Mohamed Zaki | Cairo University (original) (raw)

Papers by Mohamed Zaki

Wireless Personal Communications, 2007

One of the challenging tasks in Personal Communication Services (PCS) is to efficiently maintain ... more One of the challenging tasks in Personal Communication Services (PCS) is to efficiently maintain the location of PCS subscribers who move from one region to another (hereafter called mobile users). When a mobile user receives a call, the network has to quickly determine its current location. The existing location management scheme suffers from high signaling traffic in locating the mobile users. Two-level forwarding pointer scheme has been proposed from per-user forwarding pointer scheme to reduce the cost of signaling traffic. In this paper, we enhance the two-level forwarding pointer scheme. When a mobile user moves from its current Registered Area (RA), which is served by Mobile Switching Center (MSC), to another RA the local switch that acts as a parent of those two MSCs maintains this movement in its memory (hereafter called cache entry). A cache entry is used to locate rapidly the mobile user instead of querying the Home Location Register (HLR) and waiting for its reply. HLR is centralized in the network and far away from the mobile users so that the signaling traffic crossing it is expensive. Sometimes the cache entry may be failed to reach the mobile user then a two-level forwarding pointers will be created from the corresponding Visitor Location Register (VLR), attached to its MSC, through a correct path to locate the mobile user. Thus, there is a saving in cost of querying the underlying HLR. The analytical results indicate that such proposal efficiently reduces the signaling traffic cost for all values of Call to Mobility Ratio (CMR), this is especially considerable when CMR ≥1, without any increase in the call setup delay.

Lecture Notes in Computer Science, 2011

2009 Formal Methods in Computer-Aided Design, 2009

2008 International Conference on Microelectronics, 2008

2009 4th International Design and Test Workshop (IDT), 2009

2009 3rd International Conference on Signals, Circuits and Systems (SCS), 2009

One of the challenges for the verification of analog and mixed signal (AMS) designs is the stocha... more One of the challenges for the verification of analog and mixed signal (AMS) designs is the stochastic behavior associated. In this paper, we propose a runtime verification approach to verify the statistical property of the AMS design. The methodology is based on the combination of the statistical method and Mont Carlo simulation. The verification procedure produces confidence level and error margin that provide the tolerance and accuracy for the verification results. We apply the proposed methodology to study the jitter property of a PLL design.

10th IEEE International NEWCAS Conference, 2012

2006 IEEE North-East Workshop on Circuits and Systems, 2006

Proceedings of the 16th ACM Great Lakes symposium on VLSI - GLSVLSI '06, 2006

Intelligent Systems Design and Applications, 2010

Abstract The problem of object detection in image and video has been treated by a large number of... more Abstract The problem of object detection in image and video has been treated by a large number of researchers. Many design factors degrade the reliability of the problem solutions, such as manual modeling of the object, manual features selection, handcrafting ...

Formal Methods in Computer-Aided Design, 2007

Analog and mixed signal (AMS) designs are important integrated circuits that are usually needed a... more Analog and mixed signal (AMS) designs are important integrated circuits that are usually needed at the interface between the electronic system and the real world. Recently, several formal techniques have been introduced for AMS verification. In this paper, we propose a difference equations based bounded model checking approach for AMS systems. We define model checking using a combined system of difference equations for both the analog and digital parts, where the state space exploration algorithm is handled with Taylor approximations over interval domains. We illustrate our approach on the verification of several AMS designs including Delta Sigma modulator and oscillator circuits.

IEEE International Mixed-Signals, Sensors, and Systems Test Workshop, 2009

Analog and mixed signal (AMS) circuits play an important role in today's System on Chip design. T... more Analog and mixed signal (AMS) circuits play an important role in today's System on Chip design. They pose, however, many challenges in the verification of the overall system due to their complex behavior. Among many developed verification techniques, runtime verification has been shown to be effective by experimenting finite executions instead of going through the whole state space. In this paper, we present a methodology for the specification and verification of AMS designs using online monitoring at runtime based on the notion of System of Recurrence Equations (SREs). We implement the proposed methodology in a C language based tool, called C-SRE, and utilize it to verify several properties of a PLL design. We compare our proposed online monitoring techniques with the offline approach. Finally, we apply the proposed methodology to monitor the jitter noise associated with a voltage controlled oscillator.

