• Journal of Communications and Networks
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• v.14 no.5
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• pp.487-494
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• 2012

A standard paradigm for the allocation of wireless resources in communication demands symmetry, that is, all users are assumed to be on equal footing and hence get equal shares of the system's communication capabilities. However, there are situations in which "prime users" should be given priority, as for example in the transmission of emergency messages. We examine prioritization policies that could be implemented at the physical layer and propose a new one, termed interference priority (IP), which is shown to have excellent performance. We evaluate the performance of these prioritization techniques both in controlled settings and within the context of a full cellular system and discuss the impact of prioritized use of resources on the unprioritized users.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.2
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• pp.102-110
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• 2012

ZigBee networks developed for low power and short range communication are being used as home network solution for ubiquitous computing. However, as smart phones and tablet PCs have been widely used, WLANs which use same frequency with ZigBee networks have been increasingly used. Therefore, radio frequency interference causes many problems. To solve radio frequency interference problem among ZigBee networks and WLANs, many researches focus on designing interference minimization schemes in ZigBee networks. However, existing schemes have problems that have waste of resource for detecting interference, and have unnecessary time to avoid interference. In this paper, we propose an interference minimization scheme to solve radio frequency interference in ZigBee networks. The proposed scheme detects interference using ACK mechanism to reduce waste of resource, and avoids interference using table driven channel hopping scheme which is faster than existed schemes. The performance of proposed interference minimization scheme is evaluated by using OPNET simulator. Through the simulation result, we prove that proposed scheme has faster channel hopping than existing schemes.

• KIPS Transactions on Computer and Communication Systems
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• v.4 no.1
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• pp.5-10
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• 2015

D2D (Device-to-Device) communication underlaying LTE-advanced networks is a promising technology to improve the system capacity and spectral efficiency. By sharing the same radio resources with cellular user equipments, D2D communications can significantly enhance the overall spectral efficiency. However, it may cause interference between D2D link and cellular link. Careful resource allocation and interference coordination between cellular and D2D communications are very important and need to be properly handled. This paper proposes a radio resource allocation scheme based on FFFR (Flexible Fractional Frequency Reuse) for D2D communication underlaying cellular networks. The base station selects randomly resource blocks assigned to cellular users, and reuses them for a D2D pair. Through simulations, we have confirmed that the proposed scheme improves the system throughput, reduces the computational complexity, and mitigates the interference of D2D link and cellular link.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.8
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• pp.1532-1541
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• 2015

D2D(Device-to-Device) communication is a promising technology to improve the system capacity and spectral efficiency. By sharing the same radio resources with cellular user equipments, D2D communications can significantly enhance the overall spectral efficiency. However, it may cause interference between D2D link and cellular link. So, careful resource allocation and interference coordination between them are very important and need to be properly handled. This paper proposes a radio resource allocation scheme that decreases interference through the use of area grouping and D2D pair grouping. Simulations results are provided to verify the performance improvement of the proposed scheme in terms of the number of assigned resource blocks and computational complexity.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.4
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• pp.1424-1441
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• 2014

Two-tier femtocell networks, consisting of a conventional cellular network underlaid with femtocell hotspots, play an important role in the indoor coverage and capacity of cellular networks. However, the cross- and co-tier interference will cause an unacceptable quality of service (QoS) for users with universal frequency reuse. In this paper, we propose a novel downlink interference mitigation strategy for spectrum-shared two-tier femtocell networks. The proposed solution is composed of three parts. The first is femtocells clustering, which maximizes the distance between femtocells using the same slot resource to mitigate co-tier interference. The second is to assign macrocell users (MUEs) to clusters by max-min criterion, by which each MUE can avoid using the same resource as the nearest femtocell. The third is a novel adaptive power control scheme with femtocells downlink transmit power adjusted adaptively based on the signal to interference plus noise ratio (SINR) level of neighboring users. Simulation results show that the proposed scheme can effectively increase the successful transmission ratio and ergodic capacity of femtocells, while guaranteeing QoS of the macrocell.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.5A
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• pp.414-420
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• 2009

