• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제11권2호
• /
• pp.611-627
• /
• 2017

For enhancing the coverage of wireless networks and increasing the spectrum efficiency, small cell networks (SCNs) are considered to be one of the most prospective schemes. Most of the existing literature on resource allocation among non-cooperative small cell base stations (SBSs) has widely drawn close attention and there are only a small number of the cooperative ideas in SCNs. Based on the motivation, we further investigate the cooperative approach, which is formulated as a coalition formation game with power control algorithm (CFG-PC). First, we formulate the downlink sub-channel resource allocation problem in an SCN as a coalition formation game. Pareto order and utilitarian order are applied to form coalitions respectively. Second, to achieve more availability and efficiency power assignment, we expand and solve the power control using particle swarm optimization (PSO). Finally, with our proposed algorithm, each SBS can cooperatively work and eventually converge to a stable SBS partition. As far as the transmit rate of per SBS and the system rate are concerned respectively, simulation results indicate that our proposed CFG-PC has a significant advantage, relative to a classical coalition formation algorithm and the non-cooperative case.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제11권7호
• /
• pp.3501-3523
• /
• 2017

It is a classical integer optimization difficulty to design an optimal selection scheme in cooperative relay networks considering co-channel interference (CCI). In this paper, we solve single-objective and multi-objective relay selection problem. For the single-objective relay selection problem, in order to attain optimal system performance of cooperative relay network, a novel quantum differential evolutionary algorithm (QDEA) is proposed to resolve the optimization difficulty of optimal relay selection, and the proposed optimal relay selection scheme is called as optimal relay selection based on quantum differential evolutionary algorithm (QDEA). The proposed QDEA combines the advantages of quantum computing theory and differential evolutionary algorithm (DEA) to improve exploring and exploiting potency of DEA. So QDEA has the capability to find the optimal relay selection scheme in cooperative relay networks. For the multi-objective relay selection problem, we propose a novel non-dominated sorting quantum differential evolutionary algorithm (NSQDEA) to solve the relay selection problem which considers two objectives. Simulation results indicate that the proposed relay selection scheme based on QDEA is superior to other intelligent relay selection schemes based on differential evolutionary algorithm, artificial bee colony optimization and quantum bee colony optimization in terms of convergence speed and accuracy for the single-objective relay selection problem. Meanwhile, the simulation results also show that the proposed relay selection scheme based on NSQDEA has a good performance on multi-objective relay selection.

• 한국정보통신학회논문지
• /
• 제20권8호
• /
• pp.1444-1451
• /
• 2016

본 논문에서는 무선 애드 혹 네트워크에서 협력 통신을 이용하여 소스 노드에서 목적 노드로 데이터를 전송함에 있어 필요한 에너지를 최소화하기 위한 타부 서치 알고리즘을 제안한다. 무선 애드 혹 네트워크에서 노드의 수가 증가함에 따라 노드 간 경로 설정을 위한 계산량은 급격히 늘어나게 된다. 본 논문에서는 노드 밀도가 높은 무선 애드 혹 네트워크에서 적정한 시간 내에 최적의 협력 통신 경로를 찾기 위한 타부 서치 알고리즘을 제안하며, 효율적인 검색을 위해 타부 서치 알고리즘의 효과적인 이웃해 생성 동작을 제안한다. 제안된 알고리즘은 소스 노드와 목적 노드간의 전송을 위한 최소 에너지와 실행시간 관점에서 성능을 평가하며, 평가 결과에서 제안된 알고리즘이 기존의 알고리즘에 비해 성능이 우수함을 보인다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제17권9호
• /
• pp.2590-2608
• /
• 2023

The high-altitude and mobility characteristics of unmanned aerial vehicles (UAVs) have made them a key element of new radio systems, particularly because they can exceed the limits of terrestrial networks. However, at high altitudes, UAVs can be significantly affected by intercell interference at a high line-of-sight probability. To mitigate this drawback, we propose an algorithm that selects the optimal beam to reduce interference and maximize transmission efficiency. The proposed algorithm comprises two steps: constructing a user-location-based fingerprint database according to the user types presented herein and cooperative beam selection. Simulations were conducted using cellular cooperative downlink systems for analyzing the performance of the proposed method, and the signal-to-interference-plus-noise cumulative distribution function and spectral efficiency cumulative distribution function were used as performance analysis indicators. Simulation results showed that the proposed algorithm could reduce the effect of interference and increase the performance of the desired signal. Moreover, the algorithm could efficiently reduce overheads and system cost by reducing the amount of resources required for information exchange.