International Conference on Microelectronics, 2007

Due to challenges associated with its verification process, analog and mixed signal designs like ... more Due to challenges associated with its verification process, analog and mixed signal designs like PLLs require a considerable portion of the total design time. In this paper, we propose a run-time verification approach for PLL designs. The essence of this approach is to monitor properties of interest by timed automata integrated within an automatic stimulus generation framework. The objective is to guide simulation by an appropriate simulation trace in order to quickly detect errors by the property monitor.

International Conference on Computational Science, 2007

In this paper, we show how symbolic algebra in Mathematica can be used to formally verify analog ... more In this paper, we show how symbolic algebra in Mathematica can be used to formally verify analog and mixed signal designs. The verification methodology is based on combining induction and constraints solving to generate correctness for the system with respect to given properties. The methodology has the advantage of avoiding exhaustive simulation usually utilized in the verification. We illustrate this methodology by proving the stability of a ΔΣ modulator.

Annual IEEE Northeast Workshop on Circuits and Systems, 2007

Wireless Personal Communications - WIREL PERS COMMUN, 2007

One of the challenging tasks in Personal Communication Services (PCS) is to efficiently maintain ... more One of the challenging tasks in Personal Communication Services (PCS) is to efficiently maintain the location of PCS subscribers who move from one region to another (hereafter called mobile users). When a mobile user receives a call, the network has to quickly determine its current location. The existing location management scheme suffers from high signaling traffic in locating the mobile users. Two-level forwarding pointer scheme has been proposed from per-user forwarding pointer scheme to reduce the cost of signaling traffic. In this paper, we enhance the two-level forwarding pointer scheme. When a mobile user moves from its current Registered Area (RA), which is served by Mobile Switching Center (MSC), to another RA the local switch that acts as a parent of those two MSCs maintains this movement in its memory (hereafter called cache entry). A cache entry is used to locate rapidly the mobile user instead of querying the Home Location Register (HLR) and waiting for its reply. HLR is centralized in the network and far away from the mobile users so that the signaling traffic crossing it is expensive. Sometimes the cache entry may be failed to reach the mobile user then a two-level forwarding pointers will be created from the corresponding Visitor Location Register (VLR), attached to its MSC, through a correct path to locate the mobile user. Thus, there is a saving in cost of querying the underlying HLR. The analytical results indicate that such proposal efficiently reduces the signaling traffic cost for all values of Call to Mobility Ratio (CMR), this is especially considerable when CMR ≥1, without any increase in the call setup delay.

Wireless Personal Communications, 2012

Microelectronics Journal, 2008

Wireless Personal Communications - WIREL PERS COMMUN, 2007

An integrated model is proposed that comprises essentially, an Enhanced Profile-Based Strategy (E... more An integrated model is proposed that comprises essentially, an Enhanced Profile-Based Strategy (EPBS) for small-scale roaming and a Caching Two-Level Forwarding Pointer (C2LFP) strategy for large-scale roaming. The idea behind the integrated model is how those two location management solutions are applied, and what is the suitable approach to specify the physical parameters of PCS networks from mobility management’s point of view so that our solutions can be more cost effective for location management. An evolutionary method, using a constrained Genetic Algorithm (GA) has been used to achieve network parameters optimization. For convenience, we selected the underlying planning problem with an appropriate set of parameters so that it can be treated, in what follows, both genetically and analytically. Thus one can easily verify the accuracy and efficiency of the evolutionary solution that would be obtained from the genetic algorithm. For more realistic environments, GA could be used reliably to build up sophisticated models that integrate the small-scale and large-scale roaming parameters of PCS networks. The results that have been obtained from a case study are presented in order to provide a deep explanation for the proposed integration approach.

