Sanghun Kim

A Novel Unambiguous Multipath Mitigation Scheme for BOC(kn, n) Tracking in GNSS

Binary offset carrier (BOC) signal tracking is one of the challenging problems in future Global Navigation Satellite Systems (GNSS) including Galileo and Global Positioning System (GPS), because false lock could be generated in the tracking procedure due to multiple side-peaks in BOC autocorrelation. Multipath mitigation is another challenging problem in GNSS systems, because the presence of multi-path signals gives a range error. Recently, a novel tracking scheme for the BOC signal was proposed by Garin. However, it cannot completely resolve the ambiguity problem due to the false lock and has not enough multipath mitigation performance. Moreover, Garins scheme is applicable to only BOC (n, n). In this paper, we propose a novel unambiguous multipath mitigation scheme. The proposed scheme is applicable to various BOC signals (i.e., BOC (kn, n)) and does not incur false lock point in the tracking procedure. In addition, the proposed scheme has appropriate multipath mitigation performance than traditional and Garins schemes

New Correlation Functions for CBOC Satellite 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, a new correlation function with no side-peaks was proposed for sine or cosine phased BOC signal synchronization by the authors [7]. In this paper, we propose a novel correlation function for composite binary offset carrier (CBOC) signals by using the similar method to that in [7], which has a better power ratio than the CBOC autocorrelation.

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 Novel Multipath Mitigated Side-peak Cancellation Scheme for BOC(kn, n) in GNSS

Binary offset carrier (BOC) signal synchronization is one of the most important steps to recover the navigation data in global navigation satellite system (GNSS) including Galileo and global positioning system (GPS). The main error sources in synchronizing BOC signals are the multiple side-peaks in the BOC autocorrelation and the multipath delay. Recently, a novel correlator receiver for the BOC signal was proposed by Garin (shaping correlator receiver), which was shown to shrink the side-peaks and mitigate the multipath effect to a certain degree. However, a shaping correlator receiver cannot completely remove the side-peaks and is affected by a wider multipath delay range than that of the traditional correlator receiver. Moreover, it is applicable to only BOC(n, n) signal. In this paper, we propose a new correlator receiver for BOC signals. The proposed correlator receiver does not have any side-peak in its correlator output, and has smaller multipath delay range that incurs the tracking error than that in the shaping correlator receiver. Furthermore, the proposed correlator receiver is applicable to various types of BOC signals (i.e., BOC(kn, n)) and requires only a half of the number of the correlators used in the shaping correlator receiver.

A New GNSS Synchronization Scheme

Due to multiple side-peaks in the binary offset carrier (BOC) autocorrelation function, BOC signal synchronization is one of the most challenging tasks for global navigation satellite systems (GNSSs) including Galileo and global positioning system (GPS). Recently, a novel correlation function with reduced side-peaks was proposed for BOC signal synchronization by Julien (6); however, Juliens correlation function still has the side-peaks and can be possible only for sine phased BOC( n,n), where n is the ratio of the pseudo random noise (PRN) code rate to 1.023 MHz. In this paper, we propose a new correlation function for BOC signal synchronization, investigating how multiple side-peaks arise in BOC autocorrelation function. The proposed correlation function does not have any side-peaks and can be generated for any type of BOC signal, sine/cosine phase BOC(kn,n), where k is the ratio of a PRN chip duration to the period of a square wave sub-carrier used in BOC modulation. In addition, an efficient correlator structure is presented for generating the proposed correlation function.

A Novel Scheme for Frequency Offset Estimation in OFDM Systems

In this paper, a novel integer frequency offset estimation scheme which is not affected by the timing offset is proposed for orthogonal frequency division multiplexing (OFDM) systems. Most of the schemes proposed for the integer frequency offset estimation assume the absence of the timing offset; however, such an assumption is not appropriate in practical systems. In this paper, using differential combining between two successive subcarriers, we propose a novel frequency offset estimation scheme. The simulation results show that the proposed scheme is robust to the timing offset variation, and thus, performs better than the conventional scheme when the timing offset range is not known.

An Improved Timing Synchronization Scheme for BOC Signals

Binary offset carrier (BOC) signal synchronization is one of the most important steps to recover the transmitted information in a global navigation satellite system (GNSS) such as Galileo and global positioning system (GPS). Generally, BOC signal synchronization is achieved 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, a novel correlation function with reduced side-peaks was proposed for BOC signal synchronization by Julien [8]; however, Juliens correlation function not only still has the side-peaks, but also is only applicable to sine phased BOC(n, n), where n is the ratio of the pseudo random noise (PRN) code rate to 1.023 MHz. In this paper, we propose a new correlation function for BOC signal synchronization, which does not have any side-peaks and is applicable to general types of BOC signals, sine/cosine phased BOC(kn, n), where k is the ratio of a PRN chip duration to the period of a square wave sub-carrier used in BOC modulation. In addition, an efficient correlator structure is presented for generating the proposed correlation function.

A low complexity and robust frequency offset estimation algorithm for OFDM-Based WLAN systems

This paper addresses the frequency offset estimation problem in the presence of the timing error for OFDM-based WLAN systems. When the timing error exists, the correlation value used for the frequency offset estimation could be reduced significantly due to the timing error, resulting in considerable degradation in estimation performance. In this paper, using the coherence phase bandwidth (CPB) and a threshold, a novel frequency offset estimation algorithm is proposed and based on which, an efficient timing error estimation algorithm is also proposed for the re-estimation of the frequency offset.

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.

Bacteriocidal Effects of Ultraviolet Irradiation for Reducing Bovine Mastitis Derived from Environmental Contamination

Bovine mastitis is an important disease causing serious economic loss in dairy production and food poison in public health. The major causative agents of bovine mastitis include Escherichia coli (E. coli), Streptococcus agalactiae (S. agalactiae), Staphylococcus aureus (S. aureus). These bacteria were found in milk and environmental condition such as feces, water, soil and so on. Recently, many cases of mastitis are derived from environmental contamination of micro-organisms, which important factors for the spread of this disease in farm. Ultraviolet irradiation (UV) has been used as disinfection for waste and water in clinical and industrial facilities. Moreover the UV irradiation has been used as useful bactericidal agents to remove bacterial biofilms in environmental condition. In this study, we determined the bacterial replication in different percentage of water content (PWC) in sterilized saw dust and feces complexes from farm, and results showed that slightly decreased growth pattern of E. coli and S. agalactiae but increased growth pattern of S. aureus in various PWC (200, 400 and 600%) until 144 h incubation. In the bacteriocidal effect of UV irradiation to bacteria in saw dust and feces complex, the results showed that bacteriocidal effect was depended on the UV irradiation time, irradiation distance and PWC. Especially the antibacterial activity of UV irratiation is stronger in low PWC (50%), long time irradiation (50 sec), and short distance (5 cm) than other condition of this study. Furthermore UV irradiation with stirring showed increased the bactericidal effect compared without stirring. These results suggested that bovine mastitis causing agents may survive long time in environmental condition especially saw dust and feces complexes in farm and can cause a various disease including mastitis. Moreover, these data can be used as basis for application and development of UV disinfection to control of bovine mastitis from environmental contaminated bacteria in dairy farm.