Regaining synchronisation with watermarks and neural networks

**Authors:**Knoetze, Reolyn**Date:**2008-06-06T10:29:44Z**Subjects:**Synchronization , Watermarks , Neural networks (Computer science) , Reed-Solomon codes**Type:**Thesis**Identifier:**uj:9134 , http://hdl.handle.net/10210/558**Description:**Reliable communication is an important part of everyday living. When transmitting a message over a physical channel, noise is introduced that causes errors in the message. These errors can be inversion errors or synchronization errors. The aim of this thesis is to investigate coding techniques to minimise the effect of synchronization errors that occurred in a transmitted message. Watermarks are inserted into the encoded sequence. A neural network system is implemented before the decoder to detect the watermark and regain synchronization. , Prof. H. C. Ferreira**Full Text:**

**Authors:**Knoetze, Reolyn**Date:**2008-06-06T10:29:44Z**Subjects:**Synchronization , Watermarks , Neural networks (Computer science) , Reed-Solomon codes**Type:**Thesis**Identifier:**uj:9134 , http://hdl.handle.net/10210/558**Description:**Reliable communication is an important part of everyday living. When transmitting a message over a physical channel, noise is introduced that causes errors in the message. These errors can be inversion errors or synchronization errors. The aim of this thesis is to investigate coding techniques to minimise the effect of synchronization errors that occurred in a transmitted message. Watermarks are inserted into the encoded sequence. A neural network system is implemented before the decoder to detect the watermark and regain synchronization. , Prof. H. C. Ferreira**Full Text:**

Analysis of the probability of sync-words in Reed-Solomon codes

**Authors:**Shongwe, Thokozani**Date:**2017**Subjects:**Reed-Solomon codes , Frame Synchronization , Sync-words**Language:**English**Type:**Article**Identifier:**http://ujcontent.uj.ac.za8080/10210/374952 , http://hdl.handle.net/10210/244556 , uj:25291 , Citation: Shongwe, T. 2017. Analysis of the probability of sync-words in Reed-Solomon codes.**Description:**Abstract: Given binary data transmission encoded using a Reed-Solomon (RS) code and employing binary sync-words (markers) for synchronization, we calculate the probability of finding the sync-word in the codewords of the RS code as PS. We give analytical expressions for calculating PS, which is applicable to RS codes. Knowledge of PS can be used to calculate the probability of finding a sync-word that is used as a marker in RS encoded data, PT . The probability PT is called the false acquisition probability in the synchonization of RS encoded data.**Full Text:**

**Authors:**Shongwe, Thokozani**Date:**2017**Subjects:**Reed-Solomon codes , Frame Synchronization , Sync-words**Language:**English**Type:**Article**Identifier:**http://ujcontent.uj.ac.za8080/10210/374952 , http://hdl.handle.net/10210/244556 , uj:25291 , Citation: Shongwe, T. 2017. Analysis of the probability of sync-words in Reed-Solomon codes.**Description:**Abstract: Given binary data transmission encoded using a Reed-Solomon (RS) code and employing binary sync-words (markers) for synchronization, we calculate the probability of finding the sync-word in the codewords of the RS code as PS. We give analytical expressions for calculating PS, which is applicable to RS codes. Knowledge of PS can be used to calculate the probability of finding a sync-word that is used as a marker in RS encoded data, PT . The probability PT is called the false acquisition probability in the synchonization of RS encoded data.**Full Text:**

