Browsing by Author "Theethayi, Nelson"

Now showing 1 - 17 of 17
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    Broadband Power Line Communications: Analysis of Indoor Power Line Network in Developing Countries
    (JKUAT, 2006) Anatory, Justinian; Theethayi, Nelson; Kissaka, Mussa; Mvungi, Nerey H.
    The effects of load impedance, line length and branches on the performance of an indoor voltage broadband power line communications (BPLC) are presented in this paper. The power line network topology adopted here is similar to that of the system found in Tanzania. Investigation on effects of network load impedances, direct transmitter to receiver line length, branched line length and numbers of branches have been carried out. The frequency response of the power line transfer function shows that position of notches and peaks in the magnitude and phase responses are largely affected by the above network parameters particularly attenuation and dispersion. The response was also observed in the time domain. The observations made in this work could be useful in the design of high performance PLC systems for data transfer
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    Broadband Power Line Communications: Analysis of Indoor Power Line Network in Developing Countries
    (JKUAT, 2006) Anatory, Justinian; Theethayi, Nelson; Kissaka, Mussa; Mvungi, Nerey H.
    The effects of load impedance, line length and branches on the performance of an indoor voltage broadband power line communications (BPLC) are presented in this paper. The power line network topology adopted here is similar to that of the system found in Tanzania. Investigation on effects of network load impedances, direct transmitter to receiver line length, branched line length and numbers of branches have been carried out. The frequency response of the power line transfer function shows that position of notches and peaks in the magnitude and phase responses are largely affected by the above network parameters particularly attenuation and dispersion. The response was also observed in the time domain. The observations made in this work could be useful in the design of high performance PLC systems for data transfer
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    Broadband Power line Communications: Performance Analysis: transactions on Engineering, Computing and Technology
    (2006-12) Anatory, Justinian; Kissaka, Mussa; Theethayi, Nelson; Mvungi, Nerey H.
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    Broadband Power Line Communications: The factors Influencing Wave Propagations in the Medium Voltage Lines
    (IEEE, 2007-03) Anatory, Justinian; Theethayi, Nelson; Kissaka, Mussa; Mvungi, Nerey H.
    This paper presents the influencing of load impedance, line length and branches on the performance of medium voltage power line communication (PLC) network. The power line network topology adopted here is similar to that of the system in Tanzania. Different investigation with regard to network load impedances, direct line length (from transmitter to receiver), branched line length and number of branches has been investigated. From the frequency response of the transfer function (ratio of the received and transmitted signal), it is seen that position of notches and peaks in the magnitude responses are largely affected in terms of attenuation and dispersion by the above said network parameters/configuration. The observations presented in the paper could be helpful in suitable design of the PLC systems for a better data transfer and system performance.
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    Broadband Power Line Communications: The factors Influencing Wave Propagations in the Medium Voltage Lines
    (IEEE, 2007) Anatory, Justinian; Theethayi, Nelson; Kissaka, Mussa; Mvungi, Nerey H.
    this paper presents the influencing of load impedance, line length and branches on the performance of medium voltage power line communication (PLC) network. The power line network topology adopted here is similar to that of the system in Tanzania. Different investigation with regard to network load impedances, direct line length (from transmitter to receiver), branched line length and number of branches has been investigated. From the frequency response of the transfer function (ratio of the received and transmitted signal), it is seen that position of notches and peaks in the magnitude responses are largely affected in terms of attenuation and dispersion by the above said network parameters/configuration. The observations presented in the paper could be helpful in suitable design of the PLC systems for a better data transfer and system performance.
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    Broadband Power-Line Communication Channel Model: Comparison between Theory and Experiments
    (IEEE, 2008) Anatory, Justinian; Theethayi, Nelson; Thottappillil, Rajeev; Kissaka, Mussa; Mvungi, Nerey H.
    Recently different models have been proposed for analyzing the BPLC systems based on transmission line (TL) theory. In this paper one such BPLC model is validated using laboratory experiments by comparing the channel transfer functions. A good agreement between the BPLC model based on TL theory and experiments is found for channel frequencies up to about 100MHz
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    A Broadband Power-Line Communication System Design Scheme for Typical Tanzanian Low-Voltage Network
    (IEEE, 2009) Anatory, Justinian; Theethayi, Nelson; Thottappillil, Rajeev; Mvungi, Nerey H.
    This paper presents the influence of line length, number of branches (distributed and concentrated), and terminal impedances on the performance of a low-voltage broadband power-line communication channel. For analyses, the systems chosen are typical low-voltage power-line networks found in Tanzania. The parameters varied were the network’s load impedances, direct line length (from transmitter to receiver), branched line lengths, and number of branches. From the frequency responses of the transfer functions (ratio of the received and transmitted signal), it is seen that the position of notches and peaks in the amplitude responses are affected by the aforementioned network parameters and topology. As a result, the time-domain responses are attenuated and distorted. Time-domain responses of power-line channels under various conditions are also investigated for a given pulse input at the transmitter. The observations presented in this paper could be useful for suitable power-line communication system design.
