• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.2
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• pp.251-256
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• 2001

An error probability analysis is performed far a hybrid DS/SFH spread-spectrum system using minimum shift keying(MSK) modulation. The channel is assumed to be a Rayleigh fading channel with partial-band noise interference. Expressions are derived for the bit error rate(BER) in the context of Rician and Rayleigh fading channels, as a function of the average signal-to-noise ratio(SNR) $E_b/N_0$, the average signal-to- interference ratio(SJR) $E_b/N_J$, and channel parameters. As a result, in the fading channel with large Rician factor, K, which denotes the ratio of power of the direct and the diffused components, the partial-band interference is the worst case. On the other hand, in Rayleigh fading channel(K=0), the full-band interference($\rho$=1) brings the system to the worst case. Performance comparisons among various channels show that the factor K has much large effect on overall performance. For example, in conditions of $\rho$=0.1 and BER=$10^-2$, the system in Rician channel with K=10 requires more 1.9 dB SNR than that in AWGN channel, whereas it is less 5 dB SNR than that in the Rayleigh channel with K=0.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.3
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• pp.477-483
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• 2016

In this paper, we propose a distributed user scheduling with interference-aware power control (IAPC) to maximize signal to generating interference plus noise ratio (SGINR) in uplink multi-cell networks. Assuming that the channel reciprocity time-division duplexing (TDD) system is used, the channel state information (CSI) can be obtained at each user from pilot signals from other BSs. In the proposed scheduling, to be specific, each user reduces the transmit power if its generating interference to other BSs is larger than a predetermined threshold. Each BS selects the user with the largest SGINR among users. Simulation results show that the proposed technique significantly outperforms the existing user scheduling algorithms. It is worth noting that the proposed technique operates with distributed manner without information exchange among cells. Hence, it can be easily applied to the practical wireless systems like 3GPP LTE without significant modifications of the specification.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.5
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• pp.1077-1083
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• 2015

In this paper, we introduce an energy-efficient opportunistic interference alignment (OIA) scheme that greatly improves the sum-rates in multi-cell uplink networks. Each user employs optimal transmit vector design and power control in the sense of minimizing the amount of generated interference to other-cell base stations while satisfying a required signal quality. As our main result, it is shown that owing to the reduced interference level, the proposed OIA schemes attains larger sum-rates than those of OIA with no power control for almost all signal-to-noise ratio regions. In addition, when both zero-forcing and minimum mean square error (MMSE) detectors are employed at the receiver along with the OIA scheme, it is shown that the OIA scheme with MMSE detection shows superior performance.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.12
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• pp.8-16
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• 2010

NAND multilevel cell (MLC) flash memory is widely issued because it can increase the capability of storage by storing two or more bits to a single cell. However if a number of levels in a cell increases, some physical features like cell to cell interference result cell voltage shift and it is known that a VT shift is unidirectional. To reduce errors by the effects, we can consider error correcting codes(ECC) or signal processing methods. We focus signal processing methods for the cell to cell interference voltage shift effects and propose the algorithms which reduce the effects of the voltage shift by estimating it and making level read voltages be adaptive. These new algorithms can be applied with ECC at the same time, therefore these algorithms are efficient for MLC error correcting ability. We show the bit error rate simulation results of the algorithms and compare the performance of the algorithms.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.8
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• pp.39-44
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• 2013

Long Term Evolution (LTE) - Advanced has developed Heterogeneous Network (HetNet) that consists of a mix of macrocells and low-power nodes such as picocells to improve the system performance. Also, to encourage data offloading in HetNet, Cell Range Expansion (CRE) have been introduced. In this paper, we propose a cell selection scheme based on Signal to Interference plus Noise Ratio (SINR) for optimal offloading effect. And we manage the interference for user located in cell range expanded region using Almost Blank Subframe (ABS) with flexible ABS ratio to improve the spectrum efficiency in time domain. Simulation results show that proposed scheme can improve spectrum efficiency of macrocell and picocell user. Eventually, proposed scheme can imporve overall user performance.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.2
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• pp.117-122
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• 2020

