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Motivated by recent efforts to harness millimeter-wave (mmWave) bands, known to have high outage probabilities, we explore a K-user parallel packet-erasure broadcast channel that consists of orthogonal subchannels prone to packet-erasures. Our main result is two-fold. First, in the homogeneous channel where all subchannels have the same erasure probability, we show that the separation principle holds,...
Delays are crucial in mission-critical applications such as safety networks that exchange information in a short period of time to prevent impending accidents. When such applications are implemented in wireless systems, delays are inevitable, due to a defining characteristic of unstable wireless channels. Information signals sent over the air are inherently prone to distortion, thus often need to...
Network intrusion detection systems rely on a signature-based detection engine. When under attack or during heavy traffic, the detection engines need to make fast decision whether a packet or a sequence of packets is normal or malicious. However, if packets have a heavy payload or the system has a great deal of attack patterns, the high cost of payload inspection severely diminishes the detection...
Approximation in the adder logic is a promising solution for energy-efficient designs in various applications. In this study, new hybrid adder design, which consists of an accurate adder for higher bits and proposed approximate adders for lower bits, is investigated. The XOR-based inexact adder is modified to be used in the approximation part. Simulation results of 16-bits adders show that error rates...
Approximate computing is a solution for energy-efficient designs providing trade-off between accuracy and power. Especially vision-related processors are suitable applications to use approximation. So both error distance and error rate, which are important for output quality, are essential metrics in approximate computing logics. In this study, we propose an adaptive approximate adder by using of...
The source of conducted emission (CE) noise from a power converter is modeled as a current source and an admittance. The noises of multiple parallel power converters are also modeled from the source models of individual converters. The worst case CE noise due to the multiple converters is calculated and experimentally validated. The proposed method should be useful in predicting the noise levels and...
We explore the role of a relay in multiuser networks where some physical perturbation shared around the users may generate data traffic for them simultaneously, hence cause their transmission patterns to be correlated. We investigate how the gain from the help of a relay varies with correlations across the users' transmission patterns in a bursty multiple access channel where the users send signals...
Techniques for visualization of 3-D objects must present to the user photo-realistic images in addition to offering various 3-D manipulations including rotation and translation as well as panning and zooming capabilities. The image-based visualization can satisfy these requirements at low-cost by capturing images of the 3-D object at all view angles. This technique naturally offers photo-realistic...
In this paper, radio propagation measurements and analysis are presented to investigate the channel characteristics of millimeter wave (mmWave) transmission for outdoor cellular communication systems. The measurement campaign is performed in a ski resort town placed in Pyeongchang, South Korea, which is the venue of the coming Winter Olympics in 2018. A 28 GHz synchronous channel sounder system is...
Today, the developing signal processing technology leads to the medical discoveries as well as the fast and elaborate communication. Especially, neurological findings on brain connectivity are one of the interesting issues. However, in spite of the effort to study the brain connectivity by the neuroscientists and engineers, a large part of brain functions are unknown. Among them, the consciousness...
We investigate the role of relays in multiple access channels (MACs) with bursty user traffic, where intermittent data traffic restricts the users to bursty transmissions. Specifically, we examine a K-user bursty MIMO Gaussian MAC with a relay, where bursty traffic of each user is governed by a Bernoulli random process. As our main result, we characterize the degrees of freedom (DoF) region. To this...
We explore the benefits of relays1 in multi-user wireless networks with bursty user traffic, where intermittent data traffic restricts the users to bursty transmissions. Specifically, we investigate a two-user bursty MIMO Gaussian interference channel (IC) with a relay, where two Bernoulli random states govern the bursty user traffic. We show that an in-band relay can provide a degrees of freedom...
In a Wi-Fi Direct network, a single battery-powered mobile device called group owner (GO) helps other mobile devices communicate each other without relying on a pre-existing infrastructure such as base stations. Hence, the Wi-Fi Direct defines two power saving schemes for the energy efficiency of GO, called opportunistic power save (OPS) and notice of absence (NoA). However, the Wi-Fi Direct specification...
This paper proposes a compact dual band PIFA (Planar Inverted F Antenna) covering GPS (Global Positioning System) and WLAN (Wireless Local Area Network) bands for the full metal rimmed mobile handset. The proposed antenna is positioned on the full metal rim which is connected to ground plane via several ground bridges as a ground contact. This ground bridge can be used to obtain the additional resonant...
In this paper we describe remote manipulator systems for use in pyroprocessing facilities where direct access to an in-cell by human workers is not possible because of the toxicity of argon gas. These remote manipulator systems can be classified into two types, i.e., a BDSM (Bridge transported Dual arm Servo-Manipulators) and a Telemanipulator, depending on the environment they are installed in. The...
In this paper, we describe the design of a simulator for use in pyroprocessing technology development. This simulator is a virtual facility of a pyroprocessing mock-up facility to be constructed later. The simulator will be designed to include all the pyroprocessing equipment, utilities, remote maintenance and handling devices and auxiliary devices or tools, in the form of virtual models which are...
Passive RFID tags share a common channel and they use back-scattering modulation because of no self battery. It causes reader collision problems when signal from a reader interferes with signal from other readers. The evolving standards use CSMA based protocol called 'Listen Before Talk (LBT)' and FDMA based protocol called 'Frequency Hopping Spread Spectrum (FHSS)' to reduce reader collision problems...
Passive RFID tags, which have no self-battery and just backscatter the energy from a reader, share a common channel. It causes a tag-to-tag collision problem when at least two or more tags communicate to the reader simultaneously. The dynamic frame slotted Aloha (DFS-Aloha) protocol is one of the well-known anti-collision algorithms to solve this problem. To maximize the system performance and enhance...
Spectrum sensing, a technique to recognize unused or idle spectrum, is a key function for cognitive radio (CR) and requires high precision and fast signal processing technique. To satisfy these requirements, two-stage sensing architecture that combines an energy detector and a feature detector was proposed by IEEE 802.22 working group (WG). For an energy detector, various techniques such as receive...
Code division multiplexing (CDM) based MIMO channel sounder architecture is excellent at measuring fast fading channel. In this paper, loosely synchronous (LS), Kasami and chaotic sequences are suggested as candidates for the code that will be used in CDM architecture. Among those sequences, then, the best suitable sequence for channel sounding is examined through simulation. And by proposing the...
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