Nafees Mansoor

Spectrum aware cluster-based architecture for cognitive radio ad-hoc networks

To encounter the mounting necessity of radio spectrum, proper utilization of the radio spectrum is must. Cognitive radio practices an open spectrum allocation technique to make efficient utilization of the wireless radio spectrum and reduces the bottleneck on the frequency bands. A robust architecture with suitable communication protocol is a precondition in the deployment of cognitive radio networks. A novel cluster-based architecture for an ad-hoc cognitive radio network is proposed in this paper, where the spatial variations of spectrum opportunities are considered for clustering. Our cluster formation is defined as a maximum edge biclique problem. Each cluster consists with a set of free common channels, which benefits smooth shift between control channels. A set of cognitive radio nodes are grouped into the same cluster if they sense similar free channels and are within the communication range of the leader node called cluster head. The selection of cluster head is based on a parameter called Cluster Head Determination Factor (CHDF). Considering the re-clustering issue for mobile nodes, we also introduce the concept of secondary cluster-head. The secondary cluster-head takes charge of a cluster whenever a cluster-head moves out from the cluster. Proposed clusters adapt themselves dynamically with respect to spectrum availability, and the high mobility of the nodes. Finally, we simulate the proposed architecture to evaluate the performance of our method.

CoAd: A cluster based adhoc cognitive radio networks architecture with broadcasting protocol

Considering the mounting demand of radio frequencies, proper utilization of the spectrum is very essential. Cognitive radio, which uses an open spectrum allocation technique, can solve this spectrum congestion problem. Effective deployment of cognitive radio networks highly depends on a robust architecture with appropriate communication protocols. Considering the limitations of recently developed cognitive radio network architectures and associated broadcasting protocols, a dynamic cluster-based simple architecture is proposed for Ad-hoc cognitive radio network. For effective routing and load balancing, proposed architecture is dividing Ad-hoc architecture into clusters. The paper also introduces time slotted based broadcasting protocol for the proposed clustered architecture. Simulation results show the clustering efficiency of the proposed architecture.

Clustering Analysis in Wireless Sensor Networks: The Ambit of Performance Metrics and Schemes Taxonomy

Research on wireless sensor network (WSN) has increased tremendously throughout the years. In WSN, sensor nodes are deployed to operate autonomously in remote environments. Depending on the network orientation, WSN can be of two types: flat network and hierarchical or cluster-based network. Various advantages of cluster-based WSN are energy efficiency, better network communication, efficient topology management, minimized delay, and so forth. Consequently, clustering has become a key research area in WSN. Different approaches for WSN, using cluster concepts, have been proposed. The objective of this paper is to review and analyze the latest prominent cluster-based WSN algorithms using various measurement parameters. In this paper, unique performance metrics are designed which efficiently evaluate prominent clustering schemes. Moreover, we also develop taxonomy for the classification of the clustering schemes. Based on performance metrics, quantitative and qualitative analyses are performed to compare the advantages and disadvantages of the algorithms. Finally, we also put forward open research issues in the development of low cost, scalable, robust clustering schemes.

Mobility-aware medium access control protocols for wireless sensor networks: A survey

Abstract The popularity of wireless sensor networks has grown rapidly in recent years, with new directions including healthcare monitoring and disaster response. This increased use in mobile applications has naturally led to new challenges to the design of sensor protocols, especially in the media access control (MAC) sublayer. In order to design a MAC protocol which takes mobility awareness into account, understanding how mobility can be described by mobility models is crucial. Moreover, for applications that transform between static, periodic-mobile, random-mobile, or variable number of nodes, flexibility in design is a key consideration. Therefore, in this paper mobility pattern, mobility models and mobility estimation algorithms for wireless sensor networks are discussed. The state of the art of medium access control protocols with mobility-handling capabilities is overviewed and a comparative study of the most well-known mobility aware MAC protocols is given. Finally, future research directions for mobility-aware MAC protocols are presented. We believe this paper will aid researchers by serving as a reference to orient future research in this area.

A framework for dynamic vehicle pooling and ride-sharing system

Due to the ever-advancing technology, usage of information technology in modern life is increasing at a fast pace. Hence, ICT based systems have enormous potential providing accessibility and affordability to the urban inhabitants in developing countries. In this paper, a framework for a dynamic vehicle pooling system for Dhaka city is proposed. Comparing to existing systems, some new concepts have been incorporated in the proposed framework. One of the unique features in the proposed framework is that the system is not limited to any particular type of vehicle. Thus, any type of vehicle such as car, bus or even lorry can be pooled using the proposed system. Moreover to ensure payment security, the system is designed as a prepaid system. Hence, rider has to ensure payment before getting into the ride, where the drives account is credited once the rider reaches his/her destination.

