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Publication Metadata only 3DTV and 3D video communications(Assoc Computing Machinery, 2010) Department of Electrical and Electronics Engineering; Tekalp, Ahmet Murat; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; 26207With wider availability of low cost multi-view cameras, 3D displays, and broadband communication options, 3D media is destined to move from the movie theater to home and mobile platforms. In the near term, popular 3D media will most likely be in the form of stereoscopic video with associated spatial audio. Recent trials indicate that consumers are willing to watch stereoscopic 3D media on their TVs, laptops, and mobile phones. While it is possible to broadcast 3D stereoscopic media (two-views) over digital TV platforms today, streaming over IP will provide a more flexible approach for distribution of 3D media to users with different connection bandwidths and different 3D displays. In the intermediate term, free-view 3D video and 3DTV with multi-view capture are next steps in the evolution of 3D media technology. Recent free-view 3D auto-stereoscopic displays can display multi-view video, ranging from 5 to 200 views. Transmission of multi-view 3D media, via broadcast or on-demand, to end users with varying 3D display terminals and bandwidths is one of the biggest challenges to realize the vision of bringing 3D media experience to the home and mobile devices. This requires flexible rate-scalable, resolution-scalable, view-scalable, view-selective, and packet-loss resilient transport methods. In this talk, first I will briefly review the state of the art in 3D video formats, coding methods, IP streaming protocols and streaming architectures. We will then take a look at 3D video transport options. There are two main platforms for 3D broadcasting: standard digital television (DTV) platforms and the IP platform. I will summarize the approach of European project DIOMEDES which is developing novel methods for adaptive streaming of multi-view video over a combination of DVB and IP platforms. I will also summarize additional challenges associated with real-time interactive 3D video communications for applications such as 3D telepresence. Finally, open research challenges for the long term vision of haptic video and holographic 3D video will be presented.Publication Metadata only A chain-binomial model for pull and push-based information diffusion(IEEE, 2006) Department of Mathematics; Department of Computer Engineering; Çağlar, Mine; Özkasap, Öznur; Faculty Member; Faculty Member; Department of Mathematics; Department of Computer Engineering; College of Sciences; College of Engineering; 105131; 113507We compare pull and push-based epidemic paradigms for information diffusion in large scale networks. Key benefits of these approaches are that they are fully distributed, utilize local information only via pair-wise interactions, and provide eventual consistency, scalability and communication topology-independence, which make them suitable for peer-to-peer distributed systems. We develop a chain-Binomial epidemic probability model for these algorithms. Our main contribution is the exact computation of message delivery latency observed by each peer, which corresponds to a first passage time of the underlying Markov chain. Such an analytical tool facilitates the comparison of pull and push-based spread for different group sizes, initial number of infectious peers and fan-out values which are also accomplished in this study. Via our analytical stochastic model, we show that push-based approach is expected to facilitate faster information spread both for the whole group and as experienced by each member.Publication Metadata only A classification and performance comparison of mobility models for ad hoc networks(Springer-Verlag Berlin, 2006) N/A; Department of Computer Engineering; Atsan, Emre; Özkasap, Öznur; Master Student; Faculty Member; Department of Computer Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 113507In mobile ad hoc network research, simulation plays an important role in determining the network characteristics and measuring performance. On the other hand, unrealistic simulation conditions may be misleading, instead of being explanatory. For this reason, constructing simulation models closer to the real circumstances is very significant. Movement behavior of mobile entities is one of the most important concepts for the realistic simulation scenarios in mobile ad hoc networks. In this study, we first provide a survey and a new hybrid classification of existing mobility models in the literature. We implemented the random direction and boundless simulation area models on Scalable Wireless Ad Hoc Network Simulator (SWANS) and conducted simulations of Ad Hoc On-Demand Distance Vector (AODV) protocol for these as well as the random walk