In this paper, we study the electromagnetic interference in adjacent antenna aperture of multi-function radar for Integrated MAST of naval ship, which is operating plural radars, with test result of two different X-band antennas. Two antennas is placed in the test fixture copying the part of Integrated MAST for the experiment. The test figure is modeled to see the electromagnetic interference when antenna beam is steered by using electromagnetic analysis tool. Also, 6 test scenarios is determined to verify experimentally and each test scenario is run in an anechoic chamber. At the test antenna #1 radiates a pulse signal and the signal from the antenna #2 is stored and analyzed in the optic data format through a receiving device. Based on the result, the effect of electromagnetic interference is suggested when multi-function radars in the Integrated MAST are operating in adjacent distance.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.10
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• pp.53-59
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• 2011

In recent years, mobile communication service is used extensively as a larger service area for the maintenance of quality of service required by the expansion of service areas and As the ever-increasing role in relays, and the location is relatively easy to install and less constrained costs, operating cost savings in terms of ICS(Interference Cancellation System) repeaters are required. However, an adaptive algorithm that is applied when updating the filter due to the increase in volume of operations increase the complexity of hardware implementation is fraught with many difficulties. In this paper, if there is a path that feedback. ICS repeater utilizing baseband signal processing for the removal of interfering signals from the feedback operation, significantly reducing the amount of reducing hardware complexity Complex Singed Signed LMS adaption algorithm is proposed. Proposed algorithm for evaluating the performance of Static channel WCDMA signal environment for the ICS, the results of the simulation algorithm, convergence speed and better performance in therms of convergence errors that are required through the implementation of the operation greatly reduces the amount of hardware complexity able to reduce the effect was visible.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.4
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• pp.1976-1981
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• 2013

In this paper, we propose a frequency-domain interference cancellation algorithm for direct-sequence spread spectrum systems. In the previously proposed frequency-domain interference cancellation algorithms that protocol defines the rules concerning the collection of means of Transmission Control Protocol (TCP: Transmission Control Protocol) is the most widely used in the transport layer. Two-way traffic through the network path to the same end-to-end transfer of data in the opposite direction between pairs of nodes are infused with two or more TCP connection using the network traffic patterns from the exchanger and routers share results of approval. Per-flow input/output structure of matter using the LTS online reaction when evaluated as this is the most important factor. TCP-MT when the connection duration is one of the largest performance gains.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.7B
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• pp.505-516
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• 2012

According to distribute of resource of macro cell and reduce distance between transmitter and receiver, Femto cell system is promising to provide costeffective strategy for high data traffic and high spectral efficient services in future wireless cellular system environment. However, the co-channel operation with existing Macro networks occurs some severe interference between Macro and Femto cells. Hence, the interference cancellation or management schemes are imperative between Macro and Femto cells in order to avoid the decrease of total cell throughput. First, we briefly investigate the conventional resource allocation and interference cancellation scheme between Macro and Femto cells. So we found that cell throughput and frequency reuse ware decreased Then, we propose an adaptive resource allocation scheme based on the distribution of Femtocell traffic in order to increase the cell throughput and also maximize the spectral efficiency over the FFR (Fractional Frequency Reuse) based conventional resource allocation schemes. Simulation Results show that the proposed scheme attains a bit similar SINR (Signal to Interference Noise Ratio) distribution but achieves much higher total cell throughput performance distribution over the conventional resource allocation schemes for FFR and future IEEE 802.16m based Femtocell network environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.5C
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• pp.351-360
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• 2008

In cellular mobile radio systems with frequency reuse, the interference signals degrade the channel estimation and signal detection performance due to the low signal-to-interference ratio near coverage boundaries. When the preamble pilot sequences from different cells are orthogonal or located in disjointed positions, they can be used for multi-cell channel estimation and interference cancellation. In time-varying channels caused by Doppler spread, data pilot symbols are needed for channel estimations. However, data pilot symbols are usually located in identical positions for the overhead reduction, which degrades the channel estimation performance. In this paper, we demonstrate a significant amount of performance improvement is achieved by multiplying different pseudonoise(PN) sequences to the data pilot symbols from adjacent interference cells. In particular, for detection scheme using maximal ratio combining(MRC) and inter-cell spatial demultiplexing(ISD), quantitative performance gain of spectral efficiency for different values of Doppler frequency and interference power is presented.