Mohammad Mahfuzul Islam

New mobility based call admission control with on-demand borrowing scheme for QOS provisioning

In this paper, an advanced call admission control strategy is proposed in which bandwidth is allocated more efficiently and effectively to neighbouring cells by exploiting key mobility parameters to provide consistent Quality of Service (QoS) guarantees for multimedia traffic. Concomitantly, to ensure continuity of on-going calls with better utilization of resources, bandwidth is borrowed from existing adaptive calls without affecting the minimum QoS guarantee. The performance of the scheme is compared with other techniques including the rate-based borrowing scheme and implicit QoS provisioning strategy. Simulation results prove that this new scheme offers significant improvements in the requisite performance metrics of call blocking probability, call dropping probability, and bandwidth utilization, under a variety of differing traffic conditions.

Hybrid LEACH: A relay node based low energy adaptive clustering hierarchy for wireless sensor networks

Prolonging the lifetime of a sensor node powered by battery in both homogeneous and heterogeneous wireless sensor networks is a massive challenging area of research now-a-days. To achieve this target many research works including low energy adaptive clustering hierarchy (LEACH) and its variants use clustering techniques to reduce energy spent by keeping most of the nodes in sleeping mode whenever possible. LEACH cannot solve the problem of extending the networks life time due to loosing huge energy of sensor nodes selected as cluster heads for communications. To save energy of cluster heads, relay node based schemes use independent relay nodes as cluster heads. These schemes, however, still suffer from the problems of relay node placement, blind spots and immature death of cluster heads. Addressing the above mentioned problems, this paper proposes a new robust relay node based hybrid LEACH which incorporates the recently developed energy comparison LEACH within the relay nodes based technique so that the network still operates, in absence of relay nodes, as long as even a single node having energy to communicate. The proposed scheme also maintains the efficiency of energy utilization through controlling the size of cluster in a distributed manner for the first time. Simulation results prove the superiority of the proposed scheme over the relay node based scheme with an improvement of 6%-30% extra network lifetime and significant reduction of packet loss during communications.

Novel velocity and call duration support for QoS provision in mobile wireless networks

This article presents a novel mobility-based resource reservation and call admission control scheme that is applicable to any real wireless multimedia network. The scheme exploits three key mobility parameters - the position, direction, and speed of a mobile unit - together with the duration of a particular call to accurately estimate the cell visiting probability in order to identify a shadow cluster of cells the unit is most likely to visit. Each cell in the cluster reserves resources for an estimated time interval, which is adapted depending on the aggregated probability of all active units visiting a particular cell. Simulation results confirm the superiority of the new scheme over the existing predictive mobility support scheme in terms of three QoS parameters: call blocking rate, call dropping rate, and channel utilization.

Parametric mobility support dynamic resource reservation and call admission control scheme for cellular multimedia communications

This paper presents an advanced resource reservation and call admission control scheme for cellular networks. It exploits user mobility information in order to achieve efficient network resource utilization, and avoid severe network congestion. At the same time it achieves reduced service dropping and reduced blocking probabilities. To support the migrating services from the neighbouring cells, the proposed mobility model employs an enhanced cell visiting probability estimator in order to achieve improved mobility prediction. It does this through exploiting the key mobility parameters (speed, direction, and distance) to produce a better estimation of resource reservation requirements. It also uses a probabilistic approach to identify a cluster of cells, the shadow cluster, which the mobile unit is likely to visit. A self-learning, expected travel distance estimation, technique is proposed to overcome the obstacles faced due to the real-world road networks, as well as geographical and physical features of the cells. In each cell of the shadow cluster, the proposed resource reservation strategy identifies a reservation time window, and estimates the amount of resources to be reserved. The call admission control algorithm is invoked when a new or handoff service arrives and needs to allocate resources more efficiently, in order to provide consistent quality of service (QoS) guarantees for multimedia traffic. Concomitantly, to ensure the continuity of on-going services with better utilization of resources, bandwidth is borrowed from the existing adaptive services without affecting the minimum QoS guarantees. Simulation results prove that the proposed scheme offers substantial improvements over recent existing schemes under different traffic patterns.

A dynamic round-time based fixed low energy adaptive clustering hierarchy for wireless sensor networks

Extending the lifetime of energy constrained wireless sensor network is an immense demanding part of research. To attain this goal many research works including low energy adaptive clustering hierarchy (LEACH) and its variants use clustering techniques to reduce energy consumption by dividing the network coverage area into clusters and sending the accumulated information through a representative of each region, known as cluster head. All of these schemes, except fixed LEACH, suffer from the problem of accomplishing huge energy of sensor nodes due to forming repeated cluster at each fixed time interval. Fixed LEACH surmounts the repeated clustering formation problem by forming fixed clusters only once. This scheme, however, still wastes huge energy and incurs loss of information due to premature dead of cluster heads before expiring the fixed round time. The research work in this paper presents a novel dynamic round time based fixed LEACH where round time is determined based on the remaining energy, at the same time special care is taken to avoid the increase of complexity in round time measurement. The proposed scheme, therefore, provides better quality of services by circumventing packet loss periods and lengthens the network life time significantly. Simulation results proved the superior performances of proposed dynamic round time based fixed LEACH compared with the traditional fixed one.

