• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.2C
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• pp.219-228
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• 2010

In this paper, performance of RS (Reed-Solomon), turbo and LDPC (low density parity check) code in the binary symmetric erasure channel is investigated. When the average erasure length is reduced, the frequency of short erasures is increased. The RS code shows serious performance degradation in such an environment since decoding is carried out symbol-by-symbol. As the erasure length is increased, however, the RS code shows much improved en-or performance. On the other hand, the message and corresponding parity symbols of the turbo code can be erased at the same time for the long erasures. Accordingly, iterative decoding of the turbo code can not improve error performance any more for such a long erasure. The LDPC code shows little difference in error performance with respect to the variation of the average erasure length due to the virtual interleaving effect. As a result, the LDPC code has much better erasure decoding performance than the RS and turbo code.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.11A
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• pp.1045-1050
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• 2010

This paper proposes a new $2{\times}2$ spatial-multiplexing(SM) scheme which is constructed by serially concatenating an orthogonal precoder with a conventional SM. Compared to the conventional SM, the proposed scheme achieves improved performance under erasure fading channels without any performance loss under non-erasure fading channels. Particularly the performance gain is more larger as a correlation value between two receive antennas increases.

• ETRI Journal
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• v.31 no.5
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• pp.518-524
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• 2009

Single parity check (SPC) product codes are simple yet powerful codes that are used to correct errors and/or recover erasures. The focus of this paper is to evaluate the performance of such codes under erasure scenarios and to develop a closed-form tight upper bound for the post-decoding erasure rate. Closed-form exact expressions are derived for up to seven erasures. Previously published closed-form bounds assumed that all unrecoverable patterns should contain four erasures in a square. Additional non-square patterns are accounted for in the proposed expressions. The derived expressions are verified using exhaustive search. Eight or more erasures are accounted for by using a bound. The developed expressions improve the evaluation of the recoverability of SPC product codes without the need for simulation or search algorithms, whether exhaustive or novel.

• Journal of the Korean Institute of Telematics and Electronics
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• v.23 no.5
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• pp.719-725
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• 1986

Reed-solomon(R-S) code is very effective to coerrect both random and burst errors over a noise communication channel. However, the required hardware is very complex if the B/M algorithm was employed. Moreover, when the error correction system consists of two R-S decoder and de-interleave, the I/O data bns lines becomes 9bits because of an erasure flag bit. Thus, it increases the complexity of hardware. This paper describes the R-S decoder which consisits of a error correction section that uses a direct decoding algorithm and erasure generation section and a erasure generation section which does not use the erasure flag bit. It can be shown that the proposed R-S dicoder is very effective in reducing the size of required hardware for error correction.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.12
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• pp.27-35
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• 2012

In this paper, we look into a Jong Nang Channel which is the origin of digital communications and has been used in Jeju Island since AD 1234. It is one kind of communication ways which informs people of whether a house owner is in one's house or not using its own protocol. It is comprised of three timber and two stone pillars whose one side has three holes respectively. In this paper, we analyze the Jong-Nang Channel both in the light of logic and bit error probability. In addition, we compare it with a conventional binary erasure channel when some errors occur over them respectively. We also show that a capacity of NOR channel approaches Shannon limit.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.8
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• pp.1492-1499
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• 2015

In this paper, we propose a clipping method for LDPC coded FH BFSK system over partial-band jamming channel. We apply the erasure insertion technique, which had been studied much earlier, now to LDPC codes and discuss its performance degradation region. By using clipping technique, the performance degradation can be removed. Finally, we discuss the erasure insertion and clipping techniques for various jamming conditions.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.1
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• pp.62-77
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• 2010