Wireless Personal Communications, 2007

One of the challenging tasks in Personal Communication Services (PCS) is to efficiently maintain ... more One of the challenging tasks in Personal Communication Services (PCS) is to efficiently maintain the location of PCS subscribers who move from one region to another (hereafter called mobile users). When a mobile user receives a call, the network has to quickly determine its current location. The existing location management scheme suffers from high signaling traffic in locating the mobile users. Two-level forwarding pointer scheme has been proposed from per-user forwarding pointer scheme to reduce the cost of signaling traffic. In this paper, we enhance the two-level forwarding pointer scheme. When a mobile user moves from its current Registered Area (RA), which is served by Mobile Switching Center (MSC), to another RA the local switch that acts as a parent of those two MSCs maintains this movement in its memory (hereafter called cache entry). A cache entry is used to locate rapidly the mobile user instead of querying the Home Location Register (HLR) and waiting for its reply. HLR is centralized in the network and far away from the mobile users so that the signaling traffic crossing it is expensive. Sometimes the cache entry may be failed to reach the mobile user then a two-level forwarding pointers will be created from the corresponding Visitor Location Register (VLR), attached to its MSC, through a correct path to locate the mobile user. Thus, there is a saving in cost of querying the underlying HLR. The analytical results indicate that such proposal efficiently reduces the signaling traffic cost for all values of Call to Mobility Ratio (CMR), this is especially considerable when CMR ≥1, without any increase in the call setup delay.

Lecture Notes in Computer Science, 2011

2009 Formal Methods in Computer-Aided Design, 2009

2008 International Conference on Microelectronics, 2008

2009 4th International Design and Test Workshop (IDT), 2009

2009 3rd International Conference on Signals, Circuits and Systems (SCS), 2009

One of the challenges for the verification of analog and mixed signal (AMS) designs is the stocha... more One of the challenges for the verification of analog and mixed signal (AMS) designs is the stochastic behavior associated. In this paper, we propose a runtime verification approach to verify the statistical property of the AMS design. The methodology is based on the combination of the statistical method and Mont Carlo simulation. The verification procedure produces confidence level and error margin that provide the tolerance and accuracy for the verification results. We apply the proposed methodology to study the jitter property of a PLL design.

10th IEEE International NEWCAS Conference, 2012

2006 IEEE North-East Workshop on Circuits and Systems, 2006

Proceedings of the 16th ACM Great Lakes symposium on VLSI - GLSVLSI '06, 2006

Intelligent Systems Design and Applications, 2010

Abstract The problem of object detection in image and video has been treated by a large number of... more Abstract The problem of object detection in image and video has been treated by a large number of researchers. Many design factors degrade the reliability of the problem solutions, such as manual modeling of the object, manual features selection, handcrafting ...

Formal Methods in Computer-Aided Design, 2007

Analog and mixed signal (AMS) designs are important integrated circuits that are usually needed a... more Analog and mixed signal (AMS) designs are important integrated circuits that are usually needed at the interface between the electronic system and the real world. Recently, several formal techniques have been introduced for AMS verification. In this paper, we propose a difference equations based bounded model checking approach for AMS systems. We define model checking using a combined system of difference equations for both the analog and digital parts, where the state space exploration algorithm is handled with Taylor approximations over interval domains. We illustrate our approach on the verification of several AMS designs including Delta Sigma modulator and oscillator circuits.

IEEE International Mixed-Signals, Sensors, and Systems Test Workshop, 2009

Analog and mixed signal (AMS) circuits play an important role in today's System on Chip design. T... more Analog and mixed signal (AMS) circuits play an important role in today's System on Chip design. They pose, however, many challenges in the verification of the overall system due to their complex behavior. Among many developed verification techniques, runtime verification has been shown to be effective by experimenting finite executions instead of going through the whole state space. In this paper, we present a methodology for the specification and verification of AMS designs using online monitoring at runtime based on the notion of System of Recurrence Equations (SREs). We implement the proposed methodology in a C language based tool, called C-SRE, and utilize it to verify several properties of a PLL design. We compare our proposed online monitoring techniques with the offline approach. Finally, we apply the proposed methodology to monitor the jitter noise associated with a voltage controlled oscillator.

