• Journal of Korea Society of Digital Industry and Information Management
• /
• v.12 no.4
• /
• pp.81-87
• /
• 2016

Recently, as the heterogeneous network (HetNet) has been deployed widely to support various kinds of Radio Access Networks(RANs) with a combination of Macro, Pico, and/or Femto cells, research and standardization efforts have been very active regarding the concept of Licensed Shared Access (LSA) for supporting spectrum sharing. In order for a mobile device to efficiently support the spectrum sharing, the mobile device shall be reconfigurable, meaning that its radio application code has to be adaptively changed in accordance with the hopping of desired spectral band. Especially, Working Group 2 (WG2) of Technical Committee (TC) Reconfigurable Radio System (RRS) of European Telecommunications Standards Institute (ETSI) has been a main driving force for developing standard architecture for Multi-mode Mobile Device (MD) that can be applied to the LSA system. In this paper, we introduce the Multi-mode MD architecture for supporting LSA-based spectrum sharing. An implementation of a test-bed of Multi-mode MD is presented in order to verify the feasibility of the standard MD architecture for the purpose of LSA-based spectrum sharing through various experimental tests.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.10 no.12
• /
• pp.5149-5173
• /
• 2016

Cooperative forwarding has shown a substantial network performance improvement compared to traditional routing in multi-hop wireless network. To further enhance the system throughput, especially in the presence of highly congested multiple cross traffic flows, a promising way is to incorporate the multi-radio multi-channel (MRMC) capability into cooperative forwarding. However, it requires to jointly address multiple issues. These include radio-channel assignment, routing metric computation, candidate relay set selection, candidate relay prioritization, data broadcasting over multi-radio multi-channel, and best relay selection using a coordination scheme. In this paper, we propose a simple and efficient cluster-based cooperative data forwarding (CCDF) which jointly addresses all these issues. We study the performance impact when the same candidate relay set is being used for multiple cross traffic flows in the network. The network simulation shows that the CCDF with MRMC not only retains the advantage of receiver diversity in cooperative forwarding but also minimizes the interference, which therefore further enhances the system throughput for the network with multiple cross traffic flows.

• The Journal of the Korea Contents Association
• /
• v.8 no.8
• /
• pp.28-36
• /
• 2008

The worth of frequency resources is growing up because of development of wireless communication. However, frequency resources is short, because demand is much more than supply. So it needs Cognitive Radio(CR), which manages frequency resources efficiently. In this paper, we apply the efficient Spectrum Sensing method based on CR in an embedded board. We examine various Spectrum Sensing methods and apply these methods to an embedded platform on CR environment and verify the performance through the MAC message.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.15 no.6
• /
• pp.2128-2147
• /
• 2021

Cognitive radio systems are being implemented recently to tackle spectrum underutilization problems and aid efficient data traffic. Spectrum sensing is the crucial step in cognitive applications in which cognitive user detects the presence of primary user (PU) in a particular channel thereby switching to another channel for continuous transmission. In cognitive radio systems, the capacity to precisely identify the primary user's signal is essential to secondary user so as to use idle licensed spectrum. Based on the inherent capability, a new spectrum sensing technique is proposed in this paper to identify all types of primary user signals in a cognitive radio condition. Hence, a spectrum sensing algorithm using improved convolutional neural network and long short-term memory (CNN-LSTM) is presented. The principle used in our approach is simulated annealing that discovers reasonable number of neurons for each layer of a completely associated deep neural network to tackle the streamlining issue. The probability of detection is considered as the determining parameter to find the efficiency of the proposed algorithm. Experiments are carried under different signal to noise ratio to indicate better performance of the proposed algorithm. The PU signal will have an associated modulation format and hence identifying the presence of a modulation format itself establishes the presence of PU signal.

• The Bulletin of The Korean Astronomical Society
• /
• v.37 no.2
• /
• pp.74.1-74.1
• /
• 2012

We observed the radio sources found from the First Look Survey (FLS) field at the 1.4 GHz radio continuum emission with the Very Large Array (VLA) using the A configuration. We identify point sources and multi component sources at ${\geq}4{\sigma}$ level. We also present the submillimeter properties of the selected radio sources in the FLS field from the Herschel/SPIRE 250/350/500/${\mu}m$ and AzTEC 1.1mm surveys. The counterparts of the radio sources at submillimeter for these called 'submillimeter galaxies (SMGs)' are detected at infrared wavelength with the Spitzer MIPS 24 & 70 ${\mu}m$ sources. Based on the MMT/HECTOSPEC red-shift survey, IRS spectroscopy, and SDSS photometric red-shift survey, the radio sources are likely to be the extragalactic sources. Here, we use the star formation rate (SFR) derived from the MIPS 24 and 70 ${\mu}m$ luminosity to compare the measured SFR from the VLA 1.4 GHz luminosity. These results show that a tight correlation between the SFR from the radio luminosity and the MIPS $24{\mu}m$ rather than that from the MIPS $70{\mu}m$ luminosity. Radio and IR correlation is also used to indicate the radio and IR properties of star-formation in the galaxies and active galactic nuclei (AGNs). Using the counterpart sources selected at IR and radio wavelengths, we employ the IR/radio flux ratios to determine the properties and population of the selected galaxies.

