Browsing by Author "Thottappillil, Rajeev"

Now showing 1 - 12 of 12
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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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    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, 2009-04) Anatory, Justinian; Kissaka, Mussa; Thottappillil, Rajeev; Theethayi, N.; 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 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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    Expressions for Current/Voltage Distribution in Broadband Power-Line Communication Networks Involving Branches
    (IEEE, 2008-01) Anatory, Justinian; Kissaka, Mussa; Thottappillil, Rajeev; Theethayi, N.; Mvungi, Nerey H.
    Estimation of electromagnetic (EM)-fleld emissions from broadband power-line communication systems (BPLC) is necessary, because at its operating frequencies, the radiated emissions from BPLC systems act as sources of interference/crosstalk to other radio-communication systems. Currently, the transmission-line (TL) system used for BPLC is complex, involving arbitrarily/irregularly distributed branched networks, arbitrary termination loads, varying line lengths, and line characteristic impedance. In order to study the electromagnetic-compatibility (EMC) issues associated with the radiated emissions of such complex BPLC networks, knowledge of current and voltage distributions along the length of the power-line channels is needed. This paper attempts to derive and present generalized expressions for either the current or voltage distribution along the line (whose TL parameters are known) between the transmitting and receiving ends for any line boundary condition and configuration based on the TL theory. The expressions presented in this paper could be beneficial for direct calculation of EM emissions from BPLC systems.
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    The Influence of Load Impedance, Line Length, and Branches on Underground Cable Power-Line Communications (PLC) Systems
    (IEEE, 2008-01) Kissaka, Mussa; Theethayi, N.; Anatory, Justinian; Mvungi, Nerey H.; Thottappillil, Rajeev
    An underground cable power transmission system is widely used in urban low-voltage power distribution systems. In order to assess the performance of such distribution systems as a low-voltage broadband power-line communication (BPLC) channel, this paper investigates the effects of load impedance, line length, and branches on such systems, with special emphasis on power-line networks found in Tanzania. From the frequency response of the transfer function (ratio of the received and transmitted signals), it is seen that the position of notches and peaks in the magnitude are largely affected (observed in time-domain responses too) by the aforementioned network configuration and parameters. Additionally, channel capacity for such PLC channels for various conditions is investigated. The observations presented in this paper could be helpful as a suitable design of the PLC systems for better data transfer and system performance.
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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.