Synchronization with permutation codes and Reed-Solomon codes

**Authors:**Shongwe, Thokozani Calvin**Date:**2014-09-23**Subjects:**Coding theory , Synchronization , Data transmission systems , Reed-Solomon codes , Permutations**Type:**Thesis**Identifier:**http://ujcontent.uj.ac.za8080/10210/386508 , uj:12373 , http://hdl.handle.net/10210/12157**Description:**D.Ing. (Electrical And Electronic Engineering) , We address the issue of synchronization, using sync-words (or markers), for encoded data. We focus on data that is encoded using permutation codes or Reed-Solomon codes. For each type of code (permutation code and Reed-Solomon code) we give a synchronization procedure or algorithm such that synchronization is improved compared to when the procedure is not employed. The gure of merit for judging the performance is probability of synchronization (acquisition). The word acquisition is used to indicate that a sync-word is acquired or found in the right place in a frame. A new synchronization procedure for permutation codes is presented. This procedure is about nding sync-words that can be used speci cally with permutation codes, such that acceptable synchronization performance is possible even under channels with frequency selective fading/jamming, such as the power line communication channel. Our new procedure is tested with permutation codes known as distance-preserving mappings (DPMs). DPMs were chosen because they have de ned encoding and decoding procedures. Another new procedure for avoiding symbols in Reed-Solomon codes is presented. We call the procedure symbol avoidance. The symbol avoidance procedure is then used to improve the synchronization performance of Reed-Solomon codes, where known binary sync-words are used for synchronization. We give performance comparison results, in terms of probability of synchronization, where we compare Reed-Solomon with and without symbol avoidance applied.**Full Text:**

**Authors:**Shongwe, Thokozani Calvin**Date:**2014-09-23**Subjects:**Coding theory , Synchronization , Data transmission systems , Reed-Solomon codes , Permutations**Type:**Thesis**Identifier:**http://ujcontent.uj.ac.za8080/10210/386508 , uj:12373 , http://hdl.handle.net/10210/12157**Description:**D.Ing. (Electrical And Electronic Engineering) , We address the issue of synchronization, using sync-words (or markers), for encoded data. We focus on data that is encoded using permutation codes or Reed-Solomon codes. For each type of code (permutation code and Reed-Solomon code) we give a synchronization procedure or algorithm such that synchronization is improved compared to when the procedure is not employed. The gure of merit for judging the performance is probability of synchronization (acquisition). The word acquisition is used to indicate that a sync-word is acquired or found in the right place in a frame. A new synchronization procedure for permutation codes is presented. This procedure is about nding sync-words that can be used speci cally with permutation codes, such that acceptable synchronization performance is possible even under channels with frequency selective fading/jamming, such as the power line communication channel. Our new procedure is tested with permutation codes known as distance-preserving mappings (DPMs). DPMs were chosen because they have de ned encoding and decoding procedures. Another new procedure for avoiding symbols in Reed-Solomon codes is presented. We call the procedure symbol avoidance. The symbol avoidance procedure is then used to improve the synchronization performance of Reed-Solomon codes, where known binary sync-words are used for synchronization. We give performance comparison results, in terms of probability of synchronization, where we compare Reed-Solomon with and without symbol avoidance applied.**Full Text:**

Reed-Solomon coding for power line communications and networks

- Versfeld, Daniël Johannes Jacobus

**Authors:**Versfeld, Daniël Johannes Jacobus**Date:**2012-06-06**Subjects:**Reed-Solomon codes , Electric lines , Electric networks , Coding theory**Type:**Thesis**Identifier:**uj:2522 , http://hdl.handle.net/10210/4978**Description:**D.Ing. , In this study we consider the application of Reed-Solomon codes on two distinct channels. The first channel is the packet erasure channel, where packets are either received errorfree,or packets are lost. The second channel is the power line channel where additive Gaussian noise,, impulsive noise and narrowband noise are encountered In this thesis we focus on M-FSK modulation for the power line channel. For the packet erasure channel,we develop two new erasures-only decoders .The distinction between the two decoders is that the one is optimized for burst erasure correction, while the second decoder is optimized for random erasure correction.It is found that for single burst erasures, or bursterasures contained within n - k elements (where n is the code length and k is the number of information elements to be encoded), the best performance is obtained with the burst erasure decoder. When used in conjunction with a modified interleaver found in the literature, the developed random erasure decoder yields the best all-round performance. The main contribution to the power line channel is the development of a combined demodulation and decoding strategy to detect narrowband interference When standard Reed-Solomon codes operate in a channel where narrowband interference is present, undetected errors result. With the proposed decoding strategy it is found that wideband noise (a generalization of impulsive noise) affects the performance more negatively than narrowband noise for M-FSK modulation. .**Full Text:**