• Journal of rehabilitation welfare engineering & assistive technology
• /
• v.8 no.2
• /
• pp.101-107
• /
• 2014

In order to understand people's ideas about radio pagers and effects of the radio pagers on school violence prevention, the study analyzed a radio pager demonstration which was being participated by a total of 606 students. According to the findings from the analysis, first, when it comes to statistical differences between the two groups with the experience of school violence as either a victim or a assailant, both the victims and the assailants believed that the radio pagers is useful to prevent school violence. Both the groups were observed to be willing to use the radio pagers constantly. Second, regarding effects of the radio pagers on the school violence prevention, they were understood to have even a more positive influence both on the school violence prevention and the students' satisfaction with their school lives as a more number of the students possess the radio pagers, as the more the students need the radio pagers and lastly as the more the students feel content with the radio pagers. Based on the results of the analysis, implications and limits of the study were proposed.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.8 no.8
• /
• pp.2663-2674
• /
• 2014

For cognitive radio sensor networks (CRSNs) that use underlay-based spectrum access, the location of the primary user (PU) plays an important role in the power control of the secondary users (SUs), because the SUs must keep the minimum interference level required by the PU. Received signal strength (RSS)-based localization schemes provide low-cost implementation and low complexity, thus it is suitable for the PU localization in CRSNs. However, the RSS-based localization schemes have a high localization error because they use an inexact path loss exponent (PLE). Thus, applying a RSS-based localization scheme into the PU localization would cause a high interference to the PU. In order to reduce the localization error and improve the channel reuse rate, we propose a RSS-based PU localization scheme that uses distance calibration for CRSNs using underlay model-based spectrum access. Through the simulation results, it is shown that the proposed scheme can provide less localization error as well as more spectrum utilization than the RSS-based PU localization using the mean and the maximum likelihood calibration.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.4B
• /
• pp.620-629
• /
• 2010

The analogue radio broadcasting was proven to be a successful and efficient media of delivering information because of free content and wide availability of cheap receivers. But the competition was more dropped than any other media due to the limited amount of radio spectrum that is available. The risk of doing nothing is to miss the opportunity and to loss existing audiences in the long term, or to be locked into inefficient proprietary systems. That is the reason why it is important to act now. It is time for regulators and market participants to hone their strategies, by clearly establishing factors to adopt the digital radio and to facilitate its diffusion. The purpose of this study is to find adoption factors that affected to potential users of digital radio broadcasting. Former research based on diffusion of innovation theory showed that adoption of innovation is affected by demographic variables, media usage and consumer's attitude of innovation. In this study based on a consumer survey, we examined those factors and characteristics of each steps that suggested in diffusion of innovation theory. The findings of this study have implications to explore the suitable technologies and services of digital radio broadcasting.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.12A
• /
• pp.1014-1022
• /
• 2009

In this paper, interference analysis is carried out to obtain the operating criterion and coexistence condition between digital television devices and cognitive radio-based mobile wimax devices in the UHF (Ultra High Frequency) broadcasting frequency bands. To this end, an efficient interfering calculation tool known as SEAMCAT (Spectrum Engineering Advanced Monte-Carlo Analysis Tool) is employed to acquire the coexistence criterions between heterogeneous radio links operating in the same portion of spectrum. As a result, these criterions will be used to achieve interference temperature limit level applied to interference temperature model for analyzing the capacity of cognitive radio receivers accurately.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.10 no.9
• /
• pp.4123-4144
• /
• 2016

Vehicular Ad Hoc Networks (VANETs) utilize radio propagation models (RPMs) to predict path loss in vehicular environment. Modern urban vehicular environment contains road infrastructure units that include road tunnels, straight roads, curved roads flyovers and underpasses. Different RPMs were proposed in the past to predict path loss, but modern road infrastructure units especially flyovers and underpasses are neglected previously. Most of the existing RPMs are computationally complex and ignore some of the critical features such as impact of infrastructure units on the signal propagation and the effect of both static and moving radio obstacles on signal attenuation. Therefore, the existing RPMs are incapable of predicting path loss in flyovers and underpass accurately. This paper proposes an RPM to predict path loss for vehicular communication on flyovers and inside underpasses that considers both the static and moving radio obstacles while requiring only marginal overhead. The proposed RPM is validated based upon the field measurements in 5 GHz frequency band. A close agreement is found between the measured and predicted values of path loss.