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    Broadband Power-Line Communications: The Channel Capacity Analysis
    (IEEE, 2008-01) Anatory, Justinian; Kissaka, Mussa; Theethayi, Nelson; Thottappillil, Rajeev; Mvungi, Nerey H.
    The power line has been proposed as a solution to deliver broadband services to end users. Various studies in the recent past have reported a decrease in channel capacity with an increase in the number of branches for a given channel type whether it is an indoor or low-voltage (LV) or medium-voltage (MV) channel. Those studies, however, did not provide a clear insight as to how the channel capacity is related to the number of distributed branches along the line. This paper attempts to quantify and characterize the effects of channel capacity in relation to the number of branches and with different terminal loads for a given type of channel. It is shown that for a power spectral density (PSD) between 90 dBm/Hz to 30 dBm/Hz, the channel capacity decreases by a 20-30 Mb/s/branch, 14-24 Mb/s/branch, and a 20-25 Mb/s/branch for an MV channel, LV channel, and indoor channel, respectively. It is also shown that the channel capacity is minimum when the load impedance is terminated in characteristic impedances for any type of channel treated here. It is shown that there could be a significant loss in channel capacity if a ground return was used instead of a conventional adjacent conductor return. The analysis presented in this paper would help in designing appropriate power-line communication equipment for better and efficient data transfer.
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    Broadband PowerLine Communications: Performance Analysis
    (World Academy of Science, Engineering and Technology, 2008) Anatory, Justinian; Theethayi, Nelson; Kissaka, Mussa; Mvungi, Nerey H.
    Power line channel is proposed as an alternative for broadband data transmission especially in developing countries like Tanzania [1]. However the channel is affected by stochastic attenuation and deep notches which can lead to the limitation of channel capacity and achievable data rate. Various studies have characterized the channel without giving exactly the maximum performance and limitation in data transfer rate may be this is due to complexity of channel modeling being used. In this paper the channel performance of medium voltage, low voltage and indoor power line channel is presented. In the investigations orthogonal frequency division multiplexing (OFDM) with phase shift keying (PSK) as carrier modulation schemes is considered, for indoor, medium and low voltage channels with typical ten branches and also Golay coding is applied for medium voltage channel. From channels, frequency response deep notches are observed in various frequencies which can lead to reduce the achievable data rate. However, is observed that data rate up to 240Mbps is realized for a signal to noise ratio of about 50dB for indoor and low voltage channels, however for medium voltage a typical link with ten branches is affected by strong multipath and coding is required for feasible broadband data transfer
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    The Effects of Interconnections and Branched Network in the Broadband Powerline Communications
    (Vigyan Bhavan, 2005-10-29) Anatory, Justinian; Theethayi, Nelson; Thottappillil, Rajeev; Kissaka, Mussa; Mvungi, Nerey H.
    The frequency responses of a single-phase powerline channel with interconnections are derived. Different loading at different branches is considered. The results indicate that there are significant attenuations and distortions as the number of branches are increased. Broadband signal with pulse width smaller than the channel delay spread causes a series of pulses at the receiver. The small impedances at the terminations cause severe distortions. As the number of interconnections at the same point increases the signal from the source to that point increases in negative sides, which has implications to electromagnetic interference.
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    The Effects of Load Impedance, Line Length, and Branches in the BPLC—Transmission-Line Analysis for Indoor Voltage Channel
    (IEEE, 2007-10) Anatory, Justinian; Kissaka, Mussa; Thottappillil, Rajeev; Theethayi, Nelson
    This paper presents the effects of load impedance, line length and branches on the performance of an indoor voltage broadband power line communications (BPLC) network. The power line network topology adopted here is similar to that of the system found in Tanzania. Different investigations with regard to network load impedances, direct line length from transmitter to receiver, branched line length, and number of branches has been carried out. From the frequency response of the transfer function (ratio of the received and transmitted signal), it is seen that position of notches and peaks in the magnitude and phase responses are largely affected by the above said network parameters/configuration, mainly in terms of attenuation and dispersion. These effects are observed in the time domain responses also. The observations presented in the paper could be helpful in the suitable design of the BPLC systems for a better data transfer and system performance.
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    The Effects of Load Impedance, Line Length, and Branches in the BPLC—Transmission-Lines Analysis for Medium-Voltage Channel
    (2007-10) Kissaka, Mussa; Anatory, Justinian; Thottappillil, Rajeev; Theethayi, Nelson; Mvungi, Nerey H.
    This paper presents the effects of load impedance, line length and branches on the performance of medium-voltage power-line communication (PLC) network. The power-line network topology adopted here is similar to that of the system in Tanzania. Different investigation with regard to network load impedances, direct line length (from transmitter to receiver), branched line length and number of branches has been investigated. From the frequency response of the transfer function (ratio of the received and transmitted signal), it is seen that position of notches and peaks in the magnitude and phase responses are largely affected in terms of attenuation and dispersion by the above said network parameters/configuration. These are observed in the time domain responses too. The observations presented in the paper could be helpful in suitable design of the PLC systems for a better data transfer and system performance.
