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A multilevel construction for mappings from binary sequences to permutation sequences

- Swart, Theo G., Ferreira, Hendrik C.

Authors: Swart, Theo G. , Ferreira, Hendrik C.
Date: 2006
Subjects: Mappings , Binary sequences , Permutation sequences
Language: English
Type: Conference proceedings
Identifier: http://hdl.handle.net/10210/18365 , uj:15991 , Citation: Swart, T.G. & Ferreira, H.C. 2006. A multilevel construction for mappings from binary sequences to permutation sequences. Proceedings of the IEEE International Symposium on Information Theory, 9-14 July, 2006, Seattle, USA.
Description: Abstract: A multilevel construction is introduced to create distance-preserving mappings from binary sequences to permutation sequences. It is also shown that for certain values, the new mappings attain the upper bound on the sum of Hamming distances obtainable for such mappings, and in the other cases improve on those of previous mappings.
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A note on non-binary multiple insertion/deletion correcting codes

- Paluncic, Filip, Swart, Theo G., Weber, Jos H., Ferreira, Hendrik C., Clarke, Willem A.

Authors: Paluncic, Filip , Swart, Theo G. , Weber, Jos H. , Ferreira, Hendrik C. , Clarke, Willem A.
Date: 2011
Subjects: Insertion/deletion , Correcting codes
Language: English
Type: Conference proceedings
Identifier: http://hdl.handle.net/10210/20202 , uj:16077 , ISBN: 978-1-4577-0437-6 , Citation: Paluncic, F. et al. 2011. A note on non-binary multiple insertion/deletion correcting codes. Proceedings of the IEEE Information Theory Workshop, 16-20 October, 2011, Paraty, Brazil.
Description: Abstract: We propose the construction of a non-binary multiple insertion/deletion correcting code based on a binary multiple insertion/deletion correcting code. In essence, it is a generalisation of Tenengol’ts’ non-binary single insertion/deletion correcting code. We evaluate the cardinality of the proposed construction based on the asymptotic upper bound on the cardinality of a maximal binary multiple insertion/deletion correcting code derived by Levenshtein.
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A preliminary investigation of the UHF properties of LV cable for WiFi over power line communications

- Jordaan, Sean, Janse van Rensburg, Petrus A., De Beer, Arnold S., Ferreira, Hendrik C., Han Vinck, A. J.

Authors: Jordaan, Sean , Janse van Rensburg, Petrus A. , De Beer, Arnold S. , Ferreira, Hendrik C. , Han Vinck, A. J.
Date: 2015-03-29
Subjects: Power line communications , Wireless protocol , Wireless communication systems
Type: Article
Identifier: uj:5244 , http://hdl.handle.net/10210/14844
Description: In pursuit of a wireless (contactless) power line communications (W-PLC) system for low voltage (LV) power distribution networks, a commonly utilized bundled low voltage electrical cable called Cabtyre, was energized with a range of frequencies up to 3 GHz. The intention was to characterize the cable from a radio frequency radiation perspective for the utilization of standard low voltage distribution cables as antennas in ultra high frequency (UHF) PLC systems. The range of test frequencies extends 550 MHz beyond the present IEEE 802.11g protocol which has a centre frequency of 2.45 GHz and a 80 MHz total bandwidth. The applied tests therefore allow adequately for the maximum bandwidth required with 40 MHz modulation on either side of the 2.45 GHz centre frequency.
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A pricing policy to mitigate interference management in femtocell network

- Akinlabi, O. A., Paul, B. S., Joseph, M., Ferreira, Hendrik C.

Authors: Akinlabi, O. A. , Paul, B. S. , Joseph, M. , Ferreira, Hendrik C.
Date: 2014
Subjects: Femtocells , Nash equilibrium , OFDDMA system , Wireless network systems , Game theory
Type: Article
Identifier: uj:4766 , ISSN 1793-8201 , http://hdl.handle.net/10210/11941
Description: Recently, the concepts of game theory has attract the attention of researcher for self-governing decision making to study the performance of wireless network. There has been growing interest in accepting game theoretic method to wireless systems. The problem of interference management in femtocell network is approached from the prospective of game theory with the concept of price policy. Whereby price is used to control the power transmission of each femto users in the cell coverage. In this paper, we propose a price policy to reduce the effect of interference between the femto users at both center and edge regions of cell network. The performance of our proposed algorithm is demonstrated by simulation results.
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A semi-hidden Markov modeling of a low complexity FSK-OOK in-House PLC and VLC integration

- Familua, A. D., Ndjiongue, A. R., Ogunyanda, K., Cheng, L., Ferreira, Hendrik C., Swart, Theo G.

