Sharif Digital Repository

TETRA (TErrestrial Trunked RAdio) is one of the mobile telecommunication standards which has improved in several aspects (voice, data, video, coverage, etc.), especially the security section during the last two decades. Although communication could be quite secure in TETRA when the encryption is used, however, attackers create new ways to bypass the encryption without the knowledge of the legitimate user. Security is performed in different levels and forms to create reliable operation and to protect information through the transmission path from interception and tampering. Since most of the TETRA users require the highest possible level of security, in this thesis we introduce a new... 

Different beamforming methods are prevalent in wireless and mobile communication systems. However, a lot of practical issues, such as the quality of these methods in compact arrays and the huge computational burden are the major defects of the proposed methods. These problems restrict most of the algorithms to the theoretical domain and render them anappropriate for commercial applications. Therefore, the major focus of this thesis is on the practical issues in the implementation of the digital beam steering and direction of arrival estimation systems for linear, circular and random array configurations. To do so, compact arrays with super directivity are presented and considered. Different... 

Brain-inspired methods are now widely used to process the data generated by the brain with the aim of improving our understanding of how the brain functions and produces the remarkable intelligence exhibited by humans, which is the source of all realizations, perception and actions. Therefore brain-computer interface (BCI) is one of the most challenging scientific problems which focuses scientists attention, in most cases these systems are based on EEG signals recorded from the surface of the scalp because this method of the brain activity monitoring is noninvasive, easy to use and quit inexpensive. Brain computer interface (BCI) systems analyse the EEG signals and translate person’s... 

A Radio Frequency Power Amplifier was designed for IS-95 standard in 0.18μm / 1.8V CMOS technology. In order to increase output voltage swing and protect gate oxide of devices, pseudo-differential cascode topology was exploited. Bondwire inductors with exact modeling were used to tune out parasitic capacitances. A low-pass, L match impedance transformation network, realized using bondwire inductors, was used at output of power amplifier. An impedance transformation network design process was developed which considers the quality factor of inductors, from the first step. Also having examined the nonlinearity phenomena in power amplifiers, a fast simulation or measurement method was proposed... 

From the cache of the personal computers to the main memory unit of SOCs, medical and wearable chips, Static Random Access Memory (SRAM) is widely utilizes. Preferable performance for SRAM varies with regard to the operating field. For instance, high speed access and performance is emphasized in the design of the cache for PCs. In contrast, power consumption and the area of the memory are the key design considerations for SOCs. Hence, the field in which SRAM is used, should be thoroughly studied. SOCs and medical chips suffer limitations in design due to using batteries as the source of energy and SRAMs consume a significant part of total power and occupy a large area on these chips. One of... 

Cardiovascular diseases (CVDs) have ranked first cause of deaths globally. In 2016, about 17.7 million people died from CVDs representing 31% of all world deaths. So, early intelligent detection of cardiovascular disease could help to save many lives in worldwide. There are several methods to analyze heart activity and to detect any abnormalities including Electrocardiogram, Stress test, Echocardiography, cardiac catheterization and coronary angiography.Among all methods, Electrocardiogram (ECG) is the most common and convenient type where it measures heart electrical activity and records it as a series of pulses. Analyzing these pulses would provide useful information about normal and... 

Weed management is the important issue in agriculture. Using herbicides is one of the strategies to control weed. But using huge amount of herbicides are destructive for environment. Smart spraying system is an impressive solution for this problem. This system detects weeds and sprays just them instead of spraying overall field. In this thesis a new method for plant detection is presented by using Lab color space. We determine the type of plants (broadleaf/grass) to spray specific herbicides onto specific type of plant. One feature of grass plants (the parallel edges of leaf) is used to detect grass plants. A convolutional neural network with four layers and fuzzy logic are used to separate... 

Few years ago, when people were talking about image sensors, the minds were automatically focusing on the pictures and photos that were/are taken for recording the memories. Nowadays, however, image sensors have prominent and unbelievable role in different aspects of our life, which "image" is only representing part of this role. A wide variety of applications image sensors can be enumerated such as, Scientific, security, medical, machine vision, ITs, biometrics, automotive, etc. To evaluate the quality of an image sensor, there are different parameters, from the dynamic range, high resolution and suitable speed to low noise, low power consumption and other parameters. The art of companies... 

In this thesis, the problem of locating a source based on the time difference of arrival (TDOA) has been studied and three different methods have been presented to improve the precision of the positioning. The first method is a solution to the least square error (LSE) by utilizing a convex problem. Generally, the mentioned problem is a non-convex problem; however, it is possible to convert it to a convex one by some relaxation in the constraints. By some justifiable and insightful relaxation, not only we obtain a convex problem, but also the exact solution of the main problem is derived. The second method is using high perturbed TDOA measurements which severely affected the localization.... 

Cerebrovascular Attack has been ranked the second or third of top 10 death causes in Taiwan. It has caused about 13,000 deaths every year since 1986. Once Cerebrovascular Attack (CVA) occurs, it not only leads to the huge cost of medical care, but even death. All developed countries in the world put CVA prevention and treatment in high priority. However, it is necessary to build a detective model to enhance the accurate diagnosis of CVA. From this detective model, CVA classification rules were extracted and used to improve the diagnosis and detection of CVA. This study acquired 2449 valid samples from this CVA prevention and treatment program, and adopted three classification algorithms,... 

