• Journal of IKEEE
• /
• v.16 no.2
• /
• pp.153-158
• /
• 2012

A new diversity combining scheme is proposed for time-of-arrival (TOA) estimation of chirp signal in dense multipath channel. In the multipath channel, the performance of TOA estimation using conventional correlation matrix-based diversity combining scheme is degraded due to the lack of de-correlation effect. To increase the de-correlation effect, the proposed diversity scheme employs interleaving method based on the property of de-chirped signal. As a result, the proposed scheme increases de-correlation effect and also reduces the noise of TOA estimation. Finally, the diversity achieved from the proposed scheme improves TOA estimation performance. The de-correlation effect is analyzed mathematically. The estimation accuracy of the proposed diversity scheme is superior to that of conventional diversity scheme in multipath channel.

• Journal of Electrical Engineering and Technology
• /
• v.10 no.5
• /
• pp.1983-1988
• /
• 2015

This paper proposes the enhanced application of superconducting magnetic energy storage (SMES) for the effective compensation of power fluctuations based on the interleaving technique. With increases in demand for renewable energy based photovoltaic (PV) generation system, the output power fluctuations from PV generation system due to sudden changes in environmental conditions can cause serious problems such as grid voltage and frequency variations. To solve this problem, the SMES system is applied with its superior characteristics with respect to high power density, fast response for charge and discharge operations, system efficiency, etc. In particular, the compensation capability is effectively improved by the proposed interleaving technique based on its parallel structure. The dynamic performance of the system designed using the proposed method is evaluated with several case studies through time-domain simulations.

• Journal of Power Electronics
• /
• v.10 no.2
• /
• pp.132-137
• /
• 2010

Interleaving techniques are widely used to reduce input/output ripples and to increase the power capacity of boost converters operating in critical conduction mode. Two types of phase-shift control schemes are studied in this paper, the turn-on time shifting method and the turn-off time shifting method. It is found that although the turn-off time shifting method exhibits better performance, it suffers from sub-harmonic oscillations at high input voltages. To solve this problem, an intensive quantitative analysis of the sub-harmonic oscillation phenomenon is made in this paper. Based upon that, a novel modified turn off time shifting control scheme for interleaved boost converters operating in critical conduction mode is proposed. An important advantage of this scheme is that both the master phase and the slave phase can operate stably in critical conduction mode without any oscillations in the full input voltage range. This method is implemented with a FPGA based digital PWM control platform, and tests were carried out on a two-phase interleaved boost PFC converter prototype. Experimental results demonstrated the feasibility and performance of the proposed phase-shift control scheme.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.19 no.9
• /
• pp.1000-1009
• /
• 2008

The purpose of this paper is to analyze the performance of MB-OFDM UWB system when the interference signal that can be WIMAX signal or 4 G system signal is received by detection limit of -80 dBm/MHz proposed in Korea for DAA(Detect And Avoid) to permit UWB in $3.1{\sim}4.8$ GHz. MB-OFDM UWB system supports two transmission modes; one is TFI(Time frequency Interleaving) mode that transmits OFDM symbols using different carrier frequency from symbol to symbol according to Time Frequency(TF) codes, the other is FFI(Fixed Frequency Interleaving) mode that transmits OFDM symbols using a specific carrier frequency. In this paper, we considered the TX average power and the synchronization structure to reflect the effect of frequency hopping according to TFC. Interference analysis results show that the WiMAX system is fenced thoroughly from UWB interference in domestic DAA regulation, but the performance of MB-OFDM UWB system is degraded seriously by an interference signal with the DAA detection limit even in frequency Hopping mode that can get frequency diversity effect.

• The KIPS Transactions:PartC
• /
• v.13C no.6 s.109
• /
• pp.677-684
• /
• 2006

This paper investigates the link margin of MB-OFDM UWB system quantitatively. Various simulations are performed considering the implementation loss by imperfect synchronization unit and the effect of multi-path fading channels. MB-OFDM UWB system uses ZP(Zero Padding) instead of CP(Cyclic Prefix) and supports two transmission modes; one is TFI(Time Frequency Interleaving) mode that transmits OFDM symbols using different carrier frequency from symbol to symbol according to Time Frequency(TF) codes, the other is FFI(Fixed Frequency Interleaving) mode that transmits OFDM symbols using a specific carrier frequency. The advantage of if and TFI is to be able to increase the transmitting power effectively compared to the existed OFDM systems that transmit the signal continuously at the same average transmitting power. From the analysis results of Ink margin, to guarantee the service range of 4m in 200Mbps mode, TFI mode must necessarily be implemented and the service range of 480Mbps mode is estimated about 1-2m in the line-of-sight multi-path channel (CMI).