**Authors:**Versfeld, Daniël Johannes Jacobus**Date:**2012-06-06**Subjects:**Reed-Solomon codes , Electric lines , Electric networks , Coding theory**Type:**Thesis**Identifier:**uj:2522 , http://hdl.handle.net/10210/4978**Description:**D.Ing. , In this study we consider the application of Reed-Solomon codes on two distinct channels. The first channel is the packet erasure channel, where packets are either received errorfree,or packets are lost. The second channel is the power line channel where additive Gaussian noise,, impulsive noise and narrowband noise are encountered In this thesis we focus on M-FSK modulation for the power line channel. For the packet erasure channel,we develop two new erasures-only decoders .The distinction between the two decoders is that the one is optimized for burst erasure correction, while the second decoder is optimized for random erasure correction.It is found that for single burst erasures, or bursterasures contained within n - k elements (where n is the code length and k is the number of information elements to be encoded), the best performance is obtained with the burst erasure decoder. When used in conjunction with a modified interleaver found in the literature, the developed random erasure decoder yields the best all-round performance. The main contribution to the power line channel is the development of a combined demodulation and decoding strategy to detect narrowband interference When standard Reed-Solomon codes operate in a channel where narrowband interference is present, undetected errors result. With the proposed decoding strategy it is found that wideband noise (a generalization of impulsive noise) affects the performance more negatively than narrowband noise for M-FSK modulation. .**Full Text:**

Reducing the probability of sync-word false acquisition with Reed-Solomon codes

- Shongwe, Thokozani, Han Vinck, A. J., Ferreira, Hendrik C.

**Authors:**Shongwe, Thokozani , Han Vinck, A. J. , Ferreira, Hendrik C.**Date:**2013**Subjects:**Reed-Solomon codes , Sync-words , Sync-word based synchronization**Type:**Article**Identifier:**uj:4754 , ISSN 1555-5798 , http://hdl.handle.net/10210/11740**Description:**In our previous work we introduced a method for avoiding/excluding some symbols in Reed-Solomon (RS) codes, called symbol avoidance. In this paper, we apply the symbol avoidance method in sync-word based synchronization of RS encoded data. With the symbol avoidance method we reduce the probability of the RS encoded data being mistaken for the sync-word used to delimit the start/end of the data. The symbols in the RS code are avoided according to the sync-word used, such that the sync-word has very low probability of being found in the RS codewords, where it was not inserted. Therefore, for different sync-words, different symbols need to be avoided in the RS code. The goal here is to reduce the probability of false acquisition of the sync-word in the RS encoded framed data.**Full Text:**

**Authors:**Shongwe, Thokozani , Han Vinck, A. J. , Ferreira, Hendrik C.**Date:**2013**Subjects:**Reed-Solomon codes , Sync-words , Sync-word based synchronization**Type:**Article**Identifier:**uj:4754 , ISSN 1555-5798 , http://hdl.handle.net/10210/11740**Description:**In our previous work we introduced a method for avoiding/excluding some symbols in Reed-Solomon (RS) codes, called symbol avoidance. In this paper, we apply the symbol avoidance method in sync-word based synchronization of RS encoded data. With the symbol avoidance method we reduce the probability of the RS encoded data being mistaken for the sync-word used to delimit the start/end of the data. The symbols in the RS code are avoided according to the sync-word used, such that the sync-word has very low probability of being found in the RS codewords, where it was not inserted. Therefore, for different sync-words, different symbols need to be avoided in the RS code. The goal here is to reduce the probability of false acquisition of the sync-word in the RS encoded framed data.**Full Text:**