Authors: Familua, A. D. , Ndjiongue, A. R. , Ogunyanda, K. , Cheng, L. , Ferreira, Hendrik C. , Swart, Theo G.
Date: 2015
Subjects: Light emitting diodes , Power line communications , Visible light communications
Language: English
Type: Article
Identifier: http://hdl.handle.net/10210/69648 , uj:17896 , Citation: Familua, A.D. et al. 2015. A semi-hidden Markov modeling of a low complexity FSK-OOK in-house PLC and VLC integration.
Description: Abstract: The integration of power line communication (PLC) and visible light communication (VLC) is increasingly receiving a lot of research interest with the advent of (IEEE 1901, ITUT G.9960/61) and IEEE 802.15.7 standards for PLC and VLC respectively. In particular, there is an underlying gain that could be achieved by leveraging the existing ubiquitous power line network infrastructure to render connectivity, while we also exploit the illumination system of power-saving Light Emitting Diodes (LEDs) for wireless data communication. The ubiquitous nature of these two systems makes us belief that VLC can offer a good complementary wireless data transmission technology to the existing In-House PLC in a similar manner broad-band Ethernet connections enjoys the support of Wi-Fi. This paper thus reports an implementation of a low complexity FSK-OOK In-House PLC and VLC Integration, as well as it’s Second-Order Semi-Markov Model. The resulting statistical models facilitates the design and evaluation of forward error correcting codes to mitigate burst error occurrences, as well as optimizing the performance of the overall system.
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A simplistic channel model for cascaded PLC-VLC systems

- Nlom, Stephane M., Ndjiongue, A. R., Ouahada, K., Ferreira, Hendrik C., Han Vinck, A. J.

Authors: Nlom, Stephane M. , Ndjiongue, A. R. , Ouahada, K. , Ferreira, Hendrik C. , Han Vinck, A. J.
Date: 2017
Subjects: Channel model , Cascaded PLC-VLC , PLC and VLC channels
Language: English
Type: Conference proceedings
Identifier: http://hdl.handle.net/10210/237866 , uj:24380 , Citation:
Description: Abstract: In this a paper, we propose a simplistic channel model for cascaded PLC-VLC system which highlights the noise scenario in such hybrid systems. The model utilises previously proposed channel transfer functions of both PLC and VLC channels and highlights the effects of the LED supply in the system. The noise scenario implemented on the model is based on the observations obtained from a practical measurement of PLC and VLC noise amplitude spectrum (NAS). The PLC-VLC channel is generalised and then simulated based on realistic data. In our results, we highlight the effect of the model’s parameters and noise present in both PLC and VLC channels.
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A study on impulse noise and its models

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

Authors: Shongwe, Thokozani , Han Vinck, A. J. , Ferreira, Hendrik C.
Date: 2015
Subjects: Impulse noise models , Multi-carrier modulation , Single-carrier modulation
Language: English
Type: Article
Identifier: http://ujcontent.uj.ac.za8080/10210/380056 , http://hdl.handle.net/10210/73970 , uj:18479 , Citation: Shongwe, T., Han Vinck, A.J. & Ferreira, H.C. 2015. A study on impulse noise and its models.
Description: Abstract: Please refer to full text to view abstract
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Adaptive permutation coded differential OFDM system for power line communications

- Ogunyanda, K., Familua, A. D., Swart, Theo G., Ferreira, Hendrik C., Cheng, L.

Authors: Ogunyanda, K. , Familua, A. D. , Swart, Theo G. , Ferreira, Hendrik C. , Cheng, L.
Date: 2015
Subjects: Channel coding , G3-PLC , OFDM Modulation
Language: English
Type: Conference proceedings
Identifier: http://hdl.handle.net/10210/85798 , uj:19389 , Citation: Ogunyanda, K. et al. 2015. Adaptive permutation coded differential OFDM system for power line communications.
Description: Abstract: With a view to improving the capacity of the differential OFDM modulation scheme, specified in the narrowband power line communications (PLC) standards, in combating PLC channel associated noise, we hereby propose a permutation coded modulation scheme, which employs the hybridization of two kinds of DPSK (differential phase shift keying) modulations in an adaptive manner. The algorithm for deducing the encoded information from the hybridized modulations is described as well. This scheme is simulated and its performance is compared with a recently reported differential quinary PSK-OFDM system in the literature, whose behaviour has been shown to be better than the conventional permutation coded D8PSK-OFDM scheme at lower signal power to noise spectral density. Due to the simplicity in its encoding and decoding algorithms, this scheme is a good candidate for a number of low speed telemetry signaling in smart grids.
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AF cooperative VLC communication systems : cascaded channel analysis

- Ndjiongue, A. R., Ngatched, Telex M. N., Ferreira, Hendrik C.