Grid Approximation Based Inductive Charger Deployment Technique in Wireless Sensor Networks

Ensuring sufficient power in a sensor node is a challenging problem now-a-days to provide required level of security and data processing capability demanded by various applications scampered in a wireless sensor network. The size of sensor nodes and the limitations of battery technologies do not allow inclusion of high energy in a sensor. Recent technologies suggest that the deployment of inductive charger can solve the power problem of sensor nodes by recharging the batteries of sensors in a complex and sensitive environment. This paper provides a novel grid approximation algorithm for efficient and low cost deployment of inductive charger so that the minimum number of chargers along with their placement locations can charge all the sensors of the network. The algorithm proposed in this paper is a generalized one and can also be used in various applications including the measurement of network security strength by estimating the minimum number of malicious nodes that can destroy the communication of all the sensors. Experimental results show the effectiveness of the proposed algorithm and impacts of the different parameters used in it on the performance measures.

Capacity improvement of reversible data hiding scheme through better prediction and double cycle embedding process

For better protection of surreptitious information from the intruders, steganography is now a widely used technique for hiding information through bits embedding inside a picture, speech and other multimedia contents. Among many different steganography schemes, prediction errors based reversible data hiding methods are more effective for security reasons. Nevertheless such techniques presented so far can embed limited number of message bits in a cover media and thus limit the length of covert message to be sent through embedding. In this paper, the authors presented a novel embedding process, called double cycle embedding scheme, where embedding capacity is increased significantly by modifying the scheme of estimation of pixel values, the block-variance calculation technique, selecting two highest most peaks in the histogram regardless their positions and embedding twice in the same cover image. The scheme also modified the pixel-prediction technique for the better predictions and for generalization of block-sizes in the cover image to increase the robustness of the policy. The experimental results demonstrate that the proposed scheme dictates other competing schemes with an embedding gain of 40%~700% depending on the cover image. The experimental results also demonstrate that the scheme exhibits stronger resistance against several statistical attacks, e.g. Benford generalized laws, SPAM features.

Enhancing the embedding payload by handling the affair of association and mapping of block pixels through prediction errors histogram

Images are intentionally distorted in many reversible data hiding schemes. This distortion is performed either by encrypting before data embedment or by applying histogram association mapping (HAM) during data concealment. The later one minimizes the processing complexity and demolishes the requirement of sharing secret keys. In the HAM, each blocks pixels belong to a segment in the gray scale are associated and mapped by the message bits to another gray part. The quantity of embedded bits are determined by the range of block pixels, i.e. limit within which pixels spread out. Though, smaller valued ranges contribute much to embedding payload, the frequency of such ranges decreases in archetype images. However, a predictor, if applied on the block pixels, huddles its prediction errors together. Consequently, the range of absolute values of the prediction errors become smaller. The proposed scheme, therefore, applies HAM to prediction errors and shifts the block pixels accordingly. Experiments were conducted using three different standard image datasets to examine the enhancement in the embedding payload and to investigate the performance on different block-sizes. The investigation reveals that the average payloads in the proposed scheme is 1.5 to 2 times of the competing one in all the cases.

Dynamic service policy-based clustered wireless sensor networks

Energy is one of the main obstacles to deploying wireless sensor networks (WSNs) because tiny sensor nodes cannot accommodate sufficient energy for achieving the desired level of usage. The clustering protocols of wireless sensor network attain the acme popularity among researchers because of effective usage clustering concepts based on locality and the election of a cluster head for each of them. We derive motivation from energy saving clustering schemes and propose an enhancement by saving energy and prolonging the lifetime of a sensor network significantly. The Low Energy Adaptive Clustering Hierarchy (LEACH) achieves popularity for its simplicity and applicability in WSNs. A large number of works exist that modify LEACH to strengthen the applicability of this scheme in practice, but only limited to the cluster set-up phase. In this paper, we observe a major problem that exists in all of the clustering protocols based on LEACH. That is, LEACH and its variants encounter premature death of cluster heads because data transmission time of each cycle of communication is fixed. Our proposed dynamic service policy-based scheme decreases the premature death of cluster heads and packet loss significantly.

Min-max fairness scheme for resource allocation in cellular multimedia networks

This paper proposes a new method of bandwidth sharing policy which dynamically adjusts the bandwidth among the different services within the cell with changing network traffics. The proposed method, called min-max fairness scheme, exhibits good performances in cellular network applications where bandwidth is at a premium such as in multimedia communications. The improved efficiency of the scheme is achieved by considering the online and the offline services in different ways as well as using a strategy of temporary borrowing the reserved bandwidth for offline services. The scheme distributes the bandwidth among the services as evenly as possible and guarantees the minimum bandwidth to all the services besides maintaining the quality of service at various traffic loads. Simulation results are presented to confirm the superior performance compared with other recent existing schemes.