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When a standard TCP implementation using the minimum retransmission timeout (RTOmin) of 200 ms is used in distributed file systems in data centers, a well-known throughput degradation called TCP Incast occurs, because 200 ms is too large as an RTOmin in data centers. In order to avoid TCP Incast, a TCP implementation using a much smaller RTOmin attained by a fine-grained kernel timer is proposed....
A flying ad hoc network (FANET) that consists of multiple unmanned aerial vehicles (UAVs) is a promising technology for future networked systems. In this paper, we study a way to construct a topology for the FANET that guarantees end-to-end communication between the ground control station (GCS) and each mission UAV that performs its given task via optimizing the locations of the relay UAVs. To this...
The connectivity is one of the fundamental properties for wireless sensor networks (WSNs). However, because of the presence of Rayleigh fading channel and other unstable factors, it is difficult to study the wireless sensor network being connected. In this paper, we present a new approximate expression for lower bound of the conditional probability of the network being connected and obtain the whole...
In Software Defined Networking (SDN), connections between the controller and the switches are maintained in two ways: out-of-band and in-band. In out-of-band controlling, the control channels are constructed via separate links. However, due to several reasons, sometimes in-band controlling is needed instead of out-of-band controlling. In in-band controlling, the data paths are used for control channels...
For augmented reality (AR), computer-generated virtual objects are overlapped on the image of a real world. Since a disturbing real object (e.g, a moving human) on the display of an AR device reduces the immersion to AR experiences, the virtual objects need to be augmented after eliminating the disturbing object. From this motivation, this paper presents mediated reality (MR) photography, where the...
In this paper, we investigate the state of the art for the deployment of ECN (Explicit Congestion Notification) on the Internet from a different viewpoint. We carefully choose four data sets as the hosts to be tested. We negotiate an ECN-Capable and a Not-ECN-Capable connections with each host and collect all packets belonging to the connections. By analyzing the TCP/IP header fields of packets belong...
An application framework is proposed in this paper that considers low cost surveillance mechanism and data acquisition in the forest. An application is developed as proof of concept with detailed design that can take advantage of unmanned urban vehicle to be directly configured and controlled in real-time. The advantages are numerous; it can be used for many purposes. For example, it can be used for...
Concept of computing and communication convergence has many years of history — as strategic concept it started about 1977 and yet have many definitions. The idea behind convergence concept mostly related to getting closer computing and telecommunication common technologies, services and service provider's business models. In this academic position paper some less significant obstacles of influence-reflection...
While many companies have launched various wireless chargers in mobile industries, conventional wireless power transfer (WPT) technologies are available only for a very short distance due to large attenuation of the magnetic fields. A magnetic beamforming WPT system achieves an enhanced power transfer efficiency (PTE) with a longer wireless charging distance than conventional WPT technologies by adjusting...
In distributed network function virtualization (NFV) environments, the latency can be significantly increased as the length of service function chain (SFC) increases. To reduce the latency, the order dependency allowing parallel processing of service functions (SFs) can be exploited. In this paper, we propose an order dependency-aware SF placement scheme and analyze its advantages and challenges compared...
This paper presents signaling architecture models and protocol procedures for SDN-based wireless access networks with Media Independent Management (MIM) capabilities. Three models are described for the framework of SDN and MIM controls, which are decoupled interworking, loosely-coupled integration, and tightly-coupled integration between SDN and MIM controls.
IEEE 802.15.8 develops the specification of PHY and MAC for the peer aware communication (PAC) network, which is an infraless area network supporting low power wireless peer group communication. For providing efficient synchronized group communication, the PAC MAC superframe and cyclic-superframe structure are proposed. The devices of a PAC group can sleep and wake up synchronously at specific periods...
Many challenges for efficiently supporting MTC (Machine-Type Communications) in LTE network have been investigated. In particular, access control schemes have been investigated to protect the system from excessive connectivity of MTC devices. Nonetheless, as the number of devices with data to send increases, it is inevitable that the energy consumed by the preamble collision and retransmission increases...
Wireless network users are increasing vastly in present days and the data traffic in mobile communications systems is increasing explosively too. To cover maximum user with limited radio resources and to provide high quality of service (QoS) to the user, a fractional frequency reuse (FFR) techniques have been proposed for hybrid cellular wireless network. A femtocell can provide high-quality services...
The full potential of multiple-input multiple-output (MIMO) wireless technology can be achieved through iterative MIMO decoding with soft information. In iterative MIMO decoder, the complexity can be major obstacle for practical implementation. The soft interference cancellation-minimum mean squared error (SIC-MMSE) approach for detection is considered as a feasible approach due to its complexity-performance...
We have proposed synchronized Spread-Spectrum Code-Division Multiple-Access (SS-CDMA) communication for location and short message communication system using Quasi-Zenith Satellite System (QZSS) as a safety confirmation system at the time of grade disaster. In this communication, the satellite reception timings of all uplink signals are synchronized using transmission timing control method in order...
In this study, we introduce an efficient dual-band polar transmitter architecture to reduce the required bandwidth of phase-modulated signal for polar transmitter. We derive a time-domain expression of dual-band band-pass signal, and show comparison of receiving signal-to-noise performance between the conventional polar transmitter and the proposed scheme. Simulation results show two-stage digital...
In recent years, a new communication technology emerged by taking advantage of the high-speed switching capabilities of LED known as VLC (Visible Light Communication) has been getting more attention. On the other hand, OFDM is one of the technology that can efficiently utilize a frequency band. In this paper, our goal is to develop a VLC OFDM system, that is easily operable, and capable of high speed...
Human behaviors may change over time, but people always tend to preserve their preference. People typically like similar types of contents, for example, movies that they watch in regular intervals with the same amount of interests. On the other hand, the Internet is moving towards a content-oriented structure from the host-oriented structure. Content-Centric Networking (CCN), a content-oriented paradigm,...
We propose an enhanced automatic modulation classification algorithm based on Kolmogorov-Smirnov test. The proposed classifier employs the real and imaginary components extracted from the received signal as separate decision statistics. Also, unlike the conventional K-S test based algorithm, mean square error (MSE) between the empirical cumulative distribution and the hypothesized distribution for...
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