Multiple description image coding: A low complexity approach for lossy networks

The development of an efficient and reliable multiple descriptions coding (MDC) scheme over lossy communication networks has been described. The advantage of MDC is that, if all the channels work, a high quality, possibly lossless, reconstruction can be achieved from all the received descriptions. On the other hand, a lower but still acceptable quality can be achieved if some of the channels are not received at all. In this article, a general framework of an efficient multiple description robust communication system with 2- and 4-channel cases is presented with a proposed block-based DC reallocation approach using intrinsic correlation. The peak signal-to-noise ratio (PSNR), mean squared error (MSE), bit rate, and entropy are calculated with the proposed method to analyze the reconstruction quality and the calculated results are compared with those of the other MDC methods. It is found that the proposed method, which uses an intrinsic correlation, gives comprehensive improvements over the other recently developed methods.

Dynamic spectrum allocation for cognitive radio ad hoc network

This paper proposes a novel cross-layer dynamic spectrum allocation for cluster-based cognitive radio ad hoc network. A primary focus is on the cluster formation and maintenance. The proposed clustering mechanism divides the network into clusters based on three values: spectrum availability, power level of node and current speed of the node. Therefore, clusters form with the highest stability and flexibility to avoid frequent re-clustering in the network. Moreover, the proposed method integrates the spectrum sensing at physical (PHY) layer with the packet scheduling at MAC layer to be more robust to Primary Users (PUs) activity as well as node mobility in a network. The simulation results show that the proposed protocol outperforms the conventional protocols in terms of throughput, power consumption and packet transmission delay.

A novel node joining alogoritm for spectrum aware cluster-based cognitive radio ad-hoc networks

With the rapid development of wireless technologies, the demand for radio spectrum is ever increasing. Along with the spectrum scarcity problem, radio spectrums are also under utilized. Cognitive radio practices an open spectrum allocation technique, which can make sure efficient handling of the frequency bands. Suitable network is a must for the implementation of cognitive radio networks. This paper presents a novel node-joining algorithm for spectrum aware cluster-based cognitive radio ad-hoc network architecture. The spectrum aware architecture splits the network into groups of clusters where the spatial variations of spectrum availability are considered for clustering. Set of free common channels resides every cluster for smooth shifting among control channels. To maintain the integrity of the clustering method, node-joining protocol is developed. Conclusively, simulation is conducted and the result is presented to evaluate the performance of the protocol.

Construction of a Robust Clustering Algorithm for Cognitive Radio Ad-Hoc Network

With the swift expansion of wireless technologies, the demand for radio spectrum is ever growing. Besides the spectrum scarcity issue, spectrums are also underutilized. Cognitive radio customs an open spectrum allocation technique, which ensures efficient handling of the frequency bands. However, suitable network architecture is must for the implementation of cognitive radio networks. This paper presents a robust cluster-based architecture for cognitive radio ad-hoc network. Considering the spatial variance of the spectrum, the proposed architecture splits the network into groups of cluster. Set of free common channels resides every cluster that enables smooth shifting among control channels. The paper also introduces a parameter called Cluster Head Determining Factor (CHDF) to select cluster-heads. Each cluster comprises of a secondary cluster-head to combat the re-clustering issue for mobile nodes. Conclusively, to evaluate the performance of the proposed architecture, simulation is conducted and comparative studies are performed. From the simulation result, it is found that the proposed cluster-based architecture outperforms other recently developed clustering approaches by upholding a reduced number of clusters in the network.

Multiple description discrete cosine transform-based image coding using DC coefficient relocation and AC coefficient interpolation

Abstract. The development of an effective and dependable multiple description coding scheme over a lossy communication system is described. A general framework of an effective multiple description robust communication system with two-channel and four-channel cases is presented with a proposed block-based DC coefficient relocation and AC coefficient interpolation approach. A benefit of such system is that, if all the channels work properly, a very good quality, probably lossless, reconstruction can be obtained from the received descriptions. On the other hand, if some of the channels do not work properly, a lower but still quiet satisfactory quality of reconstruction can be obtained. The performance of the proposed scheme is measured with mean squared error, peak signal-to-noise ratio, entropy, and bit rate to analyze the reconstruction quality, and the computed results are matched with that of the other schemes. The system complexity is also computed and compared. Comparing the simulation results, it is observed that the proposed scheme, which uses a DC coefficient relocation and AC coefficient interpolation scheme, gives comprehensive enhancements over the other recently developed schemes.