Ibrahim Mustapha | UPM - Universiti Putra Malaysia (original) (raw)
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Papers by Ibrahim Mustapha
IEEE Transactions on Vehicular Technology, 2000
In this paper, we evaluate and improve the performance of the medium access control (MAC) protoco... more In this paper, we evaluate and improve the performance of the medium access control (MAC) protocol for safety applications in a dedicated short range communication (DSRC) environment. We first develop an analytical model to study the IEEE 802.11 distributed coordination function (DCF) MAC protocol that has been adopted by the IEEE 802.11p standard for DSRC. Explicit expressions are derived for the mean and standard deviation of the packet delay, as well as for the packet delivery ratio (PDR) at the MAC layer in an unsaturated network formed by moving vehicles on a highway. The proposed model is validated using extensive simulations and its superior accuracy compared to that of other existing models is demonstrated. Insights gained from our model reveal that the principal reason for the low PDR of the DCF protocol is packet collision due to transmissions from hidden terminals. We then present a novel protocol based on DCF that uses an out-of-band busy tone as a negative acknowledgment to provide an efficient solution to the aforementioned problem. We extend our analytical model to the enhanced protocol and show that it preserves predictive accuracy. Most importantly, our numerical experiments confirm that the enhanced protocol improves the PDR by up to 10%, and increases the supported vehicle density by up to two times for a range of packet arrival rates, while maintaining the delay below the required threshold level.
Applied Mechanics and Materials, 2014
In this paper Quantum Genetic Algorithm (QGA) is combined with The Newton Raphson power flow (NR ... more In this paper Quantum Genetic Algorithm (QGA) is combined with The Newton Raphson power flow (NR power flow) to optimize the placement and sizing of Distributed Generations (DG's) in electrical power systems. QGA is used to find the optimal placement and generate real power of DG in accordance with mathematical calculations and NR Power Flow is used to calculate the loss on the network and determine the voltage at bus. The goal is to minimize the losses, while at the same time still maintain the acceptable voltage profiles. DG's may be placed at any load bus. Which load buses to have the DG's and of what size they are respectively are determined using this proposed method. Observations are based on standard IEEE 14 buses input and results are compared to the results of network without DG and network with DG by other methods.
It is well-known that clustering partitions network into logical groups of nodes in order to ach... more It is well-known that clustering partitions network into logical groups of nodes in
order to achieve energy efficiency and to enhance dynamic channel access in cognitive radio
through cooperative sensing. While the topic of energy efficiency has been well investigated
in conventional wireless sensor networks, the latter has not been extensively explored. In
this paper, we propose a reinforcement learning-based spectrum-aware clustering algorithm
that allows a member node to learn the energy and cooperative sensing costs for neighboring
clusters to achieve an optimal solution. Each member node selects an optimal cluster that
satisfies pairwise constraints, minimizes network energy consumption and enhances channel
sensing performance through an exploration technique. We first model the network energy
consumption and then determine the optimal number of clusters for the network. The
problem of selecting an optimal cluster is formulated as a Markov Decision Process (MDP) in the algorithm and the obtained simulation results show convergence, learning and adaptability
of the algorithm to dynamic environment towards achieving an optimal solution. Performance
comparisons of our algorithm with the Groupwise Spectrum Aware (GWSA)-based algorithm
in terms of Sum of Square Error (SSE), complexity, network energy consumption and
probability of detection indicate improved performance from the proposed approach. The
results further reveal that an energy savings of 9% and a significant Primary User (PU)
detection improvement can be achieved with the proposed approach.