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    The Effects of Load Impedance, Line Length,and Branches in Typical Low-Voltage Channels of the BPLC Systems of Developing Countries: Transmission-Line Analyses
    (IEEE, 2009) Justinian, Anatory; Theethayi, Nelson; Thottappillil, Rajeev; Kissaka, Mussa; Mvungi, Nerey H.
    This paper presents the influence of line length, number of branches (distributed and concentrated), and terminal impedances on the performance of a low-voltage broadband power-line communication channel. For analyses, the systems chosen are typical low-voltage power-line networks found in Tanzania. The parameters varied were the network’s load impedances, direct line length (from transmitter to receiver), branched line lengths, and number of branches. From the frequency responses of the transfer functions (ratio of the received and transmitted signal), it is seen that the position of notches and peaks in the amplitude responses are affected by the aforementioned network parameters and topology. As a result, the time-domain responses are attenuated and distorted. Time-domain responses of power-line channels under various conditions are also investigated for a given pulse input at the transmitter. The observations presented in this paper could be useful for suitable power-line communication system design.
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    The Effects of Multipath on OFDM Systems for Broadband Power-Line Communications a Case of Medium Voltage Channel
    (World Academy of Science, Engineering and Technology, 2009) Anatory, Justinian; Theethayi, Nelson; Mwase, Christine; Thottappillil, Rajeev; Mvungi, Nerey H.
    Power-line networks are widely used today for broadband data transmission. However, due to multipaths within the broadband power line communication (BPLC) systems owing to stochastic changes in the network load impedances, branches, etc., network or channel capacity performances are affected. This paper attempts to investigate the performance of typical medium voltage channels that uses Orthogonal Frequency Division Multiplexing (OFDM) techniques with Quadrature Amplitude Modulation (QAM) sub carriers. It has been observed that when the load impedances are different from line characteristic impedance channel performance decreases. Also as the number of branches in the link between the transmitter and receiver increases a loss of 4dB/branch is found in the signal to noise ratio (SNR). The information presented in the paper could be useful for an appropriate design of the BPLC systems.
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    An Experimental Validation for Broadband Power-Line Communication (BPLC) Model
    (IEEE, 2008-07) Anatory, Justinian; Theethayi, Nelson; Kissaka, Mussa; Mvungi, Nerey H.
    Recently, different models have been proposed for analyzing the broadband power-line communication (BPLC) systems based on transmission-line (TL) theory. In this paper, we make an attempt to validate one such BPLC model with laboratory experiments by comparing the channel transfer functions. A good agreement between the BPLC model based on TL theory and experiments are found for channel frequencies up to about 100 MHz. This work with controlled experiments for appropriate validation could motivate the application and extension of TL theory-based BPLC models for the analysis of either indoor or low-voltage or medium-voltage channels.
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    Investigation on Factors Influencing the Channel Capacity of Power line Network for BPLC Systems
    (IEEE, 2007) Anatory, Justinian; Theethayi, Nelson; Thottappillil, Rajeev; Mvungi, Nerey H.; Kissaka, Mussa
    Power line has been proposed as a solution to deliver broadband services to end users. Various studies in the recent past have reported the decrease in channel capacity with increase in number of branches for a given channel type (indoor channel or access (low voltage) channel or medium channel) [1- 4]. Those studies however did not provide a clear insight as to how the channel capacity is related to the number of distributed branches along the line. This paper attempts to quantify and characterize the effects of channel capacity in relation to number of branches and also with different terminal loads for a given type of channel. It is shown that for power spectral density (PSD) between -90dBm/Hz to -30dBm/Hz, the channel capacity decreases by 20-30Mbps/branch, 14-24Mbps/branch and 20- 25Mbps/branch for medium voltage channel, low voltage channel and indoor channel respectively. In additional, it is shown that the channel capacity is minimum when the load impedance is terminated in characteristic impedances for any type of channel treated here. It is shown that there could be significant loss in channel capacity if a ground return were used instead of adjacent conductor return. The analysis presented in the paper would help in designing appropriate power line communication equipment for better and efficient data transfer.
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    Power Line Channel Models: Comparisons between different Modeling Adopted in BPLC Systems
    (Università degli Studi di Udine, 2009) Anatory, Justinian; Theethayi, Nelson; Mvungi, Nerey H.
    The paper compares different power channel models used for modeling power line system. The models compared are Zimmermann and Dostert, Philipps, Anatory et al and generalized TL approach. The validity of the modeling was compared with ATP-EMTP which also uses transmission line approach. It is found that for a power-line network with one branch Philipps , Anatory et al and generalized TL approach have similar results with ATP-EMTP, however Zimmermann and Dostert model indicates the same amplitude with other model but different time delay. It is observed that when the numbers of branches were increased only generalized TL approach results were comparable with ATP-EMTP results. The results in paper can read to the improvements in BPLC system design.