• Journal of the Institute of Electronics and Information Engineers
• /
• v.54 no.7
• /
• pp.36-46
• /
• 2017

The turbo code, an error correction code, needs a long decoding time since the same decoding process must be repeated several times in order to obtain a good BER performance. Thus, parallel processing may be used to reduce the decoding time, in which case there may be a memory contention that requires additional buffers. The QPP interleaving has been proposed to avoid such case, but there is still a possibility of memory contention when a decoder is constructed using the so-called double flow technique. In this paper, we propose an even-odd cross mapping technique to avoid memory conflicts even in decoding using the double-flow technique. This method uses the address generation characteristic of the QPP interleaving and can be used to implement the interleaving circuit between the decoding blocks and the LLR memory blocks. When the decoder implemented by applying the double flow and the proposed methods is compared with the decoder by the conventional MDF techniques, the decoding time is reduced by up to 32% with the total area increase by 8%.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.6A
• /
• pp.600-606
• /
• 2004

An interleaving delay diversity scheme is investigated in this paperand the applications in the multi-code WCDMA system along with antenna selection diversity is proposed. The proposed algorithm utilizes interleaving and delayed duplicated transmission mechanism to mitigate the effect of noise and fading. The interleaved signal and the original signal are both transmitted at intervals to obtain time diversity without any increase in required capacity. By adjusting the number of retransmissions of the information signal properly, the system achieve the receive diversity efficiently. For transmission power efficiency the proposed system also applies antenna selection diversity. By computer simulation, it has been shown that the proposed algorithm achieves better performance than the conventional algorithms by more than 2dB.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.27 no.6
• /
• pp.901-909
• /
• 1990

With a wide spread of 32 bit personal computers, a simple structure and high performance memory system have been highly required. In this paper, a memory block is constructed by using a modified hierarchical bit line in which the DRAM bit line and the latch which works as a SRAM cell are integrated by an interface gate. And the new architecture memory DSRAM(Dynamic Static RAM) is proposed by interleaving the 16 memory block. Because the DSRAM works with 16 page, the page is miss ratio becomes small and the RAS precharge time which is incurred by page miss is shortened. So the DSRAM can implement an optimum page interleaving and it has good compatibility to the existing DRAMs. The DSRAM can be widely used in small computers as well as a high performance memory system.

• Journal of Communications and Networks
• /
• v.5 no.2
• /
• pp.174-183
• /
• 2003

Space-Time (ST) codes are known to provide high transmission rates, diversity and coding gains. In this paper, a tight upper bound on the error probability of ST codes over rapid fading channels is presented. Moreover, ST codes suitable for rapid fading channels are presented. These codes are designed using the QPSK and 16-QAM signal constellations. The proposed codes are based on two different encoding schemes. The first scheme uses a single trellis encoder, whereas the second scheme uses the I-Q encoding technique. Code design is achieved via partitioning the signal space such that the design criteria are maximized. As a solution for the decoding problem of I-Q ST codes, the paper introduces a low-complexity decoding algorithm. Results show that the I-Q ST codes using the proposed decoding algorithm outperform singleencoder ST codes with equal complexity. The proposed codes are tested over fading channels with different interleaving conditions, where it is shown that the new codes are robust under such imperfect interleaving conditions.

• Journal of Advanced Navigation Technology
• /
• v.15 no.2
• /
• pp.227-233
• /
• 2011

This paper presents a small-area ISDB-T time deinterleaver structure. ISDB-T is an mobile TV standard that is widely used in Japan and many South American countries. One of the strong points of the standard is the long interleaving depth, which enhance the communication performance. However, long interleaving requires many delay buffers, in other words many pointer registers. This paper reduces the number of pointer registers with the deinterleaver equivalent transformation. The experimental results show that the area is reduced with the proposed structure.