• ETRI Journal
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• v.32 no.2
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• pp.255-264
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• 2010

Interference scenarios and methodologies between a terrestrial mobile service (MS) system and mobile-satellite service (MSS) system in a co-channel environment are established. Taking into account a practical deployment situation for both systems, we perform computational simulation of interference in terms of carrier-to-interference ratio (C/I) and interference-to-noise ratio (I/N) to evaluate the cofrequency interference from an MS system into an MSS system, and from an MSS system into an MS system, respectively. The methodology and results can be used as a guide when planning the deployment of MSS and MS systems with no unacceptable interference impact between them.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.3A
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• pp.353-361
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• 2000

The performance of a multi-carrier CDMA system is analyzed considering frequency selective multipath fading and Near/Far effects. The number of multicarrier, multiuser, and arms of RAKE receiver, and the decay ratio of frequency selective multipath fading are used as a parameter for the performance analysis. More over, the distribution and the strength of multiuser interference are also considered. To evaluated the Near/Far effects in a multi-carrier CDMA system, three distribution models are assumed. In the first model. interference to carrier Ratio, I/C, ranges form -4 dB to 4dB, and at each 2 dB interval 20 % of multiuser is assumed to be uniformly distributed. In the second one, I/C ranges from -2 dB to 2 dB, and 33.3% of multiuser is assumed to be equally dispersed at each 2dB interval. The third model is 0 dB of I/C, that is, with perfect power control, multiuser are assumed to be evenly located. In this paper, multi-carrier CDMA system adoption RAKE receiver is proposed to mitigate the frequency selective multipath fading. Form the results, the third model(i.e. perfect power control)shows the best performance, and the narrower range of I/C causes the less effects to the desired signal, which reads to the better performance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.9
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• pp.1057-1063
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• 2007

To analyze the performance of mobile communication systems, the exact information of the carrier-to-interference ratio is important. Under the presence of an interferer in a cell, the carrier-to-interference ratio of the receiver is determined by the ratio between the informer-receiver distance$(d_0)$ and the receiver-interferer distance$(d_1)$. In this paper, we derive the carrier-to-interference distribution based on $d_0/d_1$ values using the geometric relation among the informer, interferer and receiver, and confirm its exactness using the simulation result. We also apply the derivation result to a system with the adjacent channel interference, and analyze the outage probability.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.3A
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• pp.352-361
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• 2000

The performance of a multi-carrier CDMA system is analyzed considering frequency selective multipath fading and Near/Far effects. The number of multicarrier, multiuser, and arms of RAKE receiver, and the decay ratio of frequency selective multipath fading are used as a parameter for the performance analysis. More over, the distribution and the strength of multiuser interference are also considered. To evaluate the Near/Far effects in a multi-carrier CDMA system, three distribution models are assumed. In the first model, interference to carrier Ratio, I/C, ranges from -4 dB to 4dB, and at each 2 dB interval, 20 % of multiuser is assumed to be uniformly distributed. In the second one, I/C ranges from -2 dB to 2 dB, and 33.3% of multiuser is assumed to be equally dispersed at each 2dB interval. The third model is 0 dB of I/C, that is, with perfect power control, multiuser are assumed to be evenly located. In this paper, multi-carrier CDMA system adoption RAKE receiver is proposed to mitigate the frequency selective multipath fading. From the results, the third model(i.e. perfect power control) shows the best performance, and the narrower range of I/C causes the less effects to the desired signal, which reads to the better performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4B
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• pp.275-280
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• 2002

Wireless communications have been developed time and time to satisfy more demands of users for internet service, mobile communication service and so on. One of infrastructures leading the next generation wireless communication is HAPS(High Altitude Platform Station). This paper analyzed outage probability when a mobile communication system was constructed by using HAPS. First, an approach to evaluate the carrier to interference power ratio' was introduced and results from the analysis were calculated and simulated. from the results, carrier to interference power ratio (C/I) and fading depth (K) had an effect on outage probability; outage probability decreases when K increases far constant C/I or C/l increases for constant K. In addition, when outage probability for a platform with elevation 30 degrees is expanded into it for 24-platforms, outage probability(C/I=9.8dB) was worse because of many interferers relatively.