Authors: Ndjiongue, A. R. , Ngatched, Telex M. N. , Ferreira, Hendrik C.
Date: 2019
Subjects: Cascaded VLC system , Amplify-and-forward strategy , Relay-assisted VLC system
Language: English
Type: Conference proceedings
Identifier: http://hdl.handle.net/10210/294522 , uj:32048 , Citation: Ndjiongue, A.R., Ngatched, T.M.N. & Ferreira, H.C. 2019. AF cooperative VLC communication systems : cascaded channel analysis.
Description: Abstract: Visible light communications (VLC) technology is a relatively new emerging telecommunication paradigm. It offers the opportunity to design cost-effective communication systems due to the dual use of the light sources, which are exploited as illumination devices and as communication antennas. However, this technology is mostly deployed in short-range communication applications because of the light diffusion range, which is short by nature. One good response to this dilemma is the imple- mentation of relay-assisted cooperative communication systems. Cooperative VLC systems provide three advantages, which are an increase in the transmission range, an improvement of the detection, hence of the bit error rate (BER), and an improved lighting system. In this paper, we analyze the channel response of a single-relay indoor VLC system based on an amplify-and- forward (AF) strategy. The system takes into account the fact that the relay also receives a reflected message. Results show the influence of the room’s reflection index, Lambertian index, the number of scattered rays on the overall channel response and confirms the importance of relay-assisted strategies in improving systems’ reliability.
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An analogue to SNR for timing synchronisation motivated by jitter and insertion/deletion errors

- Paluncic, Filip., Clarke, Willem A., Swart, Theo G., Ferreira, Hendrik C.

Authors: Paluncic, Filip. , Clarke, Willem A. , Swart, Theo G. , Ferreira, Hendrik C.
Date: 2007
Subjects: Signal-to-noise ratio , Timing jitter , Insertion/deletion errors
Language: English
Type: Conference proceedings
Identifier: http://hdl.handle.net/10210/15424 , uj:15659 , Citation: Paluncic, F. et al. 2007. An analogue to SNR for timing synchronisation motivated by jitter and insertion/deletion errors. In: Proceedings of the International Symposium on Communication Theory and its Applications, Ambleside, England, July 16-20, 2007.
Description: Abstract: This paper takes a closer look at the relationship between insertion/deletion errors and one of its most common causes, timing jitter. We consider two insertion/deletion channel models based on different assumptions about the timing jitter. In the literature, only channels with equal insertion/deletion probabilities for each bit have been considered. However, this assumption is only true under certain conditions. A channel, where the probability of insertion/deletion errors increases with time, is another feasible scenario. We derive an approximation for the probability of insertion/deletion errors for both models. With these ideas, we also define a possible counterpart in the time domain to the signal-to-noise ratio (defined in the amplitude domain). As an analogue to Gaussian noise in the amplitude domain, we only consider random Gaussian distributed jitter.
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An overview of colour LED & CFL lighting interference on the low voltage PLC network

- Emleh, A., De Beer, A. S., Cheng, L., Ferreira, Hendrik C., Han Vinck, A. J.

Authors: Emleh, A. , De Beer, A. S. , Cheng, L. , Ferreira, Hendrik C. , Han Vinck, A. J.
Date: 2017
Subjects: CFL , EMC , EN 50065-1
Language: English
Type: Conference proceedings
Identifier: http://hdl.handle.net/10210/247461 , uj:25695 , Citation: Emleh, A. et al. 2017. An overview of colour LED & CFL lighting interference on the low voltage PLC network.
Description: Abstract: Light sources are being competitive in the current market. Several types of these products have been widely used in the last two decades. They play a major role on the low voltage network as they produce and inject undesired noise onto the transmission lines of the PLC channel. This noise can be of a serious and negative effect when using the power line communications system to control the automatic switching of lamps in residential areas and public places. The main colour low-energy indoor light sources that exist in the market, such as, LEDs and CFLs have been tested for the noise generation on the PLC channel and the results are analyzed and shown in this study. A mathematical analysis of LED bridge rectifier is introduced in this study.
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An overview of outdoor visible light communications

- Ndjiongue, A. R., Ferreira, Hendrik C.