Emerging applications with high data rates will need to transport bulk data reliably in wireless sensor networks. ARQ (Automatic Repeat request) or Forward Error Correction (FEC) code schemes can be used to provide reliable transmission in a sensor network. However, the naive ARQ approach drops the whole frame, even though there is a bit error in the frame and the FEC at the bit level scheme may require a highly complex method to adjust the amount of FEC redundancy. We propose a bulk data transmission scheme based on erasure-resilient code in this paper to overcome these inefficiencies. The sender fragments bulk data into many small blocks, encodes the blocks with LT codes and packages several such blocks into a frame. The receiver only drops the corrupted blocks (compared to the entire frame) and the original data can be reconstructed if sufficient error-free blocks are received. An incidental benefit is that the frame error rate (FER) becomes irrelevant to frame size (error recovery). A frame can therefore be sufficiently large to provide high utilization of the wireless channel bandwidth without sacrificing the effectiveness of error recovery. The scheme has been implemented as a new data link layer in TinyOS, and evaluated through experiments in a testbed of Zigbex motes. Results show single hop transmission throughput can be improved by at least 20% under typical wireless channel conditions. It also reduces the transmission time of a reasonable range of size files by more than 30%, compared to a frame ARQ scheme. The total number of bytes sent by all nodes in the multi-hop communication is reduced by more than 60% compared to the frame ARQ scheme.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.5
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• pp.91-103
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• 2015

This paper presents "The 3-User NOR switching channel based on interference decoding with receiver cooperation" in succession to "Jeju Jong Nang channel code I, II". The Jeju Jong Nang code is considered as one of the earliest human binary coded communication (HBCC) in the world with a definite "1" or "0" binary symbolic analysis of switching circuits. In this paper, we introduce a practical example of interference decoding with receiver cooperation based on the three user Jong Nang NOR switching channel. The proposed system models are the three user Jong Nang (TUJN) NOR logic switching on-off, three-user injective deterministic NOR switching channel and Gaussian interference channel (GIC) with receiver cooperation. Therefore, this model is well matched to Shannon binary symmetric and erasure channel capacity. We show the applications of three-user Gaussian interference decoding to obtain deterministic channels which means each receiver cooperation helps to adjacent others in order to increase degree of freedom. Thus, the optimal sum rate of interference mitigation through adjacent receiver cooperation achieves 7 bits.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.11A
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• pp.1073-1077
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• 2010

This paper proposes a new 4-dimensional(4D) constellation-rotation(CR) method which obtains diversity gain of 4 under Rayleigh fading channels. The proposed scheme uses two consecutive CR operations for the constellation of QAM signals unlike a conventional 2-dimensional(2D) CR method using only one CR operation. The computer simulation results show that the new method outperforms the conventional one even more as both the channel code rate and the erasure ratio increase. In a point of system flexibility, the proposed scheme has a great advantage since the conventional 2D CR scheme can be simply implemented by only changing rotation angle values used in the proposed scheme.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.7-10
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• 2000

본 논문은 이동통신상에서 송신측의 송신 채널 에러정보를 수신측에서 송신측으로 전달하는 음성패킷을 이용하여 송신측에 알려주어 압축과정에 이용하게 할 수 있는 방법을 제안한다. ACELP(Algebraic CELP)구조 방식을 가지고 있는 음성압축기들 중 G.729을 사용하며 음성 패킷정보 중 Pitch Delay와 Fixed Codebook를 이용하여 전송음성 패킷안에 상대방의 송신 채널정보를 싣는다. 수신측에서 받은 패킷이 Erasure로 판단되었을 때 패킷정보들 중 Fixed Codebook Index를 만들게 되는 4개의 Optimal 펄스 중 2개의 펄스만 사용하며 나머지 2개의 펄스는 약속된 임의의 위치에 위치시킨 후 송신측에 전송시킨다. 상대방에서 약속에 맞는 위치의 펄스를 보내왔을 때를 체크함으로써 자신의 송신채널 상태를 알 수 있게 된다 송신채널에$5\%$ Erasure 채널 에러가 발생했을 때 채널정보를 가진 패킷의 음질은 약 0.1dB 정도 떨어지게 된다. 하지만 음성압축 전송 시 송신채널의 정보를 이용하여 무선채널에러에 강하게 할 수 있다.