• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권1호
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• pp.149-168
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• 2015

In cognitive radio networks (CRNs), hybrid overlay and underlay sharing transmission mode is an effective technique for improving the efficiency of radio spectrum. Unlike existing works in the literature, where only one secondary user (SU) uses overlay and underlay modes, the different transmission modes should be allocated to different SUs, according to their different quality of services (QoS), to achieve the maximal efficiency of radio spectrum. However, hybrid sharing mode allocation for heterogeneous services is still a challenge in CRNs. In this paper, we propose a new resource allocation method for hybrid sharing transmission mode of overlay and underlay (HySOU), to achieve more potential resources for SUs to access the spectrum without interfering with the primary users. We formulate the HySOU resource allocation as a mixed-integer programming problem to optimize the total system throughput, satisfying heterogeneous QoS. To decrease the algorithm complexity, we divide the problem into two sub-problems: subchannel allocation and power allocation. Cutset is used to achieve the optimal subchannel allocation, and the optimal power allocation is obtained by Lagrangian dual function decomposition and subgradient algorithm. Simulation results show that the proposed algorithm further improves spectrum utilization with a simultaneous fairness guarantee, and the achieved HySOU diversity gain is a satisfactory improvement.

• 한국국방경영분석학회지
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• 제35권3호
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• pp.47-59
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• 2009

A hybrid Genetic Algorithm is applied to military resource allocation problem. Since military uses many resources in order to maximize its ability, optimization technique has been widely used for analysing resource allocation problem. However, most of the military resource allocation problems are too complicate to solve through the traditional operations research solution tools. Recent innovation in computer technology from the academy makes it possible to apply heuristic approach such as Genetic Algorithm(GA), Simulated Annealing(SA) and Tabu Search(TS) to combinatorial problems which were not addressed by previous operations research tools. In this study, a hybrid Genetic Algorithm which reinforces GA by applying local search algorithm is introduced in order to address military optimization problem. The computational result of hybrid Genetic Algorithm on Missile Interceptor Allocation problem demonstrates its efficiency by comparing its result with that of a simple Genetic Algorithm.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권10호
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• pp.3256-3274
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• 2022

With the rapid development of information and communications technology, the construction of efficient, reliable, and safe Internet of Things (IoT) is an inevitable trend in order to meet high-quality demands for the forthcoming 6G communications. In this paper, we study a secure intelligent reflecting surface (IRS)-assisted IoT system where malicious eavesdropper trying to sniff out the desired information from the transmission links between the IRS and legitimate IoT devices. We discuss the system overall performance and propose a hybrid resource allocation scheme for maximizing the secrecy capacity and secrecy energy efficiency. In order to achieve the trade-off between transmission reliability, communication security, and energy efficiency, we develop a quantum-inspired marine predator algorithm (QMPA) for realizing rational configuration of system resources and prevent from eavesdropping. Simulation results demonstrate the superiority of the QMPA over other strategies. It is also indicated that proper IRS deployment and power allocation are beneficial for the enhancement of system overall capacity.

• Journal of information and communication convergence engineering
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• 제10권2호
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• pp.117-122
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• 2012

We propose a hybrid multiple access (HMA) for uplink orthogonal frequency division multiple access (OFDMA) systems, which combines two resource sharing schemes: a scheduling-based resource allocation (SBRA) scheme and a contentionbased resource allocation (CBRA) scheme. The SBRA scheme is appropriate for non-real time high data rate traffic, and, CBRA is appropriate for near-real time low/medium data rate traffic. Thus, the proposed HMA scheme supports various types of traffic. As a CBRA scheme, our proposed random frequency hopping (RFH)-OFDMA scheme was presented. Simulation results show that the proposed HMA yields the best performance among various resource allocation schemes for uplink OFDMA systems.

• 한국통신학회논문지
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• 제32권11A호
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• pp.1120-1127
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• 2007

셀룰라 기반의 멀티홉 시스템에서 각 홉이 필요로 하는 자원의 양에 따라 동적으로 자원을 할당하는 GPS-DRA(Generalized Processor Sharing-Dynamic Resource Allocation) 기법을 제안하였다. 논문에서 가정한 하이브리드 분산식 시스템에서는 네트워크에 연결되어있는 중앙의 controller가 각 홉에 자원을 적절히 할당해 주어야 한다. 하지만 전송환경이 시간에 따라 수시로 변하기 때문에 홉 별로 필요한 자원의 양에 맞게 자원을 할당하기가 쉽지 않다. GPS-DRA 기법은 홉 별로 이전에 사용한 자원의 양을 근거로 하여 홉 별로 필요한 자원의 양에 맞게 동적으로 자원을 할당한다. 본 기법을 사용하면 중앙의 controller에서 자원할당에 필요한 링크 정보를 모두 수집할 필요가 없으므로, 이 기법을 적용하기 위하여 추가적으로 필요한 control overhead의 증가량을 매우 적게 할 수 있다. 제안한 기법을 적용하여 모의실험을 수행한 결과, 고정 자원할당 방식에 비해 채널사용효율이 약 16% 증가하고 셀 용량이 최대 약 65% 커지게 되는 것을 확인하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권1호
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• pp.38-55
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• 2013

