• Journal of applied mathematics & informatics
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• v.33 no.1_2
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• pp.211-217
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• 2015

A dynamic spectrum access scheme with channel partitioning for secondary handover calls in cognitive radio networks is proposed to reduce forced termination probability due to spectrum handover failure. A continuous-time Markov chain method for evaluating its performance such as blocking probability, forced termination probability, and throughput is presented. Numerical and simulation results are provided to demonstrate the effectiveness of the proposed scheme with channel partitioning.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.5 s.120
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• pp.465-470
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• 2007

The co-channel interference is a primary factor of loss in multimedia mobile communications. In this paper, we present a performance of the frequency reuse partitioning to refrain the co-channel interference and maximize system performance. First, we analyze the co-channel interference using the frequency reuse partitioning through the statistical modeling. From this results, we decide on the frequency reuse partitioning for the system throughput which is maximized. Finally, analysis and simulation results show that the frequency reuse partitioning based cellular system can mitigate the co-channel interference and maximize the system throughput. The experimental results show that system throughput is maximized from 0.7 to 0.8 according to traffic road. We can maximize the system throughput using the results with cellular system design parameter.

• Journal of Communications and Networks
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• v.8 no.1
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• pp.13-20
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• 2006

In cellular mobile communications, how to achieve optimum system capacity with limited frequency spectrum is one of the main research issues. Many dynamic channel assignment (DCA) schemes have been proposed and studied to allocate the channels more efficiently, thus, the capacity of cellular systems is improved. Reuse partitioning (RP) is another technique to achieve higher capacity by reducing the overall reuse distance. In this paper, we present a network-based DCA scheme with the implementation of RP technique, namely dynamic reuse partitioning with interference information (DRP-WI). The scheme aims to minimize the effect of assigned channels on the availability of channels for use in the interfering cells and to reduce their overall reuse distances. The performance of DRP-WI is measured in terms of blocking probability and system capacity. Simulation results have confirmed the effectiveness of DRP-WI scheme. Under both uniform and non-uniform traffic distributions, DRP-WI exhibits outstanding performance in improving the system capacity. It can provide about 100% capacity improvement as compared to conventional fixed channel assignment scheme with 70 system channels.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.9B
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• pp.892-899
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• 2009

Reuse-partitioning is a simple technique that can be used to improve the capacity of a cellular system. In the previous researches, authors do not explain how a channel is selected and what happens when there is no channel available when a call arrives. Therefore, in this paper, we describe a simple channel selection procedure and analyze the performance of a system. The performance is presented in terms of the channel utilization and call blocking probability by varying offered load per cell. Our analytical results may be added in a realistic performance analysis of reuse-partitioning-based system.

• Journal of Korea Multimedia Society
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• v.16 no.5
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• pp.601-609
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• 2013

One of the most serious factors constraining the next generation cellular mobile consumer communication systems will be the severe co-channel interference experienced at the cell edge. Such a capacity-degrading impairment combined with the limited available spectrum resource makes it essential to develop more spectrally efficient solutions to enhance the system performance and enrich the mobile user's application services. This paper proposes a unique hybrid method of frequency hopping (FH) and subcarrier-reuse-partitioning that can maximize the system capacity by efficiently utilizing the available spectrum while at the same time reduce the co-channel interference effect. The main feature of the proposed method is that it applies an optimal combination of different frequency reuse factors (FRF) and FH-subcarrier allocation patterns into the partitioned cell regions. From the simulation results, it is shown that the proposed method can achieve the optimum number of subcarrier subsets according to the frequency-reuse distance and results in better performance than the fixed FRF methods, for a given partitioning arrangement. The results are presented in the context of both blocking probability and BER performances. It will also be shown how the proposed scheme is well suited to FH-OFDMA based cellular systems aiming at low co-channel interference performance and optimized number of subcarriers.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.6
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• pp.808-816
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• 2016

