• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.5
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• pp.62-73
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• 2010

In this paper we proposed a candidate algorithm on G.711.1 and G.722 superwideband extension codec which is under standardization by ITU-T. The proposed codec not only provides an interoperable bitstream with ITU-T G.711.1 and G.722, but also encodes a superwideband signal with a bandwidth of 50-14,000 Hz using superwideband extension layer. The candidate codec consists of a core layer to provide an interoperability with conventional wideband codecs and superwideband extension layer using linear prediction-based sinusoidal coding. The proposed extension codec operates on 5ms frame and provides four superwideband bitrates of 64, 80, 96, and 112 kbit/s depending on the core codec. Since the resulting bitstream has an embedded structure, it can be converted into core bitstream by simple truncation without transcoding. The proposed codec has a short algorithmic delay and low complexity and passed the qualification test of G.711.1 and G.722 superwideband extension codec performed by ITU-T.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.40 no.5
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• pp.397-409
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• 2003

This paper describes an implementation of radix-4 trellis parallel architecture and backward state transition control trace back Viterbi decoder, and presents the application results to high speed wireless LAN. The radix-4 parallelized architecture Vietrbi decoder can not only improve the throughput with simple structure, but also have small processing delay time and overhead circuit compared to M-step trellis architecture one. Based on these features, this paper addresses a novel Viterbi decoder which is composed of branch metric computation, architecture of ACS and trace back decoding by sequential control of backward state transition for the implementation of radix-4 trellis parallelized structure. With the proposed architecture, the decoding of variable code rate due to puncturing the base code can easily be implemented by the unified Viterbi decoder. Moreover, any additional circuit and/or peripheral control logic are not required in the proposed decoder architecture. The trace back decoding scheme with backward state transition control can carry out the sequential decoding according to ACS cycle clock without additional circuit for survivor memory control. In order to evaluate the usefulness, the proposed method is applied to channel CODEC of the IEEE 802.11a high speed wireless LAN, and HDL coding simulation results are presented.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.4
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• pp.6-14
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• 2011

The fast growing of the number of users requires the development of reliable communication systems able to provide higher data rates. In order to meet those requirements, techniques such as Multiple Input Multiple Out (MIMO) and Orthogonal Frequency Division multiplexing (OFDM) have been developed in the recent years. In order to combine the benefits of both techniques, the research activity is currently focused on MIMO-OFDM systems. In addition, for a fast wireless channel environment, the data rate and reliability can be optimized by setting the modulation and coding adaptively according to the channel conditions; and using sub-carrier frequency, and power allocation techniques. Depending on how accurate the feedback-based system obtain the channel state information (CSI) and feed it back to the transmitter without delay, the overall system performance would be poor or optimal. In this paper, we propose a Signal to Noise Ratio (SNR) estimation algorithm where the preamble is known for both sides of the transciever. Through simulations made over several channel environments, we prove that our proposed SNR estimation algorithm is more accurate compared with the traditional SNR estimation. Also, We applied AMC on several channel environments using the parameters of IEEE 802.11n, and compared the Throughput performance when using each of the different SNR Estimation Algorithms. The results obtained in the simulation confirm that the proposed algorithm produces the highest Throughput performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.10B
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• pp.939-945
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• 2008

Tn this paper we described the process and the results of an implementation of Internet terminal using G.729.1 wideband speech codec for next generation network. For this purpose firstly we chose a high performance RISC application processor having DSP features for speech codec processing and enhanced Multimedia Accelerator(eMMA) function for video codec. In the implementation of this terminal, we used G.729.1 codec recently standardized in ITU-T which is a new scalable speech and audio codec that extends 0.729 speech coding standard. To adopt G.729.1 codec to this terminal we transformed most of the fixed point C codes which require more complexity into assembly codes so as to minimize processing time in the processor. As a result of this work we reduced the execution time of the original C codes about 80% and operated in real time on the terminal. For video we used H.263/MPEG-4 codec which is supported by the eMMA with hardware in the processor. In the SIP call processing test connected to real network we obtained under looms end-to-end delay and 3.8 MOS value measured with PESQ instrument. Besides this terminal operated well with commercial terminals.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.11A
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• pp.1908-1924
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• 2001

