• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.5
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• pp.2009-2028
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• 2018

Considering a dual-hop energy-harvesting (EH) relaying system, this paper advocates novel relaying protocols based on adaptive time power switching-based relaying (AR) architecture for amplify-and-forward (AF) mode. We introduce novel system model relaying network with impacts of co-channel interference (CCI) and derive analytical expressions for the average harvested energy, outage probability, and the optimal throughput of the information transmission link, taking into account the effect of CCI from neighbor cellular users. In particular, we consider such neighbor users procedure CCI both on the relay and destination nodes. Theoretical results show that, in comparison with the conventional solutions, the proposed model can achieve optimal throughput efficiency for sufficiently small threshold SNR with condition of reasonable controlling time switching fractions and power splitting fractions in concerned AR protocol. We also explore impacts of transmission distances in each hop, transmission rate, the other key parameters of AR to throughput performance for different channel models. Simulation results are presented to corroborate the proposed methodology.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.6
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• pp.2014-2034
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• 2015

This paper focuses on solving co-channel interference (CCI) issues arising in the open subscriber group (OSG) mode of heterogeneous networks (HetNets). Considering a general framework consisting of arbitrary number of picocells within a macro cell, where the inter-user interference (IUI) is the main CCI to macro user equipments (UEs), while the the inter-cell interference (ICI) is the major CCI to pico UEs. In this paper, three IA based transceiver design schemes are proposed. For macro cell, we uniformly use block diagonalization (BD) scheme to eliminate the IUI. And for picocells, three IA schemes are proposed to mitigate the ICI. The first scheme, named as zero forcing IA (ZF-IA) scheme, aligns the inter picocell interference onto an arbitrary sub-space of the cross-tier interference using ZF scheme. Considering the channel state information (CSI) of the desired channel of pico UEs, the second scheme, named as optimal desired sub-channel selected IA (ODC-IA) scheme, aligns the inter picocell interference onto a certain sub-space of the cross-tier interference, which guarantees the largest channel gain of the desired signal of pico UEs. The third IA scheme, named as maximum cross-tier interference selected IA (MI-IA) scheme, is designed for the system with less receive antennas. The inter picocell interference is aligned onto the space of the strongest cross-tier interference and only the interference on this space is nullified. The complexity analysis and simulations show that the proposed transceiver design schemes outperform the existing IA schemes in the OSG mode of HetNets, and the MI-IA scheme reduces the requirement of the receive antennas number with lower complexity.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.9
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• pp.2153-2169
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• 2012

Femtocells provide high quality indoor communications with low transmit power. However, when femtocells are applied in cellular systems, a co-channel interference problem between macrocells and femtocells occurs because femtocells use the same spectrum as do the macrocells. To solve the co-channel interference problem, a previous study suggested a resource allocation scheme in LTE cellular systems using FFR. However, this conventional resource allocation scheme still has interference problems between macrocells and femtocells near the boundary of the sub-areas. In this paper, we define an optimization problem for resource allocation to femtocells and propose a femtocell resource allocation scheme to solve the optimization problem and the interference problems of the conventional scheme. The evaluation of the proposed scheme is conducted by System Level Simulation while varying the simulation environments. The simulation results show that the proposed scheme is superior to the conventional scheme and that it improves the overall performance of cellular systems.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.3
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• pp.542-546
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• 2009

In this Paper, a back propagation neural network learning algorithm based on the complex multilayer perceptron is represented for controling and detecting interference of the received signals in cellular mobile communication system. We proposed neural network adaptive correlator which has fast convergence rate and good performance with combining back propagation neural network and the receiver of cellular. We analyzed and proved that NNAC has lower bit error probability than that of traditional RAKE receiver through results of computer simulation in the presence of the tone and narrow - band interference and the co-channel interference.

• Journal of electromagnetic engineering and science
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• v.9 no.3
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• pp.141-145
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• 2009

Interference scenarios involving and a methodology for a terrestrial international mobile telecommunication(IMT) system and mobile-satellite service(MSS) system in a co-channel environment are established. Taking into account a practical deployment situation for both systems, a computational simulation of interference in terms of the ratio of interference power to thermal noise(I/N) is performed in order to evaluate the co-frequency interference with the IMT system caused by the MSS system. The methodology and results could be used for planning an IMT deployment without an unacceptable interference impact caused by the MSS system.

