Browsing by Author "Khalifa, Othman O."

Now showing 1 - 9 of 9
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    Analysis of multicomponent transient signals using MUSIC superresolution technique
    (IEEE, 2008-05-13) Jibia, Abdussamad U.; Salami, Momoh-Jimoh E.; Khalifa, Othman O.
    The problem of estimating the parameters of transient signals consisting of real decay constants has for long been a subject of study by many researchers. Such signals arise in many problems in Science and Engineering like nuclear magnetic resonance for medical diagnosis, deep-level transient spectroscopy, fluorescence decay analysis, etc. Many techniques have been suggested by researchers to analyse these signals but they often produce mixed results. A new method of analysis using modified MUSIC (multiple signal classification) subspace algorithm is successfully applied to the analysis of this signal. A noisy multiexponential signal is subjected to a preprocessing procedure consisting of Gardenerspsila transformation and inverse filtering. Modified MUSIC algorithm is then applied to the deconvolved data. The parameters of focus in this paper are the number of components and decay constants. It is shown that with this technique parameter estimates do not significantly change with signal to noise ratio. The superiority of this algorithm over conventional MUSIC algorithm is also shown.
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    Analysis of transient multiexponential signals using cepstral deconvolution
    (Academic Press, 2010-07-01) Jibia, Abdussamad U.; Salami, Momoh-Jimoh E.; Khalifa, Othman O.; Aibinu, A. M.
    We propose and test a new method of multiexponential transient signal analysis. The method based on cepstral deconvolution is fast and computationally inexpensive. The multiexponential signal is initially converted to a deconvolution model using Gardners' transformation after which the proposed method is used to deconvolve the data. Simulation and experimental results indicate that this method is good for determining the number of components but performs poorly in accurately estimating the decay rates. Influence of noise is not considered in this paper.
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    Border Gateway Protocol to provide failover in multihoming environment
    (Springer Singapore, 2017-03-01) Ahmed, Muhammed Z.; AbdallahHashim, Aisha H.; Khalifa, Othman O.; Salami, Momoh-Jimoh E.
    Nowadays Internet access across the globe is very crucial because of the huge size of useful data that the Internet stores. This stimulates most ISPs to choose a reliable routing protocol in order to preserve the security and guarantee of customer’s data on the Internet. By multi-homing a network using BGP, a more control of balancing the traffic load and achieving redundancy becomes possible. This will enhance network performance, quality throughput and better routing policies on the Internet. Single-homed Internet communication link between networks’ Internet service provider does not inspire with confidence because of excessive traffic and device or human error that may arise. We use BGP because of its ability to choose the best path to a destination particularly in a Multihoming environment. Our simulation results are achieved using GNS3 emulator and Wireshark network analyser. We carried out two simulations to run BGP Multihoming to the same service provider and to different service provider. In both scenarios we run the simulations in failover mode and in load-shearing mode. Simulation results show that BGP Multihoming to different service providers provides failover to ISP networks. For a home and enterprise network to have a certain level of failover or redundancy there is a need to employ the use of BGP Multihoming to different service provider.
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    Cramer-rao lower bound for parameter estimation of multiexponential signals
    (IEEE, 2009-05-18) Jibia, Abdussamad U.; Salami, Momoh-Jimoh E.; Khalifa, Othman O.; Elfaki, Faiz A. M.
    The Cramer Rao Lower Bound on the mean square error of unbiased estimators is widely used as a measure of accuracy of parameter estimates obtained from a given data. In this paper, derivation of the Cramer-Rao Bound on real decay rates of multiexponential signals buried in white Gaussian noise is presented. It is then used to compare the efficiencies of some of the techniques used in the analysis of such signals. Specifically, two eigendecomposition-based techniques as well as SVD-ARMA (Singular Value Decomposition Autoregressive Moving Average) method are tested and evaluated. The two eigenvector methods were found to outperform SVD-ARMA with minimum norm being the most reliable at very low SNRs (Signal to Noise Ratios).