International Conference on Microelectronics, 2007

Due to challenges associated with its verification process, analog and mixed signal designs like ... more Due to challenges associated with its verification process, analog and mixed signal designs like PLLs require a considerable portion of the total design time. In this paper, we propose a run-time verification approach for PLL designs. The essence of this approach is to monitor properties of interest by timed automata integrated within an automatic stimulus generation framework. The objective is to guide simulation by an appropriate simulation trace in order to quickly detect errors by the property monitor.

International Conference on Computational Science, 2007

In this paper, we show how symbolic algebra in Mathematica can be used to formally verify analog ... more In this paper, we show how symbolic algebra in Mathematica can be used to formally verify analog and mixed signal designs. The verification methodology is based on combining induction and constraints solving to generate correctness for the system with respect to given properties. The methodology has the advantage of avoiding exhaustive simulation usually utilized in the verification. We illustrate this methodology by proving the stability of a ΔΣ modulator.

Annual IEEE Northeast Workshop on Circuits and Systems, 2007

Wireless Personal Communications - WIREL PERS COMMUN, 2007

One of the challenging tasks in Personal Communication Services (PCS) is to efficiently maintain ... more One of the challenging tasks in Personal Communication Services (PCS) is to efficiently maintain the location of PCS subscribers who move from one region to another (hereafter called mobile users). When a mobile user receives a call, the network has to quickly determine its current location. The existing location management scheme suffers from high signaling traffic in locating the mobile users. Two-level forwarding pointer scheme has been proposed from per-user forwarding pointer scheme to reduce the cost of signaling traffic. In this paper, we enhance the two-level forwarding pointer scheme. When a mobile user moves from its current Registered Area (RA), which is served by Mobile Switching Center (MSC), to another RA the local switch that acts as a parent of those two MSCs maintains this movement in its memory (hereafter called cache entry). A cache entry is used to locate rapidly the mobile user instead of querying the Home Location Register (HLR) and waiting for its reply. HLR is centralized in the network and far away from the mobile users so that the signaling traffic crossing it is expensive. Sometimes the cache entry may be failed to reach the mobile user then a two-level forwarding pointers will be created from the corresponding Visitor Location Register (VLR), attached to its MSC, through a correct path to locate the mobile user. Thus, there is a saving in cost of querying the underlying HLR. The analytical results indicate that such proposal efficiently reduces the signaling traffic cost for all values of Call to Mobility Ratio (CMR), this is especially considerable when CMR ≥1, without any increase in the call setup delay.

Wireless Personal Communications, 2012

Microelectronics Journal, 2008

Wireless Personal Communications - WIREL PERS COMMUN, 2007

An integrated model is proposed that comprises essentially, an Enhanced Profile-Based Strategy (E... more An integrated model is proposed that comprises essentially, an Enhanced Profile-Based Strategy (EPBS) for small-scale roaming and a Caching Two-Level Forwarding Pointer (C2LFP) strategy for large-scale roaming. The idea behind the integrated model is how those two location management solutions are applied, and what is the suitable approach to specify the physical parameters of PCS networks from mobility management’s point of view so that our solutions can be more cost effective for location management. An evolutionary method, using a constrained Genetic Algorithm (GA) has been used to achieve network parameters optimization. For convenience, we selected the underlying planning problem with an appropriate set of parameters so that it can be treated, in what follows, both genetically and analytically. Thus one can easily verify the accuracy and efficiency of the evolutionary solution that would be obtained from the genetic algorithm. For more realistic environments, GA could be used reliably to build up sophisticated models that integrate the small-scale and large-scale roaming parameters of PCS networks. The results that have been obtained from a case study are presented in order to provide a deep explanation for the proposed integration approach.