• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.9B
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• pp.771-777
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• 2004

In a COMA system, the capacity is variable and mainly depends on multiple access interference. The multiple access interference has a deep relationship with transmitted or received power. The capacity of COMA2000 system is considered to be limited by the forward link capacity. In this paper, we show that the forward link cell load can be represented by the total transmitted power of base station and we propose a forward link call admission control (CAC) strategy for COMA2000 system. The proposed call admission scheme adopts the rate control algorithm for data call. This call admission scheme enables the system to utilize radio resource dynamically by controlling data rate according to the cell load status, and enhance the system throughput and grade of service (GoS). quality of service(QoS) such as blocking and outage probability.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.4
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• pp.929-935
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• 2008

As internet telephony services based on Session initiation Protocol (SIP) enter the spotlight as marketable technology, many products based on SIPs have been developed and utilized for home and office telephony services. The call connection of an internet phone is classified into specific call connections and group call connections. Group call connections have a forking function which delivers the message to all of the group members. This function requires excessive message control for a call connection and creates heavy traffic in the network. In the internet cail system model. most of the call-setup messages are directed to the proxy server during a short time period. This heavy message load brings an unwanted delay in message processing and. as a result, call setup can not be made. To solve the delay problem, we simplified the analysis of the call-setup message in the proxy server, and processed the forking function distributed for the group call-setup message. In this thesis, a new system model to minimize the load is proposed and the subsequent implementation of this model demonstrates the performance improvement.

• The Journal of the Korea Contents Association
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• v.3 no.4
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• pp.55-62
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• 2003

In this paper, a call admission contro(cac) technique is proposed to reduce the dropping probabilities of handoff calls in wireless networks while guaranteeing QoS to the users. The proposed technique is based on the estimated effective load for the target eel if a call is accepted. When the estimated effective load is higher than a predetermined threshold, a nu call is blocked and a handoff call is queued irrespective of the availability channels. The SRN, an extended Stochastic Petri Net, modes are constructed to compare the performance of the techniques. The SRN uses rewards concepts instead of the complicate numerical analysis required for the Markov chain modes. As a result, the SRN modeling techniques provide an easier way to carry out performance analysis for call admission control and channel allocation.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.11b
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• pp.1189-1192
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• 2003

초기 콜 센터는 단순히 고객에게 걸려오는 전화를 응대하는 서비스 수준으로 시작되었지만, 현재는 고객과 마주하는 최 접점으로 서비스 뿐만 아니라 마켓팅, 세일즈를 행하는 기업의 경쟁력을 유지하는데 있어 필수적인 요소로 자리잡아 가고 있다. 특히 개인고객을 많이 접하는 금융기관에서는 콜 센터를 대형화, 지방 분산화 및 백업체제 구축을 위한 Multi 센터를 구축하여 콜만 처리하는 센터로서가 아니라 다양한 채널[전화,email,fax,chating]를 통해 접속되는 고객요구 사항들을 통합된 인프라에서 One Stop 으로 처리하고자 한다. 하지만 회선 교환망을 이용하는 PBX기반 Voice 회선과 IP 환경의 DATA 를 처리하는 이원화된 구조로 Multi 콜 센터를 구축 할 경우, 타 센터의 상담원에게로 콜을 설정시 시간이 많이 소요되어 센터간 Call Load Balancing 및 상담원 Skill Based Routing 을 수행함이 어렵다는 단점이 있다. 본 논문에서는 이러한 단점을 개선할 수 있는 방안으로 Voice 와 Data 를 IP 기반 단일 망으로 구성하고 WAN상에서 음성을 전달할 때 적정한 MOS(Mean opinion score)를 측정 후 객관적으로 필요한 Bandwidth 를 검증하고 Muti 콜 센터에서 효과적인 콜 load Balancing 및 Routing을 할 수 있는 VOIP기반 Convereed Virtual Call Center Architecture 설계 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.7C
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• pp.696-703
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• 2002

In traditional approaches to IN load control, there has been a focus on the protection of individual SCPs. On the other hand, the load control of network level can be achieved by using a mobile agent technology, which is a software element responsible for moving from one system to another and performing their task. In this thesis, we propose an mobile agent mechanism and two mobile agent migration procedures and analyze the performance of the Call Gapping mechanism and the mobile agent mechanism. The mobile agent mechanism showed that the SCP load control rate and attempt the number of attempted call failure were better than those of Call Gapping mechanism. Also, the amount of SS NO.7 traffics was reduced in the case of an overload condition.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.4
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• pp.957-966
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• 1998

