• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.2A
• /
• pp.181-186
• /
• 2004

Analysis on sharing between GSO FSS and terrestrial system in the 40㎓ band, related with the problem for sharing between terrestrial services and FSS and identification of HDFSS downlink bands in World Radiocommunication Conference 2003, was practiced by assuming that both systems are operated in Korea. According to results from simulation using the characteristic parameters of GSO FSS and terrestrial FS system in 40 ㎓ described in ITU-R Recommendations, in case that elevation and azimuth angle of antenna of FS station are adjusted to point directly to the geostationary satellite, the GSO system can cause the worst interference to the FS system. This situation is possible to occur in the installation of 40 GHz FS station in urban area where there are high-rise buildings. If high-density FS stations in 40 ㎓ band are operated in the future, interference mitigation techniques to avoid GSO arc should be considered.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.28 no.3
• /
• pp.177-185
• /
• 2017

In this paper, we proposed a concept of interference load to analyze the performance of spectrum sharing technologies in unlicensed frequency bands. The interference load can quantitatively compare the technical properties of various spectrum sharing technologies, such as frequency hopping(FH), duty cycle(DC), listen-before-talk(LBT). Therefore, it can help to evaluate whether a local regulation about spectrum sharing is reasonably established or not. In order to verify the suggested concept, we applied it to 2.4 GHz frequency bands. Also, we demonstrated a real-time test-bed. Two bit error rate(BER) curves for FH with 10 random channels and DC of 10 %, show such good agreement that our proposed concept is expected to be widely used to assess various spectrum sharing technologies.

• Journal of Positioning, Navigation, and Timing
• /
• v.12 no.2
• /
• pp.177-184
• /
• 2023

In order to reserve frequency bands for stable operation of the Korean Positioning System (KPS), it must be demonstrated that the impact of interference caused by KPS on other services operating in the same bands is tolerable. The International Telecommunication Union (ITU) provides the radio regulations and a compatibility assessment methodology for the coexistence of different services in limited frequency resources. The purpose of this paper is to investigate the radio regulations regarding the compatibility issues between the KPS and other services sharing the same frequency bands. The results of the investigation show that the RNSS system can be operated in the L5-band under the condition that the Power Flux Density (PFD) and Aggregated Equivalent PFD (AEPFD) thresholds specified in the radio regulations are met. In addition, the ITU recommends that the interference-to-noise ratio (INR) protection criteria be met to prevent degradation of the performance of radar systems operating in the L2/L6-band. In the case of the S-band, coordination of allocations for RDSS space stations with respect to terrestrial services is not required if the PFD does not exceed regulated thresholds regulated by ITU.

• Journal of Advanced Navigation Technology
• /
• v.15 no.1
• /
• pp.11-17
• /
• 2011

In this paper, we consider the frequency sharing feasibility of Fixed Satellite Service (FSS) with Microwave Landing System (MLS) allocated in the C-band. On the basis of characteristics of MLS and FSS suggested by ITU and safety standards of MLS by ICAO, three interference scenarios are built and numerical simulations are carried out for investigating the frequency sharing between the two systems. From the simulation results, we calculate the separation distance between MLS and FSS ground antennas, required for frequency sharing by employing standard protection limits regulating the interference to noise ratio (I/N) of the receiver.

• The Journal of the Korea Contents Association
• /
• v.14 no.9
• /
• pp.589-597
• /
• 2014

The increasing demand for various mobile telecommunication services calls for more spectrum resource. Considering the scarcity of spectrum resource and the difficulties of development of higher frequency band, the unique way to meet the increasing demand is to maximize the utilization efficiency of the current spectrum resource. Under the circumstances, various spectrum sharing plans have been in recent studies to dissolve the excess spectrum demand. In addition, spectrum efficiency measurement methods become more important to verify the effectiveness of spectrum sharing and estimate the performance of various wireless systems. Our research addresses measurement methods to estimate spectrum utilization efficiency in a rational manner. Based on ITU-R recommendations, various measuring methods for spectrum utilization efficiency are reviewed. Then a queueing based approach is newly presented as alternatives to the current models. By using the proposed model, the spectrum efficiency increment with the adoption of spectrum sharing plans can be estimated more properly.

• Journal of Advanced Navigation Technology
• /
• v.14 no.6
• /
• pp.808-816
• /
• 2010

Spectrum sharing between wireless systems becomes a critical issue due to emerging new technologies and spectrum shortage. Since WRC-07 allocated 3400-3600MHz band for the coming fourth generation (4G) or IMT-Advanced on a co-primary basis along with existing Fixed Wireless Access (FWA), it requires spectrum sharing studies to solve the interference problems between two systems. In this paper, I propose the separation distance between service coverages as a sharing fundamental criterion based on the interference to noise power ratio (I/N) received in a FWA base station from several IMT-Advanced base stations on the cellular systems. Especially, some results imply that I/N values compared to the worst case can be greatly reduced with MIMO SDMA interference mitigation technique of IMT-Advanced base stations so that these two systems can co-exist in the same frequency with appropriate separation distance.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.13 no.6
• /
• pp.23-28
• /
• 2013

Because characteristics of diversity, large-scale and unpredictability of disaster are very difficult to make predict of disaster, rapid disaster response activity is important to reduce damage from disaster. Therefore emergency communication technology is essential to information sharing between field personnel in the field. Because the heterogeneous radios defined as some of 100MHz VHF, 400MHz UHF, and 800MHz emergency communication RF band are used in Korea, the field personnels need to have multiple radios. In order to use one radio per personnel, radio voice intercommunication is very necessary. We study on modular 3-Band RF to communicate between heterogeneous radios through single multi-band antenna and verify scalable of the number of equipped radios.

• Publications of The Korean Astronomical Society
• /
• v.15 no.1
• /
• pp.35-60
• /
• 2000

We have analyzed the frequency sharing in the range of 71-275 GHz, which was adopted as a main topic of the WARC-2000 at the previous conference WARC-97. Though the technology of the active services has not been fully developed in this frequncy range, the heavy usage of this technology is expected in foreseeable future. To protect the passive services from spurious and out-of-band emissions of active services, realignment of the spectrum between 71 GHz and 275 GHz is strongly required. In addition, some effort should be made to allocate special bands for the radio astronomy service.

• Journal of information and communication convergence engineering
• /
• v.12 no.2
• /
• pp.97-103
• /
• 2014

In spectrum sensing, there is a tradeoff between the probability of missed detection and the probability of a false alarm according to the value of the sensing threshold. Therefore, it is important to determine the sensing threshold suitable to the environment of cognitive radio networks. In this study, we consider a cognitive radio-based ad hoc network where secondary users directly communicate by using the same frequency band as the primary system and control their transmit power on the basis of the distance between them. First, we investigate a condition in which the primary and the secondary users can share the same frequency band without harmful interference from each other, and then, propose an algorithm that controls the sensing threshold dynamically on the basis of the transmit power of the secondary user. The analysis and simulation results show that the proposed sensing threshold control algorithm has low probabilities of both missed detection and a false alarm and thus, enables optimized spectrum sharing between the primary and the secondary systems.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2013.05a
• /
• pp.68-70
• /
• 2013

Wireless communications based train control system which is operated with a dedicated frequency band is used only on the fixed path. Because of that, the problem arises in the area of efficiency. In this paper, a network access management technique is proposed to make the railway dedicated frequency band accessible by a normal mobile communication users efficiently and safely.