• International Journal of Computer Science & Network Security
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• 제23권7호
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• pp.16-22
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• 2023

Enhanced radio access technologies (RAT) are deployed in Next Generation Convergence Networks by the service providers so as to satisfy the basic requirements of end-users for e.g. QoS. Whenever the available resources are being shared simultaneously and dynamically by multiple users or distribution of allocated channels randomly, the deficiency of spectral resources and dynamic behavior of Network traffic in real time Networking, we may have problem. In order to evaluate the performance of our proposed algorithm, computer simulation has been performed on NS-2 simulator and a comparison with the existing algorithms has been made.

• International Journal of Computer Science & Network Security
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• 제23권4호
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• pp.55-68
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• 2023

In recent years, the Television White Space (TVWS) has attracted the interest of many researchers due to its propagation characteristics obtainable between 470MHz and 790MHz spectrum bands. The plenty of unused channels in the TV spectrum allows the secondary users (SUs) to use the channels for broadband services especially in rural areas. However, when the number of SUs increases in the TVWS wireless network the aggregate interference also increases. Aggregate interferences are the combined harmful interferences that can include both co-channel and adjacent interferences. The aggregate interference on the side of Primary Users (PUs) has been extensively scrutinized. Therefore, resource allocation (power and spectrum) is crucial when designing the TVWS network to avoid interferences from Secondary Users (SUs) to PUs and among SUs themselves. This paper proposes a model to improve the resource allocation for reducing the aggregate interface among SUs for broadband services in rural areas. The proposed model uses joint power and spectrum hybrid Firefly algorithm (FA), Genetic algorithm (GA), and Particle Swarm Optimization algorithm (PSO) which is considered the Co-channel interference (CCI) and Adjacent Channel Interference (ACI). The algorithm is integrated with the admission control algorithm so that; there is a possibility to remove some of the SUs in the TVWS network whenever the SINR threshold for SUs and PU are not met. We considered the infeasible system whereby all SUs and PU may not be supported simultaneously. Therefore, we proposed a joint spectrum and power allocation with an admission control algorithm whose better complexity and performance than the ones which have been proposed in the existing algorithms in the literature. The performance of the proposed algorithm is compared using the metrics such as sum throughput, PU SINR, algorithm running time and SU SINR less than threshold and the results show that the PSOFAGA with ELGR admission control algorithm has best performance compared to GA, PSO, FA, and FAGAPSO algorithms.

• 한국통신학회논문지
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• 제39C권12호
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• pp.1280-1288
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• 2014

본 논문에서는 선박 내 IT 서비스에 대한 요구에 부응하기 위해 적응적이고 합리적인 무선 주파수를 활용하는 인지무선 기술 중 최초 표준인 ECMA-392 네트워크를 사용한다. 먼저, ECMA-392 기반 네트워크에 대해서 알아보고, 디바이스에게 채널 할당을 위한 고려사항 및 문제점을 살펴본다. 그리고, ECMA-392 MAC 프로토콜에서 디바이스 그룹들이 요청하는 채널을 효율적으로 보장하기 위한 공평한 채널 자원 할당 방법을 제안한다. 새로운 디바이스 그룹과 기존의 디바이스 그룹들에게 채널 할당 파라미터를 고려하여 공평하게 채널들을 재할당할 수 있는 방법이다. 시뮬레이션 결과는 제안된 방식이 기존의 방식에 비해 데이터 수율을 향상시키고 있음을 나타낸다.

• 한국전자파학회논문지
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• 제19권6호
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• pp.669-676
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• 2008

MIMO-OFDMA 시스템에서 자원 할당의 최적화 문제가 거론되고 있다. 본 논문은 SFC 방식 아래 채널에 대한 정보를 가지고 적응 변조 및 부호 기법과 전력 제어 기법을 적용하여 전체 시스템 처리량의 최대화에 목표를 두었다. 첫 번째로 수신 받은 채널에 대한 정보를 기반으로 각 서브 채널의 전력 레벨이 결정된다. 그 다음으로는 변조 타입에 맞게 서브캐리어가 할당되어진다. 시뮬레이션 결과는 실제로 전송되어진 데이터 용량 측면에서 기존의 알고리즘보다 제안한 알고리즘이 더 나은 성능을 보인다.

