Department of Electronics and Telecommunications Engineering

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Browsing Department of Electronics and Telecommunications Engineering by Title

Now showing 1 - 20 of 158
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    Access Authorization and Monitoring for Web Based Resources for e-Learning System for Secondary Schools in Tanzania
    (2007-11-16) Mkocha, K.; Kissaka, Mussa; Mwinyiwiwa, B. M. M.
    This paper presents the development of a mechanism for the authorization and monitoring of data for a web based e-learning system. System data as well as the different user groups accessing the data have been defined. Constraints to use the LAMP solution stack, the UML models are coded in PHP which is embedded in the HTML. These interfaces are used as doorways through which different users, as per their role, can access and work on the system data according to their clearance. On the other hand, the administrator can see different reports, from system logs by simply pressing a button.
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    Adaptive Charbonnier superresolution method with robust edge preservation capabilities
    (Journal of Electronic Imaging, 2013-12-16) Maiseli, Baraka J.; Liu, Qiang; Elisha, Ogada Achieng; Gao, Huijun
    Superresolution (SR) is known to be an ill-posed inverse problem, which may be solved using some regularization techniques. We have proposed an adaptive regularization method, based on a Charbonnier nonlinear diffusion model to solve an SR problem. The proposed model is flexible because of its automatic capability to reap the strengths of either linear isotropic diffusion, Charbonnier model, or semi-Charbonnier model, depending on the local features of the image. On the contrary, the models proposed from other research works are fixed and hence less feature dependent. This makes such models insensitive to local structures of the images, thereby producing poor reconstruction results. Empirical results obtained from experiments, and presented here, show that the proposed method produces superresolved images which are more natural and contain well-preserved and clearly distinguishable image structures, such as edges. In comparison with other methods, the proposed method demonstrates higher performance in terms of the quality of images it generates.
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    Analutical Modeling of a Large Local Area Network – Part I: Internet raffic Characterization
    (College of Engineering and Technology, University of Dar es Salaam, 2008-07) Luhanga, Matthew L.; Cuthbert E.B.M., Amos,
    The goal of both IP network operators and the end users is to get the highest performance from the system for a given cost. This makes Performance a key criterion in the design, procurement, and use of computer and communication systems. In order to address problems associated with performance degradation of operational communications systems, over the last decade, traffic engineering techniques have emerged in an attempt to optimize communication systems' performance and ensure more efficient use of their resources. One of these techniques is analytical modeling.
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    The Analysis of a Transmission System Employing SONET-Like Frames
    (Elsevier, 1998) Kundaeli, Herald N.
    Frame synchronization systems that employ multiple-code markers have been shown to give better synchronization performance than systems that employ single-code markers. It has been shown, however, that only a few of the codewords in the marker need to be used in order to attain optimum synchronization performance. Among the multiple-code marker systems which have gained wide usage recently is the SONET scheme for information transmissions at high data rates. In this report, a model for the analysis of the synchronization performance of systems which employ SONET-like frames is developed. The model is then applied to the SONET scheme to study how its performance varies with the choice of the parameters in its frame structure.
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    The Analysis of an Optical Fibre Communication System Using Laser Rate Equations.
    (2001) Kundaeli, Herald N.
    Fibre dispersion has been the main limitation to high-speed data transmissions employing optical fibres. Various techniques and methods for combating this limitation have therefore been proposed. Such techniques include electrical and optical dispersion compensation, optical and electrical pulse shaping, and modifications of the fibre dispersion profiles. Some of these techniques and methods have resulted into very effective but expensive systems, and it has been difficult to adopt them. Others have resulted into inexpensive systems with moderate performance, and some of these have been adopted. In the present paper, the effect of electrical pulse shaping on dispersion-induced pulse distortion is investigated by computer simulation techniques. The results show that the detrimental effects of the dispersion can be greatly reduced without incurring very high costs. Moreover, this method is applicable to systems employing standard optical fibres, the major component in the already installed systems.
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    Analysis of Powerline Channel Model for Communication from Primary Substation Node to End-Users
    (Winter-Spring, 2004) Anatory, Justinian; Mvungi, Nerey H.; Kissaka, Mussa;
    Abstract—The low voltage power networks in developing countries like Tanzania are designed without taking into consideration their application in data communication. In order to use them for data communication, powerline channel models have been developed and analysed in order to understand the factors that will affect the transmission. In this paper transfer characteristics of powerline channel from power users to primary substation have been modeled and analyzed. Simulation results show that the signal in PLC environment attenuates more with interconnections, which needs to be amplified/regenerated within a few meters.
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    Analysis of the Architecture and MAC Protocol for Power-line Networks
    (2003) Iddi, Hashim U.; Kissaka, Mussa; Mvungi, Nerey H.
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    The Application of Lognormal Mixture Shadowing Model for B2B Channels
    (IEEE, 2018-09) Cheffena, Michael; Mohamed, Marshed
    In this article, a Lognormal mixture shadowing model based on a cluster concept is utilized in the modeling of body-to-body (B2B) channels for different running and cycling activities. The mixture model addresses the inaccuracies observed using a unimodal distribution that may not accurately represent the measurement dataset. Parameters of the mixture model are estimated using the expectation-maximization (EM) algorithm. The accuracy of the proposed mixture model is compared to other commonly utilized unimodal distributions showing significant improvement in representing the empirical dataset. The measured data, as well as the developed model, can be used for accurate planning and deployments of wireless B2B networks for use in various sporting and other related activities.