Correcting bursts of adjacent deletions by adapting product codes

**Authors:**Buys, Stephanie**Date:**2015-03-25**Subjects:**Error-correcting codes (Information theory) , Synchronous data transmission systems , Reed-Solomon codes**Type:**Thesis**Identifier:**uj:13517 , http://hdl.handle.net/10210/13569**Description:**M.Ing. (Electrical and Electronic Engineering) , In this study, the problem of correcting burst of adjacent deletions by adapting product codes was investigated. The first step in any digital transmission is to establish synchronization between the sending and receiving nodes. This initial synchronization ensures that the receiver samples the information bits at the correct interval. Unfortunately synchronization is not guaranteed to last for the entire duration of data transmission. Though synchronization errors rarely occur, it has disastrous effects at the receiving end of transmission. These synchronization errors are modelled as either insertions or deletions in the transmitted data. In the best case scenario, these errors are restricted to single bit errors. In the worst case scenario, these errors lead to bursts of bits being incorrect. If these synchronization errors are not detected and corrected, it can cause a shift in the transmitted sequence which in turn leads to loss of synchronization. When a signal is subjected to synchronization errors it is difficult accurately recover the original data signal. In addition to the loss of synchronization, the information transmitted over the channel is also subjected to noise. This noise in the channel causes inversion errors within the signal. The objective of this dissertation is to investigate if an error correction scheme can be designed that has the ability to detect and correct adjacent bursts of deletions and random inversion errors. This error correction scheme needed to make use of a product code matrix structure. This product matrix needed to incorporate both an error correction and synchronization technique. The chosen error correcting techniques were Hamming and Reed-Solomon codes. The chosen synchronization techniques for this project were the marker technique or an adaptation of the Hamming code technique. In order to find an effective model, combinations of these models were simulated and compared. From the research obtained and analyzed in this document it was found that, depending on the desired performance, complexity and code rate, an error correction scheme can be used in the efficient correction of bursts of adjacent deletions by adapting product codes.**Full Text:**

**Authors:**Buys, Stephanie**Date:**2015-03-25**Subjects:**Error-correcting codes (Information theory) , Synchronous data transmission systems , Reed-Solomon codes**Type:**Thesis**Identifier:**uj:13517 , http://hdl.handle.net/10210/13569**Description:**M.Ing. (Electrical and Electronic Engineering) , In this study, the problem of correcting burst of adjacent deletions by adapting product codes was investigated. The first step in any digital transmission is to establish synchronization between the sending and receiving nodes. This initial synchronization ensures that the receiver samples the information bits at the correct interval. Unfortunately synchronization is not guaranteed to last for the entire duration of data transmission. Though synchronization errors rarely occur, it has disastrous effects at the receiving end of transmission. These synchronization errors are modelled as either insertions or deletions in the transmitted data. In the best case scenario, these errors are restricted to single bit errors. In the worst case scenario, these errors lead to bursts of bits being incorrect. If these synchronization errors are not detected and corrected, it can cause a shift in the transmitted sequence which in turn leads to loss of synchronization. When a signal is subjected to synchronization errors it is difficult accurately recover the original data signal. In addition to the loss of synchronization, the information transmitted over the channel is also subjected to noise. This noise in the channel causes inversion errors within the signal. The objective of this dissertation is to investigate if an error correction scheme can be designed that has the ability to detect and correct adjacent bursts of deletions and random inversion errors. This error correction scheme needed to make use of a product code matrix structure. This product matrix needed to incorporate both an error correction and synchronization technique. The chosen error correcting techniques were Hamming and Reed-Solomon codes. The chosen synchronization techniques for this project were the marker technique or an adaptation of the Hamming code technique. In order to find an effective model, combinations of these models were simulated and compared. From the research obtained and analyzed in this document it was found that, depending on the desired performance, complexity and code rate, an error correction scheme can be used in the efficient correction of bursts of adjacent deletions by adapting product codes.**Full Text:**

Selected subcarriers QPSK-OFDM transmission schemes to combat frequency disturbances

- Shongwe, Thokozani, Han Vinck, A. J., Ferreira, Hendrik C., Papilaya, Victor N.

**Authors:**Shongwe, Thokozani , Han Vinck, A. J. , Ferreira, Hendrik C. , Papilaya, Victor N.**Date:**2012**Subjects:**Reed-Solomon codes , Carrier transmission on power lines , Data communication , Frequency selective surfaces , Impulse noise , Quadrature phase shift keying , Power line communications**Type:**Article**Identifier:**uj:4738 , ISBN 978-1-4673-0360-6 , http://hdl.handle.net/10210/11724**Description:**To combat the impairments caused by frequency disturbances in the power line communications (PLC), a modified conventional QPSK-OFDM transmission scheme is presented. The idea of this scheme is to first group the N OFDM subcarriers into groups of M and then transmit data by selecting a subset of the subcarriers in the group. Real and imaginary parts of QPSK symbols are independently assigned to the selected subcarriers in a group, such that the minimum squared Euclidean distance is maximised. With this kind of symbol assignment to subcarriers our scheme has no net loss in terms of SNR requirements, in AWGN, in comparison to the conventional QPSK-OFDM, even though it has half the data rate of the conventional QPSK-OFDM. We refer to the conventional QPSK-OFDM as Scheme A. Our scheme displays a superior performance over Scheme A and another scheme (Scheme B), in the presence of frequency disturbances and also frequency selective fading noise. We further modify Scheme B and come up with additional two new QPSK-OFDM schemes that have better performance than Scheme B in AWGN and impulse noise. To encode, we apply a (n, k) RS code and a simple permutation code on the conventional QPSK-OFDM scheme, which significantly improves the decoder's performance in the presence of frequency disturbances. A simple narrow band noise model is developed and presented.**Full Text:**