Authors: Ndjiongue, A. R. , Ferreira, Hendrik C.
Date: 2018
Language: English
Type: Article
Identifier: http://hdl.handle.net/10210/273025 , uj:29079 , Citation: Ndjiongue, A.R. & Ferreira, H.C. 2018. An overview of outdoor visible light communications.
Description: Abstract: In visible light communications (VLC) technology, the outdoor applications are less explored when compared to those indoors. This is due to the fact that: (i) the dual use of light emitting diodes (LEDs) is not always practicable in the outdoor VLC environment; (ii) the level of interference and noise is considerably higher in outdoor VLC; (iii) many other communication technologies are available to be used which, due to their specific characteristics, adapt better to the outdoor environment when compared to VLC technology. Nevertheless, several outdoor VLC applications have been identified. They include and are not limited to building-to-building (B2B), vehicle-to-vehicle (V2V) and road-to-vehicle (R2V) communications. Deploying light fidelity (Li-Fi) using street and park lights is also feasible. Finally, some applications exploit the ability of solar panels to simultaneously harvest the electrical energy and serve as a VLC receiving antenna. The implementation of these communication systems faces lots of challenges. Most of them are related to environmental factors such as fog, rain, sunlight, haze, snow, dust, and atmospheric disturbances. Some challenges are based on parameters such as the geometrical aspect of the light diffusion, which is Lambertian in most cases. These challenges contribute to lower interest in outdoor VLC to date. However, the environment presents several opportunities. In this article, we explore the outdoor VLC environment, review and present some promising applications selected from the literature. Furthermore, we underline likely research opportunities based on the actual state-of-the-art and our outdoor VLC characterisation experiments.
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Analysis of permutation distance-preserving mappings using graphs

- Swart, Theo G., Ferreira, Hendrik C.

Authors: Swart, Theo G. , Ferreira, Hendrik C.
Date: 2007
Subjects: Mappings (Mathematics) , Permutations , Representations of graphs
Language: English
Type: Conference proceedings
Identifier: http://hdl.handle.net/10210/15518 , uj:15670 , Citation: Swart, T.G. & Ferreira, H.C. 2007. Analysis of permutation distance-preserving mappings using graphs. In: Proceedings of the International Symposium on Communication Theory and its Applications, Ambleside, England, July 16-20, 2007
Description: Abstract A new way of analyzing permutation distance preserving mappings is presented by making use of a graph representation. The properties necessary to make such graphs distance-preserving and how this relates to the total sum of distances that exist for such mappings, are investigated. This new knowledge is used to analyze previous constructions, as well as showing the existence or non-existence of simple algorithms for mappings attaining the upper bound on the sum of distances. Finally, two applications for such graphs are considered.
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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.
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Balanced runlength limited codes using Knuth’s algorithm

- Immink, Kees A. Schouhamer, Weber, Jos H., Ferreira, Hendrik C.

Authors: Immink, Kees A. Schouhamer , Weber, Jos H. , Ferreira, Hendrik C.
Date: 2011
Subjects: Balanced codes , Bipolar codewords , Knuth’s algorithm
Type: Article
Identifier: uj:6263 , ISSN 6033677 , http://hdl.handle.net/10210/8252
Description: Knuth published a very simple algorithm for constructing bipolar codewords with equal numbers of +1’s and -1’s, called balanced codes. In our paper we will present new code constructions that generate balanced runlength limited sequences using a modification of Knuth’s algorithm.
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Binary balanced codes approaching capacity

- Esenogho, Ebenezer, Mambou, Elie N., Swart, Theo G., Ferreira, Hendrik C.

Authors: Esenogho, Ebenezer , Mambou, Elie N. , Swart, Theo G. , Ferreira, Hendrik C.
Date: 2019
Subjects: Balanced codes , Redundancy , Binary alphabet
Language: English
Type: Article
Identifier: http://hdl.handle.net/10210/401121 , uj:33508 , Citation: Esenogho, E. et al. 2019. Binary balanced codes approaching capacity.
Description: Abstract: In this paper, the construction of binary balanced codes is revisited. Binary balanced codes refer to sets of bipolar codewords where the number of “1”s in each codeword equals that of “0”s. The first algorithm for balancing codes was proposed by Knuth in 1986; however, its redundancy is almost two times larger than that of the full set of balanced codewords. We will present an efficient and simple construction with a redundancy approaching the minimal achievable one.
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Binary permutation sequences as subsets of Levenshtein codes and higher order spectral nulls codes

- Ouahada, Khmaies, Swart, Theo G., Ferreira, Hendrik C.

