Mohammad Towhidul Islam

A parallel ant colony optimization algorithm for all-pair routing in MANETs

A mobile ad hoc network (MANET) consists of mobile wireless nodes that communicate in a distributed fashion without any centralized administration. The nodes instantaneously and dynamically form a network on the fly when it is needed. We define an irregular application as one that changes the network dynamically during runtime, exhibits chaotic load balancing among the processors and unpredictable communication behavior among the nodes during runtime. An ad hoc network has all these characteristics and hence could be considered as an irregular application from the parallel computing perspective. In this paper, we design an on-demand routing algorithm called source update for MANET using a meta-heuristic based on the ant colony optimization (ACO) search technique. We develop a mechanism to detect cycles, parallelize this algorithm on a distributed memory machine using MPI, and study the performance of the parallel algorithm. On a distributed network of workstations, we obtain a relative speedup of 7 with 10 processors.

Modeling Epidemic Data Diffusion for Wireless Mobile Networks

We propose an analytical model for data diffusion time/delay in a wireless mobile network using a novel peer-to-peer spatial-demand based information dissemination technique. The demand-based technique for data dissemination is beneficial for mobile network since this fully distributed and scalable network system utilizes only local urge for data and provides faster delivery of information. However, due to mobility and chaotic wireless network, it is difficult to predict the object diffusion time/delay among all the interested nodes in a mobile network. Therefore, the development of an analytical model to anticipate the expected time of data distribution among the nodes in a mobile system is an important area of research. In response to this problem, we first find the probabilities of transmitting object from one node to multiple nodes using the epidemic model of disease spreading. Utilizing these transition probabilities, we construct an analytical model based on Markov chain to calculate the expected delay of information diffusion. In addition, we adopt the mobility and scheduling impact on data transition probabilities in our analytical model. Extensive event-based simulations demonstrate that our analytical model provide near perfect estimation of data diffusion time/delay in wireless mobile networks.

Architecture of the Vision System of a Line Following Mobile Robot Operating in Static Environment

Mobile robotics and computer vision two field of artificial intelligence and are important in areas like autonomous navigation and human computer interaction. In this paper, an extremely low cost solution for the vision system of a small mobile robot has been proposed. The robot navigates in its environment by following a pre-drawn track on floor. The vision system of commercial robots requires expensive dedicated hardware and complex algorithms. The proposed architecture of the vision system would require very cheap and available hardware resources like a webcam and a PC. A unique algorithm to extract track information from a sequence of images captured from the camera has been devised. The control system of the mobile robot would use the information provided by the vision system for its lateral control. Based on the proposed architecture and related algorithms, a software system has been developed that reflects the efficiency and effectiveness of the solution

A bandwidth and effective hit optimal cache scheme for wireless data access networks with client injected updates

In this paper, we propose an optimal cache replacement policy for data access applications in wireless networks where data updates are injected from all the clients. The goal of the policy is to increase effective hits in the client caches and in turn, make efficient use of the network bandwidth in wireless environment. To serve the applications with the most updated data, we also propose two enhanced cache access policies making copies of data objects strongly consistent. We analytically prove that a cache system, with a combination of our cache access and replacement policy, guarantees the optimal number of effective cache hits and optimal cost (in terms of network bandwidth) per data object access. Results from both analysis and extensive simulations demonstrate that the proposed policies outperform the popular Least Frequently Used (LFU) scheme in terms of both effective hits and bandwidth consumption. Our flexible system model makes the proposed policies equally applicable to applications for the existing 3G, as well as upcoming LTE, LTE Advanced and WiMAX wireless data access networks.

SPID: A Novel P2P-Based Information Diffusion Scheme for Mobile Networks

In this paper, we propose a novel peer-to-peer based information diffusion scheme for mobile ad hoc networks. Due to mobility and bandwidth constraints, it is not always possible to share a complete content within a single transmission from one mobile device to another. To address this problem, we introduce segmentation of contents into smaller pieces for efficient information exchange. In mobile ad hoc networks, since it is impossible for a node to know the content of every other node in the network, we propose a Spatial-Popularity based Information Diffusion (SPID) scheme that determines urgency of dissemination of content according to the necessity in a neighborhood. Substantially, the segmentation policy and popularity based information dissemination reduce content acquiring time for each peer. Extensive simulation studies demonstrate that the proposed scheme is efficient in data distribution in mobile ad hoc networks, and prove superiority to other existing methods.

