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  1 - Language Model Adaptation Using Dirichlet Class Language Model Based on Part-of-Speech
  Ali Hatami Ahmad akbari Babak Nasersharif
  10.7508/jist.2014.01.005
  Language modeling has many applications in a large variety of domains. Performance of this model depends on its adaptation to a particular style of data. Accordingly, adaptation methods endeavour to apply syntactic and semantic characteristics of the language for langua More

  Language modeling has many applications in a large variety of domains. Performance of this model depends on its adaptation to a particular style of data. Accordingly, adaptation methods endeavour to apply syntactic and semantic characteristics of the language for language modeling. The previous adaptation methods such as family of Dirichlet class language model (DCLM) extract class of history words. These methods due to lake of syntactic information are not suitable for high morphology languages such as Farsi. In this paper, we present an idea for using syntactic information such as part-of-speech (POS) in DCLM for combining with one of the language models of n-gram family. In our work, word clustering is based on POS of previous words and history words in DCLM. The performance of language models are evaluated on BijanKhan corpus using a hidden Markov model based ASR system. The results show that use of POS information along with history words and class of history words improves performance of language model, and decreases the perplexity on our corpus. Exploiting POS information along with DCLM, the word error rate of the ASR system decreases by 1.2% compared to DCLM. Manuscript profile
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  2 - SSIM-Based Fuzzy Video Rate Controller for Variable Bit Rate Applications of Scalable HEVC
  Farhad Raufmehr Mehdi Rezaei
  10.7508/jist.2019.03.004
  Scalable High Efficiency Video Coding (SHVC) is the scalable extension of the latest video coding standard H.265/HEVC. Video rate control algorithm is out of the scope of video coding standards. Appropriate rate control algorithms are designed for various applications t More

  Scalable High Efficiency Video Coding (SHVC) is the scalable extension of the latest video coding standard H.265/HEVC. Video rate control algorithm is out of the scope of video coding standards. Appropriate rate control algorithms are designed for various applications to overcome practical constraints such as bandwidth and buffering constraints. In most of the scalable video applications, such as video on demand (VoD) and broadcasting applications, encoded bitstreams with variable bit rates are preferred to bitstreams with constant bit rates. In variable bit rate (VBR) applications, the tolerable delay is relatively high. Therefore, we utilize a larger buffer to allow more variations in bitrate to provide smooth and high visual quality of output video. In this paper, we propose a fuzzy video rate controller appropriate for VBR applications of SHVC. A fuzzy controller is used for each layer of scalable video to minimize the fluctuation of QP at the frame level while the buffering constraint is obeyed for any number of layers received by a decoder. The proposed rate controller utilizes the well-known structural similarity index (SSIM) as a quality metric to increase the visual quality of the output video. The proposed rate control algorithm is implemented in HEVC reference software and comprehensive experiments are executed to tune the fuzzy controllers and also to evaluate the performance of the algorithm. Experimental results show a high performance for the proposed algorithm in terms of rate control, visual quality, and rate-distortion performance. Manuscript profile
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  3 - Reliability Analysis of the Sum-Product Decoding Algorithm for the PSK Modulation Scheme
  Hadi Khodaei Jooshin Mahdi Nangir
  10.29252/jist.8.31.167
  20.1001.1.23221437.2020.8.31.7.1
  Iteratively decoding and reconstruction of encoded data has been considered in recent decades. Most of these iterative schemes are based on graphical codes. Messages are passed through space graphs to reach a reliable belief of the original data. This paper presents a p More

  Iteratively decoding and reconstruction of encoded data has been considered in recent decades. Most of these iterative schemes are based on graphical codes. Messages are passed through space graphs to reach a reliable belief of the original data. This paper presents a performance analysis of the Low-Density Parity-Check (LDPC) code design method which approach the capacity of the Additive White Gaussian Noise (AWGN) model for communication channels. We investigate the reliability of the system under Phase Shift Keying (PSK) modulation. We study the effects and advantages of variation in the codeword length, the rate of parity-check matrix of the LDPC codes, and the number of iterations in the Sum-Product Algorithm (SPA). By employing an LDPC encoder prior to the PSK modulation block and the SPA in the decoding part, the Bit Error Rate (BER) performance of the PSK modulation system can improve significantly. The BER performance improvement of a point-to-point communication system is measured in different cases. Our analysis is capable for applying any other iterative message-passing algorithm. The code design process of the communication systems and parameter selection of the encoding and decoding algorithms are accomplished by considering hardware limitations in a communication system. Our results help to design and select paramours efficiently. Manuscript profile
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  4 - Implementation of Uplink and Downlink Non-Orthogonal Multiple Access (NOMA) on Zync FPGA Device
  Ahmed Belhani Hichem Semira Rania Kheddara Ghada Hassis
  10.61186/jist.33595.11.44.269
  The non-orthogonal access schemes are one of the multiple access techniques that are candidates to become an access technique for the next generation access radio. Power-domain non-orthogonal multiple-access (NOMA) is among these promising technologies. Improving the ne More

  The non-orthogonal access schemes are one of the multiple access techniques that are candidates to become an access technique for the next generation access radio. Power-domain non-orthogonal multiple-access (NOMA) is among these promising technologies. Improving the network capacity by providing massive connectivity through sharing the same spectral resources is the main advantage that this technique offers. The NOMA technique consists of exploiting the power domain which multiplex multiple users on the same resources applying a superposition coding then separating the multiplexed users at the receiver side. Due to the non-orthogonality access technique, the main disadvantage of NOMA is the presence of interferences between users. That is why this scheme is based on a successive interference cancelation (SIC) detector that separates the multiplexed signals at the receiver. In this paper, an embedded system is considered for designing and implementation of the power-NOMA For two users. The implementation is realized by employing a Zynq FPGA (Field programmable gate array) device through the Zybo-Z7 board using MATLAB/Simulink environment and Xilinx System Generator. The features offered by this device, hemps to consider the design of an uplink and a downlink scenario over Rayleigh fading channel in additive white Gaussian noise (AWGN) environment. Manuscript profile
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  5 - Joint Cooperative Spectrum Sensing and Resource Allocation in Dynamic Wireless Energy Harvesting Enabled Cognitive Sensor Networks
  maryam Najimi
  10.61186/jist.33968.11.44.320
  Due to the limitations of the natural frequency spectrum, dynamic frequency allocation is required for wireless networks. Spectrum sensing of a radio channel is a technique to identify the spectrum holes. In this paper, we investigate a dynamic cognitive sensor networ More

  Due to the limitations of the natural frequency spectrum, dynamic frequency allocation is required for wireless networks. Spectrum sensing of a radio channel is a technique to identify the spectrum holes. In this paper, we investigate a dynamic cognitive sensor network, in which the cognitive sensor transmitter has the capability of the energy harvesting. In the first slot, the cognitive sensor transmitter participates in spectrum sensing and in the existence of the primary user, it harvests the energy from the primary signal, otherwise the sensor transmitter sends its signal to the corresponding receiver while in the second slot, using the decode-and-forward (DF) protocol, a part of the bandwidth is used to forward the signal of the primary user and the remained bandwidth is used for transmission of the cognitive sensor. Therefore, our purposed algorithm is to maximize the cognitive network transmission rate by selection of the suitable cognitive sensor transmitters subject to the rate of the primary transmission and energy consumption of the cognitive sensors according to the mobility model of the cognitive sensors in the dynamic network. Simulation results illustrate the effectiveness of the proposed algorithm in performance improvement of the network as well as reducing the energy consumption. Manuscript profile