Yazar "Dagdeviren, Orhan" seçeneğine göre listele

Listeleniyor 1 - 2 / 2
  • Küçük Resim Yok
    Öğe
    Low-cost and high-performance channel access strategies for Internet of Nano-Things applications
    (Elsevier B.V., 2024) Sahin, Emre; Akkas, Mustafa Alper; Dagdeviren, Orhan
    Nanodevices, which are only a few nanometers (nm) in size, are interconnected to form the Internet of Nano-Things (IoNT) that performs complex operations. One of the key challenges is ensuring efficient channel access control for nanodevices, especially when dealing with large network sizes. Medium access control (MAC) protocols serve this purpose, but traditional approaches are not practical due to the inherent constraints of nanodevices. In this paper, we propose two novel MAC protocols for IoNT applications. The first protocol, Slot Assignment-Based (SAB) MAC, is a contention-free method relying on scheduling. In contrast to its counterparts, it enables simultaneous packet transmission through Time Spread On-Off Keying (TS-OOK), effectively minimizing the collision probability and end-to-end delay. The second protocol, Receiver-Initiated and Directed (RID) MAC, adopts a contention-based approach to reduce unnecessary transmissions caused by flooding. It achieves this by limiting the number of active nanodevices within a time interval using directional antennas without incurring scheduling overhead. We evaluated the performance of these protocols through comprehensive simulations, comparing them with counterparts in terms of packet transmission success, energy consumption, end-to-end delay and setup overhead. In dense topologies, SAB-MAC outperforms Transparent (TRN) MAC by approximately twice the packet transmission success reaching up to 95.73%. It accomplishes this with 1000 times lower end-to-end delay and reduced setup overhead than Time Division Multiple Access (TDMA). Conversely, RID-MAC achieves twice the packet transmission success of TRN-MAC and ten times that of unicast-based methods, all with lower end-to-end delay and nearly equivalent energy consumption. Consequently, due to its superior performance SAB-MAC is the optimal choice for communication between nanorouters (NRs). However, RID-MAC is more suitable for communication between nanosensors (NSs), as it incurs no setup overhead. © 2023
  • Küçük Resim
    Öğe
    Nanonetwork-based search and rescue operations in debris areas
    (Elsevier, 2023) Şahin, Emre; Akkaş, Mustafa Alper; Dagdeviren, Orhan
    Earthquake is one of the most destructive natural disasters. It is vital to carry out search and rescue (SAR) operations in the debris area after such a major disaster. Although there are various technologies to rescue living things in the debris area, reaching narrow gaps in the rubble is a very difficult process. Nanonetworks operating on terahertz (THz) communication channels are composed of thousands of nanodevices that can pass through even ultrasmall gaps. In this paper, we propose an application that utilizes nanodevices for SAR operations in debris areas. To the best of our knowledge, our paper is the first study to provide a detailed and specialized analysis of this application. We work on channel models by extensively analyzing transmittance, propagation loss, absorption loss, path loss, signal-to-noise ratio (SNR), and capacity. Besides, we investigate a physical layer (PHY) model by considering the effects of using directional or omnidirectional antennas to ensure optimal throughput and energy consumption. Moreover, we present an exhaustive performance analysis of the modulation technique with respect to various nanodevice counts and densities.