OUR: Optimal Update-based Replacement policy for cache in wireless data access networks with optimal effective hits and bandwidth requirements

In mobile wireless data access networks, remote data access is expensive in terms of bandwidth consumption. An efficient caching scheme can reduce the amount of data transmission, hence, bandwidth consumption. However, an update event makes the associated cached data objects obsolete and useless for many applications. Data access frequency and update play a crucial role in deciding which data objects should be cached. Seemingly, frequently accessed but infrequently updated objects should have higher preference while preserving in the cache. Other objects should have lower preference or be evicted, or should not be cached at all, to accommodate higher-preference objects. In this paper, we proposed Optimal Update-based Replacement, a replacement or eviction scheme, for cache management in wireless data networks. To facilitate the replacement scheme, we also presented two enhanced cache access schemes, named Update-based Poll-Each-Read and Update-based Call-Back. The proposed cache management schemes were supported with strong theoretical analysis. Both analysis and extensive simulation results were given to demonstrate that the proposed schemes guarantee optimal amount of data transmission by increasing the number of effective hits and outperform the popular Least Frequently Used scheme in terms of both effective hits and communication cost. Copyright

Hit Optimal Cache for Wireless Data Access

One of the working requirements for many data access applications is the availability of the most updated information. In wireless communications service networks, remote data access consumes expensive wireless spectrum. An efficient cache can reduce the data access cost, by cutting down the amount of data transferred over the wireless channels. However, deploying an efficient cache in wireless environment is challenging, where caches are distributed all over the network and an update event invalidates all the cached copies of the updated data. In this paper, we formalize the concept of caching frequently accessed but infrequently updated data objects, and propose a cache replacement policy accordingly. To facilitate the replacement policy, two enhanced cache access policies are also proposed. The proposed caching policies are supported with strong theoretical analysis. We demonstrate that the policies guarantee an optimal number of cache hits in a caching system. Results from both analysis and our extensive simulations demonstrate that the proposed policies outperform the popular Least Frequently Used (LFU) scheme in terms of effective hits.

Modeling epidemic data diffusion for wireless mobile networks

We propose an analytical model for data diffusion time/delay in a wireless mobile network using a novel peer-to-peer spatial-demand based information dissemination technique. The demand-based technique for data dissemination is beneficial for mobile network since this fully distributed and scalable network system utilizes only local urge for data and provides faster delivery of information. However, due to mobility and chaotic wireless network, it is difficult to predict the object diffusion time/delay among all the interested nodes in a mobile network. Therefore, the development of an analytical model to anticipate the expected time of data distribution among the nodes in a mobile system is an important area of research. In response to this problem, we first find the probabilities of transmitting object from one node to multiple nodes using the epidemic model of disease spreading. Utilizing these transition probabilities, we construct an analytical model based on Markov chain to calculate the expected delay of information diffusion. In addition, we adopt the mobility and scheduling impact on data transition probabilities in our analytical model. Extensive event-based simulations demonstrate that our analytical model provide near perfect estimation of data diffusion time/delay in wireless mobile networks.

Exchanging Peers to Establish P2P Networks

Structure-wise, P2P networks can be divided into two major categories: (1) structured and (2) unstructured. In this chapter, we survey a group of unstructured P2P networks. This group of networks employs a gossip or epidemic protocol to maintain the members of the network and during a gossip, peers exchange a subset of their neighbors with each other. It is reported that this kind of networks are scalable, robust and resilient to severe network failure, at the same time very inexpensive to operate.

An ant colony optimization based routing algorithm in mobile ad hoc networks and its parallel implementation

A mobile ad hoc network (MANET) consists of mobile wireless nodes that communicate in a distributed fashion without any centralized administration. The nodes instantaneously and dynamically form a network on the fly when it is needed. We define an irregular application as one that changes the network dynamically during runtime, exhibits chaotic load balancing among the processors and unpredictable communication behavior among the nodes during runtime. An ad hoc network has all these characteristics and hence could be considered as an irregular application from the parallel computing perspective.In this chapter, we describe the design of an on-demand routing algorithm called source update for MANETs using a metaheuristic based on the ant colony optimization (ACO) search technique. We develop a mechanism to detect cycles, parallelize this algorithm on a distributed memory machine using MPI, and study the performance of the parallel algorithm. We report the performance of this algorithm on a distributed network of workstations.