Sharif Digital Repository

Many processes in the real world are multiple-input multiple-output (MIMO) systems. There are often some interactions between the inputs and outputs. In the other words, every input affects on several outputs, and every output is affected by several inputs. In order to control of these systems, we usually desire to decouple the loops into multiple non-interacting SISO systems after proper pairing of manipulated and controlled variables. Loop interactions can destabilize a control system, so tuning controllers in an interacting MIMO system can be difficult. Decoupling problem has been discussed in the two domains: linear control and nonlinear control. However, both of them need an exact model... 

Millimeter-wave (mmWave) communication systems exhibit large bandwidth and severe channel attenuations. To maintain the received signal-to-noise ratio on an acceptable level, mmWave systems use large antenna arrays and directional beamforming at both transmitter and receiver. The existence of many antenna elements, however, challenges traditional approaches for pilot transmission and channel estimation wherein the number of pilots linearly scales up with the total number of transmit antennas. For instance, for the uplink channel estimation with a constant coherence interval, adding more antennas to the users comes at the expense of a linear penalty on the number of users, which can... 

Multiple-input multiple-output (MIMO) systems have been considered a lot in the recent decade. Use of these systems results in higher data rate and higher reliability in communication systems. Use of intermediate nodes which are called relay in cooperative networks result in higher reliability and higher coverage range in wireless networks. Finally use of multiple antennas in cooperative networks results in higher data rate, higher reliability and higher coverage range in wireless networks. A drawback of multi-antenna systems is that more antennas require more RF chains. More RF chains result in higher computational complexity and higher hardware cost. A remedy for this drawback is the... 

MIMO radar is a next generation radar which transmits arbitrary waveforms at each one of its apertures. It has been shown that design of waveforms for MIMO radars in order to synthesize a desired spatial beampattern, is mapped into a waveform correlation matrix (R) design in the narrowband case. Therefore, waveform design in MIMO radar for beamforming could be broken into two steps, namely correlation matrix design and waveform synthesis for achieving given R. As of now, given a desired beampattern or estimated location information of targets, calculating R has been modeled as an optimization problem like SDP. Also, in some special cases like rectangular beampattern, close form solutions for... 

Long Term Evolution (LTE), is a standard for wireless communication of high-speed data for mobile phones and data terminals. Increasing the capacity, improved support for mobility and simplified architecture are a number of its goals. As many other standardas LTE uses Multiple Input-Multiple Output (MIMO), which is a system that uses multple antennas in the transmitter and the reciver. LTE has adopted single carrieer-frequency division multiple access (SC-FDMA) for the uplink multiple access scheme in order to decrease peak to average power ratio (PAPR). In SC-FDMA a discrete Fourier transform (DFT) is performed on the signlas before going through the OFDMA modulation.
A novel... 

There are a wide variety of radar systems that one of them is MIMO Radars. After a spark in communication in 1998 that developed MIMO communication, recently there has been a great attention towards MIMO radar systems. Researchers have studied this topic from several points of view. Generally, MIMO radar systems are divided into two categories: MIMO radars widely separated antennas and MIMO radars with collocated antennas. One of the important issues of widely separated MIMO radars, is the placement manner of receivers in the geometrical area. This radar’s performance is very dependent to placement of the antennas, because the performance is dependent to relative position of... 

MIMO (Multi Input Multi Output) Radars issue is a new topic in Radar systems field and power allocation in these systems is very important to improve their performance.In this thesis, at first, two optimum detectors for MIMO radars with widely separated antennas are designed. In the first one, received signal in all receivers is gathered in a central processor and centralized detection is performed. This type of detection needs too much process power and is complex. Because of complexity of detector, probability of detection is very difficult to derive and deflection criterion is used for evaluating system performance. In the second one, each receiver processes received signals from all... 

Intercellular coordination is a technique to mitigate intercell interference. In this technique, base stations of different cells coordinate with each other to send data for all users, so each user is serviced by several base stations. Nowadays, with the increasing use of wireless networks, the design of these networks is very important. Most problems in the design of wireless networks are due to limitations such as: interference, the lack of bandwidth and changes of channel. Using all channels in each cell is a suggested method to use the bandwidths efficiently; however it increases intercell interferences hence a method to control interference is needed. Coping with interference can be... 

Existence of time delay and interactions of control loops make control of multivariable delayed systems more difficult، therefore control of these systems is important. In this project a control scheme based on prediction of process output has been proposed. Traditional PI controllers are used in the control structure and controller parameters are tuned by genetic algorithm. Unlike the Smith predictor based methods، which become internally unstable when applied to unstable plants، unstable delayed multivariable systems can be handled by proposed method. It can also be applied to stochastic systems. The robust version of the control scheme has also been designed. Effectiveness of the proposed... 

Waveform design for Target identification and classification in MIMO radar systems has been studied in several recent works. While the previous works considered signal independent noise and found optimal signals for an estimation algorithm, here we extend the results to the case where clutter is also present and then we will find the optimum waveform for several estimators differing in the assumptions on the given statistics. Several different approaches to the optimal waveform design are proposed, including minimizing the error of MMSE estimator, minimizing the maximum error of the covariance shaping least square (CSLS) estimator and minimizing the MSE error of scaled least square (SLS)... 

