The latest High Efficiency Video Coding (HEVC) standard significantly improves coding efficiency over its previous video coding standards. The expense of such improvement is enormous computational complexity, from bot...
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The latest High Efficiency Video Coding (HEVC) standard significantly improves coding efficiency over its previous video coding standards. The expense of such improvement is enormous computational complexity, from both encoding and decoding sides. Since computational capability and power capacity are diverse across portable devices, it is necessary to reduce decodingcomplexity to a target with tolerable quality loss, so called complexity control. This paper proposes a saliency-guided complexity control (SGCC) approach for HEVC decoding, which reduces the decodingcomplexity to the target with minimal perceptual quality loss. First, we establish the SGCC formulation to minimize perceptual quality loss at the constraint on reduced decodingcomplexity, which is achieved via disabling deblocking filter (DF) and simplifying motion compensation (MC) of some non-salient coding tree units (CTUs). One important component in this formulation is the modeled relationship between decoding complexity reduction and DF disabling/MC simplification, which determines the control accuracy of our approach. Another component is the modeled relationship between quality loss and DF disabling/MC simplification, responsible for optimizing perceptual quality. By solving the SGCC formulation for a given target complexity, we can obtain the DF and MC settings of each CTU, and then decodingcomplexity can be reduced to the target. Finally, the experimental results validate the effectiveness of our SGCC approach, from the aspects of control performance, complexity-distortion performance, and fluctuation of quality loss and subjective quality.
The extended min-sum (EMS) and improved EMS (I-EMS) algorithms for non-binary low-density parity-check codes over GF(q) significantly reduce the decodingcomplexity with an acceptable performance degradation, but they...
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The extended min-sum (EMS) and improved EMS (I-EMS) algorithms for non-binary low-density parity-check codes over GF(q) significantly reduce the decodingcomplexity with an acceptable performance degradation, but they suffer from high latency because of many serial computations, including a sorting process. On the other hand, the trellis-based EMS algorithm can greatly reduce the latency, but it does not solve the complexity problem in high-order fields (q >= 64). To improve the latency problem with low-complexity advantages, the authors propose heap-based EMS (H-EMS) and heap-based I-EMS (HI-EMS) algorithms that are modifications of the EMS and I-EMS algorithms, respectively. The authors also propose double H-EMS and double HI-EMS algorithms trading off the latency against the performance by heaping messages twice. Numerical results show that the H-EMS algorithm has 2.74-9.52 times lower latency than the EMS algorithm with a negligible performance degradation over a wide range of code rates, whereas the HI-EMS algorithm has 1.20-1.62 times lower latency than the I-EMS algorithm. Furthermore, the proposed algorithms may be employed regardless of the decoding schedules.
A novel soft-decision decoding algorithm for Reed-Solomon codes over F-2m is considered. The proposed approach is based on their representation as Arikan polar codes with dynamic frozen symbols and application of the ...
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ISBN:
(纸本)9781479959990
A novel soft-decision decoding algorithm for Reed-Solomon codes over F-2m is considered. The proposed approach is based on their representation as Arikan polar codes with dynamic frozen symbols and application of the sequential successive cancellation decoding algorithm. Furthermore, permutation techniques are utilized in order to reduce the decodingcomplexity.
Low complexity modified turbo codes (MTC) offer bit error rate performance close to Shannon's limit with significantly reduced decodingcomplexity. However, since interleavers used in turbo codes interleave bit po...
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Low complexity modified turbo codes (MTC) offer bit error rate performance close to Shannon's limit with significantly reduced decodingcomplexity. However, since interleavers used in turbo codes interleave bit positions in one-dimensional (1D) array, they cannot be used for MTC which encode information bits arranged in 2D array. Moreover, MTC use several interleavers which increase the memory requirement to store permutation patterns. Objective of this study is to design two-stage interleaver for MTC with low memory requirement, large values of column spreading factor and dispersion in the interleaved pattern. Expressions have been derived for limits on maximum values of spreading factor and dispersion for 2D information array. Simulation results show superior performance of MTC with two-stage interleavers than that with random interleavers at high bit energy to noise ratio. Moreover, analysis shows that two-stage interleaver requires 50% less memory storage than random interleaver. Proposed interleaver can also be used for turbo codes in which 1D information array is being used.
Phase-shift keying (PSK) has been demonstrated as an efficient modulation format for long-haul high-bit-rate optical transmission systems. Differential encoding between successive PSK symbols is required for practical...
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Phase-shift keying (PSK) has been demonstrated as an efficient modulation format for long-haul high-bit-rate optical transmission systems. Differential encoding between successive PSK symbols is required for practical implementations in both coherent and direct detection. However, this kind of encoding increases the input bit error rate of the forward error correction (FEC) and thus affects its performance. In order to reduce the penalties induced by differential encoding, the authors, in this study, propose a structured symbol interleaving of the FEC codewords and the corresponding decoding algorithm. The authors' scheme allows obtaining a decoding complexity reduction of 50% compared to the usual decoding method and a redundancy reduction about 25% without any loss of performance.
Message passing schedules that reduce the decodingcomplexity of terminated LDPC convolutional code ensembles are analyzed. Considering the AWGN channel, various schedules are compared by means of density evolution. T...
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ISBN:
(纸本)9781457705953
Message passing schedules that reduce the decodingcomplexity of terminated LDPC convolutional code ensembles are analyzed. Considering the AWGN channel, various schedules are compared by means of density evolution. The results of the analysis together with computer simulations for some (3,6)-regular codes confirm that sliding window decoding is an attractive practical solution for low-latency and low-complexitydecoding.
Block-coded modulation (BCM) combines bandwidth-efficient modulation techniques with error-correction capabilities to allow efficient data transmission over communication channels. The disadvantage of this technique, ...
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Block-coded modulation (BCM) combines bandwidth-efficient modulation techniques with error-correction capabilities to allow efficient data transmission over communication channels. The disadvantage of this technique, however, is the complexity of the trellis used in the Viterbi decoding, process. The authors address this problem and propose a method for the reduction of decodingcomplexity. Optimal sectionalisation has been identified as an appropriate technique and it is applied to trellises of BCM schemes based on a set of new objective functions. The resulting sectionalisation algorithm has been applied to various BCM schemes including 4-PSK, 8-PSK and 16-PSK and a complexityreduction of approximately 20% is achieved. Extensive simulation las shown that both original and sectionalised trellises have the same performance: over Rayleigh, K = 6 Rician and K = 10 Rician fading channels. Furthermore, a comparison between the considered BCM schemes and ring-TCM is provided in term of code performance and decodingcomplexity.
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