• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.10A
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• pp.997-1005
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• 2008

In this paper, we propose an efficient space-time block coding (STBC) scheme in a cooperative satellite-terrestrial system. The proposed STBC scheme has code rate 1 for a 3 transmit antenna scheme. Because the channel matrix of the proposed scheme is orthogonal, we can use a simple linear decoding algorithm and also can expect improved performance over the conventional scheme. The simulation results demonstrate that the proposed scheme has improved performance for bit error rates (BER) than several conventional STBC schemes. In addition, we investigate performance simulation results by power imbalance between the terrestrial repeaters and satellite.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.1C
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• pp.18-24
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• 2005

In this paper, a new trellis-coded differential unitary space-time modulation (TC-DUSTM) scheme based on amplitude/phase-shift-keying (APSK) signals is proposed. In particular, the design criterion of the trellis coding is proposed to combine the trellis coding and DUSTM scheme based on APSK constellation. From the computer simulations, we verify the superiority of the proposed TC-DUSTM based on APSK signals at the higher transmission rate. In addition, the proposed scheme can suppress the irreducible error of the differential scheme.

• International Journal of Contents
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• v.16 no.4
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• pp.68-77
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• 2020

VR (Virtual Reality) contents make the audience perceive virtual space as real through the virtual Z axis which creates a space that could not be created in 2D due to the space between the eyes of the audience. This visual change has led to the need for technological changes to sound and sound sources inserted into VR contents. However, studies to increase immersion in VR contents are still more focused on scientific and visual fields. This is because composing and producing VR sounds require professional views in two areas: sound-based engineering and computer-based interactive sound engineering. Sound-based engineering is difficult to reflect changes in user interaction or time and space by directing the sound effects, script sound, and background music according to the storyboard organized by the director. However, it has the advantage of producing the sound effects, script sound, and background music in one track and not having to go through the coding phase. Computer-based interactive sound engineering, on the other hand, is produced in different files, including the sound effects, script sound, and background music. It can increase immersion by reflecting user interaction or time and space, but it can also suffer from noise cancelling and sound collisions. Therefore in this study, the following methods were devised and utilized to produce sound for VR contents called "A Midsummer Night" so as to take advantage of each sound-making technology. First, the storyboard is analyzed according to the user's interaction. It is to analyze sound effects, script sound, and background music which is required according to user interaction. Second, the sounds are classified and analyzed as 'simultaneous sound' and 'individual sound'. Thirdly, work on interaction coding for sound effects, script sound, and background music that were produced from the simultaneous sound and individual time sound categories is done. Then, the contents are completed by applying the sound to the video. By going through the process, sound quality inhibitors such as noise cancelling can be removed while allowing sound production that fits to user interaction and time and space.

• KIISE Transactions on Computing Practices
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• v.23 no.10
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• pp.594-598
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• 2017

Tremendous quantities of numerical data are generated every day from various sources, including the stock market. Universal codes such as Elias gamma coding, Elias delta coding and Fibonacci coding are generally used to store arrays of integers. Studies have been conducted to support fast access to specific elements in an integer array, while occupying less space. We suggest an improved code system that utilizes the concepts of succinct data structures. This system is based on a data structure that allows compressing a delimiter bit array while supporting queries in constant time. The results of an experiment show that the encoded array uses lower space, while not sacrificing time efficiency.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.6
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• pp.141-148
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• 2009

Space-time block codes (STBC) have no coding gain but they provide a full diversity gain with relatively low encoder/decoder complexity. Therefore, STBC should be concatenated with an outer code which provides an additional coding gain. In this paper, we consider the concatenation of multiple trellis-coded modulation (MTCM) codes with STBC for achieving significant coding gain with full antenna diversity. Using criteria of equal transmit power, spectral efficiency and the number of trellis states, the performance of concatenated scheme is compared to that of previously known space-time trellis codes (STTC) in terms of frame error rate (FER). Simulation results show that MTCM codes concatenated with STBC offer better performance on fast Rayleigh fading channels, than previously known STTC with two transmit antennas and one receive antenna.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.9C
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• pp.843-850
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• 2003

