• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.6A
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• pp.588-599
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• 2007

This paper presents the coexistence issues between M-WiMAX TDD and WCDMA FDD systems. To improve the M-WiMAX system performance and to reduce the adjacent channel interference to WCDMA FDD system, transmit and receive beamforming techniques are applied in the base stations of M-WiMAX system. Furthermore, we propose an adjacent channel interference modeling methodology, which captures the effect of transmit beamforming on the adjacent channel interference. Besides, we verify the performance improvement in the uplink of WCDMA system due to the transmit beamforming in M-WiMAX downlink based on the proposed adjacent channel interference modeling methodology. We also verify the performance enhancement due to the receive beamforming in the uplink of M-WiMAX system through system level Monte Carlo simulations, considering random user position, the effect of shadowing and multi-path fading channel. Discussions on the gain of applying transmit and receive beamforming in M-WiMAX system comparing the case of SISO system are also included. Furthermore, we present the performance of cosited M-WiMAX and WCDMA systems, considering commercial deployment, additional channel filter at base stations and the effects of TxBF and RxBF.

• Journal of electromagnetic engineering and science
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• v.7 no.2
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• pp.83-90
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• 2007

In this paper, the formulation of the protection ratio based upon a composite fade margin and availability is newly presented for the detailed planning of frequency coordination in the microwave relay system network, and computed results for co-channel and adjacent channel protection ratios are illustrated over an actual system with 6.2 GHz. It is shown that the protection ratio to assure a quality of service can be expressed in terms of the composite fade margin, noise-to-interference ratio, net filter discrimination, and system parameters. In addition, the net filter discrimination, depending upon the transmitter spectrum mask and the overall receiver filter characteristic, has been examined to investigate the effect of the adjacent channel protection ratio caused by the adjacent channel interference. Regarding simulated results for 6.2 GHz, 60 km, 64-QAM, and N/I=6 dB at the bit error rate of $10^{-6}$, composite fade margin and co-channel protection ratio yield 25.14 and 50.3 dB, respectively. Also, the net filter discrimination of 26.5 dB and the adjacent channel protection ratio of 23.8 dB are obtained at the first adjacent channel of 30 MHz. The proposed method provides some merits in view of a comprehensive and practical application with more detailed and various system parameters needed to access the criteria for making the proper frequency coordination.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.2
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• pp.248-255
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• 2009

We proposed a power line channel model. We adopted advantages of other power line channel models to calculate channel responses correctly and simply. Infinite geometric series reduced the calculation complexity of the multipath signal propagation. Description Matrices were also adopted to handle the network topology easily. It represents complex power line network precisely and simply. Newly proposed model considered the effect of the adjacent nodes to channel responses, which have been not considered so far. Several simulations were executed to verify the effect of the adjacent nodes. As a result we found out that it affected channel responses but its effect was limited within certain degree.

• Journal of electromagnetic engineering and science
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• v.6 no.2
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• pp.103-109
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• 2006

This paper suggests an efficient and comprehensive algorithm of the protection ratio derivation and illustrates some calculated results applicable to the initial planning of frequency coordination in the fixed wireless access networks. The net filter discrimination associated with Tx spectrum mask and overall Rx filter characteristic has been also examined to show the effect of the adjacent channel interference. The calculations for co-channel and adjacent channel protection ratios are performed for the current microwave frequency band of 6.7 GHz including Tx spectrum mask and Rx filter response. According to results, fade margin and co-channel protection ratio reveal 41.4 and 75.2 dB, respectively, for 64-QAM and 60 km at BER $10^{-6}$. It is shown that the net filter discrimination with 40 MHz channel bandwidth provides 28.9 dB at the first adjacent channel, which yields 46.3 dB of adjacent channel protection ratio. In addition, the protection ratio of 38 GHz radio relay system is also reviewed for millimeter wave band applications. The proposed method gives some advantages of an easy and systematic extension for protection ratio calculation and is also applied to frequency coordination in fixed millimeter wave networks.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.5
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• pp.473-481
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• 1988

