Mehmet Fatih Tuysuz

Minimizing Communication Interruptions Using Smart Proactive Channel Scanning Over IEEE 802.11 WLANs

Wireless connectivity is becoming pervasive in our lives as wireless networks and mobile devices have been undergoing a magnificent evolution. In this context, consumers demand to access to the wireless communication services anytime and anywhere with high performance. IEEE 802.11 wireless local area networks (WLANs) have a direct impact on this widespread use. Nevertheless, as any standard procedure, WLAN also has its own drawbacks. In IEEE 802.11 wireless networks, periodic channel scanning is an essential procedure to discover available access points in the vicinity and to achieve fast handover. However, this procedure leads to unnecessary overhead in wireless networks and also interrupts ongoing communications of stations. In this paper, we propose a smart proactive channel scanning scheme that allows stations to achieve fast handover with minimized communication interruptions. In the proposed scheme, periodic channel scanning is scheduled based on adaptive channel scanning intervals and activated after a frame transmission only if the mobile station is on move or the received signal strength indicator value drops below a pre-specified threshold. The proposed scheme is a client-side software solution that any station can benefit from, without changing the standard in any existing IEEE 802.11 environment. Analytical and simulation results show that the proposed channel scanning scheme reduces the channel scanning overhead dramatically, minimizes communication interruptions and improves the overall throughput of stations.

A survey on energy efficiency in software defined networks

Wide deployment and dense usage of computer networks may cause excessive energy consumption due to the increase in probability of network congestion, frame collisions and packet dropping rates resulting from late-received frames. Besides, based on the dramatic increase in network complexity with wireless, mobile and split tunnel connections, weak visibility into network flows and high cost of some of public and private network services, current networks can also be implied as inefficient in terms of both performance and economy. Software-Defined Networking (SDN) is a novel networking architecture, which provides a directly programmable and (logically) centralized network control, separates network control from forwarding, and enables programmable network components. SDN can have a significant role in reducing the aforementioned excessive energy consumption caused by data centers, network components, and end hosts. In this paper,11This work is supported by the Scientific and Technological Research Council of Turkey (TUBITAK) under grant no. 114E245. we examine the principles, benefits, and drawbacks of up-to-date SDN approaches that focus on energy efficiency. We also provide a brief comparison of possible energy gain ratios of existing approaches, discussion on open issues and a guideline for future research.

A Roadmap for a Green Interface Selection Standardization over Wireless HetNets

Wireless heterogeneous networks (HetNets) have been widely deployed in parallel with the dramatic increase of smart mobile devices. Nowadays, people use these devices to access the Internet, communicate, socialize and handle their short or long-term businesses. As these devices rely on their batteries, energy-efficiency has become one of the major issues in both academia and industry. Due to terminal mobility, variety of Radio Access Technologies (RATs) and need to be always best connected (ABC) to the Internet anytime and anywhere, energy-efficient interface selection has to be taken into account carefully. In this context, this roadmap intends to raise the awareness of energy efficiency, and to highlight a green interface selection process in which additional standardization is needed. The roadmap first describes essential rules of energy- efficient interface/network selection procedure. Then, it discusses future policies of green interface selection standardization for smart mobile devices, from the perspective of governments, non-governmental organizations (NGOs) and companies.

Multicopter usage for analysis productivity in agriculture on GAP region

Monitoring large agriculture land in GAP region is important for productivity in agriculture. However, the ground monitoring is not effective. It also causes serious loss of time. Therefore, the analysis by image processing algorithms of agricultural land from a certain elevation will be a very effective solution. The quadcopter that is preferred rotor system is used for image capture. Image stabilities and ease to control is important for image analysis. DJ Phantom Vision 2 is used as a prototype. The images were analyzed from color parameters that obtained from the air of agricultural areas displaying. HSI color space analysis is preferred for color. Analysis was performed with obtained images to make green colors and shades segmentation. This project is supported by TUBITAK 2241 to 2013 11 support period program.

Energy-aware access point selection for smartphones

Wireless networks have become one of the most popular network access technologies today with the mobility they provide to users. However, there are also weaknesses in radio access technologies that are becoming increasingly common. For example, energy efficiency has become one of the most important issues for users due to the limited battery that mobile devices have. In this context, Wireless Network Interface Cards (WNIC) must be carefully examined as it constitutes a major part of total energy consumption of the system. In this work, we propose an android-based energy-aware network/interface selection application that detects and connects the most proper Point of Attachment (PoA) for mobile devices. In the proposed study, estimated energy consumption amounts of the device were calculated using the channel scanning results, switching costs, channel busy times (CBT), traffic classes, number of stations stored at each connection point, and the amount of energy consumed by each WNIC.

