Mahdi Zareei

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.

EMS-MAC

Energy efficiency is a key characteristic of modern wireless sensors. Assuming that the transceiver is the most power-consuming component of a typical sensor node, then a large advantage can be achieved at the data link layer where the medium access control (MAC) protocol controls the usage of the radio unit. Many MAC protocols have been developed for traditional wireless networks. Given that the sensor network is different from the traditional wireless network in many places, researchers are looking for a MAC protocol that is specifically designed and adapted to the sensor network. Moreover, most of the contributions in the wireless sensor network have assumed static nodes. However, some applications in the area of medical care and disaster response make use of the mobile sensor network. Thus, the present paper studies and simulates the sensor MAC (S-MAC), timeout MAC and mobility-aware S-MAC (MS-MAC) protocols in terms of their energy efficiency in different mobility situations. Furthermore, an enhancement of the MS-MAC protocol, named as enhanced MS-MAC, is introduced and simulated. The results show that this enhancement can significantly improve the energy efficiency when there is a reasonable packet delivery rate.

On-Demand Hybrid Routing for Cognitive Radio Ad-Hoc Network

A novel on-demand cluster-based hybrid routing protocol for cognitive radio ad hoc network with non-uniform node distribution is proposed in this paper. At first, a novel spectrum-aware clustering mechanism is introduced. The proposed clustering mechanism divides node into clusters based on three values: spectrum availability, power level of node, and node stability. Therefore, clusters are formed with the highest stability to avoid frequent reclustering. Later, a routing algorithm is introduced to minimize the delay while achieving acceptable delivery ratio. In this paper, routing is defined as a multi-objective optimization problem to combine different individual routing metrics to form a global metric. Simulation results show that our proposed routing algorithm can guarantee a lower delay and a higher packet delivery ratio than conventional routing protocols for cognitive radio ad hoc networks. Due to our routing design specification, such as power consideration and low delay, it can be suitable to be adopted for Internet of Things applications.

A comparative study of short range wireless sensor network on high density networks

ZigBee, Wibree, Z-Wave, and RuBee are four protocol standards for short range wireless communications with low power consumption. From an application point of view, ZigBee is designed for reliable wirelessly networked monitoring and control networks, RuBee is proposed for high security applications and use in harsh environment, Wibree considered for sports and healthcare while Z-Wave is planned for residential control systems. In this paper, after an overview of the mentioned four short-range wireless protocols, we attempt to make a preliminary comparison of them and then specifically study their radio frequency, data coding, security etc. At last we have compared different protocols capabilities in high density network.

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.

Study of mobility effect on energy efficiency in medium access control protocols

Wireless sensor networks (WSN) became popular in recent years, with big variety of applications from environmental monitoring to disaster recovery. Energy efficiency is a key characteristic of todays wireless sensors. In energy constraint sensor network, mobility handling can cause some additional challenges in sensor protocol design. Recently there are many MAC protocols have been proposed and adopted specially for sensor networks. Most of the proposed MAC protocols in wireless sensor network assumed nodes to be static. However some application like medical care and disaster response make use of mobile sensors essential. In this paper, we take closer look at S-MAC, T-MAC (which are well-known energy efficient MAC protocols) and IEEE 802.15.4 (which is the ZigBee standard) MAC protocols and studies their performance in terms of energy efficiency in different situation of mobility.

ABC-PSO for vertical handover in heterogeneous wireless networks

Cloud computing is currently emerging quickly as a client-server technology structure and, currently, providing distributed service applications. However, given the availability of a diverse range of wireless access technologies, people expect continuous connection to the most suitable technology that matches price affordability and performance goals. Among the main challenges of modern communication is the accessibility to wireless networks using mobile devices, with a high service quality (QoS) based on preferences of the users. Past literatures contain several heuristic approaches that use simplified rules to look for the best network that is available. Nevertheless, attributes of mobile devices need algorithms that are quick and effective in order to select best available network near real-time. This study proposes a hybrid intelligent handover decision algorithm primarily founded on two main heuristic algorithms: Artificial Bee Colony or ABC as well as Particle Swarm Optimization or PSO named ABC-PSO to select best wireless network during vertical handover process. The ABC-PSO algorithm has been optimized to achieve small cost function that are powered using the IEEE 802.21 standard taking into account different available wireless networks, the application requirements and the user preferences to improve QoS. Numerical results demonstrate that the ABC-PSO algorithm compared to the related work has lower cost and delay, higher available bandwidth and less number of handover.

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.

Joint Channel Assignment and Routing in Multiradio Multichannel Wireless Mesh Networks

Multiradio wireless mesh network is a promising architecture that improves the network capacity by exploiting multiple radio channels concurrently. Channel assignment and routing are underlying challenges in multiradio architectures since both determine the traffic distribution over links and channels. The interdependency between channel assignments and routing promotes toward the joint solutions for efficient configurations. This paper presents an in-depth review of the joint approaches of channel assignment and routing in multiradio wireless mesh networks. First, the key design issues, modeling, and approaches are identified and discussed. Second, existing algorithms for joint channel assignment and routing are presented and classified based on the channel assignment types. Furthermore, the set of reconfiguration algorithms to adapt the network traffic dynamics is also discussed. Finally, the paper presents some multiradio practical implementations and test-beds and points out the future research directions.

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.