• Journal of Broadcast Engineering
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• v.18 no.1
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• pp.59-65
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• 2013

Recently, the digital television transition from analog television to digital television has been progressing in terrestrial broadcasting. As a result of the DTV transition, additional reassignments and deployments of TV White spaces (TVWS) caused by co-channel interference (CCI) were needed. In this paper, we investigate the TVWS caused by CCI using Longley-Rice and ITU-R P.1546 propagation model, which are the most widely-used propagation model. In addition, we analyze the service coverage radius and CCI radius according to the height of transmitter antenna and transmitting power. The results show that the ratios of CCI radius to service coverage radius in Longley-Rice and ITU-R P.1546 propagation model are about 2.54 and 2.07, respectively.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.5
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• pp.92-98
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• 2007

We propose the schemes for the dynamic channel allocation (DCA) in multi-cell OFDMA systems to avoid co-channel interference (CCI) without the additional complexity. The allocatable subcarriers areas, which is designed to avoid CCI among cells, are determined for each cell. Each cell allocates the subcarriers within the allocatable subcarriers area of the cell independently. We consider the trade off between the reduced frequency selection diversity and the amount of CCI on a subcarrier by the determination of allocatable subcarriers area. Hence, the equal allocation bound scheme for the high selectivity channel and the flexible allocation bound scheme for the low selectivity channel are proposed. Through the numerical results, it is confirmed that the proposed schemes have better performance in the aspects of the number of overlapping allocated subcarriers, the capacity and the outage probability compared to the case which does not determined the allocatable subcarriers area.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.4
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• pp.1638-1654
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• 2018

The heterogeneous network (HetNet) has been one of the key technologies in Long Term Evolution-Advanced (LTE-A) with growing capacity and coverage demands. However, the introduction of femtocells has brought serious co-layer interference and cross-layer interference, which has been a major factor affecting system throughput. It is generally acknowledged that the resource allocation has significant impact on suppressing interference and improving the system performance. In this paper, we propose a hybrid-clustering algorithm based on the $Mat{\acute{e}}rn$ hard-core process (MHP) to restrain two kinds of co-channel interference in the HetNet. As the impracticality of the hexagonal grid model and the homogeneous Poisson point process model whose points distribute completely randomly to establish the system model. The HetNet model based on the MHP is adopted to satisfy the negative correlation distribution of base stations in this paper. Base on the system model, the spectrum sharing problem with restricted spectrum resources is further analyzed. On the basis of location information and the interference relation of base stations, a hybrid clustering method, which takes into accounts the fairness of two types of base stations is firstly proposed. Then, auction mechanism is discussed to achieve the spectrum sharing inside each cluster, avoiding the spectrum resource waste. Through combining the clustering theory and auction mechanism, the proposed novel algorithm can be applied to restrain the cross-layer interference and co-layer interference of HetNet, which has a high density of base stations. Simulation results show that spectral efficiency and system throughput increase to a certain degree.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.3
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• pp.17-22
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• 2011

In this paper, we analyze co-channel interference cancellation performance to be generated in multi-hop military communication system. First, remove interference using zero-forcing (ZF) and minimum mean square error (MMSE) scheme as interference cancellation methods, and then obtain additional diversity gain and improve interference cancellation performance by applying successive interference cancellation (SIC). We consider Rayleigh fading channel and system performance is analyzed as respect of bit error probability. From simulation results, we confirm MMSE improves significantly BER performance than ZF in multi-hop wireless network environment. It is also confirmed ZF and MMSE schemes applying SIC algorithm have better performance comparing to the existing schemes. Therefore, MMSE-SIC method can provide more reliable signal transmission in the multi-hop military communication system.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.153-154
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• 2006

We propose the dynamic channel allocation (DCA) algorithm for multi-cell OFDMA systems to avoid co-channel interference (CCI). The proposed algorithm is utilized not in a centralized, but in a distributed manner which reduces complexity. The simulation results confirm that the number of overlapping allocated subcarriers is reduced and the average SINR of a sub-carrier is increased by this algorithm.