Multi Input Multi Output (MIMO) systems can be used in wireless communications in order to increase data rate. This increase in data rate becomes possible with multiplexing and diversity techniques. Indeed using MIMO systems we may achieve high spectral efficiency. High spectral efficiency is obtained by the fact that scattering environment causes each transmitted signal in each receiver antenna to be uncorrelated to a great extent with other transmitted signals. Many parameters play role in performance of a MIMO system. One of these parameters is position of each antenna in transmitter or receiver arrays relative to other antennas. In this thesis we study receiver array geometry effect on... 

Multiple Input Multiple Output (MIMO) radar is an emerging technology which has attracted many researchers recently. The problem of beampattern design of a MIMO radar in uniform arrays and with the covariance based method of point targets has been investigated by many papers so far. In this thesis it is desirable to consider this problem in non-uniform arrays. Many authors have designed the transmitted beampattern by means of designing the cross correlation matrix of transmitted signals elements, but in this paper optimizing the locations of transmitted antennas will be done as well as cross correlation matrix of transmitted signals to achieve a better results  

The implementation of high-order multiple-input multiple-output (MIMO) detectors in complex domain, which finds applications in advanced wireless standards such as WiMAX and Long Term Evolution (LTE) systems, has always been a challenge in the literature. To address this challenge, two novel detection algorithms with their high-throughput VLSI architectures for a 4×4, 64-QAM complex MIMO detector are proposed in this thesis. The proposed architectures can easily be extended to high-order constellation schemes. For the first algorithm Complexity analysis and the synthesis results in a 0.13μm CMOS technology show that compared to the reported VLSI implementations in the complex domain, the... 

Joint multi-input multi-output (MIMO) filter-and-forward relaying and post-processing at base stations (BSs) for uplink coordinated multi-point (CoMP) reception has been investigated in the case of users-to-relay and relay-to-BSs frequency-selective fading channels. Signal transmission from users to BSs is performed in two phases. In the first phase, all users transmit their data to MIMO relay at the same time slot. In order to combat the interference due to frequency-selectivity of channels, MIMO relay passes its received signals through a finite impulse response (FIR) filter. Then, in the second phase, relay transmits the processed signals to the BSs. In order to further reducemean square... 

In recent years, communication systems with multiple antennas at the transmitter side and multiple antennas at the receiver side, shortly known as MIMO systems, have attracted a lot of attentions. Capability of these systems to increase the bandwidth efficiency and capacity of communication links has made them the core technology of next generation wireless systems.
As a first step to design and evaluate the performance of a MIMO system, a suitable channel model which is able to reflect the physical characteristics of the real environment appropriately is essential. Recently, a lot of models have been suggested to investigate MIMO channels, especially correlative models which use... 

In recent years due to the advances in semiconductor technology and the ability to implement small-scale manufacturing, communication at 60 GHz band receive more attention than ever has been. The use of this frequency band is not only about 7-9 GHz unlicensed broadband access provided, but getting smaller devices make it possible to use multiple antennas at the transmitter and receiver, and thus taking advantage of multiple input – multiple output systems. Antennas used in these systems should have features such as small size , low weight, high gain and bandwidth and also they should keep their high efficiency and gainat high frequency range (about a few GHz ). To achieve these features... 

Fault occurrence is an inevitable problem in industrial plants. These faults have numerous types. Some common kinds of faults are faults in actuators, faults in system dynamics, and faults in sensors. In many cases it is not possible to change or repair the broken part immediately. On the other hand, it is not reasonable to shut-down the whole system due to a minor failure. Therefore we should take a measure to have the best output possible in a faulty plant. In this thesis we have proposed a new static compensator by which we distribute the contribution of the faulty actuator among the other ones. At the end we evaluate the method by means of simulations  

Nowadays, enormous amounts of data are transferred through data communication networks every day in order to fulfill end users’ demands all over the world.The capacities of the links between network nodes, or in other words, the amount of bandwidth available to carry data is undoubtedly one of the most expensive resources as well as the one of most importance which not only plays an essential role in communicating information packets over such a vast network, but is a major determinant of Quality of Service (QoS) in terms of rapidity as well. The idea of using cache memories to optimize network bandwidth consumption laid the foundation for developing Content Delivery Networks (CDNs). In such... 

Research on target localization in multiple-input multiple-output (MIMO) radars, has seen significant growth in recent years. In general, localization methods in these radars can be classified as direct and indirect methods. In the former, the cinematic specifications of target is directly extracted from the received signals, whereas in the indirect methods, different measurements are calculated from the received signals and then, the target position is estimated using the acquired measurements. In this thesis, by concentrating on indirect target localization methods and by taking practical problems, such as uncertainties in sensors position and velocity, asynchronous sensor clocks and... 

The PID controller has been widely used in the industry for many years because of its simple structure and satisfactory performance. If the process is time-varying or has a nonlinear dynamic, the PID controller with constant parameters can not control the process in a wide range of operation and adaptive PID controller should be used. In this thesis, two adaptive controllers proposed in the literature, one for multi-input multi-output (MIMO) affine nonlinear systems and another for single-input single-output (SISO) non-affine nonlinear systems both in the normal form that both of them are extended in to the general form. The latter extended controller includes the MIMO systems. The main...