The Bit Error Rate (BER) Performance in Multi-Carrier (OFDM) and Single-Carrier

The spectacular growth of wireless communication tools has escalated the number of mobile subscribers from almost 700 million in 2000 to more than 4 billion in 2009. The huge number of subscribers has led to several issues with how service is provided. The high user demand has forced developers to overcome the problems of the old analog systems and to introduce OFDM as a promising technique that can fulfill users\u27 high demands. This technique matches well with high data rate connection and provides a higher capacity for the subscribers\u27 usage. The OFDM, as a multi-carrier, is more complex than the single-carrier transmission scheme. However, the OFDM technique maintains better performance for high data rate in terms of bit error rate (BER). In this thesis a comparison has been presented between the multi-carrier OFDM and the single-carrier to prove, in a simulation form, the theoretical point of view. Despite the advantages of using the OFDM scheme, there are several drawbacks. One of these negatives is the high peak to average power ratio (PAPR). To overcome this problem, there are power reduction techniques that can be applied to the signal to reduce the high power. One of these techniques is the clipping and filtering technique. A maximum level is sited for the transmitted signal to reduce the power and afterward, the signal goes through a filter to remove the influence of the in-band distortion and out-of-band radiation

Physical Layer Defenses Against Primary User Emulation Attacks

Cognitive Radio (CR) is a promising technology that works by detecting unused parts of the spectrum and automatically reconfiguring the communication system\u27s parameters in order to operate in the available communication channels while minimizing interference. CR enables efficient use of the Radio Frequency (RF) spectrum by generating waveforms that can coexist with existing users in licensed spectrum bands. Spectrum sensing is one of the most important components of CR systems because it provides awareness of its operating environment, as well as detecting the presence of primary (licensed) users of the spectrum

Applications of MATLAB in Science and Engineering

The book consists of 24 chapters illustrating a wide range of areas where MATLAB tools are applied. These areas include mathematics, physics, chemistry and chemical engineering, mechanical engineering, biological (molecular biology) and medical sciences, communication and control systems, digital signal, image and video processing, system modeling and simulation. Many interesting problems have been included throughout the book, and its contents will be beneficial for students and professionals in wide areas of interest

System Modeling of Next Generation Digitally Modulated Automotive RADAR (DMR)

abstract: State-of-the-art automotive radars use multi-chip Frequency Modulated Continuous Wave (FMCW) radars to sense the environment around the car. FMCW radars are prone to interference as they operate over a narrow baseband bandwidth and use similar radio frequency (RF) chirps among them. Phase Modulated Continuous Wave radars (PMCW) are robust and insensitive to interference as they transmit signals over a wider bandwidth using spread spectrum technique. As more and more cars are equipped with FMCW radars illuminate the same environment, interference would soon become a serious issue. PMCW radars can be an effective solution to interference in the noisy FMCW radar environment. PMCW radars can be implemented in silicon as System-on-a-chip (SoC), suitable for Multiple-Input-Multiple-Output (MIMO) implementation and is highly programmable. PMCW radars do not require highly linear high frequency chirping oscillators thus reducing the size of the final solution. This thesis aims to present a behavior model for this promising Digitally modulated radar (DMR) transceiver in Simulink/Matlab. The goal of this work is to create a model for the electronic system level framework that simulates the entire system with non-idealities. This model includes a Top Down Design methodology to understand the requirements of the individual modules’ performance and thus derive the specifications for implementing the real chip. Back annotation of the actual electrical modules’ performance to the model closes the design process loop. Using Simulink’s toolboxes, a passband and equivalent baseband model of the system is built for the transceiver with non-idealities of the components built in along with signal processing routines in Matlab. This model provides a platform for system evaluation and simulation for various system scenarios and use-cases of sensing using the environment around a moving car.Dissertation/ThesisMasters Thesis Engineering 201