Energy efficient spectrum sensing and data communication to extend the lifetime of cognitive radi... more Energy efficient spectrum sensing and data communication to extend the lifetime of cognitive radio sensor network is becoming increasingly important due to resource
constraint of CR-WSN inherent from WSN. This paper presents
an energy-aware clustering (EAC) algorithm that enhances
spectrum sensing performance and reduces network energy
consumption thereby prolonging lifetime of the network. We
derived network wide energy consumption model in terms of
spectrum sensing energy consumption, intra cluster and inter
clusters energy consumptions, and then determined the optimal number of clusters for the network. Through numerical analysis, we evaluate the effectiveness of the proposed algorithm in terms of minimizing network wide energy consumption and improving spectrum sensing performance
Multi-user spatial sensing diversity exploration through cooperation spectrum sensing greatly imp... more Multi-user spatial sensing diversity exploration through
cooperation spectrum sensing greatly improves sensing
performance. However, high communication overhead and
energy costs for exchanging sensing results may limit its
viability in a realistic large scale resource constraint network
such as cognitive radio wireless sensor networks. This paper
presents a Weighted Hard Combination (WHC) scheme that
combines features of both quantized and hard combining
schemes to minimize energy cost for reporting sensing result
and improve primary user detection performance in
cooperative sensing. We evaluate the effectiveness of the
scheme through simulation. Performance comparison of the
WHC scheme in terms of detection performance, reporting
energy cost and reporting time ratio with conventional hard
combination, soft combination and quantized schemes
indicates viability of the scheme. The results indicate that
the WHC scheme minimizes reporting energy cost by 70%
and improves detection performance by 5.6% compared to
the quantized 3-bits scheme
International Journal of Communication Networks and Information Security (IJCNIS), 2011
The absence of centralized administration, multi-hop transmission, and the nature of wireless cha... more The absence of centralized administration, multi-hop transmission, and the nature of wireless channels pose many challenging research area in Mobile Ad hoc NETworks (MANETs). In this paper, a collision avoidance Medium Access Control (MAC) protocol was used for the modeling and analysis of multi-hop wireless ad hoc network, in which RTS/CTS/DATA/ACK handshake and Exponential Increase Exponential Decrease (EIED) back-off mechanism were adopted. A simple n-vertex undirected graph G(V, A) is used to model the topology of MANET while three-state Markov chain was used to model channel state and node state of MANET. Simulation results show that throughput increases with increase in persistent probability, sensing range and length of a DATA frame. Also throughput has a peak value at some point of the persistent probability, sensing range and length of a DATA frame, which is influenced by the number of nodes. In the other hand throughput increases along with the increase of transmission range for some values, then it start decreasing with increase in transmission range. Furthermore throughput decreases with increase in the number of nodes and back-off time. In order to validate the proposed models, a performance comparison of the throughput of existing model with the throughput of the proposed model by considering persistent probability, sensing range, transmission range, length of DATA transmission and back-off time was carried out. The overall results show that the proposed model achieve better throughput than the existing model.
International Journal of Network and Mobile Technologies, 2011
Performance analysis of 802.11Medium Access Control (MAC) protocol has been carried out either by... more Performance analysis of 802.11Medium Access Control (MAC) protocol has been carried out either by means of simulation or by means of analytical models with simplified back-off rule assumptions. Binary Exponential Back-off (BEB) is the widely used back-off mechanism in many contention-based IEEE 802.11 MAC protocols for its simplicity and good performance, but it has drawbacks especially in multi-hop ad hoc network and some new back-off schemes such as Multiplicative Increase and Linear Decrease (MILD) and Double Increment Double Decrement (DIDD) were proposed. This paper, investigate the performance of collision avoidance MAC protocol in multi-hop wireless ad-hoc network by adopting MILD back-off mechanism. A three state Markov chain is used to model the channel states and node states. These models were used to derive the duration time, steady-state probabilities of the states of node and throughput of Mobile Ad-hoc NETwork (MANET). Simulation results show no matter the value of average number of neighbors , transmission range , and length of DATA frames , the throughput of MANET always achieves the maximum value at some point of persistent probability and also the throughput of a MANETs increases with increase in persistent probability which is influenced by the number of neighbors, transmission range and length of DATA frame. On the other hand the throughput decreases with increase in sensing range which is also influenced by the number of neighbors, transmission range and length of DATA frame.
Journal of Engineering and Applied Sciences, 2011
Carrier sensing is a fundamental mechanism in Carrier Sense Multiple Access with Collision Avoida... more Carrier sensing is a fundamental mechanism in Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocols and it has been used as an effective way to reduce collisions and exploit spatial reuse in wireless networks. The size of the carrier sensing range has a great effect on the network performance. This paper investigates the effect of sensing range on the throughput of multi-hop wireless ad hoc network by considering two fundamental issues in Medium Access Control (MAC), i.e., collisions and spatial reuse, in terms of persistent probability, transmission range and Exponential Increase Exponential Decrease (EIED) back-off time. Markov chain models were used to derive the duration time, transmission probabilities, transition probabilities and steady-state probabilities of the states of node as well as the throughput. Simulation results show that throughput increases along with increase in sensing range , but when it reach its maximum value, its start decreasing with increase in the sensing range. This means that the larger the sensing range, the smaller the possibility that a new transmission attempt to interferes with some ongoing transmissions. Furthermore, smaller sensing range with a larger transmission range means more nodes have to defer their transmissions when one node is transmitting, which leads to lower spatial reuse and consequently decreases throughput. Similarly, smaller sensing range means more transmission hops which leads to more collisions. In the other hand, throughput decreases with increase in transmission range, number of nodes and back-off time.
