Dual-Polarization OFDM-OQAM Wireless Communication System

In this paper we describe the overall idea and results of a recently proposed radio access technique based on filter bank multicarrier (FBMC) communication system using two orthogonal polarizations: dual-polarization FBMC (DP-FBMC). Using this system we can alleviate the intrinsic interference problem in FBMC systems. This enables use of all the multicarrier techniques used in cyclic-prefix orthogonal frequency-division multiplexing (CP-OFDM) systems for channel equalization, multiple-input/multiple-output (MIMO) processing, etc., without using the extra processing required for conventional FBMC. DP-FBMC also provides other interesting advantages over CP-OFDM and FBMC such as more robustness in multipath fading channels, and more robustness to receiver carrier frequency offset (CFO) and timing offset (TO). For DP-FBMC we propose three different structures based on different multiplexing techniques in time, frequency, and polarization. We will show that one of these structures has exactly the same system complexity and equipment as conventional FBMC. In our simulation results DP-FBMC has better bit error ratio (BER) performance in dispersive channels. Based on these results, DP-FBMC has potential as a promising candidate for future wireless communication systems.Comment: 1.This paper is accepted to be published in IEEE Vehicular Technology Conference (VTC) FALL 2018. 2.In this new submitted version authors have revised the paper based on the VTC FALL reviewers comments. Therefore some typos have fixed and some results have change

PAPR Analysis for Dual-Polarization FBMC

In a recent work we proposed a new radio access technique based on filter bank multi-carrier (FBMC) modulation using two orthogonal polarizations: dual-polarization FBMC (DP-FBMC). We showed that with good cross-polarization discrimination (XPD), DP-FBMC solves the intrinsic imaginary interference shortcoming of FBMC without extra processing. DP-FBMC also has other interesting advantages over cyclic prefix orthogonal frequency-division multiplexing (CP-OFDM) and FBMC such as more robustness in dispersive channels, and it is also more robust to receiver carrier frequency offset (CFO) and timing offset (TO). In this paper we analyze the peak to average power ratio (PAPR) of DP-FBMC and compare PAPR simulation results with that of conventional FBMC, for different prototype filters and overlapping factors. According to the analysis and results, with a proper choice of prototype filter, DP-FBMC has comparable PAPR to FBMC.Comment: This paper has been published in IEEE MILCOM Conference 2018. Some results has been changed from first versio

Evaluation Of Multicarrier Air Interfaces In The Presence Of Interference For L-Band And C-Band Air-Ground Communications

The use of aeronautical vehicles and systems is continuously growing, and this means current aeronautical communication systems, particularly those operating in the very high frequency (VHF) aviation band, will suffer from severe congestion in some regions of the world. For example, it is estimated that air-to-ground (AG) communication traffic density will at least double by 2035 over that in 2012, based on the most-likely growth scenario for Europe. This traffic growth (worldwide) has led civil aviation authorities such as the FAA in the USA, and EuroControl in Europe, to jointly explore development of future communication infrastructures (FCI). According to international aviation systems policies, both current and future AG communication systems will be deployed in L-band (960-1164 MHz), and possibly in C-band (5030-5091 GHz) because of the favorable AG radio propagation characteristics in these bands. During the same time period as the FCI studies, the use of multicarrier communication technologies has become very mature for terrestrial communication systems, but for AG systems it is still being studied and tested. Aiming toward future demands, EuroControl and FAA sponsored work to define several new candidate AG radio systems with high data rate and high reliability. Dominant among these is now an L-Band Digital Aeronautical Communication Systems (L-DACS): L-DACS1. L-DACS1 is a multicarrier communication system based on the popular orthogonal frequency division multiplexing (OFDM) modulation technique. For airport surface area communication systems used in C-band, EuroControl and FAA also proposed another OFDM communication system based on the IEEE 802.16e standard, termed aeronautical mobile airport communication system (AeroMACS). This system has been proposed to provide the growing need of communication traffic in airport environments. In this dissertation, first we review existing and proposed aviation communication systems in VHF-band, L-band and C-band. We then focus our study on the use of multicarrier techniques in these aviation bands. We compare the popular and dominant multicarrier technique OFDM (which is used in cellular networks such long-term evolution (LTE) and wireless local area networks such as Wi-Fi) with the filterbank multicarrier (FBMC) technique. As far as we are aware, we are the first to propose and evaluate FBMC for aviation communication systems. We show, using analysis and computer simulations, along with measurement based (NASA) air-ground and airport surface channel models, that FBMC offers advantages in performance over the OFDM schemes. Via use of sharp filters in the frequency domain, FBMC reduces out of band interference. Specifically, it is more robust to high-power distance measurement equipment (DME) interference, and via replacement of guard bands with data-bearing subcarriers, FBMC can offer higher throughput than the contending L-DACS1 scheme, by up to 23%. Similar advantages over AeroMACS pertain in the airport surface channel. Our FBMC bit error ratio performance is comparable to that of the OFDM schemes, and is even better for our “spectrally-shaped” version of FBMC. For these improvements, FBMC requires a modest complexity increase. Our final contribution in this dissertation is the presentation of spectrally shaped FBMC (SS-FBMC). This idea allocates unequal power to subcarriers to contend with non-white noise or non-white interference. Our adaptive algorithm selects a minimum number of guard subcarriers and then allocates power accordingly to remaining subcarriers based on a “water-filling-like” approach. We are the first to propose such a cognitive radio technique with FBMC for aviation applications. Results show that SSFBMC improves over FBMC in both performance and throughput

