Papers by Mohammed Elmusrati
New and novel way for resources allocation in wireless communication has been proposed in this ... more New and novel way for resources allocation in wireless communication has been proposed in this paper. Under this new method, it has been shown that the required power budget becomes independent of the number of served terminals in the downlink. However, the required power depends only of the coverage area, i.e. the channel losses at the cell boarder. Therefore, huge number (theoretically any number) of terminals could be supported concurrently at finite and small downlink power budget. This could be very useful to support the downlink signalling channels in HSPA+, LTE, and 5G. It can be very useful also to support huge D2D communication downlinks. Moreover, and based on the same concept, a new system configuration for a single link point-to-point communication has been presented. With this new configuration, the achieved data rate becomes independent of the required transmit power. This means that any data rate can be achieved at the target BER and with small and finite transmit power. This seems violating with some major results of the Shannon theorem. This issue will be discussed in details in this article.
In this paper we propose heuristic and efficient algorithm to minimize the dropped connections in... more In this paper we propose heuristic and efficient algorithm to minimize the dropped connections in real time congested communication networks. This problem can be classified as combinatorial optimization problem. It is well known that there is no general closed form solution for this type of problems. Furthermore finding the optimal solutions in medium and large size cases of these problems is usually very expensive. Our proposed heuristic algorithm is very simple to implement and gives a close solution to the optimum in many different cases.
... ii This work is dedicated to the nearest persons to my heart my father Salem Elmusrati and in... more ... ii This work is dedicated to the nearest persons to my heart my father Salem Elmusrati and in loving memory of my mother, Zakia Mohamed (1947-1998) Page 7. ... Canada for their care and encouragement. My warm thanks for the reviewers of this thesis, Dr. Hassan El-Sallabi and ...
We study the problem of removing users from congested cells. We consider two different objectives... more We study the problem of removing users from congested cells. We consider two different objectives for the removal algorithms. The first objective is to maximize the throughput. The second objective is to minimize the number of removed connections. The optimal removing problem can be classified as a combinatorial optimization problem. It is well known that there is no general closed form solution for this type of problem. Furthermore, finding the optimal solutions in medium and large sizes of these problems is usually very exhausting. Consequently, we use heuristics to solve the problem. Our proposed heuristic algorithm is very simple to implement and gives a solution close to the optimum in many different cases.
In this paper, we investigate the performance of DS-CDMA systems with multiple-input multiple-out... more In this paper, we investigate the performance of DS-CDMA systems with multiple-input multiple-output (MIMO) antenna system and power control. The antenna array has been used in the receiving part in the base station and also in the transmitting part of the mobile station. The vector channel impulse response model (VCIP) has been used in the analysis. The CIR has been derived for different system configurations. The effects of using MIMO antenna system on the maximum achievable CIR in the cell have been also investigated. The gain of using MIMO system with power control in 3G-WCDMA systems has been illustrated by using computer simulations.
In this paper an RSSI based distance estimation technique for 802.15.4 network, based on CC2420 r... more In this paper an RSSI based distance estimation technique for 802.15.4 network, based on CC2420 radio core, is discussed. In this approach we use standard deviation (SD) of the RSSI value and the packet loss information as a part of model parameters estimation process. The SD and packet loss limits are optimized along with the curve parameters to achieve minimum distance error. The distance estimator uses these optimized limits as a measure of accuracy of the remote node's estimated distance.
When the channel measurement update rate is very slow compared to the channel fluctuations, the p... more When the channel measurement update rate is very slow compared to the channel fluctuations, the performance of conventional power control algorithms is greatly reduced. In this paper we introduce novel method to update the transmit power in such extreme situations. We propose to use random power allocation with certain distribution function and then using the channel measurements to update the statistics of this random power rather the power value itself. The truncated inverted exponential distribution is one candidate for the power distribution which is used in this paper. This distribution has one parameter which can be easily updated according to the channel quality. The signal-to-interference and noise ratio (SINR) is used as an indicator for the channel quality. The probability of outage when using the proposed power allocation is also given in mathematical form. Simulations show that, one may improve the average SINR when using the proposed algorithm compared to the conventional distributed power control algorithm.