Journal of Engineering Science and Technology , 2009
Binary Exponential Back-off (BEB) is widely used in many contention-based IEEE 802.11 MAC protoco... more Binary Exponential Back-off (BEB) is widely used in many contention-based IEEE 802.11 MAC protocols for its simplicity and good performance, but it has drawbacks especially in multi-hop ad hoc network and some new back-off schemes such as Multiplicative Increase and Linear Decrease(MILD) and Exponential Increase Exponential Decrease (EIED) were proposed. In this paper, performances of three back-off BEB, MILD, and EIED schemes in a multi-hop ad-hoc network are compared. A Markov chain is used to model the channel states and node states of a contention-based IEEE 802.11 DCF protocol in which RTS/CTS/DATA/ACK handshake and three kinds of back-off mechanisms are adopted. These models are used to derive the duration time and steady-state probabilities of the states of node as well as estimated throughput of MANETs. Simulation results revealed that throughput decreases with increase in back-off time, BEB has the longest back-off time and lowest throughput, MILD has the shortest back-off time and highest throughput while EIED has back-off time and throughput between that of BEB and MILD.
Journal of Science and Technology Research, 2010
Mobile ad hoc networks are highly dynamic networks characterized by the absence of physical infra... more Mobile ad hoc networks are highly dynamic networks characterized by the absence of physical infrastructure. In such networks, nodes are able to move, evolve concurrently and synchronize continuously with their neighbours. There have been many studies on modeling and throughput analysis of single-hop 802.11 wireless networks but only a few on the analysis of multi-hop wireless networks. In this paper, Markov chain based models of a collision avoidance MAC protocol for multi-hop wireless ad-hoc networks is employed. These models are used to derive the duration time, transmission probabilities, transition probabilities and steady-state probabilities of the states of node as well as the throughput of MANETs .Simulation results shows that throughput of a MANETs increases with increase in persistent probability, sensing range and length of a DATA frame and also it has a peak value at some point of the persistent probability, sensing range and length of a DATA frame, which is influenced by the number of nodes.
IEEE Transactions on Vehicular Technology, 2000
In this paper, we evaluate and improve the performance of the medium access control (MAC) protoco... more In this paper, we evaluate and improve the performance of the medium access control (MAC) protocol for safety applications in a dedicated short range communication (DSRC) environment. We first develop an analytical model to study the IEEE 802.11 distributed coordination function (DCF) MAC protocol that has been adopted by the IEEE 802.11p standard for DSRC. Explicit expressions are derived for the mean and standard deviation of the packet delay, as well as for the packet delivery ratio (PDR) at the MAC layer in an unsaturated network formed by moving vehicles on a highway. The proposed model is validated using extensive simulations and its superior accuracy compared to that of other existing models is demonstrated. Insights gained from our model reveal that the principal reason for the low PDR of the DCF protocol is packet collision due to transmissions from hidden terminals. We then present a novel protocol based on DCF that uses an out-of-band busy tone as a negative acknowledgment to provide an efficient solution to the aforementioned problem. We extend our analytical model to the enhanced protocol and show that it preserves predictive accuracy. Most importantly, our numerical experiments confirm that the enhanced protocol improves the PDR by up to 10%, and increases the supported vehicle density by up to two times for a range of packet arrival rates, while maintaining the delay below the required threshold level.
Applied Mechanics and Materials, 2014
In this paper Quantum Genetic Algorithm (QGA) is combined with The Newton Raphson power flow (NR ... more In this paper Quantum Genetic Algorithm (QGA) is combined with The Newton Raphson power flow (NR power flow) to optimize the placement and sizing of Distributed Generations (DG's) in electrical power systems. QGA is used to find the optimal placement and generate real power of DG in accordance with mathematical calculations and NR Power Flow is used to calculate the loss on the network and determine the voltage at bus. The goal is to minimize the losses, while at the same time still maintain the acceptable voltage profiles. DG's may be placed at any load bus. Which load buses to have the DG's and of what size they are respectively are determined using this proposed method. Observations are based on standard IEEE 14 buses input and results are compared to the results of network without DG and network with DG by other methods.