**Authors:**Shongwe, Thokozani , Han Vinck, A. J. , Ferreira, Hendrik C. , Papilaya, Victor N.**Date:**2012**Subjects:**Reed-Solomon codes , Carrier transmission on power lines , Data communication , Frequency selective surfaces , Impulse noise , Quadrature phase shift keying , Power line communications**Type:**Article**Identifier:**uj:4738 , ISBN 978-1-4673-0360-6 , http://hdl.handle.net/10210/11724**Description:**To combat the impairments caused by frequency disturbances in the power line communications (PLC), a modified conventional QPSK-OFDM transmission scheme is presented. The idea of this scheme is to first group the N OFDM subcarriers into groups of M and then transmit data by selecting a subset of the subcarriers in the group. Real and imaginary parts of QPSK symbols are independently assigned to the selected subcarriers in a group, such that the minimum squared Euclidean distance is maximised. With this kind of symbol assignment to subcarriers our scheme has no net loss in terms of SNR requirements, in AWGN, in comparison to the conventional QPSK-OFDM, even though it has half the data rate of the conventional QPSK-OFDM. We refer to the conventional QPSK-OFDM as Scheme A. Our scheme displays a superior performance over Scheme A and another scheme (Scheme B), in the presence of frequency disturbances and also frequency selective fading noise. We further modify Scheme B and come up with additional two new QPSK-OFDM schemes that have better performance than Scheme B in AWGN and impulse noise. To encode, we apply a (n, k) RS code and a simple permutation code on the conventional QPSK-OFDM scheme, which significantly improves the decoder's performance in the presence of frequency disturbances. A simple narrow band noise model is developed and presented.**Full Text:**

Reed-Solomon code symbol avoidance

- Shongwe, Thokozani, Han Vinck, A. J.

**Authors:**Shongwe, Thokozani , Han Vinck, A. J.**Date:**2014**Subjects:**Reed-Solomon codes , Subcodes**Type:**Article**Identifier:**uj:4722 , ISSN 1991-1696 , http://hdl.handle.net/10210/11444**Description:**A Reed-Solomon code construction that avoids or excludes particular symbols in a linear Reed-Solomon code is presented. The resulting code, from our symbol avoidance construction, has the same or better error-correcting capabilities compared to the original Reed-Solomon code, but with reduced efficiency in terms of rate. The codebook of the new code is a subset of the original Reed-Solomon code and the code may no longer be linear. We also present computer search results for the bound on the number of symbols that can be avoided, and we make an attempt to find an expression for the bound. Such a code, by symbol avoidance, can be well suited to a number of applications, some of which include markers for synchronization, frequency hopping signatures, and pulse position modulation.**Full Text:**

**Authors:**Shongwe, Thokozani , Han Vinck, A. J.**Date:**2014**Subjects:**Reed-Solomon codes , Subcodes**Type:**Article**Identifier:**uj:4722 , ISSN 1991-1696 , http://hdl.handle.net/10210/11444**Description:**A Reed-Solomon code construction that avoids or excludes particular symbols in a linear Reed-Solomon code is presented. The resulting code, from our symbol avoidance construction, has the same or better error-correcting capabilities compared to the original Reed-Solomon code, but with reduced efficiency in terms of rate. The codebook of the new code is a subset of the original Reed-Solomon code and the code may no longer be linear. We also present computer search results for the bound on the number of symbols that can be avoided, and we make an attempt to find an expression for the bound. Such a code, by symbol avoidance, can be well suited to a number of applications, some of which include markers for synchronization, frequency hopping signatures, and pulse position modulation.**Full Text:**

Application of symbol avoidance in reed-solomon codes to improve their synchronization

- Shongwe, Thokozani, Han Vinck, A. J., Ferreira, Hendrik C.

