Browsing by Author "Sam, Anael"

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    Assessment of Non Transmittable Codewords Enhancement to Viterbi Algorithm Decoding
    (International Journal of Computer Science and Information Security, 2014) Mrutu, Salehe; Sam, Anael; Mvungi, Nerey H.
    Researchers have shown that practical mobile communication channels introduce errors that are concentrated in a certain locality rather than random errors. These are burst errors caused by deep fading of the wireless channel or a lightning strike. The existing Viterbi Algorithm (VA) capable of correcting random errors is inefficient in correcting burst errors and therefore resulting in unacceptable amount of residual errors. This paper presents an assessment of Non- Transmittable Codewords (NTCs) enhancement technique to VA in decoding the received signals subjected to burst errors that may occur in poor channels. A hard decision, 1/2 rate and constraint length K is equal to 3 Viterbi Algorithm decoding technique, Binary Phase- Shift Keying (BPSK) and Additional White Gaussian Noise (AWGN) are components used in MATLAB software based simulation when assessing the proposed technique. Applying 6NTCs to VA decoder enables the decoder to reduce 83.7 percent of its residual errors. However, the technique reduces the encoder’s data transmission rate from 1/2 to 1/6.
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    Forward Error Correction Convolutional Codes for RTAs’ Networks: An Overview
    (MECS (http://www.mecs-press.org/), 2014-07) Mrutu, Salehe; Sam, Anael; Mvungi, Nerey H.
    For more than half a century, Forward Error Correction Convolutional Codes (FEC-CC) have been in use to provide reliable data communication over various communication networks. The recent high increase of mobile communication services that require both bandwidth intensive and interactive Real Time Applications (RTAs) impose an increased demand for fast and reliable wireless communication networks. Transmission burst errors; data decoding complexity and jitter are identified as key factors influencing the quality of service of RTAs implementation over wireless transmission media. This paper reviews FEC-CC as one of the most commonly used algorithm in Forward Error Correction for the purpose of improving its operational performance. Under this category, we have analyzed various previous works for their strengths and weaknesses in decoding FEC-CC. A comparison of various decoding algorithms is made based on their decoding computational complexity.
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    Performance of Binary Locked Convolutional Codes with Non-Transmittable Codewords in Flat and Slow Rayleigh-Fading Channel
    (International Journal of Computer Applications, 2014) Mrutu, Salehe; Sam, Anael; Mvungi, Nerey H.
    Communication over wireless media is vulnerable to distortion by noise. Therefore, the application of error control mechanism is necessary to minimize the Bit Error Rate (BER). It is proposed to use locked binary convolutional code with Non-Transmittable codewords to enhance Viterbi Algorithm decoders; as one of the forward error correction mechanisms. The proposed enhancement empowers Viterbi algorithm decoders to reduce one of its inherent limitations of residual errors due to burst errors. This paper evaluates the performance of the locked (2, 1, 2) binary convolutional code with Non-Transmittable codewords enhancement technique over flat and slow Rayleigh Fading channel using a MATLAB software simulation. Simulation result shows 80.92 percent reduction of residual errors when 6 Non-Transmittable Codewords were applied to Viterbi Algorithm (VA) decoding. On the other hand, the technique lowers the encoder’s data transmission rate from 1/2 to 1/6.
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    Trellis Analysis of Transmission Burst Errors in Viterbi Decoding
    (International Journal of Computer Science and Information Security, 2014-08) Mrutu, Salehe; Sam, Anael; Mvungi, Nerey H.
    The Viterbi decoder is the most favorable solution to the problem of decoding codewords from a convolutional encoder. Viterbi decoder performs exceptionally well when a received codewords block contains single or multiple and scattered errors in a received codewords block. However, the formation of burst errors in data transmission due to high transmission speed and the widely varying error conditions of wireless media in fading channel creates decoding challenge for such conditions which result in unbearable amount of residual errors. By using Viterbi decoders’ trellis diagrams, this paper analyses the effects of burst errors to the decoder that lead to residual errors and proposes improvement to the encoding and decoding procedures of the existing (2, 1, 2) binary convolutional encoder. The improved version facilitate effectiveness in the decoder (Viterbi algorithm) in decoding burst errors and hence reduction of residual errors in a poor channel. The proposed enhancements improve the decoder’s operational performance by 75 percent. However, the proposed modification reduces the encoder’s data transmission rate from 1/2 to 1/6.