It is well-known that clustering partitions network into logical groups of nodes in order to ach... more It is well-known that clustering partitions network into logical groups of nodes in
order to achieve energy efficiency and to enhance dynamic channel access in cognitive radio
through cooperative sensing. While the topic of energy efficiency has been well investigated
in conventional wireless sensor networks, the latter has not been extensively explored. In
this paper, we propose a reinforcement learning-based spectrum-aware clustering algorithm
that allows a member node to learn the energy and cooperative sensing costs for neighboring
clusters to achieve an optimal solution. Each member node selects an optimal cluster that
satisfies pairwise constraints, minimizes network energy consumption and enhances channel
sensing performance through an exploration technique. We first model the network energy
consumption and then determine the optimal number of clusters for the network. The
problem of selecting an optimal cluster is formulated as a Markov Decision Process (MDP) in the algorithm and the obtained simulation results show convergence, learning and adaptability
of the algorithm to dynamic environment towards achieving an optimal solution. Performance
comparisons of our algorithm with the Groupwise Spectrum Aware (GWSA)-based algorithm
in terms of Sum of Square Error (SSE), complexity, network energy consumption and
probability of detection indicate improved performance from the proposed approach. The
results further reveal that an energy savings of 9% and a significant Primary User (PU)
detection improvement can be achieved with the proposed approach.
Energy efficient spectrum sensing and data communication to extend the lifetime of cognitive radi... more Energy efficient spectrum sensing and data communication to extend the lifetime of cognitive radio sensor network is becoming increasingly important due to resource
constraint of CR-WSN inherent from WSN. This paper presents
an energy-aware clustering (EAC) algorithm that enhances
spectrum sensing performance and reduces network energy
consumption thereby prolonging lifetime of the network. We
derived network wide energy consumption model in terms of
spectrum sensing energy consumption, intra cluster and inter
clusters energy consumptions, and then determined the optimal number of clusters for the network. Through numerical analysis, we evaluate the effectiveness of the proposed algorithm in terms of minimizing network wide energy consumption and improving spectrum sensing performance
Multi-user spatial sensing diversity exploration through cooperation spectrum sensing greatly imp... more Multi-user spatial sensing diversity exploration through
cooperation spectrum sensing greatly improves sensing
performance. However, high communication overhead and
energy costs for exchanging sensing results may limit its
viability in a realistic large scale resource constraint network
such as cognitive radio wireless sensor networks. This paper
presents a Weighted Hard Combination (WHC) scheme that
combines features of both quantized and hard combining
schemes to minimize energy cost for reporting sensing result
and improve primary user detection performance in
cooperative sensing. We evaluate the effectiveness of the
scheme through simulation. Performance comparison of the
WHC scheme in terms of detection performance, reporting
energy cost and reporting time ratio with conventional hard
combination, soft combination and quantized schemes
indicates viability of the scheme. The results indicate that
the WHC scheme minimizes reporting energy cost by 70%
and improves detection performance by 5.6% compared to
the quantized 3-bits scheme
International Journal of Communication Networks and Information Security (IJCNIS), 2011
The absence of centralized administration, multi-hop transmission, and the nature of wireless cha... more The absence of centralized administration, multi-hop transmission, and the nature of wireless channels pose many challenging research area in Mobile Ad hoc NETworks (MANETs). In this paper, a collision avoidance Medium Access Control (MAC) protocol was used for the modeling and analysis of multi-hop wireless ad hoc network, in which RTS/CTS/DATA/ACK handshake and Exponential Increase Exponential Decrease (EIED) back-off mechanism were adopted. A simple n-vertex undirected graph G(V, A) is used to model the topology of MANET while three-state Markov chain was used to model channel state and node state of MANET. Simulation results show that throughput increases with increase in persistent probability, sensing range and length of a DATA frame. Also throughput has a peak value at some point of the persistent probability, sensing range and length of a DATA frame, which is influenced by the number of nodes. In the other hand throughput increases along with the increase of transmission range for some values, then it start decreasing with increase in transmission range. Furthermore throughput decreases with increase in the number of nodes and back-off time. In order to validate the proposed models, a performance comparison of the throughput of existing model with the throughput of the proposed model by considering persistent probability, sensing range, transmission range, length of DATA transmission and back-off time was carried out. The overall results show that the proposed model achieve better throughput than the existing model.