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    Development of mathematical model for the prediction of microwave signal attenuation due to duststorm
    (IEEE, 2008-05-13) Elabdin, Zain; Islam, Md Rafiqul; Khalifa, Othman O.; Raouf, Hany Essam A.; Salami, Momoh-Jimoh E.
    Signal attenuation caused by duststorm is one of the major problems in utilization of microwave bands for terrestrial and space communication especially at desert and semi desert area. This paper presented a mathematical model developed to predict the microwave signal attenuation due to duststorm. The proposed model enables the convenient calculation of the microwave signal path attenuation which relates visibility, frequency, particle size and complex permittivity of duststorm. The predicted values from the mathematical model are compared with the measured values observed in Sudan and Saudi Arabia shows relatively close agreement.
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    Effect of multiple deconvolution parameters on the resolvability of decay rates of multiexponential signals
    (IEEE, 2008-06-25) Jibia, Abdussamad U.; Salami, Momoh-Jimoh E.; Khalifa, Othman O.
    Noise reduction in deconvolution process has been a challenge to researchers in the field of signal processing. The problem is ill-posed and various algorithms have been developed to reduce noise enhancement. The effect of using multiple noise-compensating parameters in the deconvolution of multiexponential signals is considered in this paper. Three parameters are simultaneously adjusted to obtain optimal reduction in noise. It is shown that this approach performs better than a single parameter approach.
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    Effect of sampling on the parameter estimates of multicomponent transients
    (IEEE, 2010-02-26) Jibia, Abdussamad U.; Salami, Momoh-Jimoh E.; Khalifa, Othman O.
    The need to estimate the parameters of transient multiexponential signals frequently arises in different areas of applied science. A classical technique that has been frequently used with different modifications is the Gardner transform. Gardner transform is used to convert the original data signal into a convolution model. Converting this model into a discrete type for further analysis depends on the selection of correct sampling conditions. Previously, a relationship between the sampling frequency and the weighting factor in the modified Gardner transform was derived. In this paper, the effect of this relationship on the accuracy of parameter estimates is investigated.
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    Performance of Turbo Code in CDMA under AWGN Channel
    (International Journal of Future Generation Communication and Networking, 2017-05-01) Babiker, Mohanad; Khalifa, Othman O.; Hashim, Aisha H. A.; Salami, Momoh-Jimoh E.; Ahmed, Muhammed Z.
    Carrier Division Multiple Access is considered as an efficient technique in wireless communication due to its high possibility to serve an unlimited number of users. CDMA uses the same frequency concurrently with wireless communication. In this paper, the performance and evaluation of turbo code are duly presented followed by the examination of CDMA under AWGN channel was highlighted. The simulation estimated to achieve bit error rate of less than 10-2 frame size. To this end, the results of the simulation show that the Bit Error Rate is inversely proportional to the size of the frame and directly proportional the number of iteration in the decoder.
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    Queuing Theory Approach for Evaluating Rate of Transmission in Wireless Network Using Network Coding
    (SCIENCE & ENGINEERING RESEARCH SUPPORT SOC, 2017-06-01) Ahmed, Muhammed Z.; Khalifa, Othman O.; Hassan, Aisha; Hashim, Abdallah; Salami, Momoh-Jimoh E.; Babikier, Muhanad
    Due to the rapid development in the transmission of Wireless Network technologies, the need for rate evaluation using network coding demands urgent attention. This is solely dependent on how to improve on high performance communication channels for user’s interest. In this paper, an approach of using queuing theory in a wireless network is presented. The idea of network coding in a wireless environment address the transmission of packets not only in unicast form but also address the conflict in packet movement across a channel. Network coding also contributes greatly in computer communication system and other computer based electronic appliances. This means that a source is transmitting packets to a particular destination according to the user’s needs in a communication system. Packet transmission is enhanced within the wireless network using queuing theory. In this approach, the first routers are set to be the user access router and another directly connected router is set to be the source router. The user access router is set to connect 11 number of other routers where mainly the network coding is conducted. The results show an improvement in transmission rate by applying network coding as compared to other scenarios where networks coding are not utilized or the conventional routing either.