In this paper, a proposed model based on In-Place Wavelet Transform (IP-WT) was suggested to improve the performance of the Orthogonal Frequency Division Multiplexing (OFDM) under the Additive White Gaussian Noise (AWGN), and flat fading channel. The proposed model does not require additional arrays at each sweep such as in the ordered Haar wavelet transform; this ensures fast processing time with minimum memory size. The results extracted by a computer simulation and compared with the performance of the conventional model based on Fast Fourier Transform (FFT). As a result, it can be seen that the proposed technique has high performance improvement over the conventional OFDM system based FFT, where the Bit Error Rate (BER) is widely reduced under these models of channels.

تحت تأثير قناة الضوضاء (OFDM) في هذا البحث تم اقتراح نموذج لتحسين أداء مازج تقسيمات التردد المتعامدةبالاعتماد على في- مكان لتحويل الويفليت وقناة الخبو المنبسط . ان النموذج (IP-WT) الابيض التراكمية لكاوزمرحلة معالجة للإشارة مثلما يحتاجه تحويل (AWGN) المقترح لايحتاج الى مصفوفة إضافية عند كل مستوى منحجم للذاكر ة .تم مقارنة النتائج مع اداء .(FFT) الويفليت المرتب؛ وبالتالي فان سرعة المعالجة ستزداد وبأقلالنموذج الاعتيادي المعتمد على تحويل الفوري السريع النتائج بينت ان النموذج المقترح قد اعطى تحسن عاليبالاداء نسبة الى النموذج الاعتيادي ، حيث انقل بشكل كبير تحت تأثير تلك النماذج من القنوات.

In-Place --- QAM --- OFDM --- AWGN --- Flat Fading

Theory coding is methods to study for effective and exact transfer the information from point to another point. This theory had been advanced for example many applications as to decreasing the noise from received signal, when the transmission of most information in telephone line, information transfer from terminal (computer) to another terminal or from any memory to the main processor and data transmission from transmitter such as satellite communication which led images of Saturn earth. A channel is mien physical medium which the data or (information) transmission. Disturbances undesirable called noise. This noise caused the differ the information signal from the transmitted data. Noise may be caused folds in a tap magnetic, telephone competing messages, sunspots, meteor showers, lightning, radio random disturbance or other many things.In my paper I used the MATLAB program to simulations over AWGN channel by using BPSK modulation scheme I notice when used more tap point I get the decreases for bit error rate and this method one of theory coding deals with problem of correcting and detecting error transmission caused by noise in channel. In practice, we has over this noise that mast choice of good a channel to use the transmission data (information) and to used variable noise filters to combatable certain type of interference may be cannot be controlled.

نظرية الترميز هي احدى طرق البحث عن فعالية ونقل المعلومات والبيانات من نقطة إلى نقطة أخرى وبدقة عالية جدا. وقد طرحت هذه النظرية على سبيل المثال في العديد من التطبيقات لخفض الضجيج من الأشارة المستلمة او المرسلة، كما في نقل البيانات و المعلومات في خط الهاتف، وكذلك نقل المعلومات من محطة (الكمبيوتر) إلى محطة أخرى أو من أي الذاكرة إلى المعالج ونقل البيانات الأساسية في الارسال مثل الاتصالات عبر الأقمار الصناعية والصور الفضائية. وعند عملية النقل تتأثر هذه الاشارات بأشارات اخرى غير مرغوب بها تسمى الضوضاء والتي تسبب ضعف او تشويه للأشارة المستلمة او المرسلة. قد يكون سبب الضوضاء اشارات من اجهزة مغناطيسية او رسائل هاتفية اخرى أو أشياء أخرى عديدة.في هذا البحث أنا استخدم برنامج MATLAB لمحاكاة على قناة AWGN باستخدام BPSK واستخدام أكثر من نقطة لغرض الحصول على انخفاض لمعدل الخطأ وهذا أسلوب واحد من نظرية الترميز يتناول مشكلة تصحيح وكشف الخطأ في البيانات الناتج عن الضوضاء في القناة وبطريقة عملية، ويوجد لدينا أكثر من نوع للضوضاء

coding theory --- AWGN --- BER --- BPSK and ISI

Abstract – This paper demonstrates the effect of color image transmission through AWGN channel using binary phase shift key modulation (BPSK) system and transmission of compressed color image through AWGN. On the other hand, the transmission consumes a large amount of channel and needs the processing, therefore utilizes compression techniques to reduce the size of the original color image to facilitate the transmission compressed color image through AWGN and to obtain the channel optimization. In this paper, a simple hybrid lossy color image compression transmission through AWGN using convolutional coding with Viterbi decoding system is proposed. It is based on combining effective techniques, started by wavelet transform that decompose the image signal followed by polynomial approximation model of linear based to compress approximation image band. The error caused by applying polynomial approximation is coded using bit plane slice coding, whereas the absolute moment block truncation coding exploited to coded the detail sub bands. Then, the compressed information encoded using LZW, run length coding and Huffman coding techniques, the compressed information is entered to the channel coding to coded the information using convolutional coding and modulation using BPSK to transmit through channel and added AWGN, the received signal is demodulated and decoded using Viterbi decoding, the result compressed data passed to source decoding to reconstruct the compressed image. The test results indicated that the proposed system can produce a balance between the compression performance and preserving the image quality, and also simulations results observed that with increase in signal to noise ratio (SNR) values the bit error rate (BER) values decrease.

Hybrid lossy image compression --- Convolutional coding --- Viterbi decoding --- AWGN --- BPSK.

Low Density Parity-Check (LDPC) codes are one of the hottest topics in coding theory today. This code invented in the early 1960's, and it having an amazing comeback in the last few years. In this paper, a scheme is proposed to analyze the performance of LDPC which is considered important rival to turbo codes, Convolutional Code (CC) and Read Solomon (RS) in terms of performance and complexity. This code is utilized in Orthogonal Frequency Division Multiplexing (OFDM) system to evaluate the improvement in the Bit Error Rate (BER) performance of the system. Comparison is done between turbo code and LDPC code through Additive White Gaussian Noise (AWGN) and fading channels. The effect of varying the code rate channel, number of iteration and the code length on the performance of the scheme are also explained.

OFDM --- LDPC --- Turbo code --- BPSK --- AWGN --- Fading channel.

In this paper an alternative strategies will be demonstrated that mitigate interference without relying on the fact that the effective channel is shorter than the CP. Wavelet-based MC-CDMA has gained popularity in the literature recently. Due to very high spectral containment properties of wavelet filters, wavelet-based MC-CDMA can be better combat narrowband interference and is inherently more robust with respect to ICI than traditional FFT filters. The classic notion of a guard band does not apply for (DWT-MC-CDMA), hence data rates can enhanced those of FFT implementations.

DWT-MCCDMA --- Flat Fading Channel --- selective fading channel --- BER --- AWGN channel