In this paper, we investigate throughput performance of OFDMA-based relay systems according to the "sub-cell coverage configuration" of the base station (RS) and the relay station (RS). RS is exploited for improved quality of the received signal with a tradeoff of additional radio resource consumption which may result in degradation of the throughput performance of the system. Therefore, "radio resource reuse" may be necessary for high performance in relay systems. However, it also causes system performance degradation since resource reuse between RSs incurs channel interference. Therefore, effective resource reuse also should be considered for "high throughput coverage configuration" when relays are employed. We relate the resource reuse patterns of neighboring RSs to sub-cell coverage configuration. We determine the sub-cell coverage of the system depending on the ratio of received signal-interference-noise-ratio (SINR) of the mobile station (MS) from the BS and RS, respectively. Simulations illustrate the throughput performance as the function of SINR ratio, and it has different optimal point depending on the resource reuse patterns. Therefore, the "resource reuse pattern" and the "effective sub-cell coverage configuration" should be considered together for the high throughput performance of the relay system.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.302-305
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• 2000

This paper proposed an optimal register resource allocation algorithm using graph coloring for minimal register at high level synthesis. The proposed algorithm constructed interference graph consist of the intermediated representation CFG to description VHDL. and at interference graph fur the minimal select color selected a position node at stack, the next inserted spill code and the graph coloring process executes for optimal register allocation. The proposed algorithm proves to effect that result compare another allocation techniques through experiments of bench mark.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.04a
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• pp.146-148
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• 2014

In LTE-Advanced (LTE-A) networks, Relay nodes (RN) are used to improve the system coverage. However, it also brings new kind of interference to users which reduces the system performance. In this paper, we use an optimization relay node deployment to reduce the interference as much as possible and resource allocation to improve the user throughput. Our simulation results show our method is able to improve the user SINR and throughput.

• International Journal of Computer Science & Network Security
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• v.22 no.4
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• pp.329-339
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• 2022

Small cells, particularly femtocells, are regarded a promising solution for limited resources required to handle the increasing data demand. They usually boost wireless network capacity. While widespread usage of femtocells increases network gain, it also raises several challenges. Interference is one of such concerns. Interference management is also seen as a main obstacle in the adoption of two-tier networks. For example, placing femtocells in a traditional macrocell's geographic area. Interference comes in two forms: cross-tier and co-tier. There have been previous studies conducted on the topic of interference management. This study investigates the principle of categorization of interference management systems. Many methods exist in the literature to reduce or eliminate the impacts of co-tier, cross-tier, or a combination of the two forms of interference. Following are some of the ways provided to manage interference: FFR, Cognitive Femtocell and Cooperative Resource Scheduling, Beamforming Strategy, Transmission Power Control, and Clustering/Graph-Based. Approaches, which were proposed to solve the interference problem, had been presented for each category in this work.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.5
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• pp.2081-2101
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• 2016

Successive interference cancellation (SIC) is considered to be a promising technique to mitigate multi-user interference and achieve concurrent uplink transmissions, but the optimal power allocation (PA) issue for SIC users is not well addressed. In this article, we focus on the optimization of the PA ratio of users on an SIC channel and analytically obtain the optimal PA ratio with regard to the signal-to-interference-plus-noise ratio (SINR) threshold for successful demodulation and the sustainable demodulation error rate. Then, we design an efficient resource allocation (RA) scheme using the obtained optimal PA ratio. Finally, we compare the proposal with the near-optimum RA obtained by a simulated annealing search and the RA scheme with random PA. Simulation results show that our proposal achieves a performance close to the near-optimum and much higher performance than the random scheme in terms of total utility and Jain's fairness index. To demonstrate the applicability of our proposal, we also simulate the proposal in various network paradigms, including wireless local area network, body area network, and vehicular ad hoc network.