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Performance Enhancement of Wireless Mobile Adhoc Networks Through Improved Error Correction and Channel Estimation Strategy

Thesis Info

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Author

Sabir, Zeeshan

Program

PhD

Institute

University of Engineering and Technology

City

Peshawar

Province

KPK

Country

Pakistan

Thesis Completing Year

2013

Thesis Completion Status

Completed

Subject

Applied Sciences

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/2615/1/2655S.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676726853804

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PERFORMANCE ENHANCEMENT OF WIRELESS MOBILE ADHOC NETWORKS THROUGH IMPROVED ERROR CORRECTION AND CHANNEL ESTIMATION STRATEGY By Engr. Zeeshan Sabir Mobile Adhoc Networks (MANET) refer to an arrangement of autonomous wireless mobile nodes that show the tendency of freely and dynamically self-organizing into arbitrary and temporary network topologies. A variety of protocols have been implemented in MANET at the Network layer which tend to show different performance in various environments. Three of the most commonly used protocols at the Network Layer in MANET are Destination Sequenced Distance Vector (DSDV) Routing Protocol, Dynamic Source Routing (DSR) Protocol and Adhoc On- Demand Distance Vector (AODV) Routing Protocol. A comprehensive study on the performance evaluation of these three routing protocols have been given in this thesis basing upon the TCP window size using Network Simulator (NS-2.35) with two different types of network traffics. Tool iiCommand Language (TCL) scripting is used to simulate the environment. Orthogonal Frequency Division Multiplexing (OFDM) is the foremost choice for MANET system designers at the Physical Layer due to its inherent property of high data rate transmission that corresponds to its spectral efficiency. One of the problems inherent in OFDM includes its sensitivity to synchronization errors (frequency offsets and symbol time). Most of the present day techniques employing OFDM for data transmission support mobility as one of the primary feature. This mobility causes small Channel Frequency Offsets (CFO) owing to the production of Doppler frequencies. CFO tends to degrade the signal quality making the system design unsuitable for many error sensitive applications. In this work two efficient pilot-assisted channel estimation strategies have been implemented in the proposed model of OFDM. The implemented solutions for channel estimation include Zero Forcing algorithm and modified Least Square channel estimation algorithm. Both these algorithms have been implemented into the proposed environment of OFDM using two different types of pilot insertion methods i.e. block-type and comb-type pilot insertion techniques. Both these techniques have been compared amongst each other and with the already published work as well. iiiAnother serious problem faced by the OFDM based transmission systems is the sensitivity to the noise effects induced by the channel and system. These noise effects tend to increase the BER of the system making it unsuitable for many real-time applications. Turbo Codes have been integrated with the proposed model of OFDM which have the tendency to work in the Forward Error Correction (FEC) manner by not only identifying the erroneous bit locations but also correcting them thus using simplex control information link. The turbo codes have been implemented using parallel concatenation of Recursive Systematic Convolutional (RSC) Codes that tend to introduce redundant information into the user bits in order to mitigate the effects of channel induced noise from the received OFDM symbols. Results have been shown using MATLAB® simulation for changing number of iterations of MAP decoder for five different modulation schemes and are compared. The channel, through which the signal has been passed, is simulated using Stanford University Interim Channel Model parameters. These Channel models are six in number and depict three different real outdoor environments including rural, urban and hilly terrains having low, moderate and high tree densities.
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ڈاکٹر شوقی ضیف

ڈاکٹر شوقی ضیف
۱۴، ۱۵؍ مارچ ۲۰۰۵؁ء کو شعبہ عربی علی گڑہ مسلم یونیورسٹی میں ’’دوسری جنگ عظیم‘‘ کے بعد ’’عربی ادب کے نئے رجحانات‘‘ کے عنوان سے ایک نیشنل سمینار ہوا جس کی روداد اپریل کے معارف میں شایع ہوچکی ہے، اس کے لیے راقم نے ’’ڈاکٹر شوقی ضیف: افضل العلما مولانا محمد یوسف کو کن کی نظر میں‘‘ کے عنوان سے مضمون لکھا تھا جس کو ۱۵؍ مارچ کو سمینار کے صبح کے اجلاس میں پڑھا، اسی روز شام کو پہلا اجلاس پروفیسر سلیمان اشرف (دہلی) کی صدارت میں شروع ہوا تو انہوں نے یہ افسوسناک اطلاع دی کہ ابھی خبر ملی ہے کہ ۱۱؍ مارچ بہ روز جمعہ ڈاکٹر شوقی ضیف کا انتقال ہوگیا، اسی وقت تاثراتی تقریریں ہوئیں، تعزیتی تجویز منظور کی گئی اور ڈاکٹر صاحب کے لیے دعائے مغفرت کی گئی۔
سمینار کے مندوبین کو شعبہ کی جانب سے جو کتابیں دی گئی تھیں ان میں ’’مجلۃ المجمع العلمی الہندی‘‘ کاتیئیسواں شمارہ بھی تھا، اتفاق سے اس میں بھی ڈاکٹر صاحب پر ایک مقالہ شامل تھا، اس سے اپنے مضمون میں کسی قدر اضافہ کر کے معارف کے قاریین کی خدمت میں پیش کررہا ہوں۔
ڈاکٹر شوقی ضیف بیسویں صدی کے عربی زبان کے مشہور مصنف اور بلند پایہ محقق و نقاد تھے، وہ جنوری ۱۹۱۰؁ء میں مصر کے ایک گاؤں ’’اولاد حمام‘‘ میں پیدا ہوئے، ان سے پہلے ان کے دو بڑے بھائی ایام شیر خوارگی ہی میں فوت ہوگئے تھے، اس لیے جب یہ پیدا ہوئے تو ان کے والدین کو بڑی خوشی ہوئی۔
ڈاکٹر صاحب کا پورا نام احمد شوقی عبدالسلام ضیف تھا، ضیف ان کے خاندان کا لقب اور عبدالسلام والد کا نام تھا، ان کا اصلی نام احمد شوقی تھا مگر وہ اختصار کے خیال سے اپنے کو صرف شوقی ضیف لکھتے تھے، یہی ان...