International Journal of Network and Mobile Technologies, 2011
Performance analysis of 802.11Medium Access Control (MAC) protocol has been carried out either by... more Performance analysis of 802.11Medium Access Control (MAC) protocol has been carried out either by means of simulation or by means of analytical models with simplified back-off rule assumptions. Binary Exponential Back-off (BEB) is the widely used back-off mechanism in many contention-based IEEE 802.11 MAC protocols for its simplicity and good performance, but it has drawbacks especially in multi-hop ad hoc network and some new back-off schemes such as Multiplicative Increase and Linear Decrease (MILD) and Double Increment Double Decrement (DIDD) were proposed. This paper, investigate the performance of collision avoidance MAC protocol in multi-hop wireless ad-hoc network by adopting MILD back-off mechanism. A three state Markov chain is used to model the channel states and node states. These models were used to derive the duration time, steady-state probabilities of the states of node and throughput of Mobile Ad-hoc NETwork (MANET). Simulation results show no matter the value of average number of neighbors , transmission range , and length of DATA frames , the throughput of MANET always achieves the maximum value at some point of persistent probability and also the throughput of a MANETs increases with increase in persistent probability which is influenced by the number of neighbors, transmission range and length of DATA frame. On the other hand the throughput decreases with increase in sensing range which is also influenced by the number of neighbors, transmission range and length of DATA frame.
Journal of Engineering and Applied Sciences, 2011
Carrier sensing is a fundamental mechanism in Carrier Sense Multiple Access with Collision Avoida... more Carrier sensing is a fundamental mechanism in Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocols and it has been used as an effective way to reduce collisions and exploit spatial reuse in wireless networks. The size of the carrier sensing range has a great effect on the network performance. This paper investigates the effect of sensing range on the throughput of multi-hop wireless ad hoc network by considering two fundamental issues in Medium Access Control (MAC), i.e., collisions and spatial reuse, in terms of persistent probability, transmission range and Exponential Increase Exponential Decrease (EIED) back-off time. Markov chain models were used to derive the duration time, transmission probabilities, transition probabilities and steady-state probabilities of the states of node as well as the throughput. Simulation results show that throughput increases along with increase in sensing range , but when it reach its maximum value, its start decreasing with increase in the sensing range. This means that the larger the sensing range, the smaller the possibility that a new transmission attempt to interferes with some ongoing transmissions. Furthermore, smaller sensing range with a larger transmission range means more nodes have to defer their transmissions when one node is transmitting, which leads to lower spatial reuse and consequently decreases throughput. Similarly, smaller sensing range means more transmission hops which leads to more collisions. In the other hand, throughput decreases with increase in transmission range, number of nodes and back-off time.
Journal of Engineering Science and Technology , 2009
Binary Exponential Back-off (BEB) is widely used in many contention-based IEEE 802.11 MAC protoco... more Binary Exponential Back-off (BEB) is widely used in many contention-based IEEE 802.11 MAC protocols for its simplicity and good performance, but it has drawbacks especially in multi-hop ad hoc network and some new back-off schemes such as Multiplicative Increase and Linear Decrease(MILD) and Exponential Increase Exponential Decrease (EIED) were proposed. In this paper, performances of three back-off BEB, MILD, and EIED schemes in a multi-hop ad-hoc network are compared. A Markov chain is used to model the channel states and node states of a contention-based IEEE 802.11 DCF protocol in which RTS/CTS/DATA/ACK handshake and three kinds of back-off mechanisms are adopted. These models are used to derive the duration time and steady-state probabilities of the states of node as well as estimated throughput of MANETs. Simulation results revealed that throughput decreases with increase in back-off time, BEB has the longest back-off time and lowest throughput, MILD has the shortest back-off time and highest throughput while EIED has back-off time and throughput between that of BEB and MILD.
Journal of Science and Technology Research, 2010
Mobile ad hoc networks are highly dynamic networks characterized by the absence of physical infra... more Mobile ad hoc networks are highly dynamic networks characterized by the absence of physical infrastructure. In such networks, nodes are able to move, evolve concurrently and synchronize continuously with their neighbours. There have been many studies on modeling and throughput analysis of single-hop 802.11 wireless networks but only a few on the analysis of multi-hop wireless networks. In this paper, Markov chain based models of a collision avoidance MAC protocol for multi-hop wireless ad-hoc networks is employed. These models are used to derive the duration time, transmission probabilities, transition probabilities and steady-state probabilities of the states of node as well as the throughput of MANETs .Simulation results shows that throughput of a MANETs increases with increase in persistent probability, sensing range and length of a DATA frame and also it has a peak value at some point of the persistent probability, sensing range and length of a DATA frame, which is influenced by the number of nodes.