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Ultra wideband (UWB) system requires high data rate transmission for a short wireless link application. The application of turbo codes in the system will improve the bit error rate (BER) performance. In this paper, the analysis of recursive systematic convolutional (RSC) turbo codes in the multiband orthogonal frequency division multiplexing (MB-OFDM) will be investigated in UWB channel with channel...
Digital Radio Mondiale (DRM) is the most important technology to replace analog AM broadcasting into digital one. The core of DRM is based on coded orthogonal frequency division multiplexing (COFDM), so it has high spectrum efficiency including the other advantages. Modern OFDM is based on discrete Fourier transform (DFT) or inverse discrete Fourier transform (IDFT). However, due to the particularity...
In this paper, low-latency implementation of adaptive discrete Fourier transform (DFT) based channel estimator for Mobile WiMAX system is proposed. DFT based channel estimation improve the performance by suppressing time domain noise. However, conventional method use fixed channel impulse response (CIR) length which can cause significantly performance degradation in fast fading channel. In order to...
In this work, we examined the performance of conventional DFT based OFDM and wavelet based OFDM (WOFDM) with and without Alamouti coding over multipath Rayleigh fading channels with exponential power delay profile. Results show that WOFDM has slightly better bit error rate performance than the conventional OFDM with and without Alamouti code. Besides the performance improvement of WOFDM as compared...
This paper presents a novel modulation scheme which combines key characteristics of single carrier frequency division multiple access (SC-FDMA) with continuous phase modulation (CPM) to increase the power amplifier efficiency of SC-FDMA transmissions. CPM-SC-FDMA is developed based upon the observation that the samples from a CPM waveform - which are always constant modulus - may be treated as dasiadata...
In this paper, we investigate cooperative OFDM communications using amplify-and-forward (AF) protocol at the relays, in the presence of imperfect timing synchronization. In most studies on cooperative communications, perfect time synchronization among cooperating nodes is assumed. In practice, however, due to imperfect time synchronization, orthogonality among the subcarriers of the different nodes'...
In spectrum pooling applications, the spectral leakage of DFT-based OFDM systems should be divided into two parts, in-band-out-of-subband (IBOSB) leakage and out-of- band (OOB) radiation. A scheme is proposed to suppress the IBOSB leakage and redistribute OOB radiation through the frequency domain correlative coding with appropriate weighting. It introduces the correlation between adjacent subcarriers,...
Wireless digital communications is rapidly expanding resulting in a demand for systems that are reliable and have a high spectral efficiency. To fulfill these demands, the multicarrier modulation scheme, often called Multicarrier direct sequence code division multiplexing access (MC-DS-CDMA), has drawn a lot of attention. On the other hand space time block code-MC-DS-CDMA techniques have been considered...
In this paper, the bit error rate (BER) performance of conventional discrete Fourier transform (DFT) - OFDM system is compared with discrete wavelet transform (DWT)-OFDM system and discrete cosine transform (DCT)-OFDM system in an AWGN environment. Several wavelets such as Haar, Daubechie and Symlet are considered. We give the performance with two modulation format such as BPSK and QPSK. Simulation...
In this paper we propose a new type of a system for multicarrier modulation. The modulation and demodulation in the proposed system are performed by an inverse and forward vector transforms. The properties of the vector transform allow fast vector transform algorithms to be derived in a manner similar to the FFT Real-valued vector transforms are also possible. Appropriate vector transforms are designed...
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