Euihyoung Lee

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 Novel Time Delay Estimation Bias Reduction Scheme using Maximum Slope Change in GNSS

The early minus late discriminator based delay locked loop (EL-DLL), which is a general code tracking scheme of the global navigation satellite system (GNSS), has enormous time delay estimation bias (beta). The narrow correlated DLL (NC-DLL) and the double delta DLL (Delta(2)-DLL) were proposed as a beta reduction scheme, where Delta means the spacing between early and late correlation sample. However, the two schemes cannot remove the beta completely and make the dynamic range narrower than the EL-DLL, which lead to very accurate acquisition. This paper proposes a novel tracking scheme that can reduce the beta using maximum slope change without narrow dynamic range.

A Study on Propagation Characteristics of Acoustic Signals in Indoor Environments

Start This paper analyzes the propagation characteristics of acoustic signals in indoor environments, which is applicable to indoor positioning system. Indoor stereo sound system is generally valid within . So it is not possible to apply prevalent sound propagation characteristic to indoor positioning system because the prevalent acoustic signals propagation characteristic is defined under free space condition. Therefore, in this paper, we present the propagation characteristics of acoustic signals in indoor environments considering the free space propagation characteristic as well as room characteristic such as humidity, temperature, absorption of atmosphere and so on. To verify the designed propagation model of indoor acoustic signals, this paper presents the propagation characteristics of decreasing sinusoidal signals whose frequencies ate from 1kHz to 20kHz in anechoic room. In addition, this paper also presents the propagation characteristics of decreasing sinusoidal signals which have multiple frequencies.

A New UWB Synchronization Scheme Using Multipath Components Jointly

In ultra-wideband (UWB) systems, conventionally, the synchronization is to align time phases of a locally generated template and any of multipath components to within an allowable range. However, the synchronization with a low-power multipath component could incur significant performance degradation in receiver operation (e.g., detection) after the synchronization. On the other hand, the synchronization with a high-power multipath component can improve the performance in receiver operation after the synchronization. Generally, the first one among multi- path components has the largest power. Thus, the synchronization with the first path component can make better performance than that with a low-power component in receiver operations after the synchronization. Based on which, we first propose an optimal decision rule based on a maximum likelihood (ML) approach, and then, develope a simpler suboptimal decision rule for selecting the first path component. Simulation results show that the optimal and suboptimal decision rules have better performance than the conventional decision rule in UWB multipath channels.

A Novel Tracking Scheme for Band-Limited GNSS

The tracking bias is caused by two reasons: one is the distortion in symmetry of correlation values and the other is the shift of the point of time of the maximum correlation value. In band-limited multipath environments, the latter one is a more dominant error factor than the former one. This paper will mention about the characteristics of the coherent correlation values in band-limited multipath environments, and present the novel tracking bias mitigation scheme for a global navigation satellite system (GNSS) which is one of the location determination technologies (LDT) for positioning.

A Novel Code Tracking Scheme using Correlation Outputs in Advanced Offset Region for GALILEO L1 Open Service

The single delta delay lock loop is the most widely used code tracking scheme for the GALILEO system that employs the binary offset carrier modulated spreading signal. When only a line-of-sight signal is received, the single delta delay lock loop is the optimal code tracking scheme. However, when the multipath signals are received, the correlation values are distorted, and thus, the tracking bias arises, which is defined as the difference between correct and estimated synchronization points. To tackle this problem, many tracking schemes have been proposed, e.g. narrow correlator DLL, high resolution correlator DLL, and so on. These schemes use the correlation values nearby the offset of the peak correlation values. However, the coherent auto-correlation function of the binary offset carrier modulated spreading signal has additionally two locally minimum correlation values whose offsets are plusmnTc /2 , respectively, where Tc is the chip duration. In multipath environments, the correlation values nearby the locally minimum correlation value are less distorted compared with those nearby the one whose offset is plusmnTc /2 . From this observation, we propose a novel tracking scheme, and then, its tracking accuracy is assessed using Monte-Carlo simulation.