Turbo coding and turbo processing have been known as methods close to Shannon limit in the aspect of wireless MIMO communications similarly to wireless single antenna communication. The iterative processing can maximize the mutual effect of coding and interference cancellation, but turbo coding has not been used for turbo processing because of the inherent decoding process delay. This paper proposes a turbo coded MIMO system with adaptive turbo parallel space-time (Turbo-PAST) processing for high-speed wireless communications and a enhanced cyclic redundancy check (E-CRC) scheme as an efficient and simple priori stopping criterion. Simulation results show that the Turbo-PAST outperforms conventional system with 1.3dB and the proposed E-CRC scheme effectively reduces the amount of turbo processing iterations from the point of average number of iterations.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.10
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• pp.4957-4976
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• 2016

This paper investigates the error performance of the amplify-and-forward (AF) relaying systems in the context of full-duplex (FD) communication. In addition to the inherent self-interference (SI) due to simultaneous transmission and reception, coexistent FD terminals may cause crosstalk. In this paper, we utilize the information exchange via the crosstalk channel to construct a particular distributed space-time code (DSTC). The residual SI is also considered. Closed-form pairwise error probability (PEP) is first derived. Then we obtain the upper bound of PEP in high transmit power region to provide more insights of diversity and coding gain. The proposed DSTC scheme can attain full cooperative diversity if the variance of SI is not a function of the transmit power. The coding gain can be improved by lengthening the frame and proper power control. Feasibility and efficiency of the proposed DSTC are verified in numerical simulations.

• ETRI Journal
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• v.26 no.6
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• pp.565-574
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• 2004

Differential unitary space-time modulation (DUSTM) has emerged as a promising technique to obtain spatial diversity without intractable channel estimation. This paper presents a study of the application of DUSTM on multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems with frequency-selective fading channels. From the view of a correlation analysis between subcarriers of OFDM, we obtain the maximum achievable diversity of DUSTM on MIMO-OFDM systems. Moreover, an efficient implementation strategy based on subcarrier reconstruction is proposed, which transmits all the signals of one signal matrix in one OFDM transmission and performs differential processing between two adjacent OFDM blocks. The proposed method is capable of obtaining both spatial and multipath diversity while reducing the effect of time variation of channels to a minimum. The performance improvement is confirmed by simulation results.

• Journal of Navigation and Port Research
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• v.38 no.4
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• pp.349-356
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• 2014

In the underwater communication, the performance of system is reduced because of the inter-symbol interference occur by the multi-path. In the recent years, to deal with poor channel environment and improve the throughput, the efficient concatenated structure of equalization, channel codes and Space Time Codes has been studied as MIMO system in the underwater communication. Space Time Codes include Space Time Block Codes and Space Time Trellis Codes in underwater communication. Space Time Trellis Codes are optimum for equalization and channel codes among the Space Time Codes to apply in the MIMO environment. Therefore, in this paper, turbo pi codes are used for the outer code to efficiently transmit in the multi-path channel environment. The inner codes consist of Space Time Trellis Codes with transmission diversity and coding gain in the MIMO system. And Zero Forcing method is used to remove inter-symbol interference. Finally, the performance of this model is simulated in the underwater channel.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.6
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• pp.669-676
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• 2008

The adaptive resource optimization problem in multi-input multi-output orthogonal frequency division multiple access (MIMO-OFDMA) systems is addressed. This paper, adaptive modulation and coding(AMC) and power control algorithms is proposed with SFC(Space-Frequency Coding), which aims to maximize the system capacity based on the CQI(Channel Quality Information). Firstly, power level is decided to each sub-channels with received feedback signal to noise ratio(SNR). In the second step, sub-carriers are allocated according to modulation type. Simulation results show that the proposed algorithm achieves a better performance than conventional algorithm in terms of capacity.