• 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.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.618-622
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• 2009

An improvement of standard encoder has been saturated recently. However, new coding method does not have a compatibility with conventional standard. To solve this problem, new concept coding method that has a semicompatibility with standard may be discussed. On the other hand, cyclic Intra-picture coding is used for access and refreshment. However, I-picture spend large amount of bits. An enhancement of I-picture is desired with keeping its refreshment performance. Further, it's a problem that quality change at the border of GOP because of its independency. To respond these, we propose the coding which is applied an inter-frame processing at the border of GOP. Applied method is the reduction of quantization error using the motion compensated inter-picture processing. In this report, we check the improvement of the efficiency and the compatibility of proposed method. As a result of examination, we recognize that the total gain is maximally 1.2dB in PSNR. Generally, the degradation of performance in standard decoding is smaller than its gain. Also the refreshment performance is tested.

• Journal of Communications and Networks
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• v.18 no.3
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• pp.311-319
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• 2016

In this paper, we analyze the spectrum-sensing performance of a cooperative cognitive radio (CR) network consisting of a number of CR nodes and a fusion center (FC). We introduce the "log-average-SNR ratio" that relates the average SNR of the CR-node-FC link and that of the primary-user-CR-node link. Assuming that the FC utilizes the K-out-of-N rule as its decision rule, we derive exact expressions for the sensing gain and the coding gain - parameters used to characterize the CR network performance at the high SNR region. Based on these results, we determine ways to optimize the performance of the CR network.

• Journal of Broadcast Engineering
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• v.17 no.1
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• pp.95-107
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• 2012

Network coding was proposed to increase the achievable throughput of multicast in a network. Recently, combining network coding into user cooperation has attracted research attention. For cooperative transmission schemes with network coding, users combine their own and their partners messages by network coding. In previous works, it was shown that adaptive DF with network coding can achieve diversity gain and additional throughput gain. In this paper, to improve performance of conventional protocols and maximize advantage of using network coding, we propose a new network coding based user cooperation scheme which uses adaptively amplify-and-forward and decode-and-forward according to interuser channel status. We derive outage probability bound of proposed scheme and prove that it has full diversity order in the high SNR regime. Moreover, based on the outage bound, we compute optimal power allocation for the proposed scheme.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.3
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• pp.17-24
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• 2021

Recently, a lossless non-orthogonal multiple access (NOMA) implementation without successive interference cancellation (SIC) has been proposed in the literature of NOMA. This lossless non-SIC NOMA was achieved via correlated superposition coding (CSC), in contrast to conventional independent superposition coding (ISC). However, only the achievable data rates for CSC NOMA were investigated. Thus, this paper proposes a practical CSC NOMA scheme under Rayleigh fading channel environments. First, we design the practical CSC NOMA scheme, namely quadrature correlated superposition modulation (CSM) NOMA, without channel coding, i.e., uncoded systems. In addition, we calculate the symbol error rates (SERs) for this quadrature CSM NOMA scheme. Then, simulations demonstrate that for the weak channel gain's user, the SER performance of the proposed quadrature CSM NOMA is shown to be improved greatly, compared to that of the conventional quadrature amplitude modulation (QAM) NOMA, whereas for the strong channel gain's user, the SER performance of the proposed quadrature CSM NOMA degrades a little, compared to that of the conventional QAM NOMA. As a result, the proposed quadrature CSM NOMA scheme could be considered as a practical NOMA scheme for CSC NOMA schemes toward the fifth-generation (5G) and next generation communications.

• Journal of Korea Society of Digital Industry and Information Management
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• v.18 no.2
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• pp.27-37
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• 2022

In this paper, we presents a Multiple User Multiple Input Multiple Output (MU-MIMO) test-bed system for Time Division Duplex (TDD) Long Term Evolution-Advanced (LTE-A). Using two parameters, the condition number of the channel matrix and the path gain, the MU-MIMO system could switch pre-coder to maintain target Bit Error Rate (BER) level. This paper also introduces a calibration procedure for compensating error of Radio Frequency (RF) paths of the antennas and RF transceivers. From experimental measurements, dynamic pre-coding scheme could maintain target BER, set to 10^-3, with the pre-coder set configured with Zero Forcing (ZF), Tomlinson Harashima Pre-coding (THP), Lattice Reduction (LR). The simplest pre-coder ZF is adopted in stable channel, and when path gain become less than 0.25, LR is adopted. Lastly, when condition number of channel matrix become larger than 7, THP is adopted.

• Journal of Broadcast Engineering
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• v.27 no.7
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• pp.1021-1033
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• 2022

After the Versatile Video Coding (VVC)/H.266 standard was completed, the Joint Video Exploration Team (JVET) began to investigate new technologies that could significantly increase coding gain for the next generation video coding standard. One direction is to investigate signal processing based tools, while the other is to investigate Neural Network based technology. Neural Network based Video Coding (NNVC) has not been studied previously, and this is the first trial of such an approach in the standard group. After two years of research, JVET produced the first common software called Neural Compression Software (NCS) with two NN-based in-loop filtering tools at the 27th meeting and began to maintain NN-based technologies for the common experiment. The coding performances of the two filters in NCS-1.0 are shown to be 8.71% and 9.44% on average in a random access scenario, respectively. All the material related to NCS can be found in the repository of the JVET. In this paper, we provide a brief overview and review of the NNVC activity studied in JVET in order to provide trend and insight for the new direction of video coding standard.

• ETRI Journal
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• v.32 no.5
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• pp.831-834
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• 2010

This paper proposes a new joint channel coding algorithm based on principal component analysis. A conventional joint channel coder using passive downmixing undergoes a reduction of both the primary-to-ambient energy ratio (PAR) of the downmix signal and the panning gain ratio of the primary source. The proposed system preserves the PAR of the downmix signal by using active downmixing which reflects spatial characteristic. The proposed system also improves the accuracy of the panning gain ratio estimation. Computer simulations and subjective listening tests verify the performance of the proposed system.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.11
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• pp.1743-1751
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• 1989

In this paper, we consider trellis-coding techniques with the convolutional encoder R=k/(k+1) for improving the reliability of digital transimission over bandlimited noisy PRS and 49-QPRS channels. Employing the R=k/(k+1) convolutional code for the PRS channel results in over 3 dB of coding gain comparing with the baseline system. The trellis-coded 49-QPRS system can be realized by combining the 9-QPRS system with the R=1/2 convolutiona code, which can be improved by over 2dB coding gain comparing with the 9-QPRS system. In additin, we study a method of avoiding the occurance of unlimited runs of identical output to prevent operation of timing error.

• International Journal of Advanced Culture Technology
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• v.9 no.3
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• pp.283-290
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• 2021

Recently, correlated superposition coding (CSC) has been proposed to implement non-orthogonal multiple access (NOMA) without successive interference cancellation (SIC), without loss of spectral efficiency, in contrast to conventional independent superposition coding (ISC). However, correlation between signals has reduced the average total allocated power, which results in degraded performance. Thus, in order to avoid the reduction of the average total allocated power owing to correlation between signals, this paper proposes a cross-correlated quadrature amplitude modulation (QAM) NOMA scheme under Rayleigh fading channel surroundings. First, we design the cross-correlated QAM NOMA scheme. Then, simulations demonstrate that for the weaker channel gain's user, the symbol error rate (SER) performance of the proposed cross-correlated QAM NOMA improves largely, whereas for the stronger channel gain's user, the SER performance of the proposed cross-correlated QAM CSM NOMA degrades little, compared to that of the conventional QAM NOMA.