• Journal of Communications and Networks
• /
• 제14권4호
• /
• pp.461-466
• /
• 2012

Any future heterogeneous overlay network system must be able to support ubiquitous access across multiple wireless networks. To coordinate these diverse network environments, one challenging task is a call admission decision among different types of network. In this paper, we propose a new call admission control scheme to provide quality of service (QoS) while ensuring system efficiency. Based on the interplay between network structure and dynamics, we estimate the network's QoS level and adjust the service price adaptively with the aim of maximizing the network performance. A simulation shows that the proposed scheme can approximate an optimized solution while ensuring a well-balanced network performance in widely different network environments.

• Journal of Communications and Networks
• /
• 제4권3호
• /
• pp.199-208
• /
• 2002

The downlink rate scheduling problem is considered for CDMA networks with multiple users carrying packets of heterogeneous traffic (voice/audio only, bursty data only or mixed traffic), with each type having its own distinct quality of service requirements. Several rate scheduling algorithms are developed, the common factor of which is that part of the decision on which users to serve is based on a function of the deadline of their head-ofline packets. An approach of Andrews et al., in which the basic Earliest-Deadline-First algorithm is studied for similar systems, is extended to result in better performance by considering a more efficient power usage and by allowing service of more than one user per timeslot if the power resources permit it. Finally, the performance of the proposed schemes is compared through simulations.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제14권11호
• /
• pp.4611-4624
• /
• 2020

Future network scenario will be a heterogeneous wireless network environment composed of multiple networks and multimode terminals (MMT). Seamless switching and optimal connectivity for MMT among different networks and different services become extremely important. Here, a vertical handoff algorithm combined an improved entropy weighting method based on grey relational analysis (GRA) is proposed. In which, the improved entropy weight method is used to obtain the objective weights of the network attributes, and GRA is done to rank the candidate networks in order to choose the best network. Through simulation and comparing the results with other vertical handoff decision algorithms, the number of handoffs and reversal phenomenon are reduced with the proposed algorithm, which shows a better performance.

• International Journal of Computer Science & Network Security
• /
• 제22권3호
• /
• pp.1-8
• /
• 2022

Supporting real-time flows with delay and throughput constraints is an important challenge for future wireless networks. In this paper, we develop an optimal scheduling scheme to optimally choose the packets to transmit. The optimal transmission strategy is based on an observable Markov decision process. The novelty of the work focuses on a priority-based probabilistic packet scheduling strategy for efficient packet transmission. This helps in providing guaranteed services to real time traffic in Heterogeneous Wireless Networks. The proposed scheduling mechanism is able to optimize the desired performance. The proposed scheduler improves the overall end-to-end delay, decreases the packet loss ratio, and reduces blocking probability even in the case of congested network.

• 한국ITS학회:학술대회논문집
• /
• 한국ITS학회 2005년도 제4회 추계학술대회 및 정기총회
• /
• pp.173-176
• /
• 2005

• 한국정보통신설비학회:학술대회논문집
• /
• 한국정보통신설비학회 2008년도 정보통신설비 학술대회
• /
• pp.223-228
• /
• 2008

현재 WLAN, WiBro, HSDPA 등의 다양한 형태의 망 환경들이 존재함에 따라 이러한 다양한 형태의 망간 연동을 통한 시너지 효과를 활용하여 사용자에게 높은 질의 서비스를 제공하려는 수많은 시도들이 이루어지고 있으며 우선적으로 단말이 이종망간에 이동을 하더라도 서비스 연속성을 제공하여 주는 이동성 제공 기술에 관한 연구들이 활발히 진행 중에 있다. 그러나 이미 상용 서비스를 제공 중인 이종 망간(i.e., WiBro 와 HSDPA)에 서비스 연속성을 제공하는 데 있어서는 접속 망 자체의 기본적인 기술적 특성 (i.e., 전송 속도, Coverage, QoS)이외에도 이미 망을 Deployment하여 서비스를 제공 중인 사업자의 현실적인 문제 (i.e., 접속 망 기능 변경의 어려움 및 비용) 등 다양한 변수들도 존재하며 이러한 망의 다양성을 충족시키면서 망간 서비스 연속성을 제공하기 위해서는 하나의 독자적인 이동성 기술로는 한계를 가지게 된다. 따라서 본 논문에서는 이미 망이 Deployment되어 상용 서비스 중인 Wi-Bro와 HSDPA망간에 서비스 연속성을 제공하기 위해서 발생할 수 있는 현실적인 문제점들을 제시하고 이를 고려한 효율적인 이동성 프로토콜을 제안한다. 본 논문에서는 Client Mobile IPv4(CMIPv4)와 Proxy Mobile IPv4 (PMIPV4)의 기술적인 장점을 취하고, 이미 Deployment되어 서비스를 제공 중인 망의 상황에 따라 유동적으로 CMIPv4와 PMIPv4 기술을 동시에 혼재하여 적용가능 한 Hybrid Mobile IP의 이동성 기술 방안을 제안하였다.