and random waypoint models. Our comparative results for the mobility models are discussed on a variety of simulation settings and parameters.Publication Metadata only A combined interval and floating-point reciprocal unit(IEEE, 2005) N/A; N/A; Department of Computer Engineering; Küçükkabak, Umut; Akkaş, Ahmet; Master Student; Faculty Member; Department of Computer Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/AInterval arithmetic is one technique for accurate and reliable computing. Among interval arithmetic operations, division is the most time consuming operation. This paper presents the design and implementation of a combined interval and floating-point reciprocal unit. To compute the reciprocal of an operand, an initial approximation is computed first and then iterated twice by Newton-Raphson iteration. The combined interval and floating-point reciprocal unit computes the reciprocal of a double precision floating-point number in eleven clock cycles and the reciprocal of an interval in twenty-one clock cycles. The unit is implemented in VHDL and synthesized to estimate the area and the worst case delay. Simulation results showed that the least significant bit of the floating-point result cannot be guaranteed to be same for all cases compared to the result based on an infinite precision. For interval reciprocal, however, the true result is contained in the result interval.Publication Metadata only A communication theoretical analysis of synaptic multiple-access channel in hippocampal-cortical neurons(IEEE-Inst Electrical Electronics Engineers Inc, 2013) N/A; N/A; Department of Electrical and Electronics Engineering; Malak, Derya; Akan, Özgür Barış; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 6647Communication between neurons occurs via transmission of neural spike trains through junctional structures, either electrical or chemical synapses, providing connections among nerve terminals. Since neural communication is achieved at synapses, the process of neurotransmission is called synaptic communication. Learning and memory processes are based on the changes in strength and connectivity of neural networks which usually contain multiple synaptic connections. In this paper, we investigate multiple-access neuro-spike communication channel, in which the neural signal, i.e., the action potential, is transmitted through multiple synaptic paths directed to a common postsynaptic neuron terminal. Synaptic transmission is initiated with random vesicle release process from presynaptic neurons to synaptic paths. Each synaptic channel is characterized by its impulse response and the number of available postsynaptic receptors. Here, we model the multiple-access synaptic communication channel, and investigate the information rate per spike at the postsynaptic neuron, and how postsynaptic rate is enhanced compared to single terminal synaptic communication channel. Furthermore, we analyze the synaptic transmission performance by incorporating the role of correlation among presynaptic terminals, and point out the postsynaptic rate improvement.Publication Metadata only A communication theoretical modeling and analysis of underwater magneto-inductive wireless channels(Ieee-Inst Electrical Electronics Engineers Inc, 2012) N/A; Department of Electrical and Electronics Engineering; Gülbahar, Burhan; Akan, Özgür Barış; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; 234525; 6647Underwater physical medium is a challenging environment for communication using radio frequency (RF) or acoustic waves due to strong attenuation, delay, multi-path fading, power and cost limitations. Discovered a century ago, magneto-inductive (MI) communication technique stands as a strong alternative paradigm due to its independence of environmental impairments including multi-path fading, dynamic channels and high propagation delays experienced by acoustic waves. Furthermore, MI technique yields networking solutions exploiting low-cost, easily-deployable and flexible antenna structures, and the possibility of forming networks of magnetic waveguides defeating path loss. In this work, highly power efficient and fully connected underwater communication networks (UWCNs) composed of transceiver and relay induction coils are presented. Three dimensional (3D) UWCNs are analysed in terms of basic communication metrics, i.e, signal-to-noise ratio, bit-error rate, connectivity and communication bandwidth. The performance studies of realistic 3D networks covering hundreds of meters sea depths and a few km(2) areas show that fully connected multi-coil networks with communication bandwidths extending from a few to tens of KHz are possible. Furthermore, the performance dependence on coil properties and network size is theoretically modelled. Results show that MI wireless communication is a promising alternative for UWCNs and future research