS performance. The size of the unit cell is 10 mm, which is about 0.037 wavelength at the first resonant frequency. Simulation results indicate that the proposed FSS has a frequency shift smaller than 1% for different polarizations with an oblique incident angle of 60°. A prototype of the FSS is fabricated and measured. The measurement results show that the FSS is polarization-insensitive and angle-insensitive.
This paper presents the low profile, planar, and small-size antenna design for WWAN, LTE, and 5G (5th generation wireless systems) for use in portable communication equipment. The antenna occupies only 65 × 13 × 0.4 mm3, and the antenna is combined with a 200 × 260 mm2 copper plate to simulated system ground plane. In the low band, a direct-fed right-side arm and a coupled-fed arm implemented can excite a 1/4 λ fundamental resonant mode at 0.85 and 0.76 GHz to cover 0.698–0.96 GHz and upper 3/4 λ and 5/4 λ resonant modes are controlled by L-shaped element at 2.34, 2.69, 3.4, and 4.0 GHz to cover 1.71–2.69 GHz and 3.2–4.2 GHz. The direct-fed left-side arm produced 1/4 λ to cover 5.15–5.85 GHz. In far-field measured, peak gain and efficiency in low, middle, and high bands are 0.43–5.67 dBi and 55–86%. Finally, experiments demonstrate that the present antenna exhibits a good performance for portable devices.
Interference between ultrawideband (UWB) antennas and other narrowband communication systems has spurred growth in designing UWB antennas with notch characteristics and complicated designs consisting of irregular etched slots and larger physical size. This article presents a simplified notched design method for existing UWB antennas exhibiting four frequency-band-rejecting characteristics. The investigation has been conducted by introducing four semicircular U-shaped slot structures based on a theoretical formulation. The formulation is validated with the equivalent LC lumped parameters responsible for yielding the notched frequency. A novel feature of our approach is that the frequency notch can be adjusted to the desired values by changing the radial length based on the value calculated using a derived formula for each semietched U-slot, which is very simple in structure and design. Additionally, by introducing the rectangular notch at the ground plane, the upper passband spectrum is suppressed while maintaining the wide impedance bandwidth of the antenna applicable for next-generation wireless communications, 5G. The measured result shows that the antenna has a wide impedance bandwidth of 149% from 2.9 to 20 GHz, apart from the four-notched frequencies at 3.49, 3.92, 4.57, and 5.23 GHz for a voltage standing wave ratio (VSWR) of <2 rejecting the Worldwide Interoperability for microwave Access (WiMAX) band at (3.38-3.7 GHz), the European C-band at (3.84-4.29 GHz), the Indian national satellite (INSAT) at (4.47-4.92 GHz), and wireless local area networks (WLANs) at (5.09-5.99 GHz). Measured and simulated experimental results reveal that the antenna exhibits nearly an omnidirectional pattern in the passband, low gain at the stopband, and good radiation efficiency within a frequency range. The LC equivalent notched frequency has been proposed by analyzing the L and C equivalent formula, and it has been validated with simulated and measured results. The measurement and simulated results correspond well at the LC equivalent notch band rejecting the existing narrowband systems.
While the majority of states have adopted child psychiatric telephone consultation programs, allowing pediatric providers who may lack the training to treat children's mental health disorders to consult with a specialist, up until now, no multistate studies have been conducted to determine the effectiveness of such programs.
We present the design of a new microwave all-dielectric chiral metasurface with circular dichroism behavior based on elliptic dielectric resonators (EDRs). During the design procedure, we have first optimized numerically the effects of the main design parameters such as the resonator’s size and orientation, as well as the size of the slot within them, on the metasurface transmission over the frequency band 10–20 GHz. Measurements on the final metasurface prototype have shown a large circular dichroism (Δ=0.61 and Δ=0.5) over two bands (17.55–17.61 GHz and 17.91–18.05 GHz) with ellipticities close to 45° which means that the developed device can be used as a circular polarization filter and circular polarizer at microwave frequencies.
Paulo R. B. Gomes, André L. F. de Almeida, João Paulo C. L. da Costa
et al.
The estimation of spatial signatures and spatial frequencies is crucial for several practical applications such as radar, sonar, and wireless communications. In this paper, we propose two generalized iterative estimation algorithms to the case in which a multidimensional (R-D) sensor array is used at the receiver. The first tensor-based algorithm is an R-D blind spatial signature estimator that operates in scenarios where the source’s covariance matrix is nondiagonal and unknown. The second tensor-based algorithm is formulated for the case in which the sources are uncorrelated and exploits the dual-symmetry of the covariance tensor. Additionally, a new tensor-based formulation is proposed for an L-shaped array configuration. Simulation results show that our proposed schemes outperform the state-of-the-art matrix-based and tensor-based techniques.
A multiple-user-port antenna tuner having the structure of a multidimensional π-network has recently been disclosed, together with design equations which assume lossless circuit elements. This paper is about the design of this type of antenna tuner, when losses are taken into account in each circuit element of the antenna tuner. The problem to be solved is the tuning computation, the intended results of which are the reactance values of the adjustable impedance devices of the antenna tuner, which provide an ideal match, if such reactance values exist. An efficient iterative tuning computation technique is presented and demonstrated.
A compact small-size coupled-fed antenna composed of an inverted L-shaped feeding strip and a shorting strip with double branches for the WWAN/LTE bands operation in the internal smartphone application is presented. With the help of a novel distributed LC resonant circuit, the proposed antenna can not only realize the miniaturization (15 × 28 × 4 mm3) and multiband to cover 2G/3G/4G bands but also be tuned and optimized easily. The measured bandwidth with 3 : 1 VSWR is 163 MHz (804–967 MHz) at the low-band and 1615 MHz (1665–3280 MHz) at the high-band. What is more, the lowest measured efficiency in the whole frequency band is more than 52% for practical applications. The operating principles and main parameters are detailed below. And successful simulation, fabrication, and measurement of the proposed antenna are shown in this paper.
We make preliminary investigations on a new approach to reducing radar cross section (RCS) of conducting objects. This approach employs novel planar metasurfaces characterizing nonuniform distribution of reflection phase. The operation principle of this approach and the design rule of the associated metasurfaces are explained using a simplified theoretical model. We then present a design example of such metasurfaces, in which three-layer stacked square patches with variable sizes are utilized as the reflecting elements. The proposed RCS-reduction approach is verified by both numerical simulations and measurements on the example, under the assumption of normal plane wave incidence. It is observed that, in a fairly wide frequency band (from 3.6 to 5.5 GHz), the presented example is capable of suppressing the specular reflections of conducting plates significantly (by more than 7 dB) for two orthogonal incident polarizations.