• 한국통신학회논문지
• /
• 제37권2B호
• /
• pp.110-119
• /
• 2012

본 논문은 이종 무선망 환경에서 효과적인 영상 스트리밍 시스템에 대해 다룬다. 제안하는 영상 스트리밍 시스템은 파운틴 코드를 영상 스트리밍 서비스에 적합하도록 변형하고, 파운틴 코드의 지연 및 블록 복구 실패율 제약 조건들을 만족시키면서 다중 경로를 통해 영상 스트림의 비트율을 최대화한다. 마지막으로, 제안하는 시스템이 이종 무선망 환경에서 각 경로의 상태 정보를 기반으로 제어 변수를 동적으로 설정함으로써 고화질의 안정적인 영상 스트리밍 서비스를 사용자에게 제공할 수 있음을 보인다.

• 한국산학기술학회논문지
• /
• 제10권10호
• /
• pp.2715-2720
• /
• 2009

이종 망 환경에서 멀티미디어 서비스의 QoS를 보장하는 것은 3GE 시스템 개발을 위한 중요한 이슈이다. 이동 단말기가 이종 망간의 이동 시 끊임없는 서비스(seamless service)를 지원하기 위해서는 종단간(end-to-end) 협상 정보에 근거하여 사용자의 QoS를 보장할 수 있는 QoS 운영 구조(QoS management structure)를 제공해야 한다. 본 논문에서는 SLA(Service Level Agreement)에 기반한 종단간 QoS 제어 방안을 제시한다. 이를 위하여, QoS 지원을 위한 SLA 제어 구조 및 알고리즘을 제안하고, 시뮬레이션을 통하여 평균 지연과 패킷 손실률을 평가한다. 제안된 방식을 적용한 시스템이 기존의 망보다 더 좋은 성능을 보인다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제12권3호
• /
• pp.1083-1097
• /
• 2018

This paper presents a novel range-free localization algorithm based on quantum particle swarm optimization. The proposed algorithm is capable of estimating the distance between two non-neighboring sensors for multi-hop heterogeneous wireless sensor networks where all nodes' communication ranges are different. Firstly, we construct a new cumulative distribution function of expected hop progress for sensor nodes with different transmission capability. Then, the distance between any two nodes can be computed accurately and effectively by deriving the mathematical expectation of cumulative distribution function. Finally, quantum particle swarm optimization algorithm is used to improve the positioning accuracy. Simulation results show that the proposed algorithm is superior in the localization accuracy and efficiency when used in random and uniform placement of nodes for heterogeneous wireless sensor networks.

• 한국정보과학회논문지:정보통신
• /
• 제29권2호
• /
• pp.181-187
• /
• 2002

Connection admission control(CAC), which decides whether or not to accept a new call request, is one of the most Important preventive congestion control techniques in asynchronous transfer mode(ATM) networks. To develop a practical CAC scheme, first we propose a "Modified Cell Loss Probability MP${\nu}"$, which is based on "Virtual Cell Loss Probability P${\nu}"$, taking into account mean burst duration of input traffic source and buffer size in ATM networks. MP${\nu}"$ computes more accurate cell loss probability than P${\nu}"$ without increasing computational complexity, since P${\nu}"$ is formulated simply form the maximum and the average cell rate of input traffic. P${\nu}"$ is overestimated as compared to the real cell loss probability when the mean burst duration is relatively small to the buffer capacity. Then, we Propose a CAC scheme, based on "Modified Virtual Bandwidth(MVB)" method, which may individualize the cell loss probabilities in heterogeneous traffic environments. For the proposed approach, we define the interference intensity to identify interferences between heterogeneous traffic sources and use it as well as MP${\nu}"$ to compute MVB. Our approach is well suitable for ATM networks since it provides high bandwidth utilization and guarantees simple and real time CAC computation for heterogeneous traffic environments.heterogeneous traffic environments.