• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.10
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• pp.72-79
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• 2014

This paper presents a method for constructing a pipeline-aware quasi-cyclic irregular repeat accumulate low-density parity-check (PA-QC-IRA-LDPC) codes and efficient rate-1/2 (2016, 1008) PA-QC-IRA-LDPC decoder architecture. A novel pipeline scheduling method is proposed. The proposed methods efficiently reduce the critical path using pipeline without any bit error rate (BER) degradation. The proposed pipeline-aware LDPC decoder provides a significant improvement in terms of throughput, hardware efficiency, and energy efficiency. Synthesis and layout of the proposed architecture is performed using 90-nm CMOS standard cell technology. The proposed architecture shows more than 53% improvement of area efficiency and much better energy efficiency compared to the previously reported architectures.

• Journal of Multimedia Information System
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• v.5 no.3
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• pp.163-170
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• 2018

We developed a multicast communication packet radio protocol using a time-sharing tablet system ("wireless token ring") to achieve the efficient exchange of files among packet radio terminals attached to swans. This paper provides an overview of the system and the protocol of the packet communications. The packet device forming the main part of the transceiver developed is the Texas Instruments CC2500. This device consists of one call-up channel and one data transmission channel and could improve error frame correction using FEC (forward error correction) with 34.8 kbps MSK and receiving power of at least -64 dBm (output 1 dBm at distance of 200 m using 3 dBi antenna). A time-sharing framework was determined for the wireless token ring using call sign ordinals to prevent transmission right loss. Tests using eight stations showed that resend requests with the ARQ (automatic repeat request) system are more frequent for a receiving power supply of -62 dBm or less. A wireless token ring system with fixed transmission times is more effective. This communication protocol is useful in cases in which frequency resources are limited; the energy consumed is not dependent on the transmission environment (preset transmission times); multiple terminals are concentrated in a small area; and information (position data and vital data) is shared among terminals under circumstances in which direct communication between a terminal and the center is not possible. The method allows epidemiological predictions of avian influenza infection routes based on vital data and relationships among individual birds based on the network topology recorded by individual terminals. This communication protocol is also expected to have applications in the formation of multiple in vivo micromachines or terminals that are inserted into living organisms.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.6A
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• pp.577-586
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• 2011

Modem digital communication systems are required to use forward error correction (FEC) codes to combat inevitable channel impairment. Turbo codes or low density parity check (LDPC) codes, using iterative decoding with soft decision detection (SDD) information, are the most common examples. The excellent performance of these codes should be conditioned on accurate estimation of soft decision detection information. In order to use FEC codes with iterative decoding for Multi-Input Multi-Output (MIMO) system, reliable soft decision channel gain should be provided. In this paper, we investigate efficient SDD methods for turbo-coded MIMO system, and derive the corresponding formulas of SDD for various MIMO detection schemes. We present simulation results of the derived SDD schemes for turbo-coded MIMO systems, and show that the presented results almost approximate to maximum likelihood detection performance with much less computational load.

• Journal of Broadcast Engineering
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• v.13 no.5
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• pp.719-731
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• 2008

This paper defines QoE (Quality of Experience) for multi-view video streaming service over WiBro and proposes the CLO (Cross-Layer Optimization) algorithm can maximize this. Proposal CLO algorithm contains from physical layer to video layer. Under the time-varying wireless channel condition, the CLO technique takes view-wise and the temporal priority of the multi-view video into consideration in order to decide the transmission of frames and its FEC level. At the handover situation, it is shown through computer simulation that the optimal quality of the multi-view video can be achieved using the minimum amount of resources if the proposed CLO technique is applied.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.2
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• pp.179-190
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• 1998

One of the most important topics of recent years is that a multimedia technology such as wireless ATM has been introduced in radio systems for video, voice and data transmission. A major problem in such systems is the occurrence of errors due to multipath fading or interference. To combat this problem, forward error correction (FEC) coding is commonly used as a means of eliminating these errors. This paper has analyzed theoretically the effect of fading to design effective wireless ATM system. The BER, CLR, and CER of wireless ATM system adopting FEC coding and diversity reception techniques have been derived in fading environment. Also, simulations of BER and CLR have been carried out and compared with the above theoretical results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.6A
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• pp.420-425
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• 2012

A forward error correction (FEC) coding techniques is one of time diversity techniques with which the effect of channel impairments due to noise and fading are spreaded over independently, and thus the performance could be improved. Therefore, the performance of the FEC scheme can be maximized if we minimize the correlation of channel information across over a codeword. In this paper, we propose a block turbo code with the maximized time diversity effect which may be reduced due to utilization of high order modulation schemes and due to transmission over a comparatively fast fading environment. Especially, we propose a very simple formula to calculate the address of coded bit allocation, and thus we do not need any additional outer interleavers, i.e., inter-codeword interleavers. The simulation resuts investigated in this paper reveal that the proposed scheme can provide the performance gain of more than a few decibels compared to the conventional schemes.

