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This paper proposes a computationally efficient approach of estimating a sampling frequency offset (SFO) in multi-band ultra wideband orthogonal frequency division multiplexing systems. In order to devise the post-FFT based SFO estimator with low complexity, the partial pilot subset is chosen such that it provides an equivalent estimation performance to the conventional SFO estimator using the full pilot symbols. Mean square error of the low-overhead frequency estimation scheme is derived and simulation results are provided to verify our analysis. [ABSTRACT FROM AUTHOR]

In orthogonal frequency division multiplexing (OFDM) systems, the loss of orthogonality between the subcarriers due to carrier frequency offset (CFO) can degrade the performance of the system. In this paper, a residual CFO synchronization method is proposed for ultra wideband OFDM (UWB-OFDM) systems. The proposed fine frequency synchronization scheme uses a channel estimation sequence and physical layer convergence protocol (PLCP) header information which are equipped with frequency-domain spreading. A UWB-OFDM receiver with algorithm for fine frequency error synchronization is simulated and is evaluated in terms of mean square error. [ABSTRACT FROM AUTHOR]

In this paper, a fine carrier frequency offset synchronizer is presented for ultra-wideband multi-band orthogonal frequency division multiplexing (UWB MB-OFDM) systems. The proposed scheme uses a channel estimation (CE) sequence provided in the current UWB MB-OFDM system and is designed to be insensitive to a sampling clock frequency offset. To demonstrate the efficiency of the proposed fine frequency synchronizer, comparisons are made with the conventional frequency synchronizer in terms of mean square error. [ABSTRACT FROM AUTHOR]

A combination of orthogonal frequency division multiplexing (OFDM) with multiband frequency hopping (FH) is regarded as a promising solution for realizing ultra-wideband (UWB) systems. This paper deals with a modified maximum likelihood approach for frequency ambiguity resolution in the multiband UWB system. By using computer simulation, the synchronization performance of the traditional and proposed methods is evaluated in terms of probability of synchronization failure. [ABSTRACT FROM AUTHOR]

A combination of orthogonal frequency division multiplexing (OFDM) with frequency-division multiple access (FDMA) called OFDMA is regarded as a promising solution for improving the performance of interactive wireless broadcasting systems. This work focuses on the performance of OFDM when used as a modulation and access technique for the uplink of an interactive wireless broadcasting system. In such an application, we present our investigations of the effects of symbol timing misalignments and peak-to-average power ratio (PAR). Under the condition of the same side information bits, the selective mapping (SLM) approach can be implemented by decimating OFDM samples, which is less complex compared to the ordinary SLM incurring a slight degradation of the PAR performance. Taking into account the effects of clipping operation and symbol timing misalignment, the bit error rate (BER) and throughput performances are investigated for a typical OFDMA uplink scenario. [ABSTRACT FROM AUTHOR]

Orthogonal frequency-division multiple access (OFDMA), which is a combination of orthogonal frequency division multiplexing (OFDM) with frequency-division multiple access (FDMA), is regarded as a promising solution for enhancing the performance of interactive broadcasting wireless systems. This paper presents our investigation for the impacts of symbol timing errors and peak-to-average power ratio (PAR) on OFDMA-based interactive broadcasting systems. Under the condition of the same side information bits, the selective mapping (SLM) approach can be implemented by decimating OFDM samples, which is less complex compared to the ordinary SLM incurring a slight degradation of the PAR performance. Including the effects of clipping operation and symbol timing misalignment, the bit error rate (BER) performance is investigated for a typical OFDMA uplink scenario. [ABSTRACT FROM AUTHOR]

A simplified orthogonal frequency division multiplexing (OFDM) system with low peak-to-average power ratio (PAPR) and frequency diversity is proposed. The considered OFDM system exploits a frequency diversity by using a simple symbol repetition as is the case in previous work (i.e. Ko et aL, MILCOM2002). From the presented results, it can be seen that a modified OFDM signal can be easily implemented with low PAPR, still maintaining the same diversity gain at the receiver as in Ko et al. However, a small increase of decoding delay may be expected. [ABSTRACT FROM AUTHOR]

A fast scattered pilot synchronisation algorithm is presented which detects the pilot pattern of the currently received OFDM symbol for the DVB-H. The proposed synchronisation scheme is based on the correlation between the neighbouring pilot subcarriers in one received OFDM symbol. Therefore, it can reduce the burst synchronisation time with robustness compared with the conventional method used for DVB-H. [ABSTRACT FROM AUTHOR]

This article discusses PAPR analysis for multi-band OFDM signals. A multi-band orthogonal frequency division multiplexing (MB-OFDM) is being considered as a possible candidate for the IEEE 802.15 high rate alternative PHY. A MB-OFDM system exploits a frequency diversity introduced by both a multi-band hopping over two OFDM symbols and a conjugate symmetric input to inverse fast Fourier transform. In this article, researchers analyse the PAPR statistics for MB-OFDM signal and provide the selective mapping and partial transmit sequence-based MB-OFDM signals.