Youngyoon Lee

AltBOC and CBOC Correlation Functions for GNSS Signal Synchronization

Binary offset carrier (BOC) signal synchronization is based on the correlation between the received and locally generated BOC signals. Thus, the multiple side-peaks in BOC autocorrelation are one of the main error sources in synchronizing BOC signals. Recently, new correlation functions with no side-peak were proposed for sine and cosine phased BOC signal synchronization, respectively, by the authors [3]. In this paper, we propose new correlation functions with no side-peak for alternative BOC (AltBOC) and composite BOC (CBOC) signals by using the similar approach to the previous work.

A New Pilot-Aided Integer Frequency Offset Estimation Method for Digital Video Broadcasting (DVB) Systems

In this paper, a new integer frequency offset estimation method is proposed for orthogonal frequency division multiplexing (OFDM)-based digital video broadcasting (DVB) systems. Several pilot-aided frequency offset estimation methods have been proposed for OFDM-based DVB systems. In the conventional methods, however, the information of some combinations that pilots provide is used only. Thus, in this paper, we propose a new integer frequency offset estimation method exploiting the information of all combinations that pilots provide. The simulation results show that the proposed method outperforms the conventional method in terms of the probability of integer frequency offset estimation failure.

A pilot-aided integer frequency offset estimation scheme robust to influence of timing offset for OFDM-based DVB-T systems

A pilot-aided integer frequency offset (IFO) estimation scheme robust to the timing offset is proposed for orthogonal frequency division multiplexing (OFDM)-based digital video broadcasting-terrestrial (DVB-T) systems. The proposed scheme first produces correlation values between each continual pilot (CP) and a predetermined scattered pilot (SP), and then, recorrelates the correlation values in order to reduce the influence of the timing offset. Simulation results show that the proposed IFO estimation scheme is robust to the timing offset and has better estimation performance than the conventional scheme.

An OFDM Carrier Frequency Offset Estimation Scheme with Wide Fractional Offset Estimation Range

In this paper, we propose a carrier frequency offset (CFO) estimation scheme which is robust to the fractional CFO variation for orthogonal frequency division multiplexing (OFDM) systems. The proposed scheme first performs the envelope equalization process to convert the offset estimation problem to a carrier estimation problem, and then, estimates the integer and fractional parts of CFO by using periodogram of the received signal. Especially, in the estimation stage for fraction CFO, the ratio of the square-roots of periodograms is employed enlarging the estimation range of the stage than that of the conventional scheme. Numerical results demonstrate that the proposed scheme has better estimation performance than the conventional scheme for wider fractional CFO range in various channel conditions.

UWB acquisition based on combining multiple correlator outputs

This paper proposes a novel two-stage detection scheme based on multiple correlator outputs to enhance the detection performance in ultra-wideband (UWB) signal acquisition. Due to the rich multipath of UWB channels, the signal energy spreads over multiple correlator outputs, which makes each correlator output have only a portion of the signal energy, and thus, degrades the detection performance of the conventional scheme where a single correlator output is used as the decision variable for detection. In the proposed two-stage detection scheme, the decision variable is formed by combining multiple correlator outputs, making it possible to collect the signal energy spread by the multipath. Simulation results show that the proposed scheme can provide a better detection performance over the conventional scheme in various UWB channel environments.

An integer frequency offset estimation scheme robust to fractional frequency offset variation

In this paper, we propose a new periodogram-based integer frequency offset (IFO) estimation scheme robust to the fractional frequency offset (FFO) variation. We first observe the reason why the conventional IFO estimation scheme in [10] is sensitive to the variation of the FFO, and then, propose a new IFO estimation scheme using the modified maximum-likelihood (ML) metric. The numerical results demonstrate that the proposed scheme is more robust to the variation of the FFO and has better IFO estimation performance than the conventional scheme in [10].

A Novel BOC Signal Synchronization Scheme for Maritime Satellite Communications

The satellite communication is an important method for maritime communications. Binary offset carrier (BOC) signal is a promising candidate of next generation global navigation satellite systems (GNSS). Synchronization of BOC signal is one of the most important processes to demodulate BOC signal in GNSS. However, in maritime environment, the synchronization of BOC signal is suffered from the problem of side-peak of BOC autocorrelation function and multipath fading caused by the sea surface reflection. In this paper, we proposed a novel synchronization scheme which can eliminate side-peak perfectly and is robust in multipath channel. Simulation results show that the proposed scheme has better performance than conventional schemes in multipath channel.

A frequency ambiguity resolution for digital video broadcasting-terrestrial service

This paper deals with the integer frequency offset (IFO) estimation issue for reliable transmission in orthogonal frequency division multiplexing (OFDM)-based digital video broadcasting-terrestrial (DVB-T) systems. To estimate the IFO the conventional scheme uses only partial information of combinations that pilots provide. However, since the conventional scheme exploits a small number of correlations, it does not use sufficient signal energy for the IFO estimation. Thus, in this paper, we propose novel IFO estimation schemes efficiently using the additional correlations between pilots. The simulation results show that the proposed schemes are highly accurate in terms of the IFO detection probability.

New schemes of integer frequency offset estimation using pilots for DVB-T systems

This paper proposes two novel schemes for pilot-aided integer frequency offset (IFO) estimation in orthogonal frequency division multiplexing (OFDM)-based digital video broadcasting-terrestrial (DVB-T) systems. The conventional scheme proposed for estimating the IFO uses only partial information of combinations that pilots can provide, which stems from a rigorous assumption that the channel responses of pilots used for estimating the IFO change very rapidly. Thus, in this paper, we propose the novel IFO estimation schemes exploiting additional information of combinations that pilots can provide to improve the performance of the IFO estimation. The simulation results show that the proposed schemes are highly accurate in terms of the IFO detection probability.

A Novel ML Decoding Scheme for MIMO Signals

In this paper, we propose a novel maximum-likelihood (ML) decoding scheme based on the combination of depth- and breadth-first search methods on a partitioned tree for multiple input multiple output systems. The proposed scheme first partitions the searching tree into several stages, each of which is then searched by a depth- or breadth-first search method, possibly exploiting the advantages of both the depth- and breadth-first search methods in an organized way. Numerical results indicate that, when the depth- and breadth-first search algorithms are adopted appropriately, the proposed scheme exhibits substantially lower computational complexity than conventional ML decoders while maintaining the ML bit error performance.