• International Journal of Control, Automation, and Systems
• /
• 제6권3호
• /
• pp.401-412
• /
• 2008

This paper discusses a design methodology of cooperative path planning for dynamical multi-agent systems with spatial and temporal constraints. The cooperative behavior of the multi-agent systems is specified in terms of the objective function in an optimization formulation. The path of achieving cooperative tasks is then generated by the optimization formulation constructed based on a differential flatness approach. Three scenarios of multi-agent tasking are proposed at the cooperative task planning framework. Given agent dynamics, both spatial and temporal constraints are considered in the path planning. The path planning algorithm first finds trajectory curves in a lower-dimensional space and then parameterizes the curves by a set of B-spline representations. The coefficients of the B-spline curves are further solved by a sequential quadratic programming solver to achieve the optimization objective and satisfy these constraints. Finally, several illustrative examples of cooperative path/task planning are presented.

• 한국전자파학회논문지
• /
• 제21권11호
• /
• pp.1311-1317
• /
• 2010

본 논문에서는 셀 간 협동을 수행하는 cooperative spatial multiplexing(CSM)의 상향 링크 용량을 개선하기 위한 무선 자원 관리 알고리즘을 제안한다. 인접 기지국에 대한 상향 링크 간섭을 억제하기 위해 각 이동국에서 독립적으로 수행되는 최대 송신 전력 제한 알고리즘을 제안한다. 또한 서비스 기지국과 간섭 기지국이 서로 상향 링크 채널 정보를 공유하는 coordinated CSM 시스템에서 셀 간 상향 링크 간섭 억제를 통해 용량을 개선하는 협동 스케줄링 알고리즘을 제안한다. 제안하는 알고리즘들은 낮은 복잡도로 동작하지만 인접 기지국의 상향 링크 간섭을 효과적으로 억제하여 상향 링크 시스템 용량을 증가시킬 수 있다.

• 한국통신학회논문지
• /
• 제35권12A호
• /
• pp.1122-1127
• /
• 2010

본 논문에서는 우선 랜 환경에서 반복 전송 알고리즘을 적용한 중계기 기반의 분산 시공간 블록 부호(distributed space-time block code: D-STBC) 복호 후 전송(decode-and-forward: DF) 협력 통신 방식을 제안한다. 반복 전송 기법에 의하여 추가적인 전송 다이버시티 이득을 얻을 수 있지만, 기존의 기법에 비해 데이터 전송률이 절반으로 감소하기 때문에 데이터 변조 성상도를 기존 기법의 2배로 사용한다. 또한, 소스 노드와 중계 노드간 전송에만 반복 전송 알고리즘을 적용하여 시스템 복잡도를 줄이고 성능 열화를 최소화했다. 제안한 알고리즘을 HiperLAN/2 레일레이 페이딩 채널에서 시뮬레이션을 통하여 비부호화 비트 오류율 성능을 검증하였다.

• 한국지능시스템학회논문지
• /
• 제22권6호
• /
• pp.687-693
• /
• 2012

본 논문에서는 군집로봇의 효과적인 협조탐색을 위한 탐색영역에 대한 군집로봇의 최적배치을 제안한다. 먼저, 탐색영역에 대한 최적의 배치를 위해 보로노이 테셀레이션과 K-mean 알고리즘을 이용하여 탐색영역을 분할한다. 분할된 영역을 안전한 주행을 위해 전역경로계획과 지역경로계획을 한다. 전역경로계획은 A*알고리즘을 이용하여 전역경로계획을 하여 최적의 전역경로를 찾고, 지역경로계획은 포텐셜 필드방법을 이용하여 장애물 회피 통해 안전하게 목표점에 이르게 한다. 마지막으로 제안한 알고리즘은 시물레이션을 통해 그 응용가능성을 검토한다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2001년도 합동 추계학술대회 논문집 정보 및 제어부문
• /
• pp.95-98
• /
• 2001

A hierarchical structure for the cooperative control of multiple mobile robots using coordinates of objects obtained from vision system is proposed. The order-level perceives environments represented by workspace sets. The algorithm selects an object to be moved using an object discrimination part and determines the robot actions. The action-level generates a trajectory of each wheel velocity of robot. The simulation results show the effectiveness of the proposed algorithm.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 하계학술대회 논문집 D
• /
• pp.2411-2413
• /
• 2004

In this paer, we propose a method to apply a decentralized control algorithm for passive velocity field control using virtual flywheel system to cooperative mobile robots. The considered system convey a common rigid object in a horizontal plain. The effectiveness of proposed control algorithm is examined by numerical simulation for cooperative tasks.