• ETRI Journal
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• 제45권5호
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• pp.874-886
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• 2023

A joint resource-optimization scheme is investigated for nonorthogonal multiple access (NOMA)-enhanced scalable video coding (SVC) multicast in unmanned aerial vehicle (UAV)-assisted radio-access networks (RANs). This scheme allows a ground base station and UAVs to simultaneously multicast successive video layers in SVC with successive interference cancellation in NOMA. A video quality-maximization problem is formulated as a mixed-integer nonlinear programming problem to determine the UAV deployment and association, RAN spectrum allocation for multicast groups, and UAV transmit power. The optimization problem is decoupled into the UAV deployment-association, spectrum-partition, and UAV transmit-power-control subproblems. A heuristic strategy is designed to determine the UAV deployment and association patterns. An upgraded knapsack algorithm is developed to solve spectrum partition, followed by fast UAV power fine-tuning to further boost the performance. The simulation results confirm that the proposed scheme improves the average peak signal-to-noise ratio, aggregate videoreception rate, and spectrum utilization over various baselines.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.271-272
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• 2008

TD-SCDMA combines TDMA and CDMA components to provide more efficient use of radio resources, and includes a new feature called HSDPA (high-speed downlink packet access) in the R5 stage. The TD-HSDPA supports high-speed traffic with a shared channel, but its uplink mechanism causes feedback problem for scheduling. Since the base station of TD-SCDMA can estimate the location of mobile terminals precisely, it can also estimate the possible path loss. In this paper, the base station utilizes the estimated path loss for scheduling, which is related with CQI (channel quality indicator) values. The proposed mechanism can provide the TD-HSDPA scheduler with an intial CQI value for efficient transmission.

• 전기전자학회논문지
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• 제23권1호
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• pp.214-223
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• 2019

본 논문은 재난통신 시스템을 실제적으로 활용하기 위해 반드시 필요한 표준운영절차(SOP)를 개발하기 위한 방법론과 전략들을 제시하고자 한다. 따라서 재난안전통신망의 SOP와 연계되는 다양한 요소들을 규명하고 특성을 분석하였고, 이를 기반으로 SOP의 효과적인 개발을 위한 프로세스와 전략을 개발하여 제시하였다. 아울러 개발되는 SOP를 재난안전통신망 구현 기술인 LTE에 반영하여 무선자원 할당의 토대가 되는 우선순위와 QoS가 어떻게 운영되어야 하는지도 제시하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권1호
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• pp.68-86
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• 2015

Future wireless network aims to integrate different radio access networks (RANs) to provide a seamless access and service continuity. In this paper, a new resource denotation method is proposed in the WLAN and LTE heterogeneous networks based on a concept of spectral bandwidth mapping. This method simplifies the denotation of system resources and makes it possible to calculate system residual capacity, upon which an economic model-based network selection algorithm is designed in both under-loaded and over-loaded scenarios in the heterogeneous networks. The simulation results show that this algorithm achieves better performance than the utility function-based access selection (UFAS) method proposed in [12] in increasing system capacity and system revenue, achieving load balancing and reducing the new call blocking probability in the heterogeneous networks.

• ETRI Journal
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• 제19권3호
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• pp.98-115
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• 1997

The architecture of the CDMA mobile system (CMS) is developed based on three function groups - service resource, service control, and service management groups. In this paper, the CMS architecture is discussed from the point of view of implementing these functions. The variable length packets are used for transmission. The synchronization clock signals are derived form the GPS receiver. The open loop and closed loop techniques are used for the power control. The internationally accepted signaling and network protocols are employed. The call control for the primary services in designed to provide efficient mobile telecommunication services. The softer handoff is implemented in one card. The mobile assisted handoff and the network assisted handoff are employed in the soft and hard handoffs. The authentication is based on the secret data which includes random numbers. The management functions, which include the location management, resource management, cell boundary management and OAM management, are implemented to warrant the system efficiency, maximum capacity and high reliability. The architecture ensures that the CMS is flexible and expandable to provide subscribers with economic and efficient system configuration. The dynamic power control, adaptive channel allocation. and dynamic cell boundary management are recommended for future work.

• 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.