Mohamed H. M. Nerma

On DT-CWT Based OFDM: PAPR Analysis

High peak — to — average power ratio (PAPR) of transmitted signals is a major shortcoming for multicarrier modulation system. This paper introduces a novel OFDM system based on dual—tree complex wavelet transform (DT-CWT). In the proposed scheme, DT-CWT is used in place of fast Fourier transform (FFT). The complementary cumulative distribution function (CCDF) of PAPR for the proposed scheme signal achieves about 3 dB improvement in PAPR over the traditional OFDM and wavelet packet modulation (WPM) signals at 0.1% of CCDF at the cost of acceptable increase in computational complexity without using any pruning techniques.

Pre-coding based multi-user OFDM system

In most communication system, multiple users need to be supported. In OFDM systems, multiple access is achieved through combining TDMA and FDMA. OFDM supports multiusers with popular multiple access schemes, these schemes are MC - CDMA and OFDMA. In this paper we propose a precoding based approach to multiple access in OFDM systems using singular value decomposition (SVD). The scheme is like a CDMA scheme, in that the entire bandwidth can be used at all times, except that it does not entail expanding the bandwidth. This scheme combats the Multiuser Interference (MUI) caused by other users.

The effects of shift-invariance property in DTCWT-OFDM system

This paper proposed a new OFDM system based on dual - tree complex wavelet transform (DTCWT). In this work, the advantages of the shift invariance property are shown from the results of the average bit error rate (BER) performance of the proposed system under different filters length. The results are compared with that of the conventional OFDM and wavelet packet modulation (WPM) in Rayleigh channel environment. Simulation results show the superior of the OFDM based on DTCWT over the conventional OFDM and WPM systems.