In this study, the design of improved Luby transform codes with decreasing ripple size (LTC-DRS) with feedback is presented. Under the proposed design, a new degreedistributionalgorithm named generaliseddegree dist...
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In this study, the design of improved Luby transform codes with decreasing ripple size (LTC-DRS) with feedback is presented. Under the proposed design, a new degreedistributionalgorithm named generalised degree distribution algorithm (GDDA) is proposed, which can achieve arbitrary ripple size revolution accurately. On the basis of GDDA, an accurate ripple size revolution based on binomial fitting is proposed, which can keep the ripple size to a suitable value throughout the decoding process. Furthermore, the authors introduce the feedback and propose a shifted ripple size revolution to diversify the degree values. The improved LTC-DRS with feedback is evaluated and compared with the existing schemes. The simulation results demonstrate that it outperforms other existing schemes in terms of average overhead, average degree of encoded symbols, memory usage and energy consumption.
Goal-oriented Luby transform (LT) codes are required in different scenarios. Based on the random walk model, analysis of ripple size evolution provides an effective method to design LT codes. However, the ripple addit...
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Goal-oriented Luby transform (LT) codes are required in different scenarios. Based on the random walk model, analysis of ripple size evolution provides an effective method to design LT codes. However, the ripple addition in each step depends on both the number of symbols released in the current step and the ripple size in the last step, leading to distortion. Therefore, the authors propose a random walk algorithm with barrier (RWA-B) to model the ripple addition directly. To evaluate the performance of ripple size evolution, they utilise generalised degree distribution algorithm to generate corresponding degreedistribution. Through analysing the relationship between the performance of generated ripple size evolution and the parameters of RWA-B, they design an iterator greedy algorithm to search the optimal ripple size evolution for desired goals. As a result, they compare three goal-oriented degreedistributions with others through numerical simulations. In binary erasure channel, both the memory usage oriented and block error rate (BER) oriented degreedistributions outperform others with lowest average overhead, and the overhead oriented degreedistribution outperforms others in terms of average overhead and average degree. In additive white Gaussian noise channel, the BER-oriented degreedistribution outperforms others in terms of BER and average overhead.
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