• ETRI Journal
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• v.32 no.2
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• pp.273-280
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• 2010

The overall channel capacity of a multihop wireless path drops progressively over each hop due to the cascading effect of noise and interference. Hence, without optimal rate adaptation, the video quality is expected to degrade significantly at any client located at a far-edge of an ad-hoc network. To overcome this limitation, decoding and forwarding (DF), which fully decodes codewords at each intermediate node, can be employed to provide the best video quality. However, complexity and memory usage for DF are significantly high. Consequently, we propose syndrome-based partial decoding (SPD). In the SPD framework an intermediate node partially decodes a codeword and relays the packet along with its syndromes if the packet is corrupted. We demonstrate the efficacy of the proposed scheme by simulations using actual 802.11b wireless traces. The trace-driven simulations show that the proposed SPD framework, which reduces the overall processing requirements of intermediate nodes, provides reasonably high goodput when compared to simple forwarding and less complexity and memory requirements when compared to DF.

• ETRI Journal
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• v.30 no.2
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• pp.261-267
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• 2008

In this paper, we propose and demonstrate a cost-effective technique to upgrade the capacity of dense wavelength division multiplexing (DWDM) networks to a 40 Gb/s line rate using the existing 10 Gb/s-based infrastructure. To accommodate 40 Gb/s over the link optimized for 10 Gb/s, we propose applying a combination of super-FEC, carrier-suppressed return-to-zero, and pre-emphasis to the 40 Gb/s transponder. The transmission of 40 Gb/s DWDM channels over existing 10 Gb/s line-rate long-haul DWDM links, including $40{\times}40$ Gb/s transmission over KT's standard single-mode fiber optimized for 10 Gb/s achieves successful results. The proposed upgrading technique allows the Q-value margin for a 40 Gb/s line rate to be compatible with that of 10 Gb/s.

• Journal of Satellite, Information and Communications
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• v.10 no.3
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• pp.73-77
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• 2015

In this paper, we present two simulation methods to investigate the effect of excluding bit errors on generating the extrinsic information transfer (EXIT) chart for low density parity check (LDPC) and turbo codes. We utilized the simulation methods including and excluding bit errors to generate EXIT chart which was originally proposed for turbo codes. The generated EXIT charts for LDPC and turbo codes shows that the presented methods appropriately demonstrates the performance behaviours of iterative decoding for LDPC and turbo codes. Analysis on the simulation results demonstrates that the EXIT chart excluding the bit errors shows only a small part of the curves where the amount of information is too large.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.72-74
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• 2005

전력선통신은 현재 홈 네트워크 및 검침기술과 같은 다양한 분야에서 활발하게 응용이 되고 있는 기술이다. 이러한 전력선 통신을 위한 전송선로는 통신을 위한 정보데이터를 전송하는 기능과 더불어 선로상의 전력 부하들을 위한 전력 공급용으로서의 용도도 가지고 있다. 그러므로 선로상의 부하변동은 다양한 형태의 임 펄스 잡음을 야기 시키고 이러한 임펄스성 잡음은 전송 데이터에 군집에러를 발생시킴으로써 통신성능을 크게 열화 시키는 요인이 되고 있다. 따라서 효율적인 전력선 통신시스템을 위해서는 전력 선로상의 임펄스 잡음의 특성을 명확히 분석하고, 그에 따른 에러제거기법을 적용하는 것이 필수적이라고 할 수 있다. 이러한 관점에서 본 논문에서는 새롭게 가정의 전력 선로에 연결되는 부하들의 동작 및 변동에 따른 임펄스 잡음 특성을 다양한 부하의 유형별로 디지털 하드웨어를 이용하여 실측 및 분류한 후, 새롭게 도출한 임펄스 잡음 모델을 기반으로 순방향 오류정정방식(FEC;Forward Error Correction)인 컨벌루션 부호화(Convolution Coding) 및 인터리빙(Interleaving) 방식을 가미하여 시스템의 비트오율 개선효과를 확인하였다. 본 논문에서 수행된 새로운 실측기반의 임펄스 잡음이 반영된 채널부호화 방식에 의한 성능평가 결과는 향후 홈네트워크기반의 전력선 통신시스템의 실질적인 참고데이터로서 유용하게 활용되리라 기대된다.