Wireless network systems provide fast data transmission rates and various services to users of mobile devices such as smartphones and smart pads. Because many people use high-performance mobile devices, the use of real-time multimedia services is increasing rapidly. However, the preoccupation of resources by real-time traffic users is causing harm to other services-for example, frequent call interference, lowered service quality, and poor network performance. This paper suggests a resource allocation algorithm for effective traffic service support in a hybrid network. The main objective is to obtain an optimum value of data rates by comparing user requirements with the amount of resources that can be allocated. A new mechanism based on Adaptive-Quality of Service (QoS) and a monitoring system based on Queue-Aware are proposed. Adaptive-QoS supports effective resource control according to the type of traffic service, and the monitoring system based on Queue-Aware measures the amount of resources in order to calculate the maximum that can be allocated. We apply our algorithm to a test system and use Qualnet 4.5.1 to evaluate its performance.

• 정보학연구
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• 제4권3호
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• pp.65-75
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• 2001

코드 분할 다중 접속은 이동 통신 시스템에 있어서 주요한 다원 접속 계획으로서 넓게 받아들여지고 있다. 광대역 코드분할 다원접속과 그 복합형 시분할 코드분할 다원접속은 무선이동 통신 시스템에 있어서 중요한 요소로서 10년 전부터 코드분할다원접속을 바탕으로 한 수용력 분석이 활발하게 진행되고 있다. 최근 들어서 서비스 향상 및 고품질 유지 와 무선자원 할당에 대한 관심은 이슈가 되고 있다. 본 논문은 고품질에 관련한 정보량 서비스를 유연하게 지원하고, 정보량 저하요인을 최소로 수용할 수 있는 코드분할다원접속을 기반으로 한 무선 자원할당에 관한 일반사항을 연구 제시한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권4호
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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.

• 산업공학
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• 제23권2호
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• pp.147-155
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• 2010

Reliability allocation is defined as a problem of determination of the reliability for subsystems and components to achieve target system reliability. The determination of both optimal component reliability and the number of component redundancy allowing mixed components to maximize the system reliability under resource constraints is called reliability-redundancy allocation problem(RAP). The main objective of this study is to suggest a mathematical programming model and a hybrid parallel genetic algorithm(HPGA) for reliability-redundancy allocation problem that decides both optimal component reliability and the number of component redundancy to maximize the system reliability under cost and weight constraints. The global optimal solutions of each example are obtained by using CPLEX 11.1. The component structure, reliability, cost, and weight were computed by using HPGA and compared the results of existing metaheuristic such as Genetic Algoritm(GA), Tabu Search(TS), Ant Colony Optimization(ACO), Immune Algorithm(IA) and also evaluated performance of HPGA. The result of suggested algorithm gives the same or better solutions when compared with existing algorithms, because the suggested algorithm could paratactically evolved by operating several sub-populations and improve solution through swap, 2-opt, and interchange processes. In order to calculate the improvement of reliability for existing studies and suggested algorithm, a maximum possible improvement(MPI) was applied in this study.

• Current Optics and Photonics
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• 제1권4호
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• pp.325-335
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• 2017

Hybrid radio frequency/free space optical (RF/FSO) wireless mesh networks have attracted increasing attention for they can overcome the limitations of RF and FSO communications and significantly increase the throughput of wireless mesh networks (WMNs). In this article, a resource assignment optimization scheme is proposed for hybrid RF/FSO wireless mesh networks. The optimization framework is proposed for the objective of maximizing throughput of overall hybrid networks through joint transmission slot assignment, FSO links allocation and power control with the consideration of the fading nature of RF and FSO links. The scheme is formulated as an instance of mixed integer linear program (MILP) and the optimal solutions are provided using CPLEX and Gurobi optimizers. How to choose the appropriate optimizer is discussed by comparing their performance. Numerous simulations are done to demonstrate that the performance of our optimization scheme is much better than the current case of having the same topology.