Myocardial infarction risk factors in the patients referred to Chaharmahal and Bakhtiary province hospitals, 2005

چکیده: زمینه و هدف: شناسایی عوامل خطرزای انفارکتوس میوکارد مهمترین اقدام در جهت به حداقل رساندن، تعدیل و اصلاح عوامل خطرزا در جمعیت های در معرض خطر است که نتیجه آن کاهش عوارض، کاهش مرگ و میر و در نهایت حفظ نیروی مولد جامعه است. هدف ازاین پژوهش تعیین و مقایسه فاکتورهای خطر زای انفارکتوس میوکارد در استان چهارمحال و بختیاری بود. روش بررسی:در یک بررسی توصیفی - تحلیلی از نوع مورد – شاهدی تعداد 247 نفر از بیماران مبتلا به انفارکتوس میوکارد بستری در بیمارستانهای استان چهارمحال و بختیاری در سال 1384 و 240 نفر از سایر بیماران که دارای شرایط تعریف شده تحقیق بودند به روش نمونه گیری در دسترس انتخاب و از نظر عوامل خطر ساز ابتلا به انفارکتوس میوکارد مورد مقایسه قرار گرفتند. اطلاعات بوسیله پرسشنامه چهار قسمتی شامل: اطلاعات دموگرافیک و متغیرهایی فیزیولوژیک، مقیاس هولمز و راهه که سطح استرس افراد را در طی یکسال گذشته مشخص می کرد، برنامه فعالیت تضمین سلامت که بیانگر میزان حرکت افراد در طول فراغت و کار بود و پرسشنامه ثبت دفعات مصرف مواد غذایی در طول یک سال گذشته، گرد آوری و با استفاده از آزمونهای آماری رگرسیون لجستیک ، کای دو، فیشر و نسبت شاخص بخت (OR=Odds Ratio) تجزیه و تحلیل گردید. یافته ها: بر اساس نتایج بین دو گروه از نظر سن، جنس، سطح تحصیلات، شغل و محل زندگی اختلاف معنی داری وجود نداشت. در گروه مورد و شاهد به ترتیب درصد فراوانی سابقه فشار خون بالا 5/40 و 6/29 (01/0

The prevalence and types of domestic violence against pregnant women referred to maternity clinics in Shahrekord, 2003

چکیده: زمینه و هدف: خشونت خانگی در دوران بارداری تهدید جدی بر سلامت جسمی‌، ‌روانی و روحی مادر و جنین است و در نهایت تهدید جدی بر سلامت و ساختار جامعه است. هدف از این تحقیق تعیین شیوع و نوع همسر آزاری در زنان باردار مراجعه کننده به درمانگاه های شهرستان شهرکرد بوده است. روش بررسی: این پژوهش ِیک مطالعه توصیفی - تحلیلی با نمونه گیری به روش در دسترس بوده که نمونه های این پژوهش را 1600 زن باردار مراجعه کننده به مراکز بهداشتی، درمانی شهرستان شهرکرد که دارای پرونده مراقبت بارداری بوده و بطور ماهانه جهت مراقبت بارداری به درمانگاه مراجعه می نمودند تشکیل داده اند. اطلاعات به وسیله پرسشنامه که مشتمل بر دو بخش، مشخصات و متغیرهای دموگرافیک و پرسشنامه استاندارد خشونت خانگی بود، به روش مصاحبه حضوری جمع آوری گردید و سپس داده ها با استفاده از آزمون های آماری توصیفی و آزمون کای دو تجزیه و تحلیل شد. یافته ها: شیوع همسر آزاری در کل نمونه های مورد مطالعه برابر 5/67 و شامل همسر آزاری جسمی 5/34، همسر آزاری روحی و روانی7/51 و همسر آزاری جنسی 8/13 بود. همچنین آسیب های شدید ناشی از همسر آزاری در بعد جسمی برابر 44/17، در بعد روحی و روانی برابر 56/12 و در بعد جنسی برابر 4/ بود. بین خشونت خانگی با محل زندگی (شهر، روستا)، سطح تحصیلات و سن ازدواج ارتباط معنی دار آماری وجود نداشته، اما سطح خشونت در افرادی که طول مدت ازدواج آنان کمتر از 5 سال، اولین بار حاملگی، سطح اقتصادی پایین و شوهرانشان بیکار و اعتیاد داشتند از نظر آماری قابل توجه بود (05/0

On the Structure of Decision Diagram-Representable Mixed Integer Programs with Application to Unit Commitment

Over the past decade, decision diagrams (DDs) have been used to model and solve integer programming and combinatorial optimization problems. Despite successful performance of DDs in solving various discrete optimization problems, their extension to model mixed integer programs (MIPs) such as those appearing in energy applications has been lacking. More broadly, the question which problem structures admit a DD representation is still open in the DDs community. In this paper, we address this question by introducing a geometric decomposition framework based on rectangular formations that provides both necessary and sufficient conditions for a general MIP to be representable by DDs. As a special case, we show that any bounded mixed integer linear program admits a DD representation through a specialized Benders decomposition technique. The resulting DD encodes both integer and continuous variables, and therefore is amenable to the addition of feasibility and optimality cuts through refinement procedures. As an application for this framework, we develop a novel solution methodology for the unit commitment problem (UCP) in the wholesale electricity market. Computational experiments conducted on a stochastic variant of the UCP show a significant improvement of the solution time for the proposed method when compared to the outcome of modern solvers