Energy-efficient access point design with aurduino yun

Nowadays, IEEE 802.11 Wireless Local Area Networks (WLAN) has become a common technology for wireless access, making considerable progress with low cost, easy installation and mobility. This rapid rise of wireless networks has led to the design of an efficient network access protocol, which can provide high throughput for data traffic and Quality of Service (QoS) support for real-time applications, becoming one of the most important research topics in wireless networks. In this study, a novel energy-efficient network access protocol for IEEE 802.11 wireless networks was proposed. The proposed model avoids collisions by making important changes in the operational logic of wireless networks. In this context, beacon frames to be sent by the Access Points and a few bits of data to be added to ACK and CTS frames allow stations to remain in the sleep mode for the duration of time that stations will not transmit. By waking up, stations find the correct slot reserved for them, transmit frames in a collision-free environment, and achieve significant throughput increase.

Energy-Efficient Vertical Handover Parameters, Classification and Solutions over Wireless Heterogeneous Networks: A Comprehensive Survey

In the last few decades, the popularity of wireless networks has been growing dramatically for both home and business networking. Nowadays, smart mobile devices equipped with various wireless networking interfaces are used to access the Internet, communicate, socialize and handle short or long-term businesses. As these devices rely on their limited batteries, energy-efficiency has become one of the major issues in both academia and industry. Due to terminal mobility, the variety of radio access technologies and the necessity of connecting to the Internet anytime and anywhere, energy-efficient handover process within the wireless heterogeneous networks has sparked remarkable attention in recent years. In this context, this paper first addresses the impact of specific information (local, network-assisted, QoS-related, user preferences, etc.) received remotely or locally on the energy efficiency as well as the impact of vertical handover phases, and methods. It presents energy-centric state-of-the-art vertical handover approaches and their impact on energy efficiency. The paper also discusses the recommendations on possible energy gains at different stages of the vertical handover process.

Collision-free MAC approaches in wireless networks

Nowadays, wireless networks are widely used due to their low costs and mobile communication support for the users. Medium Access Control in wireless networks are provided by DCF (Distributed Coordination Function) algorithm. However, this algorithm does not perform well, especially when the delay and throughput are taken into consideration. Additionally, this procedure is always open to collisions. In this paper, although stations shares the wireless channel, we aim to examine the works in the literature that prevent collisions, support Quality of Service (QoS) and increase throughput for stations, compare their advantages and disadvantages, and finally present some suggestions for an optimal solution.

An energy-efficient medium access control over IEEE 802.11 WLANs

Energy-efficiency has become one of the major issues for mobile devices as these devices rely on their batteries. In this paper, we aim to reduce the energy consumption of mobile devices in wireless networks by maintaining mobile stations in the doze state as much as possible, without degrading the expected throughput even in highly-dynamic channel conditions. In the proposed scheme, each station only makes use of its local information and does not cause any overhead on network. Therefore, the proposed scheme can be easily implemented without any changes on current IEEE 802.11 standard. Performance of the proposed scheme has been examined by numerical analyses and extensive simulations. The results illustrate that the proposed scheme is very efficient and reduces the energy consumption of stations under a wide range of contention levels.

A novel energy-efficient medium access control over saturated IEEE 802.11 WLANs

Nowadays, people mostly use mobile devices to access the Internet, communicate, socialize and handle their short or long-term business. As these devices rely on their batteries, energy-efficiency has become one of the major issues for mobile devices. In this context, the Wireless Network Interface Card (WNIC) has to be taken into account carefully as it consumes a significant portion of the overall system energy. In this paper1, we aim to reduce the energy consumption of mobile devices in wireless networks by maintaining mobile stations in the doze state as much as possible, without degrading the expected throughput even in highly-dynamic channel conditions. In the proposed scheme, each station only makes use of its local information and does not cause any overhead on the network. Therefore, the proposed scheme can be easily implemented without any changes on the current IEEE 802.11 standard. Stations performing the proposed scheme can fairly coexist with the other stations that use the standard DCF protocol in the network. Performance of the proposed scheme has been examined by numerical analyses and extensive simulations. The results illustrate that the proposed scheme is very efficient and reduces the energy consumption of mobile stations under a wide range of contention levels.