Detection, Receivers, and Performance of CPFSK and CPCK

Continuous Phase Modulation (CPM) is a power/bandwidth efficient signaling technique for data transmission. In this thesis, two subclasses of this modulation called Continuous Phase Frequency Shift Keying (CPFSK) and Continuous Phase Chirp Keying (CPCK) are considered and their descriptions and properties are discussed in detail and several illustrations are given. Bayesian Maximum Likelihood Ratio Test (MLRT) is designed for detection of CPFSK and CPCK in AWGN channel. Based on this test, an optimum receiver structure, that minimizes the total probability of error, is obtained. Using high- and low-SNR approximations in the Bayesian test, two receivers, whose performances are analytically easy-to-evaluate relative to the optimum receiver, are identified. Next, a Maximum Likelihood Sequence Detection (MLSD) technique for CPFSK and CPCK is considered and a simplified and easy-to-understand structure of the receiver is presented. Finally, a novel Decision Aided Receiver (DAR) for detection of CPFSK and CPCK is presented and closed-form expressions for its Bits Error Rate (BER) performance are derived. Throughout the thesis, performances of the receivers are presented in terms of probability of error as a function of Signal-to-Noise Ratio (SNR), modulation parameters and number of observation intervals of the received waveform. Analytical results wherever possible and, in general, simulation results are presented. An analysis of numerical results is given from the viewpoint of the ability of CPFSK and CPCK to operate over AWGN Channel

Simulation of Adjacent Channel Interference Cancellation

In this thesis we studied method of subtractive interference cancellation applied to multiuser systems. We developed algorithms for simulation of a point-to-point communication system that uses the techniques of interference cancellation. Initially we made a choice of the optimal modulation technique, pulse shape and its corresponding roll-off factor, which improve the bandwidth efficiency. The next step was to generate adjacent channels to our channel of interest and study the degradation of the BER performance for different frequency separation between the channels. Further we explored the SIC and PIC techniques applied in one and two stages. For the one stage implementation our simulations indicate that the BER of the PIC technique is slightly better. The results for the two stages implementation scheme show a clear improvement over the single stage scheme. However, in this case the SIC technique performs visibly better. By using the IC techniques we can pack the channels much closer on a given frequency band such that there is a place for more channels, i.e., users

Design and Investigation of CDMA Baseband Transceiver Based Fourier Signals for Different Channel Estimation Algorithms in SUI Channels

Code Division Multiple Access (CDMA) and Orthogonal Frequency Division Multiplexing (OFDM) and are the technology used in all third generation cellular communications networks, and it is a promising candidate for the definition of fourth generation standards. This paper refers to channel estimation based on time-domain channel statistics. Using a general model for Stanford University Interim SUI channels model, the aim of the paper is to find out the most suitable channel estimation algorithms for the existing CDMA and modified the bit error rate for this system. Starting with the analysis of channel estimation algorithms, we present the Minimum Mean Square Error (MMSE (and Least Square (LS (estimators and compromising between performances under different channel scenarios. The bit error rate for a 16-QAM system is presented by methods of Matlab simulation results. Keywords: CDMA, OFDM, MMSE, LS, SUI

Error-related potentials for adaptive decoding and volitional control

Locked-in syndrome (LIS) is a condition characterized by total or near-total paralysis with preserved cognitive and somatosensory function. For the locked-in, brain-machine interfaces (BMI) provide a level of restored communication and interaction with the world, though this technology has not reached its fullest potential. Several streams of research explore improving BMI performance but very little attention has been given to the paradigms implemented and the resulting constraints imposed on the users. Learning new mental tasks, constant use of external stimuli, and high attentional and cognitive processing loads are common demands imposed by BMI. These paradigm constraints negatively affect BMI performance by locked-in patients. In an effort to develop simpler and more reliable BMI for those suffering from LIS, this dissertation explores using error-related potentials, the neural correlates of error awareness, as an access pathway for adaptive decoding and direct volitional control. In the first part of this thesis we characterize error-related local field potentials (eLFP) and implement a real-time decoder error detection (DED) system using eLFP while non-human primates controlled a saccade BMI. Our results show specific traits in the eLFP that bridge current knowledge of non-BMI evoked error-related potentials with error-potentials evoked during BMI control. Moreover, we successfully perform real-time DED via, to our knowledge, the first real-time LFP-based DED system integrated into an invasive BMI, demonstrating that error-based adaptive decoding can become a standard feature in BMI design. In the second part of this thesis, we focus on employing electroencephalography error-related potentials (ErrP) for direct volitional control. These signals were employed as an indicator of the user’s intentions under a closed-loop binary-choice robot reaching task. Although this approach is technically challenging, our results demonstrate that ErrP can be used for direct control via binary selection and, given the appropriate levels of task engagement and agency, single-trial closed-loop ErrP decoding is possible. Taken together, this work contributes to a deeper understanding of error-related potentials evoked during BMI control and opens new avenues of research for employing ErrP as a direct control signal for BMI. For the locked-in community, these advancements could foster the development of real-time intuitive brain-machine control