• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.3A
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• pp.259-266
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• 2011

Femtocells are expected as the surest way to increase the system capacity with higher-quality links and more spatial reuse in future networks. In spite of their great potential, the system capacity is highly susceptible to network density because a large portion of users are exposed to inter-cell interference (ICI). In this work, we proposed a dynamic interference avoidance scheme in densely deployed cell environments. Our proposed DDIA (Distributed Dynamic ICI Avoidance) scheme not only works in a fully distributed manner, but also controls interference link connectivity of users with high agility so that it is suited for self-organizing networks (SONs). We introduced the concept of ICI-link and two-tier scheduling in designing the DDIA scheme. To avoid ICI without any central entity, our scheme tries to harmonize all base stations (BSs) with users adaptively. Through extensive simulations, it was shown that our proposed scheme improves the throughput of users by more than twice on average compared to the frequency reuse factor 1 scheme, who are exposed to ICI while maintaining or even improving overall network performance. Our scheme operates well regardless of network density and topology.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.9
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• pp.764-774
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• 2013

The number of users and data packets has increased in 4G cellular networks. Therefore, 4G cellular network providers suffer from the network capacity problem. In order to solve this problem, femtocell concept is suggested. It can reduce the coverage hole and enhance the QoS. However, only small number of femtocells experience the large amount of loads. To solve this problem, Mobility Load Balancing (MLB) algorithm is suggested, which is a kind of load balancing algorithm. To distribute the traffic load, MLB algorithm modifies the handover region. If the handover region is reduced by MLB algorithm, some cell edge users are compulsively handed over to neighbor femtocell. In this paper, we analyze the relation between MLB performing period and performance indicators. For example throughput and blocking probability is reduced, if period is decreased. On the contrast, if period is increased, the number of handover frequency is decreased. Using this relation, we suggest the adaptive periodic MLB algorithm. This algorithm includes the advantage of both long period and short period MLB algorithm, such as high throughput, the small number of handover frequency, and low blocking probability.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.8
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• pp.197-210
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• 2016

Lately smartphone uasage is increasing and many Internet of Things (IoT) devices support wireless communications. Accordingly, small base stations which called femtocells are supplied to prevent saturation of existing base stations. However, unlike the original purpose of the femtocell with the advanced hacking technologies, Vulnerability such as gaining the administrator authority was discovered and this can cause serious problems such as the leakage of personal information of femtocell user. Therefore, identify security threats that may occur in the femtocell and it is necessary to ways for systematic vulnerability analysis. In this paper, We analyzed the security threats that can be generated in the femtocell and constructed a checklist for vulnerability analysis using the Threat Modeling method. Then, using the constructed checklist provides a scheme that can improve the safety of the femto cell through the actual analysis and taken the results of the femtocell vulnerabilities analysis.