Taner Çevik

A Multichannel Cross-Layer Architecture for Multimedia Sensor Networks

Depending upon the technological developments, the same fast evolution has occurred in the structures of sensor networks, their composing devices which are sensor nodes, and their application areas. Those tiny, energy-constrained, mostly non-real-time data transmitting sensor nodes have evolved to more energy-containing, camera-adapted, real-time multimedia-data-transmitting devices. Developments in the usage areas and the capabilities have revealed some other problems such as time limited data transmission. In this paper, we propose a multichannel cross-layer architecture for Quality of Service (QoS) constrained multimedia sensor networks. The proposed architecture considers both the time and energy efficiency concepts. Energy efficiency is succeeded by ensuring the fair load distribution among the nodes during a real-time multimedia packet stream transmission. Besides ensuring the fair load distribution, on-time packet transmission is also assured by constructing the paths with a hard reservation technique depending on the predetermined QoS constraints. Simulations show that the proposed architecture provides higher performance than the Greedy approach and the LEERA scheme.

A Hybrid OFDM-TDM Architecture with Decentralized Dynamic Bandwidth Allocation for PONs

One of the major challenges of passive optical networks is to achieve a fair arbitration mechanism that will prevent possible collisions from occurring at the upstream channel when multiple users attempt to access the common fiber at the same time. Therefore, in this study we mainly focus on fair bandwidth allocation among users, and present a hybrid Orthogonal Frequency Division Multiplexed/Time Division Multiplexed architecture with a dynamic bandwidth allocation scheme that provides satisfying service qualities to the users depending on their varying bandwidth requirements. Unnecessary delays in centralized schemes occurring during bandwidth assignment stage are eliminated by utilizing a decentralized approach. Instead of sending bandwidth demands to the optical line terminal (OLT) which is the only competent authority, each optical network unit (ONU) runs the same bandwidth demand determination algorithm. ONUs inform each other via signaling channel about the status of their queues. This information is fed to the bandwidth determination algorithm which is run by each ONU in a distributed manner. Furthermore, Light Load Penalty, which is a phenomenon in optical communications, is mitigated by limiting the amount of bandwidth that an ONU can demand.

A survey of multimedia streaming in wireless sensor networks: progress, issues and design challenges

Advancements in Complementary Metal Oxide Semiconductor (CMOS) technology have enabled Wireless Sensor Networks (WSN) to gather, process and transport multimedia (MM) data as well and not just limited to handling ordinary scalar data anymore. This new generation of WSN type is called Wireless Multimedia Sensor Networks (WMSNs). Better and yet relatively cheaper sensors that are able to sense both scalar data and multimedia data with more advanced functionalities such as being able to handle rather intense computations easily have sprung up. In this paper, the applications, architectures, challenges and issues faced in the design of WMSNs are explored. Security and privacy issues, over all requirements, proposed and implemented solutions so far, some of the successful achievements and other related works in the field are also highlighted. Open research areas are pointed out and a few solution suggestions to the still persistent problems are made, which, to the best of my knowledge, so far have not been explored yet.

Localized energy efficient routing for wireless sensor networks

With the evolution of electronics, wireless sensor networks have been very popular in many domains of human life such as health, industry and military. This popularity has taken the attention on to the researches about wireless sensor networks. Wireless Sensor Networks are especially very favorable in conditions where it is physically difficult and dangerous for human being to gather information. Therefore, lifetime of those networks must be prolonged as much as possible, since it will be also infeasible to replace the energy depleted sensors with the new ones deployed in such geographical areas that are difficult and dangerous for human being to enter. In this paper, we present a localized energy aware routing method LEERA-MS and an alternative LEERA-MS-TH method that are used incorporation with an energy efficient sleep-wakeup schedule which is included with pipelining mechanism we have proposed before. Employing multiple sinks improve the performance by providing the fairly distribution of the load. Simulation results show that this routing method applied on a multiple sinks topology when employed together with the pipelined sleep-wakeup schedule provides 40% longer lifetime for wireless sensor networks.

Delay efficient STEM by pipelining

Abstract Wireless sensor networks are comprised of energy constraint, battery powered small devices that sense the environment and transmit the data to the sink in order to take action according to data. Since the sensors are small energy constraint devices energy consumption is the main problem for wireless sensor networks. Energy spent during data communication is much more than spent during in-sensor computing. Most of the effort is spent on designing protocols in order to conserve energy. This paper proposes an improved version of energy efficient MAC protocol STEM by including pipelining mechanism. Results show that the proposed method overperform the original version of STEM by sustaining less delay.

Performance analysis of GLCM-based classification on Wavelet Transform-compressed fingerprint images

Fingerprint detection is one of the primary methods for identifying individuals. Gray Level Co-occurrence Matrix (GLCM) is the oldest and prominent statistical textual feature extraction method applied in many fields for texture analysis. GLCM holds the distribution of co-occurring intensity patterns at a given offset over a given image. However, images occupy excessive space in storage by its original sizes. Thus, Discrete Wavelet Transform (DWT) based compression has become popular especially for reducing the size of the fingerprint images. It is important to investigate whether GLCM-based classification can be utilized efficiently on DWT-compressed fingerprint images. In this paper, we analyze the performance of GLCM-based classification on DWT-compressed fingerprint images. We performed satisfying simulations for different levels of DWT-compressed images. Simulation results identify that classification performance sharply decreases by the increase of DWT-compression level. Besides, instead of utilizing all Haralick features, it is recognized that 8 of them are the most prominent ones that affect the accuracy performance of the classification.

ECMTADR: energy conservative multitier architecture with data reduction for cluster-based wireless sensor networks

Regarding the energy shortage problem of wireless sensor networks (WSNs), various schemes and protocols are proposed to prolong the network lifetime. Data communication is undoubtedly the most important determinant for this energy scarce network type. In this paper, we propose a sophisticated architecture comprising data reduction, load balance, and topology control. Data reduction is ensured by the parameter spatial correlation proximity range (SCPR) that can be adjusted statically at the setup phase or dynamically revised depending on the necessities in the network. Four-layer virtual architecture is applied for implementing topology control. Furthermore, network area is partitioned into fixed-size hexagonal clusters. Depending on the regions in which the clusters take place, cluster heads (CHs) are elected from the respective subregions of the clusters. Load balance is achieved by considering residual energies and distances to the sink during both CH election and data transmission stages. Aggregated data in each cluster is transmitted towards the sink by using a load balancing single-hop intercluster routing protocol instead of direct transmission as offered in LEACH. Simulation results demonstrate that the proposed architecture ECMTADR shows almost 50% better performance in terms of energy conservation and network lifetime when it is compared to LEACH and HEED.