… Conference, 2003. VTC 2003-Fall. 2003 …, 2003
In this paper we have constructed a centralized power control algorithm based on the tradeoff bet... more In this paper we have constructed a centralized power control algorithm based on the tradeoff between the maximization of the total throughput of the users and the minimization of their total transmitted power in cellular systems. Power control algorithm for total throughput maximization has been proposed in K. Chawla et al. (1998). In our algorithm, we use the same throughput maximization objective, but another objective for power minimization has been added. The multi-objective optimization problem has been solved using weighting method. A centralized power control algorithm has been obtained. The algorithm is a scaled version of the maximum throughput algorithm obtained in K. Chawla et al. (1998). The simulations show that at low additive white noise levels the total transmitted power can be reduced up to 95% compared with the algorithm given in K. Chawla et al. (1998) while the total throughput has reduced only by less than 3%.
Journal of Electromagnetic …, 2007
In this paper we propose the use of the State of Polarization (SOP) encoding in order to realize ... more In this paper we propose the use of the State of Polarization (SOP) encoding in order to realize an optical CDMA system. The SOP of the optical beam is alternately switched between two orthogonal SOPs according to a given codeword. Multiple users can use the network simultaneously each with a distinct codeword. Gold and Hadamard codes can be applied with minimal interference in the latter case. The optical beam power is constant in such case, therefore, self-phase and cross-phase effects can be eliminated.
In this paper we propose Multi-objective Distributed Power Control Algorithm for Spectrum-sharing... more In this paper we propose Multi-objective Distributed Power Control Algorithm for Spectrum-sharing Cognitive Radios (MODPCCR). As we know that for spectrum sharing cognitive radios the most important factor is the strict limited interference caused to the primary users. Our proposed MODPCCR algorithm is able to achieve certain SINR under the strict interference power constraint to primary users, where we assume that there is no perfect channel state information (CSI) of the secondary-primary links to be provided to secondary transmitters. Implementing MODPCCR algorithm on secondary users could protect primary users and achieve certain signal to noise and interference ratio (SINR) for secondary users as well.
European Transactions on …, 2009
When there is no feedback channels in wireless sensor networks or when the sensors are deaf (cann... more When there is no feedback channels in wireless sensor networks or when the sensors are deaf (cannot listen to the feedback channels), the conventional and practical method for power allocation is to use fixed power transmission. This method has many limitations such as near-far problems where the relatively far away sensors are blocked by near sensors and also the unnecessarily high power consumption for good channel sensors. One recent proposal to overcome such limitations is to use uniform random power allocation for terminals. In that work the system performance is analysed for static channels (i.e. snapshot assumption), where it shows that there is a considerable obtained gain when using uniform random power allocation over fixed power. An important question is about the performance of such transmission power strategy in case of a more realistic channel scenario such as Rayleigh fading channels. This paper answers this question. Detailed mathematical analysis as well as Monte-Carlo simulations for the system performance in Rayleigh fading channels are given in this paper. We show that the performance of uniform power allocation is much worse in case of fading channels than in static channels. Almost there is no gain of using uniform random power over fixed power in terms of average probability of outage. However, uniform random power may considerably reduce the total power consumption at small degradation of the average performance. This can be critical feature in energy constrained networks. n denote the interference and noise powers at the receiver, respectively. Let γ denotes the minimum required SINR at the receiver. The
In this paper we propose a new power control scheme for cognitive radios, Distributed Power Contr... more In this paper we propose a new power control scheme for cognitive radios, Distributed Power Control Algorithm for Cognitive Radios (DPCACR). As we know that in a cognitive system, the secondary users (SU) either transmit in an opportunistic way or coexist with the primary users to transmit simultaneously under the constraints that will not harm to the primary users. Previously, the interference temperature was announced to limit the transmit power of SUs. However, in 2007 the FCC has abandoned the concept which is not workable. In this paper, we consider the elastic transmission scenario for secondary system. The cognitive networks using code-division multiple access (CDMA) technology to transmit simultaneously with primary users in the same spectral band.
