Modified pulse shaping and path loss modeling for UWB

مقدم أطروحة جامعية

Abd al-Hadi, Haidar Malik

مشرف أطروحة جامعية

al-Qaraawy, Salih M.

الجامعة

الجامعة التكنولوجية

الكلية

-

القسم الأكاديمي

قسم الهندسة الكهربائية

دولة الجامعة

العراق

الدرجة العلمية

دكتوراه

تاريخ الدرجة العلمية

2011

الملخص الإنجليزي

-Ultra wideband (UWB) communication is based on the transmission of very narrow pulses with relatively low energy.

UWB systems operate in large bandwidth about several GHz.

Consequently, they may share the spectrum with other users as well as with existing communication systems and therefore, interferences may occur.

Pulse shaping techniques based on changing pulse width or order of derivative of the transmitted waveform and comparing the resulting Power Spectral Density (PSD) of signal with Federal Communication Commission (FCC) spectral mask to reach to optimum shape.

To improve the comparison manner between PSD of the transmitted waveform and FCC emission masks, two new parameters has been proposed in this work.

The first parameter named matching factor while the second named violating factor.

In UWB system, maximization of the received signal to noise ratio requires efficient utilization of the bandwidth and power allowed by the FCC spectral masks.

A combined waveform consists of two Gaussian pulses with time delay difference between them has been proposed in this work.

As a comparison with waveform consist of single Gaussian pulse, matching factor can be improved about 3% by using combined waveform consist of two identical Gaussian pulses and 15% by using two different pulses.

By using the same method, another group of combined waveforms have been proposed which can be used for narrowband interference mitigation.

This can be achieved by introducing spectral nulls at center frequency of narrowband signals to limit interference.

Path loss is a fundamental characteristic of electromagnetic wave propagation and is incorporated in the system design and link budgets, to predict expected received power.

The key differences of path loss between UWB propagation channels and conventional channels (narrow/wideband continuous wave) lie in the frequency dependence of path loss value.

The path loss model adopted by UWB systems which is set by IEEE 802.15.4a work group is modeled as function of link distance that is treated as deterministic.

The variability is possible in receiver performance due to the mobility in wireless personal area network (WPAN), to deal with unfixed positions for the WPAN nodes in small area environments; it is useful to consider the distance as a random variable.

In this work, four modified path models have been presented.

These models treat the distance as undeterministic value which is useful when the distance is unknown and has a random value such as calculation of path loss between nodes of WPAN having unfixed positions or to learn the path loss information of the outsiders from other networks.

The modified path loss models named: MIPLM, MGPLM, MFDIPLM and MFDNPLM have been introduced by modifying PL model defined by 802.15.4a standard.

The dependency of the path loss model had been ignored for the first two models, while it was considered in the other two models.

Both original and modified models represent random value having Gaussian distribution with defined mean and variance values.

The numerical results show that, the variation about the mean value in the modified model is more than in original model.

This may be thought that it is drawback in the modified model but in fact it is the tax for replacement of the deterministic distance with random distance, this may be accepted when there is need to predict the received power in case of unknown distance.

All numeric results in this thesis are computed by using programs written by usingMATLAB software package.

التخصصات الرئيسية

هندسة الاتصالات

• APA
• MLA
• AMA

لغة النص

الإنجليزية

نوع البيانات

رسائل جامعية

رقم السجل

BIM-305007