challenges are pointed out.Publication Metadata only A consensus protocol with deterministic finality(Ieee, 2021) N/A; N/A; N/A; Hassanzadeh-Nazarabadi, Yahya; Boshrooyeh, Sanaz Taheri; PhD Student; PhD Student; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; N/A; N/AProof-of-Validation (PoV) is a fair, immutable, and fully decentralized blockchain consensus protocol with an O(1) asymptotic message complexity. The original PoV proposal lacks deterministic finality, which guarantees that a valid block will not be revoked once it is committed to the blockchain. Supporting deterministic finality yields a fork-resistant blockchain. In this extended abstract, we pitch the architectural outline of our proposed Finalita, which is the extension of PoV that enables deterministic finality. Blockchains running with Finalita feature deterministic finality, in addition to all qualities supported by the original PoV.Publication Metadata only A containerized proof-of-concept implementation of LightChain system(Ieee, 2020) N/A; N/A; Department of Computer Engineering; N/A; Department of Computer Engineering; Department of Computer Engineering; Hassanzadeh-Nazarabadi, Yahya; Nayal, Nazir; Hamdan, Shadi Sameh; Özkasap, Öznur; Küpçü, Alptekin; PhD Student; Faculty Member; Master Student; Faculty Member; Faculty Member; Department of Computer Engineering; Graduate School of Sciences and Engineering; College of Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; N/A; N/A; 113507; 168060LightChain is the first Distributed Hash Table (DHT)-based blockchain with a logarithmic asymptotic message and memory complexity. In this demo paper, we present the software architecture of our open-source implementation of LightChain, as well as a novel deployment scenario of the entire LightChain system on a single machine aiming at results reproducibility.Publication Metadata only A correlation-based and spectrum-aware admission control mechanism for multimedia streaming in cognitive radio sensor networks(Wiley, 2017) Hosseini, Elahe S.; Esmaeelzadeh, Vahid; Berangi, Reza; Department of Electrical and Electronics Engineering; Akan, Özgür Barış; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; 6647Bandwidth management and traffic control are critical issues to guarantee the quality of service in cognitive radio networks. This paper exploits a network load refinement approach to achieve the efficient resource utilization and provide the required quality of service. A connection admission control approach is introduced in cognitive radio multimedia sensor networks to provide the data transmission reliability and decrease jitter and packet end-to-end delay. In this approach, the admission of multimedia flows is controlled based on multimedia sensors' correlation information and traffic characteristics. We propose a problem, connection admission control optimization problem, to optimize the connection admission control operation. Furthermore, using a proposed weighting scheme according to the correlation of flows issued by multimedia sensors enables us to convert the connection admission control optimization problem to a binary integer-programming problem. This problem is a kind of a Knapsack problem that is solved by a branch and bound method. Simulation results verify the proposed admission control method's effectiveness and demonstrate the benefits of admission control and traffic management in cognitive radio multimedia sensor networks.Publication Metadata only A cross-layer design for Qos support in cognitive radio sensor networks for smart grid applications(Ieee, 2012) Shah, Ghalib Asadullah; Güngör, Vehbi Çağrı; Department of Electrical and Electronics Engineering; Akan, Özgür Barış; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; 6647In this paper, we propose a cross-layer design to meet the QoS requirements for smart grids employing the cognitive radio sensor networks for their control and monitoring operations. Existing routing protocols pertaining to QoS support are not able to simultaneously handle traffic of different characteristics present in smart grids. Therefore, considering the traffic heterogeneity of smart grid applications exhibiting diverse QoS requirements, a set of priority classes is defined in order to differentiate the traffic for the respective service. Specifically, the problem is formulated as a weighted network utility maximization (WNUM) whose objective is to maximize the weighted sum of flows service. A cross-layer heuristic solution is provided to solve the utility optimization problem by performing joint routing, dynamic spectrum allocation and medium access. Performance of the proposed protocol is evaluated using ns-2, which shows that the number of flows belonging to each class are served according to their weight fraction with their respective data rate, latency and reliability requirement.