In this paper we study the capacity of spectrum sharing cognitive radios (CR) with Maximal Ratio ... more In this paper we study the capacity of spectrum sharing cognitive radios (CR) with Maximal Ratio Combining (MRC) diversity at the secondary receiver under asymmetric fading, where the channel from secondary transmitter to primary receiver suffer Nakagami-m fading while the one from secondary transmitter to its receiver follows Rayleigh Multipath fading. Our mathematical analysis and numerical results show that with MRC combining diversity at the secondary receiver, more capacity is achieved. In addition, when the SU tx-PUrx channel has less severe fading which strongly affects the capacity of CR channel, utilizing MRC combining technique for CR system could reduce the effects.
… 2010), 2010 IEEE, 2010
In this paper we study the capacity of spectrum sharing cognitive radios (CR) with Maximal Ratio ... more In this paper we study the capacity of spectrum sharing cognitive radios (CR) with Maximal Ratio Combining (MRC) diversity at the secondary receiver under asymmetric fading, where the channel from secondary transmitter to primary receiver suffer Nakagami-m fading while the one from secondary transmitter to its receiver follows Rayleigh Multipath fading. Our mathematical analysis and numerical results show that with MRC combining diversity at the secondary receiver, more capacity is achieved. In addition, when the SU tx-PUrx channel has less severe fading which strongly affects the capacity of CR channel, utilizing MRC combining technique for CR system could reduce the effects.
IEEE Transactions on Dielectrics and Electrical Insulation, 2012
In Finland, overhead covered conductors (CC) are commonly used in the medium voltage (MV) network... more In Finland, overhead covered conductors (CC) are commonly used in the medium voltage (MV) networks because the distribution loads in rural areas are not heavy and are widely distributed in the forested terrain. Such parts of the network are exposed to leaning trees and therefore partial discharging into the overhead CC frequently occurs. In this paper, a multi-end correlation-based technique for locating partial discharge (PD) sources on CC lines is presented. The theory of maximum correlation factor is used in order to find the time differences between signal arrivals at three synchronized-measuring points. This helps to solve the problem of varying parameters of the CC line that can change the propagation velocity and the problem of identifying the arrival times of the corresponding PD pulses at different measuring points. The algorithm is developed and tested using a simulated study and experimentally verified using an alternating current (ac) energized system. The Electromagnetic Transient Program-Alternative Transient Program (EMTP-ATP) is used to implement and analyze a PD monitoring system. The Discrete Wavelet Transform (DWT) is used to de-noise PD signals measured from a Rogowski coil utilized as a high frequency transducer. The noise model is added to the simulated-power network signals and then a DWT-based de-noising process is carried out. The proposed algorithm performance is evaluated by extracting the high frequency features using a windowed-standard deviation. The simulated and experimental evaluations prove that accurate PD source location can be achieved using the proposed algorithm technique.
… Conference, 2003. VTC …, 2003
In this paper, we suggest a method to estimate the carrier to interference ratio (CIR) informatio... more In this paper, we suggest a method to estimate the carrier to interference ratio (CIR) information of the uplink using the power control ON-OFF commands at the mobile station (MS). The estimated CIR information is used to adjust the transmitted power from the mobile terminal using the distributed constrained power control (DCPC) algorithm. The main advantage of our algorithm is that it can improve the performance of power control without any increase in power control signaling. The suggested algorithm is compared with the conventional fixed step power control (FSPC) algorithm by computer simulations. Considerable improvements in system performance are observed when using the suggested algorithm in comparison with the FSPC algorithm.
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Papers by Mohammed Elmusrati