• Journal of the Institute of Convergence Signal Processing
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• v.1 no.2
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• pp.115-121
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• 2000

This paper presents the analytic results of outage probability, considering the effect of Rician fading, interference and interference-reduction techniques, when a mobile communication system was constructed by using Stratospheric platform, one of the next generation wireless communication infrastructure which provides high speed multimedia services. The results show that carrier to interference power ratio C/I and fading depth K have an effect on outage probability. That is, outage probability decreases as K value increases for constant C/I value and C/I value increases for constant K value.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.1 s.343
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• pp.133-142
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• 2006

This paper suggests an efficient method of protection ratio(PR) calculation and shows some results of point-to-point radio relay system for frequency coordination. The proposed PR can be expressed as a function of C/N of modulation scheme, noise-to-interference ratio(N/I), multiple interference allowance, fade margins of multi-Path and rain attenuation and net filter discrimination. And PR calculation is performed in view of fade margin, modulation scheme, distance, and interference for actual point-to-point radio relay frequency. According to results for 6.2 GHz, 64-QAM and 60 km at BER 10-6, fade margin and co-channel Protection ratio reveal 41.1dB and 74.9 dB, respectively The merit of presented method provides a systematic and easy calculation by means of PR correction factor related with various parameters and can apply the same concept to frequency coordination of millimeter wave radio relay system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.2
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• pp.196-206
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• 1999

In this paper, we have estimated the interference effects between the NGSO/MSS system and the fixed-service M/W system for sharing the NGSO/MSS system into the frequency band operated by the existing M/W system. Between above two systems, the interference effects must be analyzed in the following three points. That is, PFD(Power Flux Density) level must be obtained in the case of the interference from NGSO satellites into M/W stations, C/I(Carrier-to-Interference Ratio) and the coordination contour in the case of the interference between NGSO/MSS feeder link and a M/W station, and the interference power level and coordination contour in the case of the interference between NGSO/MSS service link(handsets) and M/W stations. Therefore, in order to obtain above three criteria, we have developed the analytical model, introduced the related equations and estimated the system performance by means of the simulation and the theoretial analysis. It is expected that the results will be utilized in setting the criterion for sharing between the NGSO/MSS system and the M/W station.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.6
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• pp.2770-2776
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• 2011

Mutual Interference scenarios between Wireless Broadband (WiBro) and Wireless LAN (WLAN) in DTV bands are assumed. Co-channel interference and adjacent channel interference are respectively evaluated in terms of carrier to interference ratio (C/I) by using Spectrum Engineering Advanced Monte Carlo Analysis Tool (SEAMCAT) based on the Monte-Carlo simulation method. For the simulation, three frequencies such as 185 MHz, 481 MHz and 687 MHz are chosen. Analysis results indicate that interference situation of using frequency of 185 MHz is the worst case, which requires longer protection distance between WiBro MS and WLAN User Equipment (UE), lower transmit power of WiBro Mobile Station (MS) and WiBro Base Station (BS) and WLAN UE and larger guard band. Comparing to cases of using frequency of 185 MHz and 481 MHz, interference situation of using frequency of 687 MHz is slighter. Therefore, using frequency of 687 MHz is easier for coexistence between WiBro and WLAN. Analysis results can be used as reference and guideline when planning the deployment of WiBro and WLAN in DTV bands.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.52 no.1
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• pp.28-34
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• 2003

In this paper, a predistortion linearizer using series diode is proposed for linearizing the power amplifier in microwave radio systems. The power amplifier should be operated near saturation region to achieve high efficiency. But at this region, amplitude and phase distortions of the amplifier remarkably increase with the increase of input power and cause a significant adjacent channel interference. The linearizer is composed of a series diode with a parallel capacitor, which provides positive amplitude and negative phase deviations with the increasing input power. This type of linearizer using the nonlinearity of diode has improved the C/I(Carrier to Intermodulation Distortion) ratio well. By applying this linearizer to two-tone 880MHz power amplifier, adjacent channel leakage power is improved up to 5dBm.