Interoperability and inter-working in the various network and media environment with different technology background is very important to enlarge the opportunity of service access and to increase the competitive power of service. The ITU-T and advanced counties are planning ahead for provision of GII enabling user to access advanced global communication services supporting multimedia communication applications, embracing all modes of information. In this paper, we especially forced the heterogeneity of end user applications for multimedia networking. The heterogeneity has several technical aspects, like different medium access methods, heterogeneous coding algorithms for audio-visual data and so on. Among these elements, we have been itemized bit rate shaping algorithm on the compressed moving video. Previous manipulations of video has been done on the uncompressed signal domain. That is, compressed video should be converted to linear PCM signal. To do such a procedures, we should decode, manipulate and then encode the video to compressed signal once again. The traditional approach for processing the video signa1 has several critical weak points, requiring complexity to implement, degradation of image quality and large processing delay. The bit rate shaping algorithm proposed in this paper process the manipulation of moving video on the completely compressed domain to cope with above deficit. With this algorithms. we could realized efficient video bit rate shaping and the result of software simulation shows that this method has significant advantage than that of pixel oriented algorithms.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.10C
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• pp.1387-1394
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• 2004

Turbo code, a kind of error correction coding technique, has been used in the field of digital mobile communication systems. And it is well known about the fact that turbo code has better the BER performance as the number of decoding iterations increases in the AWGN channel environment. However, as the number of decoding iterations is increased under the several channel environments, any further iteration results in very little improvement, and it requires much delay, computation and power consumption in proportion to the number of decoding iterations. In this paper, it proposes the efficient iterative decoding stop criterion algorithm which can largely reduce the average number of decoding iterations of turbo code. Through simulations, it is verifying that the proposed algorithm can efficiently stop the iterative decoding by using the variance value of error probability for the soft output value, and can largely reduce the average number of decoding iterations without BER performance degradation. As a result of simulation, the average number of decoding iterations for the proposed algorithm is reduced by about 2.25% ~14.31％ and 3.79％ ~14.38% respectively compared to conventional schemes, and power consumption is saved in proportion to the number of decoding iterations.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.10
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• pp.1845-1852
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• 2008

The key elements of inter prediction are motion estimation(ME) and motion compensation(MC). Motion estimation is to find the optimum motion vectors, not only by using a distance criteria like the SAD, but also by taking into account the resulting number of 비트s in the 비트 stream. Motion compensation is compensate for movement of blocks of current frame. Inter-prediction Encoding is always the main bottleneck in high-quality streaming applications. Therefore, in real-time streaming applications, dedicated hardware for executing Inter-prediction is required. In this paper, we studied a motion estimator(ME) for H.264/AVC. The designed motion estimator is based on 2-D systolic array and it connects processing elements for fast SAD(Sum of Absolute Difference) calculation in parallel. By providing different path for the upper and lower lesion of each reference data and adjusting the input sequence, consecutive calculation for motion estimation is executed without pipeline stall. With data reuse technique, it reduces memory access, and there is no extra delay for finding optimal partitions and motion vectors. The motion estimator supports variable-block size and takes 328 cycles for macro-block calculation. The proposed architecture is local memory-free different from paper [6] using local memory. This motion estimation encoder can be applicable to real-time video processing.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.17 no.3
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• pp.92-95
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• 2017

Fabry disease (FD) is an X-linked lysosomal storage disorder caused by an ${\alpha}$-galactosidase A (GLA, MIM 300644) enzyme deficiency due to pathogenic variants in the ${\alpha}$-galactosidase A gene (GLA). The disease leads to accumulation of globotriaosylceramide (Gb3) and related glycophospholipids affecting nearly all major organ systems, with the primary sites damaged by Gb3 including renal glomeruli, myocardium, neurons of the dorsal ganglion and autonomic nervous system, and vascular endothelial and smooth muscle. Progressive deposition in these organ systems present with various clinical manifestations including acroparesthesia, renal failure and heart failure. Here, we report a Chinese male diagnosed with Fabry disease in his late $4^{th}$ decades showing improvement of acroparesthesia during enzyme replacement therapy (ERT). A 48-year-old Chinese man who presented with chronic recurrent severe burning pain in his fingers and toes since the age of 10, with worse involvement of the former visited to our clinic for further evaluation. His medical history included a transient ischemic attack aged 40 and diagnosed with stage 4-5 chronic kidney disease aged 47. In the family history, the patient's brother was found to be have Fabry disease 1 month before his visit. Except for his brother, all other members of the family are healthy. Based on his medical history and family history, he was strongly suspicious for Fabry disease. He was found to have a galactose-alpha-1,3-galactose level 4.96 (Reference range, 42.5-67.9) suggestive of Fabry disease. The followed sequencing of GLA coding region in our patient revealed hemizyosity for the mutation c.988C>T (Q330X) in Exon 7. Since ERT start, he showed significant improvement in his symptoms of burning sensation of fingers and toes. On the contrary, due to deteriorating kidney function even with ERT, he is considered for kidney transplantation. Despite of diagnostic delay until late 4th decades, ERT showed a potential improvement of acroparesthesia in our patient. However, late start of ERT can lead to poor outcome in multiorgan function. Therefore, early diagnosis with high index of suspicion followed by continuous ERT with regular monitoring have an impact on quality of life in Fabry disease.