Investigations on Filtered OFDM with Selective Mapping Method and Partial Transmit Sequence Technique for Future Generation Mobile Communication Systems

Future generation mobile communication system requires asynchronous transmission of data, reduced out-of-band power emission, low peak-to-average power ratio, low latency, high data transmission rate, better spectrum, energy, and power efficiency, etc. Investigations on suitable waveform candidates for future-generation mobile communication have been reported in this paper. Filtered Orthogonal Frequency Division Multiplexing (F- OFDM), F- OFDM with Selective Mapping Method (SLM), and F- OFDM with Partial Transmit Sequence (PTS) technique, have been investigated. Its performances have been evaluated in terms of peak-to-average power ratio (PAPR), bit error rate (BER), and out-of-band power emissions. F–OFDM is a suitable candidate for future-generation mobile communication systems that can be used with single-rate or multirate filters. It can also be used in combination with other PAPR reduction techniques. F-OFDM with PTS technique requires a smaller number of IFFT operations than F-OFDM with SLM. The result obtained from my present investigations reveals that F-OFDM with the PTS technique has 4.3 dB less PAPR than that of OFDM at the cost of marginal increase in the BER value

Digital signal processing techniques for peak-to-average power ratio mitigation in MIMO–OFDM systems

The focus of this thesis is to mitigate the very large peak-to-average transmit power ratios (PAPRs) inherent to conventional orthogonal frequency division multiplexing (OFDM) systems, particularly in the context of transmission over multi-input multi-output (MIMO) wireless broadband channels. This problem is important as a large PAPR generally needs an expensive radio frequency (RF) power amplifier at the transmitter due to the requirement for linear operation over a wide amplitude range and such a cost would be compounded when multiple transmit antennas are used. Advanced signal processing techniques which can reduce PAPR whilst retain the integrity of digital transmission therefore have considerable potential for application in emergent MIMO–OFDM wireless systems and form the technical contributions of this study. [Continues.

Performance analysis of OFDM technology on radio-over-fiber systems

Dissertação de mest., Engenharia Eletrónica e Telecomunicações, Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2011Nowadays, the demand for high speed, high quality and diversity in distributed services presents a challenge for telecommunication technology. Wireless systems provide the accessibility to end-user, but are not the solution for long distance links. Currently, the ideal technology for long-range transmissions at high data rates is optical fiber. Hence, a new concept for high capacity networks emerges, with centralized services into Base Stations (BS) engineered to provide flexibility and control over the system, and to perform operations such as electrical to optical domain conversion and modulation. Such Radio-over-Fiber (RoF) networks also appear as an attractive technology because they are efficient and cost effective. Orthogonal Frequency Division Multiplexing (OFDM) technology is widely used in a number of standards. For instance, it is actually the Multi-Carrier Modulation (MCM) technique applied in 802.11a/g/n wireless standards and in Digital Video Broadcasting-Terrestrial (DVB-T), among other prevailing systems, which makes this subject one particularly pertinent to study. OFDM systems are an appealing choice for waveform modulation, as they are very bandwidth efficient comparing to others MCM, and provide flexibility in data transmission rates. Additionally, an important advantage dwells in its natural robustness against severely interfering environments. In this thesis, fundamentals on OFDM technology are extensively described, and its application to wireless and optical fiber networks is introduced. The combined channel effects of these technologies on OFDM signals are investigated. In terms of performance analysis, this exposition focuses on understanding the importance of OFDM modulation parameters, and explores some OFDM signal properties. To achieve this, a simulator was implemented with Matlab to create arbitrary OFDM waveforms and emulate channel effects. This study also investigates the efficiency of OFDM technology over a real Radio Frequency (RF) system with an ideal communication channel. Finally, an experimental RoF configuration is implemented and its performance is assessed

Portable Waveform Development for Software Defined Radios

This work focuses on the question: "How can we build waveforms that can be moved from one platform to another?\u27\u27 Therefore an approach based on the Model Driven Architecture was evaluated. Furthermore, a proof of concept is given with the port of a TETRA waveform from a USRP platform to an SFF SDR platform

Physical Layer Watermarking of Direct Sequence Spread Spectrum Signals

Security services and mechanisms in wireless networks have long been studied and developed. However, compared to upper network layers, physical layer security did not play a signicant role in the OSI security model. Thanks to the easier implementation and verication methods brought by the development of software dened radio (SDR) techniques, physical layer security mechanisms have recently drawn increasing interest from researchers. Digital watermarking is one of the popular security techniques that can fully utilize various exclusive characteristics of the physical layer. This thesis proposes a physical layer watermarking technique named Water-marked Direct Sequence Spread Spectrum (DSSS) or WDSSS technique, which embeds authentication information into pseudonoise (PN) sequences of a DSSS system. The design and implementation of the WDSSS prototype system on the GNU Radio/USRP SDR platform is discussed, as well as two watermark embedding methods, the maximized minimum distance method and the sub-sequence method. Theoretical analysis and experimental results on the WDSSS prototype system are presented to evaluate the performances of both the content signal and the watermark signal. Results show that, for the 11-chip PN sequence, increasing articial chip errors has aquantitatively predictable impact on the content signal, requiring 2 dB higher signal-to-noise ratio (SNR) to maintain an acceptable packet error rate (PER) for one additional ipped chip. In terms of the watermark signal, the two embedding methods demonstrated individual advantages in either PER or throughput. The maximized minimum distance method outperforms the sub-sequence embedding method with a 3 dB lower SNR requirement, while the latter provides 400 more throughput than the former with adequate SN

Analysis and Simulation of LTE Downlink and Uplink Transceiver

LTE (Long Term Evolution) is a next generation standard by 3rd Generation Partnership Project (3GPPP) consortium. In this paper, the physical layer (PHY) of LTE transceiver is analyzed in downlink and uplink transmissions. Simulations of the physical layer of LTE transceiver are obtained with the use of LTE System Toolbox by Mathworks. Simulation results are presented to show the performance of LTE transceivers in Physical Downlink Shared Channel (PDSCH) and Physical Uplink Shared Channel (PUSCH). Measurements of throughput and Bit Error Rate (BER) are obtained for different simulation configurations