In this paper, we investigated bit error probabilities of GMSK, which is known to be one of promising modulation techniques for a digital mobile radio, under various mobile radio environments.: AWGN, slow Rayleigh fading channel, co-channel interference and adjacent channel interference. We employed an MSK-type receiver for a coherent detection and assumed degrading to both signals than adjacent channel interference. Especially, it is found that GMSK suffers more degradations than MSK from the co-channel interference. But with a high power adjacent channel interference, GMSK shows less bit error rate than MSK. The results confirm a higher spectrum efficiency of GMSK.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.11 s.102
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• pp.1138-1146
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• 2005

This paper makes a study of a formulation of net filter discrimination(NFD) and its computation for analyzing adjacent channel interference and suggests a systematic algorithm for calculating protection ratios of co-channel and adjacent channel applicable to frequency coordination in the fixed radio relay networks. It is shown that adjacent channel protection ratio can be derived from two factors: One is NFD depending upon receiver filter characteristic as well as transmitter spectrum mask and the other is co-channel protection ratio given by a function of fade margin, modulation scheme, and allowable interference. Actually to show the computing procedure from transmitter spectrum mask and receiver filter characteristic, NFD has been obtained for channel bandwidth of 29.65 and 40 MHz at 6.2 and 6.7 GHz band, respectively. According to the results, NFDs at the first adjacent channel of 29.65 and 40 MHz provide 27.4 and 28.9 dB, respectively. From these data, adjacent channel protection ratios corresponding to each channel bandwidth yield 47.5 and 46.3 dB for a given 64-QAM and 60 km. The proposed method gives some merits of an easy calculation, systematic extension, and applying the same concept to frequency coordination in millimeter radio relay networks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.3A
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• pp.269-276
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• 2008

In this paper, we analyze the M-WiMAX UL capacity limits under 2-Tier cell layout, considering the effects of random user position, path loss models, fading channel and adjacent channel interference from WCDMA system. In order to make the analysis approximate to the practical system capacity, we propose a MCS-based capacity analysis method considering the effects of PER requirement and the utilized MCS levels in M-WiMAX system. The proposed MCS-based method is validated through a system-level Monte Carlo simulation. Furthermore, a comparison between the conventional Shannon method and the proposed MCS-based method is presented and the optimum cell radius is suggested.

• Journal of Korea Multimedia Society
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• v.15 no.7
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• pp.903-909
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• 2012

In this paper, we analyze the sharing performances for coexistence of different communication systems between adjacent channels in TV White space. We analyze the parameter performance result according to various density of interfering transmitter and transmitter output. Two cases are analyzed to consider an interference effect between each system. First, WiBro is an interfering transmitter and WLAN is a victim receiver. Second, WLAN is an interfering transmitter and WiBro is a victim receiver. Free space channel model, Extended Hata and IEEE 802.11 model are used for channel environment. Analyzed coexistence results under various co-use scenarios may be widely applied into the technique developed to get the coexisting condition for wireless devices using many communication protocols in adjacent frequency.

• ETRI Journal
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• v.41 no.6
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• pp.703-714
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• 2019

Many use cases have been presented on providing convenience and safety for vehicles employing wireless access in vehicular environments and long-term evolution communication technologies. As the 70-MHz bandwidth in the 5.9-GHz band is allocated as an intelligent transportation system (ITS) service, there exists the issue that vehicular communication systems should not interfere with each other during their usage. Numerous studies have been conducted on adjacent interfering channels, but there is insufficient research on vehicular communication systems in the ITS band. In this paper, we analyze the interference channel performance between communication systems using distribution functions. Two types of scenarios comprising adjacent channel interference are defined. In each scenario, a combination of an aggressor and victim network is categorized into four test cases. The minimum requirements and conditions to meet a 10% packet error rate are analyzed in terms of outage probability, packet error rate, and throughput for different transmission rates. This paper presents an adjacent channel interference ratio and communication coverage to obtain a satisfactory performance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.5
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• pp.542-547
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• 2014

When a primary user transmits over some frequency band assigned to it, most of its transmission power tends to be concentrated in the band but a small portion of it spreads into the adjacent bands. Thus the false alarm probability for the adjacent bands can be higher than expected, even though no primary users are active in the bands. A previous work evaluated the effects of the adjacent channel leakage on the performance of an energy detection based spectrum sensing but it did not take into account the fading phenomenon. In this paper, we analyze the effects of the adjacent channel leakage on an energy detection based spectrum sensing scheme in terms of detection probability and false alarm probability in a fading environment.