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    Appropriate Media Access Control Protocol for Broadband Power-Line Access Network of Developing Countries: A Case of Tanzania
    (2012-06) Abdalla, Abdi T
    This paper investigates and compares the performances of different MAC protocols including ALOHA, slotted ALOHA and Carrier Sense Multiple Access with Collision Avoidance with the application to broadband powerline networks of Dar es Salaam and suggesting the appropriate one. In this investigation, the powerline network of Kariakoo was used as case study. During investigation, wireshark network protocol analyzer was used to analyze data traffic of similar existing network for projection and the data were simulated using MATLAB. From the results, pure ALOHA protocol gives the maximum throughput of 15.99%, slotted-ALOHA protocol gives 21.16% and CSMA/CA gives the maximum throughput of 30.6% under the same traffic load of 0.28Erlang keeping arrival rates and packet lengths constant.
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    Appropriate Technology for Electrical Power Metering in Tanzania
    (2004) Anatory, Justinian; Kissaka, Mussa; Mvungi, Nerey H.
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    Aspect dependent efficient multipath ghost suppression in TWRI with compressive sensing
    (Cambridge University Press and the European Microwave Association, 2017) Muqaibel, Ali; Abdalla, Abdi T; Alkhodary, Mohammad; AlDharrab, Suhail
    In through-the-wall radar imaging, multipath propagation can create ghost targets, which can adversely affect the image reconstruction process. However, unlike genuine targets, ghost positions are aspect-dependent, which means their position changes with the transceiver location. This paper proposes efficient ghost suppression methods exploiting aspect dependence feature under compressive sensing framework. This paper proposes a generalized signal model that accommodates for the reflections of the front-wall and target-to-target interactions, making the scheme more practical, yet the knowledge of the location of reflecting geometry is not a requirement as in most of the recent literatures. In addition, the sensing matrix is greatly reduced making the methods more attractive. Moreover, this paper investigates the influence of array configurations by examining two antenna array configurations: multimonostatic, and single-view bistatic configurations. Results based on synthesized data and real experiment show that the proposed method can greatly suppress multipath ghosts and hence increase signal-to-clutter ratio.
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    Aspect Dependent Multipath Ghost Suppression in TWRI Under Compressive Sensing Framework
    (2015) Abdalla, Abdi T; Muqaibel, Ali H.; Al-Dharrab, Suhail
    In through-the-wall radar imaging, multipath propagation can create ghost targets which can adversely affect the image reconstruction process. The fact that the ghost positions changes with the radar locations which is referred to as aspect dependence has been reported as among the features distinguishing ghost from true target. This paper proposes ghost suppression method which exploit the aspect dependence feature under compressive sensing framework. The existing signal model is modified so that the location of reflecting geometry is no longer a constraint. Also the sensing matrix is greatly reduced making the methods more attractive. Simulation results demonstrate the effectiveness of the proposed methods.
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    The Assessment of Vulnerability and Adaptation to Climate Change Impacts in Tanzania
    (Centre for Energy, Environment, Science and Technology, 1998, 1998) Mwandosya, Mark J.; Nyenzi, Buruhani Salum; Luhanga, Matthew L.
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    Asynch-NET: Footstep for Always-On e-Services in the Rural Areas of Developing Countries: Case Study-Tanzania
    (2006-07-12) Greyson, K.; Kissaka, Mussa; Haule, D.; Ndume, V.
    The asynchronous network (Asynch-NET) provided by mobile access point (MAP) in the community of rural areas of developing countries has proved success in many regions of the developing countries. This asynchronous network is the footstep for e-services implementation in the communities with low-income and low population density. Basically, the cost of implementing a conventional "always-on" link in the rural areas of developing countries is very high that does not attract investors to put effort on. The paper presents a technique that is applied to the Asynch-NET framework so as to provide "the always-on" e-services at the similar operating cost of Asynch-NET.
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    An automatic and cost-effective parasitemia identification framework for low-end microscopy imaging devices
    (IEEE, 2015-09-03) Maiseli, Baraka J.; Mei, Jiangyuan; Gao, Huijun; Yin, Shen
    In the detection of Malarial parasites from a patient, it is usually necessary to carefully examine the corresponding blood-slide smear and distinguish the infected and healthy Red Blood Cells (RBCs). If this process is done manually, as evidenced in common traditional approaches, the following challenges may be encountered: inaccuracy of the lab results, which originates from normal human errors or lack of experience of a person conducting diagnosis, and large processing times. Consequently, doctors and specialists are likely to provide improper prescriptions to patients. With the improvement of the computational power of computers, however, the whole diagnosis process can be automated. Several methods in literature have been proposed for this purpose. Most of these methods demand the availability of high-end microscopy imaging systems to generate reliable and accurate results. Such costly advanced devices may not be afforded by developing countries with sluggish economic growth. In this paper, therefore, we have developed a cost-effective framework which can address the mentioned challenge. Our approach introduces a Super Resolution (SR) model into the existing framework to enhance the resolution of the input images before letting them subjected to the subsequent detection stages. This provides a possibility for applying the low-end microscopy devices capable of capturing Low Resolution (LR) blood smear images for identifying the degree of Malaria in a patient. In the proposed framework, the SR component uses the nonlinear Charbonnier diffusion model in the regularization part because of its good regularity characteristics. Experimental results demonstrate strong correlation of our method and the manual one.
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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 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.