Authors: Ouahada, Khmaies , Swart, Theo G. , Ferreira, Hendrik C.
Date: 2006
Subjects: Levenshtein codes , Spectral nulls codes , Binary permutation sequences
Language: English
Type: Conference proceedings
Identifier: http://hdl.handle.net/10210/18858 , uj:16051 , Citation: Ouahada, K., Swart, T.G. & Ferreira, H.C. 2006. Binary permutation sequences as subsets of Levenshtein codes and higher order spectral nulls codes. Proceedings of IEEE Information Theory Workshop, Chengdu, 22-26 October, 2006, China, October.
Description: Abstract: We obtain long binary sequences by concatenating the columns of (0,1)-matrices derived from permutation sequences. We then prove that these binary sequences are subsets of the Levenshtein codes, capable of correcting insertion/deletion errors and subsets of the higher order spectral nulls codes, with spectral nulls at certain frequencies.
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Binary permutation sequences as subsets of Levenshtein codes, spectral null codes, run-length limited codes and constant weight codes

- Ouahada, Khmaies, Swart, Theo G., Ferreira, Hendrik C., Cheng, Ling

Authors: Ouahada, Khmaies , Swart, Theo G. , Ferreira, Hendrik C. , Cheng, Ling
Date: 2008
Subjects: Permutation codes , Insertion/deletion correcting codes , Constant weight codes , Spectral null codes , Run-length limited codes
Language: English
Type: Article
Identifier: http://hdl.handle.net/10210/18337 , uj:15986 , Citation: Ouahada, K. et al. 2008. Binary permutation sequences as subsets of Levenshtein codes, spectral null codes, run-length limited codes and constant weight codes. Designs, Codes and Cryptography, 48(2): 141-154. DOI: 10.1007s10623-007-9161-7. , DOI: 10.1007s10623-007-9161-7.
Description: Abstract: We investigate binary sequences which can be obtained by concatenating the columns of (0,1)-matrices derived from permutation sequences. We then prove that these binary sequences are subsets of a surprisingly diverse ensemble of codes, namely the Levenshtein codes, capable of correcting insertion/deletion errors; spectral null codes, with spectral nulls at certain frequencies; as well as being subsets of run-length limited codes, Nyquist null codes and constant weight codes.
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Cancellation and error correction for narrowband interference with spectral nulls codes and OFDM modulation

- Ouahada, K., Ferreira, Hendrik C., Han Vinck, A. J., Snyders, A. J., Swart, Theo G.

Authors: Ouahada, K. , Ferreira, Hendrik C. , Han Vinck, A. J. , Snyders, A. J. , Swart, Theo G.
Date: 2007
Subjects: Error-correcting codes (Information theory) , Spectral nulls codes
Language: English
Identifier: http://hdl.handle.net/10210/18135 , uj:15964 , Citation: Ouahada, K. et al. 2007. Cancellation and error correction for narrowband interference with spectral nulls codes and OFDM modulation. Proceedings of IEEE Africon, 26-28 September, 2007, Windhoek, Namibia.
Description: Conference proceedings
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Cascaded PLC-VLC channel using OFDM and CSK techniques

- Ndjiongue. A. R., Shongwe, Thokozani, Ferreira, Hendrik C., Ngatched, T. M. Nkouatchah, Han Vinck, A. J.

Authors: Ndjiongue. A. R. , Shongwe, Thokozani , Ferreira, Hendrik C. , Ngatched, T. M. Nkouatchah , Han Vinck, A. J.
Date: 2016
Subjects: PLC-OFDM , Hybrid systems , Cascaded channels
Language: English
Type: Conference proceedings
Identifier: http://hdl.handle.net/10210/92561 , uj:20242 , Citation: Ndjiongue, A.R. et al. 2016. Cascaded PLC-VLC channel using OFDM and CSK techniques.
Description: Abstract: This paper puts in Cascade the power line communications (PLC) channel and the visible light communications (VLC) channel, in order to use the PLC channel as backbone for the VLC channel. This combination is suitable for applications in which hybrid PLC-VLC systems are needed. We investigate the behaviour of the cascaded channels for a full link transmission. Quadrature phase shift keying combined with orthogonal frequency division multiplexing (QPSK-OFDM) is used over the PLC channel and color shift keying (CSK) is deployed over the VLC channel to convey the information. Cascaded channel variances are analyzed. Complete simulated bit error rate (BER) is analyzed and presented for multiple scenarii that could occur in the two channels.
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