A. K. M. Muzahidul Islam

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.

A priority aware cognitive radio based hospital system architecture, priority management and communication protocols

Recently, wireless communication in medical data and patient information transmission has received tremendous attention to the researchers since effective, timely, accurate, complete and unambiguous communication reduces errors and results in improved patient safety. However, wireless communication technology in a healthcare environment poses some major challenges. For example, medical band scarcity for future wireless healthcare system, bandwidth restriction, spectrum utilization and electromagnetic interference (EMI) are major concerned. In addition, different types of e-health applications have different priorities. Therefore, communication protocols and network maintenance policies for wireless healthcare need to be priority mechanism agile. Compared to traditional wireless network, cognitive radio network (CRN) can be more flexible and solve these problems. In this paper, a novel CRN based hospital system architecture namely CogMed, is proposed for e-health applications where priority mechanism aware heterogeneous architecture, system design and communication policies are included. The article first analyzes the shortcomings of recent wireless healthcare facility by critically analyzing the contemporary literatures on CRN centric healthcare facility. It then proposes a fully opportunistic network based hospital system architecture where dynamic spectrum access (DSA) capable medical, non-medical and sensor devices are categorized based on a dynamic priority management mechanism. The paper also presents some communication protocols.

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.

Definition, design and priority management of a cognitive radio driven hospital: CogMed

Wireless is becoming more and more common in the healthcare system in near future. These may cause issues such as EMI effects on the operating devices, shortage of medical band. To handle these issues in a proper manner, a hospital system has to be designed carefully. Therefore, in this article we propose system definition and design of a cognitive radio enabled hospital system known as CogMed. First we describe the shortcomings of recent wireless healthcare facility by critically analyzing the contemporary literatures on cognitive radio network centric healthcare facility. Then we propose a fully opportunistic network based hospital system architecture where dynamic spectrum access (DSA) capable medical, non-medical and sensor devices are characterized based on a dynamic priority management mechanism. We prioritize the medical and non-medical device according to the urgency. We also proposed a priority based channel access mechanism which is based on IEEE 802.11.e standard. The proposed priority policy emphasized not only the devices, but also the application in wireless hospital.

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.

An experimental study of WSN transmission power optimisation using MICAz motes

Adjusting nodes positioning to satisfy the needs of network connectivity and power conservation in wireless sensor networks (WSN) is not a trivial task. Too far node distance may result in unreachable transmission while too near node distance not necessarily guarantee nodes connection. By knowing an acceptable distance range to position nodes in the networks, it can greatly help researchers to better configure settings of WSN environment, while reducing precision of readings between real WSN testbed and the simulation counterpart. This paper demonstrates a real implementation of transmission power control to assist the decision-making on nodes positioning to be used in a sensor network communication. The implementation of the study is done using the MICAz motes with a nesC programming in TinyOS in an indoor environment. Our findings suggest that to assure network connectivity, motes must not be located more than 1.18 metres distance when they are placed on the floor building and not more than 2.37 metres distance when they are situated about one metre above the floor building. Our results also indicates that the maximum length the signals can travel using maximum power 0 dBm is merely about six metres long.

Energy-efficient and mobility-aware MAC protocol for wireless sensor networks

Wireless sensor networks (WSNs) have restricted use by both academic and industrial societies for a while. This is due to the limited electrical and computational power of a typical sensor node. By moving toward emergency and healthcare related applications such as the disaster response, mobility has become an important feature of WSNs. Having the mobile nodes in a WSNs causes new and even more challenging technical difficulties for its designers. The existing technologies should be revised in order to comply to the new form of applications. In this paper, an enhanced mobility-aware extension to T-MAC, as one of the popular medium access control protocols in WSNs is proposed. The simulation-based experiments show that the proposed method significantly increases the throughput and packet delivery ratio of T-MAC in exchange for a small increase in power consumption.

An overview on Dynamic Wireless Sensor Network Architectures

Typically, the sensor nodes of a Wireless Sensor Network have a large coverage area and longer range. They are also self-configuring or self-organizing. Clustering is used to leverage the underlying flat sensor network topology and provide a hierarchical organization. A Wireless Sensor Network can be called as dynamic if it is supported by two atomic operations: node-move-in and node-move-out, which means nodes getting out of and nodes joining into an existing network, respectively. In this paper, we study and examine Dynamic Wireless Sensor Network Architectures. Based on the review results we then conclude the best architectures that can support communication protocols such as broadcasting/flooding, multicasting, routing, and gathering.

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.