**Authors:**Shongwe, Thokozani , Han Vinck, A. J. , Ferreira, Hendrik C.**Date:**2016**Subjects:**Reed-Solomon codes , Frame synchronization , Sync-words**Language:**English**Type:**Article**Identifier:**http://hdl.handle.net/10210/91870 , uj:20156 , Citation: Shongwe, T., Han Vinck, A.J. & Ferreira, H.C. 2016. In our previous work we introduced a method for avoiding/excluding some symbols in Reed-Solomon (RS) codes, called symbol avoidance. In this paper, we apply the symbol avoidance method to make synchronization of RS encoded data more effective. We avoid symbols in a RS code and then perform conventional frame synchronization on RS encoded data by appending sync-words on the data. The symbols in the RS code are avoided according to the sync-word used, such that the sync-word has very low probability of being found in the RS codewords, where it was not inserted. Therefore, for different sync-words, different symbols need to be avoided in the RS code. The goal here is to reduce the probability of mistaking data for the sync-word in the RS encoded framed data. Hence, the probability of successful synchronization is improved. Not only does our symbol avoidance code improve probability of successful synchronization, it also reduces the overall amount of redundancy required when the channel is very noisy.**Description:**Abstract: In our previous work we introduced a method for avoiding/excluding some symbols in Reed-Solomon (RS) codes, called symbol avoidance. In this paper, we apply the symbol avoidance method to make synchronization of RS encoded data more effective. We avoid symbols in a RS code and then perform conventional frame synchronization on RS encoded data by appending sync-words on the data. The symbols in the RS code are avoided according to the sync-word used, such that the sync-word has very low probability of being found in the RS codewords, where it was not inserted. Therefore, for different sync-words, different symbols need to be avoided in the RS code. The goal here is to reduce the probability of mistaking data for the sync-word in the RS encoded framed data. Hence, the probability of successful synchronization is improved. Not only does our symbol avoidance code improve probability of successful synchronization, it also reduces the overall amount of redundancy required when the channel is very noisy.**Full Text:**

**Authors:**Shongwe, Thokozani , Han Vinck, A. J. , Ferreira, Hendrik C.**Date:**2016**Subjects:**Reed-Solomon codes , Frame synchronization , Sync-words**Language:**English**Type:**Article**Identifier:**http://hdl.handle.net/10210/91870 , uj:20156 , Citation: Shongwe, T., Han Vinck, A.J. & Ferreira, H.C. 2016. In our previous work we introduced a method for avoiding/excluding some symbols in Reed-Solomon (RS) codes, called symbol avoidance. In this paper, we apply the symbol avoidance method to make synchronization of RS encoded data more effective. We avoid symbols in a RS code and then perform conventional frame synchronization on RS encoded data by appending sync-words on the data. The symbols in the RS code are avoided according to the sync-word used, such that the sync-word has very low probability of being found in the RS codewords, where it was not inserted. Therefore, for different sync-words, different symbols need to be avoided in the RS code. The goal here is to reduce the probability of mistaking data for the sync-word in the RS encoded framed data. Hence, the probability of successful synchronization is improved. Not only does our symbol avoidance code improve probability of successful synchronization, it also reduces the overall amount of redundancy required when the channel is very noisy.**Description:**Abstract: In our previous work we introduced a method for avoiding/excluding some symbols in Reed-Solomon (RS) codes, called symbol avoidance. In this paper, we apply the symbol avoidance method to make synchronization of RS encoded data more effective. We avoid symbols in a RS code and then perform conventional frame synchronization on RS encoded data by appending sync-words on the data. The symbols in the RS code are avoided according to the sync-word used, such that the sync-word has very low probability of being found in the RS codewords, where it was not inserted. Therefore, for different sync-words, different symbols need to be avoided in the RS code. The goal here is to reduce the probability of mistaking data for the sync-word in the RS encoded framed data. Hence, the probability of successful synchronization is improved. Not only does our symbol avoidance code improve probability of successful synchronization, it also reduces the overall amount of redundancy required when the channel is very noisy.**Full Text:**

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