In this paper an imrpoved Signal-to-Interference ratio(SIR)-based call admission control(CAC) algorithm for DS-CDMA cellular system is proposed and its performance is analyzed. This algorithm uses Residual-Capacity defined asthe additional number of initial calls that a base station can accept such that system-wide outage probability will guaranteed to remain below a certain level. the residual capcity at each cell is calculated according to the reverse-link SIR measured not only at the home cell but also the adjacent cells. Then the adjacent cell interference-coupling coefficient .betha. is used. In this work we propose an improved algorithm that .betha. varies according to the traffic load of the home cell. The influence of traffic condition on system performance, namely blocking probability and outage probability, is then examined via simulation. The performance of the improved algorithm is evaluated both under homogeneous and hot spot traffic loads. The results show that the improved algorithm outperforms conventional algorithms under all load values. Under over-load situation, especially, the improved algorithm gives almost constant outage performance the QoS(quality of service) can be guranted.

• The Journal of the Acoustical Society of Korea
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• v.17 no.4E
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• pp.28-34
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• 1998

In most switching system, the processing unit is designed to work efficiently even at relatively high loads, but when the offered traffic exceeds a particular level, the rate of completed calls can fall drastically. A single call handled by the switching system consists of a sequence of events or messages that has to be processed by the control unit. The control unit is not only incapable of handling all of the offered calls, but also its call handling capability can drop as the offered load increases. The real time available for call processing is a critical resource that requires careful management. Therefore, the overloading of this resource must be detected by a subscriber in the from of a dial tone delay or an uncompleted call which is either blocked or mishandled. The subscriber may respond by either dialing prematurely or by re-attempting a call. This action can further escalate the processors load, which is spent for uncompleted calls. Unless a proper control is used, the switching system can finally break down. In this paper, we paper, we propose a fuzzy overload detection and control method for switching systems, which can by generating fuzzy rules via fuzzy aggregation networks. Simulation results involving a switching system is given.

• Journal of Communications and Networks
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• v.10 no.1
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• pp.38-43
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• 2008

In this paper, adaptive channel borrowing approach fuzzy neural networks for load balancing (ACB-FNN) is presented to maximized the number of served calls and the depending on asymmetries traffic load problem. In a wireless network, the call's arrival rate, the call duration and the communication overhead between the base station and the mobile switch center are vague and uncertain. A new load balancing algorithm with cell involved negotiation is also presented in this paper. The ACB-FNN exhibits better learning abilities, optimization abilities, robustness, and fault-tolerant capability thus yielding better performance compared with other algorithms. It aims to efficiently satisfy their diverse quality-of-service (QoS) requirements. The results show that our algorithm has lower blocking rate, lower dropping rate, less update overhead, and shorter channel acquisition delay than previous methods.

• The KIPS Transactions:PartA
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• v.12A no.5 s.95
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• pp.427-432
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• 2005

I studied about existent load distribution algorithms and the WLC(Weighted Least Connection) algerian that is using much at present to distribute the connection request of users to real servers efficiently in web cluster system. The efficiency of web cluster system is fallen by load imbalance between servers, because there is problem In inaccurate load status measuring of servers and measuring timing at these load distribution algorithms. In this paper, I suggest an algorithm that distributes load base on various load state of servers by real time using broadcasting RPC(Remote Procedure Call) when a user requests connection, and implement a prototype and experiment its performance. The experiment result shows that load imbalance phenomenon between reai sowers was improved greatly than existing method, and performance of web cluster system was improved by efficiency that response time is shortened.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4B
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• pp.316-323
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• 2002

In this paper, we analyze the call control scheme that is using buffer at new call and handoff call for non-uniform traffic load distribution, the multiple cell environments and the multiple types of services such as voice and data service. Considering the facts, the call admission control method using the effective bandwidth concept is employed in this paper, The bandwidth for a new call and a handoff call is allocated by the number of mobile station and dynamically assigned by taking account of the blocking rate of new calls and the dropping rate of handoff calls. The call control procedure is experimented through a simulation study by dynamically the bandwidth to new and handoff calls based on the blocking rate and the dropping rate. The results show our call control scheme can get a good quality of service for mobile users.