اسلام اور مغرب: ڈاکٹر محمود احمد غازی کے افکار کا خصوصی مطالعہ

The comparative study of civilizations, their conflicts, clashes and their harmony are the significant issues of this era. It's a reality that in the present clash of civilizations, Islam is being pushed to a tight corner. The Islamic world today is facing severe challenges and odd circumstances in maintaining their vital values and re-establishing their identity and gaining their due place in the modern world because some of the western thinkers believe that after demolishing the Soviet Union, their next encounter would be with the ideology of Islam. In this situation, the comparison of civilizations and their comprehension has acquired a significant place and it is necessary to highlight the essential elements of various civilizations in such a way that they can sustain their individuality and the misunderstandings among them may be removed to create a peaceful atmosphere which is based on love, mutual tolerance, co-existence and  the supremacy of basic human rights so that the world may return to the merger of various civilizations and harmony among different religions. Allama Iqbal is the thinker who has shown extraordinary depth in his approach towards the study of Islam and the western world, highlighting their differences and the traditions, points and levels of their merger and harmony with a balanced and impartial approach. It's necessary to comprehend Iqbal's ideas keeping in view the history of Islam and the western world, the current demands of the present age and considering organized, solid, argumentative analysis in an objective way  revealing the soul of Islam and the spirit of the west in context of Iqbal's philosophy so that the modern world can move towards a peaceful and creative situation. Dr. Mehmood Ahmad Ghazi was the realization of Iqbal's dream. He is simultaneously an educationist, a great researcher and an illustrator and interpreter of the Holy Quran and narrator of Hadiths. His personality was equally well versed in Islamic art and learning and all their offshoot disciplines. It's the trait of his personality that in spite of travelling far and wide and having done a vast study, he is not impressed at all except by the ideology of Islam. He has very successfully passed on the ancient heritage to its modern heirs with honesty, skill and sagacity. Here an effort has been made to present a review of his views where he has propounded a critical, analytical and scholarly analysis of the western world.

Bioconversion of Plant Feedstock to Fermentable Saccharides

Bioconversion of different pre-treated agricultural feed stocks into saccharides was carried out using thermophilic cellulases. Agricultural by-products i.e. sugarcane bagasse, wheat and rice straw were subjected to acid and alkali at steaming temperatures, auto-hydrolysis and microwave pre-treatments. Auto-hydrolysed and alkali pre-treated substrates showed better delignification i.e. 86.01% (wheat straw), 77.84% (sugarcane bagasse), 67.23% (rice straw) vs. 84.11% (wheat straw), 73.90% (sugarcane bagasse), 68.47% (rice straw), respectively. These de-lignified substrates were analyzed for total phenolic content (TPC) which were subsequently removed by washing with distilled water, extraction by organic solvents and detoxification by calcium hydroxide. Minimum residual TPC was observed in auto-hydrolysed substrates using calcium hydroxide i.e. 52 mg gallic acid equivalent (GAE) per g of dry weight (DW) of substrate in wheat straw, 59 mg GAE/g DW in sugarcane bagasse and 54 mg GAE/g DW in rice straw. The surface area i.e. 4 and 2mm granule size of all auto-hydrolysed substrates was assessed for saccharification potential and granule size of 2mm was found best with saccharification of 11.01% (sugarcane bagasse), 9.34% (wheat straw) and 4.36% (rice straw). Saccharification of auto-hydrolysed substrates using simultaneous addition of cellulases gave maximum saccharification in wheat straw i.e. 22.93% after 5 h of incubation at 80°C employing sodium citrate buffer of pH 6.5. Cellulase concentration of Endo-1,4-β-glucanase (125 U), Exo-1,4-β-glucanase (150 U) and β-1,4- Glucosidase (50 U) was optimized for 2% of wheat straw yielding 36.78% saccharification. Sequential addition of cellulases showed an improved saccharification of 55.64% employing Endo- 1,4-β-glucanase (75 U), Exo-1,4-β-glucanase (100 U) and β-1,4-glucosidase (50U) after 5.5 h of incubation. Scale up of the sequential saccharification in a 50 L reaction vessel resulted in increased saccharification of 57.91% with decreased time of incubation (3.5 h). In addition, substrate concentration of 2.5 % with agitation of 100 rpm was optimized with consequent saccharification of 62.12%. After saccharification, the hydrolysate was analyzed for TPC which were removed using activated charcoal. Minimum TPC i.e. 64.43 mg GAE/mL of liquid phase was achieved using 3% activated charcoal at 40°C after 20 min of incubation. The hydrolysate was analyzed by thin layer chromatography and found to have glucose and cellobiose. Wheat straw before auto-hydrolysis, after auto- hydrolysis and enzymatic breakdown was assessed for structural variance by scanning electron microscopy.