As the number of CPU/GPU cores and IPs in SOC increases and applications require explosive memory bandwidth, simultaneously achieving good throughput and fairness in the memory system among interfering applications is very challenging. Recent works proposed priority-based thread scheduling and channel partitioning to improve throughput and fairness. However, combining these different approaches leads to performance and fairness degradation. In this paper, we analyze the problems incurred when combining priority-based scheduling and channel partitioning and propose dynamic priority thread scheduling and adaptive channel partitioning method. In addition, we propose dynamic address mapping to further optimize the proposed scheme. Combining proposed methods could enhance weighted speedup and fairness for memory intensive applications by 4.2% and 10.2% over TCM or by 19.7% and 19.9% over FR-FCFS on average whereas the proposed scheme requires space less than TCM by 8%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.8B
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• pp.677-686
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• 2012

In the presence of a high power cellular network, picocells are added to a Macro-cell layout aiming to enhance total system throughput from cell-splitting. While because of the different transmission power between macrocell and picocell, and co-channel interference challenges between the existing macrocell and the new low power node-picocell, these problems result in no substantive improvement to total system effective throughput. Some works have investigated on these problems. Pico Cell Range Expansion (CRE) technique tries to employ some methods (such as adding a bias for Pico cell RSRP) to drive to offload some UEs to camp on picocells. In this work, we propose two solution schemes (including cell selection method, channel allocation and serving process) and combine new adaptive frequency partitioning reuse scheme to improve the total system throughput. In the simulation, we evaluate the performances of heterogeneous networks for downlink transmission in terms of channel utilization per cell (pico and macro), call blocking probability, outage probability and effective throughput. The simulation results show that the call blocking probability and outage probability are reduced remarkably and the throughput is increased effectively.

• Proceedings of the IEEK Conference
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• 2001.06d
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• pp.179-182
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• 2001

This paper has been studied a wavelet based still image transmission over the wireless channel. EZW(Embedded Zerotree Wavelet) is an efficient and scalable wavelet based image coding technique, which provides progressive transfer of signal resulted in multi-resolution representation. It reduces therefore the reduce cost of storage media. Although EZW has many advantages, it is very sensitive on error. Because coding are performed in subband by subband, and it uses arithmetic coding which is a kind of variable length coding. Therefore only 1∼2bit error may degrade quality of the entire image. So study of error localization and recovery are required. This paper investigates the use of reversible variable length codes(RVLC) and data partitioning. RVLC are known to have a superior error recovery property due to their two-way decoding capability and data partitioning is essential to applying RVLC. In this work, we show that appropriate data partitioning length for each SNR(Signal-to-Noise Power Ratio) and error localization in wireless channel.

• Journal of Communications and Networks
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• v.9 no.1
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• pp.11-17
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• 2007

In this paper, system performance of turbo trellis coded modulation (turbo TCM) is presented and analyzed through computer simulations over two typical channels, namely additive white Gaussian noise (AWGN) and Rayleigh fading channels. We use and compare different mapping strategies based on Ungerboeck partitioning (UP), block partitioning (BP), mixed partitioning (MP), Gray partitioning (GP), and Ungerboeck-Gray partitioning (UGP) of the signal constellation of the turbo TCM system. Furthermore, taking 8PSK modulation of turbo TCM as an example, our simulation results show that turbo TCM with UP can obtain better performance than turbo TCM with BP, MP, GP, and UGP in both AWGN and Rayleigh fading channels.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.10
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• pp.24-34
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• 2003

In this paper, we investigated the problems of the offset time based service differentiation scheme for optical burst switching (OBS) networks, and proposed the preemption-based service differentiation scheme which combines a preemption channel selection algorithm and channel partitioning algorithm. The proposed preemption channel selection algorithm minimizes the length of preempted bursts to improve the channel efficiency, while the proposed channel partitioning algorithm controls the degree of service differentiation between service classes. The simulation results showed that the proposed schemes could improve the end-to-end performance and effectively provide controllable service differentiation in the multiple hop network environments.