Neuron models are the elementary units, which determine the performance of an Artificial Spiking Neural Network (ASNN) as they are known to be a particular class of machine learning methods. The ASNNs that are inspired by the features of biological neurons and organizational structure of biological nervous system as the third generation of Artificial Neural Networks (ANN). This thesis concentrates on study of biologically plausible neuron; based on Fuzzy approach and tries to develop fuzzy state of Leaky Integrate and Fire (LIF) model, in order to resemble closely the neuron-electrical dynamics for ASNN in most efficient way. In this study, the Fuzzy methods including TAKAGI-SUGENO-KANG... 

Since traffic lights are the only mechanized system at street level, their operation mode affects traffic congestion. Since traffic lights organize vehicles at crossways, the target of traffic light smartification is to reduce waiting time based on the density of traffic flows. There are many topics that work in this field to recognize traffic before making any decision based on traffic. Hence, if it is possible to introduce an algorithm for change static timing and predetermined timing of the traffic lights, it can affect the density of traffic at the large scale. This dissertation introduces an algorithm to reduce traffic congestion using traffic lights and correct timing. In this case,... 

This thesis presents a new approach to feedback active noise cancellation. The problem of Reducing the noise level in the environment has been the focus of research over the years. Active Noise Cancellation (ANC) is one such approach that has been proposed to eliminate Noise. ANC refers to an electro acoustic approach of canceling acoustic disturbance to Produce a quieter environment. The basic principle of ANC is to introduce a canceling “anti Noise” signal that has the same amplitude but the exact opposite phase, thus resulting in Reducing the remainder noise signal. We use neural networks based on system identification And predict control to cancel acoustic noise. Canceling acoustic... 

Sigma-delta modulators have largely been implemented as discrete-time (DT) circuits because of their low sensitivity to circuit nonidealities, and their frequency scaling specification, however a continuous-time (CT) design offers significant advantage in the design of high accuracy, high speed analog to digital converters (ADC). A CT design allows for relaxed amplifier(s) bandwidth and power requirements, which enables the realization of high accuracy modulators with bandwidths of several megahertz at low power consumption. Furthermore CT modulators provide inherent anti-aliasing filtering which becomes especially important at low oversampling ratios. This thesis reports the design of a... 

Providing multimedia content to the end-user is one of the most challenging tasks in today’s digital world. Therefore choosing the best media compression method is both technically and economically important. In the context of audio codecs, MPEG-4 HE-AACv2 is capable of providing very high quality output at very low bitrates. 3GPP Enhanced aacPlus is one of the practical implementations of this codec, which is extensively adopted by several telecommunication standards as the main audio compression algorithm.
Nowadays almost every cell phone and portable digital media player includes a DSP. The C6000 family of DSPs from Texas Instruments has been exploited for the purpose of this... 

This work uses a hierarchical approach for designing the integrated UWB LNA in MOSFET technology. It first offers a brief treatment of the two important types of noise: the thermal noise of channel and the gate-induced noise, in MOSFET. Then the CS and CS-CG configurations for narrow-band LNAs are considered and the requirements for the wide-band operation in UWB are specified. Noise cancelling technique is also introduced, while five wideband prototype designs, with the noise-cancelling technique used in two designs, are re-examined and tested by simulation. Some proposed methods are then applied to these designs for better performance and obtaining practical insight. The final main... 

There are three types of Slices in an FPGA, and based on the functionality of these slices, SliceM has the most features especially for designs based on shift registers, adders, and ROMs, and from all of the slices, 25% of them are SliceM. Among the earlier designs that are FPGA-based, Anderson PUF is that is classified as a weak delay-based PUF. In Anderson’s design there always should be atleast two SliceMs that their LUTs are configured as shift registers, the Andersons PUF in some FPGA Architecture especially Series 7 FPGAs, consumes two SliceMs and two other SliceLs, so practically we are using four of our precious slices. Rather than these, in series 6 FPGAs, the design should change... 

Predicting the location of oil and gas recourses is the first challenge in the petroleum industry. One of the most popular and acceptable ways which can guide an explorer to the position of the resources is the seismic survey. By this kind of survey, geologists can observe inside of solid matter by using the ultrasound waves. The process works by sending sound waves to the surface and measuring the length it takes to be reflected from rocks underneath, then with recording these echoes by arrays of sensors, they can obtain a seismic image which has too noise, including ghosting, multiples (multiples are the waves that has been reflected more than once between the energy source and the... 

Multiple distortion coding is a promising solution for video transmission over lossy channels. In MDC multiple descriptions of a source are generated which are independently decodable and mutually refinable. When all descriptions are available, the corresponding quality is called central quality; otherwise it is called side quality. Generally, there exist a trade-off between side and central quality in all MDC schemes. The MDC methods which provide better central-side quality trade-off are of more interest to the designers.In this thesis a new MDC scheme is introduced which has better trade-off between side and central quality. In other words, for the same central quality, it provides higher... 

In recent years with the increase of cellular phone subscribers, demand for high capacity networks is inevitable. For this reason, different methods have been proposed to increase the channel capacity. One method which has become popular in recent years is utilizing of Smart Antenna Systems. Smart antennas basically attempt to enhance the desired signal power and suppress the interferers by beamforming toward the DOA (direction-of-arrival) of the desired signal and nullsteering in the interferences’ DOAs. Smart Antennas first find the direction of signal sources, and then put the main gain toward the desired signal and put the nulls toward unwanted signals. As a result, we can obtain the...