• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.20 no.5
• /
• pp.421-427
• /
• 2009

This paper has proposed 1-2-1 coded cooperative communication that is a combination of STBC and ARQ. Coded cooperative communication is a protocol that integrates channel coding with cooperative communication. In this paper consider convolution encoder. ARQ method can increase the spectral efficiency than conventional cooperative communication because if the received signal from source node is satisfied by the destination preferentially, the destination transmits ACK message to both relay node and source node and then recovers the received signal. Where each relay 1, 2 forwards a punctured portion of receive data. When relay transmit to destination apply STBC the reliability to increase. Moreover this protocol can get better BER performance of receiver using simple comparator. We verified BER performance for the proposed protocol through Monte-Carlo simulation over Rayleigh fading plus AWGN.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.5 no.7
• /
• pp.1293-1310
• /
• 2011

A simple modification of well known Low Energy Adaptive Clustering Hierarchy (LEACH) protocol is proposed to exploit cooperative diversity. Instead of selecting a single cluster-head, we propose M cluster-heads in each cluster to obtain a diversity of order M. The cluster-heads gather data from all the sensor nodes within the cluster using same technique as LEACH. Cluster-heads transmit gathered data cooperatively towards the destination or higher order cluster-head. We propose a code combining based cooperative diversity protocol which is similar to coded cooperation that maximizes the performance of the proposed cooperative LEACH protocol. The implementation of the proposed cooperative strategy is analyzed. We develop the upper bounds on bit error rate (BER) and frame error rate (FER) for our proposal. Space time block codes (STBC) are also a suitable candidate for our proposal. In this paper, we argue that the STBC performs worse than the code combining cooperation.

• Journal of Communications and Networks
• /
• v.8 no.3
• /
• pp.306-312
• /
• 2006

This paper studies theoretically the bit error rate (BER) performance of cooperative transmission using space-time block code (STBC) in a fully distributed manner. Specifically, we first propose a STBC-based cooperative signaling structure to make the cooperation of three single-antenna terminals possible. Then, we derive the closed-form BER expressions for both cooperation and noncooperation schemes under flat Rayleigh fading channel plus additive white Gaussian noise (AWGN). The validity of these expressions is verified by Monte-Carlo simulations. A variety of numerical and simulation results reveal that the cooperative transmission achieves higher diversity gain and better performance than the direct transmission for the same total transmit power.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.1
• /
• pp.141-150
• /
• 2010

In this paper, performance of a turbo-coded OFDM system is analyzed and simulated in a power line communication channel. Since the power line communication system typically operates in a hostile environment, turbo code has been employed to enhance reliability of transmitted data. The performance is evaluated in terms of bit error probability. As turbo decoding algorithms, MAP (maximum a posteriori), Max-Log-MAP, and SOVA (soft decision viterbi output) algorithms are chosen and their performances are compared. From simulation results, it is demonstrated that Max-Log-MAP algorithm is promising in terms of performance and complexity. It is shown that performance is improved 3dB by increasing the number of iterations, 2 to 8, and interleaver length of a turbo encoder, 100 to 5000. The results in this paper can be applied to OFDM-based high-speed power line communication systems.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.11
• /
• pp.7582-7588
• /
• 2015

Noncoherent receivers are favored for block-code-modulated ultrawideband impulse radio (UWB-IR) systems because of their low implementation complexity compared with coherent rake receivers. However, existing noncoherent schemes, such as transmitted reference (TR) systems and averaged differential receivers (ADR), suffer from performance degradation and energy efficiency loss. Codeword matching and signal aggregation (CMSA) is a low complexity noncoherent receiver for UWB-IR. As the frame/symbol duration is shortened to boost data rate, interframe interference (IFI) or intersymbol interference (ISI) occurs and degrades the detection performance of CMSA. In this paper, block coded correlator which consists of the delay components and the reference signal is proposed to improve the performance of the receiver. Simulation results show that the proposed system leads to the better performance compared to the conventional CMSA receiver.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.7 no.2
• /
• pp.206-212
• /
• 2006

Many image and video compression algorithms work by splitting the input image into blocks and producing variable-length coded bits for each block data. If variable-length coded data are transmitted consecutively, then the resulting coder is highly sensitive to channel errors. Therefore, most image and video techniques for providing some protection to the stream against channel errors usually involve adding a controlled amount of redundancy back into the stream. Such redundancy might take the form of resynchronization markers, which enable the decoder to restart the decoding process from the known state, in the event of transmission errors. The Error Resilient Entropy Code (EREC) is a well known method which can regain synchronization without any redundant information to convert from variable-length code to fixed-length code. This paper proposes an enhancement to EREC, which greatly improves its transmission ability for the compressed image quality without any redundant bits in the event of errors. The simulation result shows that the both objective and subjective quality of transmitted image is enhanced compared with the existing EREC at the same BER(Bit Error Rate).

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.46 no.2
• /
• pp.38-45
• /
• 2009

In this paper, we propose an efficient cooperative diversity technique, which partition the codewords of each mobile and transmit portions of each codeword through independent fading channels using duo-binary turbo codes. A coded diversity technique can achieve high cooperative diversity gain by decoding and transmitting of the re-encoded signal, while this can also cause high performance degradation due to failure of the decoding. In this paper, we introduce various coded diversity technique using duo-binary turbo codes which are defined as channel coding schemes in the IEEE WiMax specification, and also demonstrate performance simulation results with the analysis. We also propose a cooperative diversity technique using rate-compatible duo-binary turbo codes, where user terminals with different parity symbols cooperate each other. Simulation results investigated in this paper reveal that the proposed scheme show high diversity gain at a reasonal SNR range.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.2
• /
• pp.835-839
• /
• 2013

In this paper, We operate at a relatively low BER or using forward error control coding techniques on ways to increase the capacity of optical communication systems research. Coding gain is defined as the ratio of the probability of the coded signal and coding of error signal. Coding gain is increased, partly because of the period, to reduce the value of the optimal coding of the signal error probability decreases because of the effective bit binary symbol duration is longer than can be ignored. Transmission capacity on the coding gain for various code rates, which show the extent of up to 75Gb/s transmission capacity to get through it was confirmed that these coding techniques.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.10
• /
• pp.2766-2770
• /
• 2009

Recently, the Green IT is noticed because of the effects of greenhouse gas emissions, a drain on natural resources and pollution. In this paper, Visible Light Communication (VLC) systems with Turbo Coded scheme using LED is proposed and simulated in an optical wireless channel. As a forward error correction scheme to reduce information losses, turbo coding was employed. To decode the codewords, The Map (Maximum a Posteriori) algorism and SOVA (Soft Output Viterbi Algorithm) is used. The above mentioned schemes are described and simulation results are analyzed. As using turbo codes scheme, BER performance of proposed VLC systems is improved about 5 [dB].

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.4
• /
• pp.736-739
• /
• 2009

In this paper, an efficient lossless compression algorithm using motion adaptation is proposed. It is divided into two parts: a motion adaptation based nonlinear predictor part and a residual data coding part. The proposed nonlinear predictor can reduce prediction error by learning from its past prediction errors using motion adaption. The predictor decides the proper selection of the intra and inter prediction values according to the past prediction error. The reduced error is coded by existing context adaptive coding method. Experimental results show that the proposed algorithm has the higher compression ratio than context modeling methods, such as FELICS, CALIC, and JPEG-LS.