• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.40 no.8
• /
• pp.307-317
• /
• 2003

We analyze the performance of MC-CDMA and MC-DS/CDMA system on quasi-synchronized moble satellite return link. Quasi-synchronization is considered that chip offset between terminals is within a few chips. In 10-3 BER, performance of MC-DS/CDMA system with walsh code is 0.3dB better than that of MC-CDMA system when the number of user is 5 from -0.5 $T_{c}$ to 0.5 $T_{c}$ quasi-synchronization of MC-DS/CDMA system and from -5/64 $T_{c}$ $^{MC}$ to 5/64 $T_{c}$ $^{MC}$ quasi-synchronization of MC-CDMA system. MC-DS/CDMA system with walsh code is over 0.2dB better than that of MC-DS/CDMA system with extended m code and gold code. MC-CDMA system with walsh code is over 1.2dB better than that of MC-CDMA system with gold code when the number of user is 5 and lower than from -5/32 $T_{c}$ $^{MC}$ to 5/32 $T_{c}$ $^{MC}$ quasi-synchronization.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38C no.8
• /
• pp.713-718
• /
• 2013

In this paper, additional data transmission scheme was proposed based on SSB-OFDM Communication system which was know as efficient technique for bandwidth, because it used only single side band instead of double side band. When sending additional data which should be well spreaded for low power characteristics and error robustness. Gold code was selected for spreading code because it has excellent low-cross correlation characteristics. Through computer simulation, the validity was proved that proposed system is well worked with SSB-OFDM system.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.2 no.4
• /
• pp.511-517
• /
• 1998

In this paper a new technique to generate spreading code sequences in the CDMA communication is introduced. It is an effective method to generate optimal code sequences using the orthogonality of wavelet packet basis set of subspaces. With a three-stage Quadrature Mirror Filter(QMF), generation of optimal code sequences has been demonstrated. Since these generated optimal code sequences are non-binary and have an arbitrary waveform which is different from that of the conventional PN-based Gold code sequences, a strong security against the intended interceptor is feasible. Encouraging good correlation properties are also achieved with this new method.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.47 no.8
• /
• pp.32-41
• /
• 2010

We propose the use of multi-preambles using Gold codes and analyze its performance. The multi-preamble is a way of utilizing different codes for preambles according to operation modes or applications in a system. The receiver can be easily implemented using the maximum likelihood algorithm. The performance is robust against noise due to the good correlation characteristic of the Gold codes. We use 128-bit-long multi-preambles generated by 127 bit Gold codes in deriving the detection error probability and in verifying the validity through computer simulation. The results show that the theory and the experiment are in good agreement within the approximation error.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.47 no.7
• /
• pp.93-101
• /
• 2010

In this paper we generate Gold-sequence by using M-sequence which is made by two primitive polynomial of GF(2). Generally M-sequence is generated by linear feedback shift register code generator. Here we show that this matrix of appropriate permutation has Hadamard matrix property. This matrix proves that Gold-sequence through two M-sequence and additive matrix of one column has one of major properties of Hadamard matrix, orthogonal. and this matrix show another property that multiplication with one matrix and transpose matrix of this matrix have the result of unit matrix. Also M-sequence which is made by linear feedback shift register gets Hadamard matrix property mentioned above by adding matrices of one column and one row. And high-speed conversion is possible through L-matrix and the S-matrix.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• v.2
• /
• pp.261-266
• /
• 2006

A number of different techniques are available to mitigate the problem of cross correlations caused by the limited dynamic range of the 10-bit Gold codes in the GPS C/A code. These techniques include successive-interference cancellation (SIC) and parallel-interference cancellation (PIC), where the strong signals are subtracted at IF prior to attempting to detect the weak signals. In this paper, a variation of these techniques is proposed whereby the subtraction process is delayed until after the correlation process, although still employing a pure reconstructed C/A code signal to permit prediction of the cross correlation process. The paper provides details on the method as well as showing the results obtained when the method was implemented using a software GPS receiver. The benefits of this approach are also described, as is the application of the method to the cancellation of CW interference.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.8 no.10
• /
• pp.1491-1497
• /
• 2013

Radio frequency identification (RFID) is an important and essential components of ubiquitous computing, with the development of wireless communication technologies and mobile computing environment. Recently, RFID becomes the mainstream application that helps fast handling and uniquely identifying the physical objects. It utilizes the electromagnetic energy for data transmission from a tag to a reader in the presence of arbitrary interference and noise. In order to employ the portable mobile RFID reader, a tag-collision problem between two or more adjacent tags should be considered. In this paper, we present the operation of RFID system in which numerous tags are present in the interrogation zone of a single reader at the same time. Since there may exist a number of tagged objects in the narrow area, multiple RFID tags may interfere each other, caused to degrade the data reliability and efficiency of the RFID system. In order to suppress interference signals from multiple neighboring tags, we present an application of Gold code for RFID communication system, which uses spread spectrum technique. In this RFID system, data bits are spreaded in each tags with the unique Gold code and the spreaded data bits are despreaded in the reader with the same Gold code. The performance analysis of the considered RFID anti-collision system is illustrated via computer simulation examples.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.9 no.1
• /
• pp.34-41
• /
• 2010

In this paper, we analyze and simulate co-channel interference (CCI) mitigation method for cooperative communication systems employing decode-and-forward relays. In co-channel interference mitigation method, A source transmits signals that are encoded by orthogonal code. Then, the receiver can distinguish its own signals form the received signals by using the orthogonal code which is already known to the receiver. The orthogonal codes applied to this paper are orthogonal Gold codes. However, we can employ other codes, which have orthogonality, as the orthogonal code. In addition, we utilize a space time block coding (STBC) scheme for enhancing the system performance by obtaining additional array gain.

• Journal of Advanced Navigation Technology
• /
• v.21 no.3
• /
• pp.258-263
• /
• 2017

This paper analyzed GNSS signal acquisition performance of a regional navigation receiver when an interference cancellation capability is applied. Intereference between the regional navigation and GNSS signal can be mitigated by the interference cancellation technique such as the successive interference cancellation (SIC) algorithm. However signal acquisition performance will be degraded when jamming-to-signal ratio (J/S) is large due to a cross-correlation properties of residual signals. In this paper we analyzed signal acquisition performance degradation due to the interference between the Kasami and GNSS Gold code signal. Monte Carlo simulation is used for the analysis and compared results with those of GNSS Gold code only condition.

• Journal of the Korean Society of Radiology
• /
• v.10 no.3
• /
• pp.153-159
• /
• 2016

This study investigated relationship between secondary electrons produced from single gold nanoparticle as a result of its interaction with radiation and particle size and incidence energy, provided basic data related to the dose enhancement effect based on gold nanoparticles. Monte Carlo simulation was applied by using MCNPX MC code, 50, 100, 150 kV and 6, 15 MV x-ray energy was used. In a water phantom, single gold nanoparticles that are 30, 50, 70, 90, and 110 nm in diameter were placed and the tally volume was designated at every 10 nm. Difference in electrons produced from gold nanoparticles was normalized based on absence of nanoparticle. When the X ray energy decreased and the diameter of gold particles increased, more electrons were produced. When the energy was lower, in the linear formula related to nanoparticle size and electron production, the gradient was higher. And, in comparison to the MV X-ray, at kV X-ray, significantly more electrons were produced. This study can be used as data to understand the dose enhancement effect based on gold nanoparticles, and further research related to various materials that dose enhancement including gold nanoparticles needs to be conducted.