• Journal of Advanced Navigation Technology
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• v.19 no.4
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• pp.318-322
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• 2015

In wireless communication networks, most of the prediction techniques are used for predicting the amount of resource required by user's calls for improving their demanding quality of service. However, we propose a channel allocation scheme based on predicting the resources of white spectrum holes for improving the QoS of rental user's spectrum handoff calls for cognitive radio networks in this paper. This method is supported by Wiener predictor to predict the amount of white spectrum holes of license user's free spectrum resources. We classify rental user's calls into initial calls and spectrum handoff calls, and some portion of predicted spectrum-hole resources is reserved for spectrum handoff calls' priority allocation. Simulations show that the performance of the proposed scheme outperforms in spectrum handoff call's dropping rate than an existing method without spectrum hole prediction(11% average improvement in 50% reservation).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.9A
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• pp.1031-1038
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• 2004

The call admission control algorithm of hybrid scheme is proposed to enhance the QoS(quality of service) of attempted multimedia calls. In the initial stage of 3rd generation multimedia services networks, the major limitations include the small sefyice coverage and the limited radio link capacity. Because the initial massive deployment of network elements such as base stations, base station controllers, and mobile switching centers is restricted to populated areas and the other areas should be covered with the fewer network elements, the radio channel resources are hmited and coverage network is supposed to be established. Therefore the QoS of multimedia services is expected to be severely degraded when tentative traffic hot spot occurs frequently. Thus, the blocking probability of attempted calls mcreases when relatively large number of users try to place multimedia calls in a hot spot area of the wireless networks. In this situation, the proposed hybrid scheme can mitigate the degradation of the QoS of multimedia services by using the available radio channels of the neighboring cells.

• The Transactions of the Korea Information Processing Society
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• v.6 no.1
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• pp.193-202
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• 1999

A promising telecommunication system so called IMT-2000 is forecasted to cover almost 50 percent of telecommunication services, which will be provided in the beginning of the year 2000. The system offers high quality service such as data, image, and video as well as voice. UPT, which offers the personal mobility, is recognized as an important service because we can bind a variety of wire or wireless networks as single number. This paper discusses the design of IMT-2000 MSC based on AIN and UPT service in the MSC. First, we propose the system structure of the IMP-2000 MSC, as a platform of UPT service implementation. Based on this, we define main functions and its blocks of the IMP-2000 MSC. Third, we present the structure of SSF and Its operational mechanism to support the IN services such as UPT. Finally, we present the detail UPT service implementation for the IMP-2000 MSC through the design of UPT call flows between software blocks, which are the minimum units, within the IMPt-2000 MSC.

• Convergence Security Journal
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• v.8 no.4
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• pp.41-49
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• 2008

VoIP is a service that changes the analogue audio signal into a digital signal and then transfers the audio information to the users after configuring it as a packet; and it has an advantage of lower price than the existing voice call service and better extensibility. However, VoIP service has a system structure that, compared to the existing PSTN (Public Switched Telephone Network), has poor call quality and is vulnerable in the security aspect. To make up these problems, TLS service was introduced to enhance the security. In practical system, however, since QoS problem occurs, it is necessary to develop the VoIP security system that can satisfy QoS at the same time in the security aspect. In this paper, a user authentication VoIP system that can provide a service according to the security and the user through providing a differential service according to the approach of the users by adding AA server at the step of configuring the existing VoIP session is suggested. It was found that the proposed system of this study provides a quicker QoS than the TLS-added system at a similar level of security. Also, it is able to provide a variety of additional services by the different users.

• Journal of Korea Society of Industrial Information Systems
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• v.20 no.4
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• pp.1-9
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• 2015

This paper proposes CAC method that is more efficient for RRM using game theory combined with Multiple Attribute Decision Making(MADM). Because users request services with different Quality of Service(QoS), the network preference values to alternative networks for each service are calculated by MADM methods such as Grey Relational Analysis(GRA), Simple Additive Weighting(SAW) and Technique for Order Preference by Similarity to Ideal Solution(TOPSIS). According to a utility function representing preference value, non-cooperative game is played, and then network provider select the requested service that provide maximum payoff. The appropriate service is selected through Nash Equilibrium that is the solution of game and the game is played repeated. We analyze two overlaid networks among four Wireless LAN(WLAN) systems with different properties. Simulation results show that proposed MADM techniques have same outcomes for every game round.

• The KIPS Transactions:PartC
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• v.9C no.2
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• pp.283-292
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• 2002

This paper develops a scheme of resource management for guaranteeing QoS of realtime traffic in wireless mobile internet environments Mobile terminal has significant impact on the QoS originating mobility provided to a real-time application. The currently proposed MRSVP is not clear the boundary of resource reservation tregion and also can give rise to signal overhead to maintain sessions. To solve above problem, we propose the new reservation protocol, mobile cluster based H-MRSVP to combine MRSVP with moving cluster concept. In this paper, we analytically design our model for guaranteeing the QoS of realtime traffic and compare the three schemes: guard channel allocation schemes, DCA and our model. The performance measures are the probabilities of new call blocking, handoff dropping, resource utilization and service completion versus the system offered Erlang load. Consequently, Simulation indicate our model is more flexible than DCA in a view pint of channel utilization and gains the advantage over guard channel scheme with respects to the mobility.

• The Transactions of the Korea Information Processing Society
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• v.4 no.10
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• pp.2596-2604
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• 1997

There are two kinds of backends in ACK:code generator(full-fledged backend) and code expander(fast backend). Code generators generate target code using string pattern matching and code expanders generate target code using macro expansion. ACK translates EM to SPARC code using code expander. The corresponding SPARC code sequences for a EM code are generated and then push-pop optimization is performed. But, there is the problem of maintaining hybrid stack. And code expander is not considered to passes parameters of a procedure call through register windows. The purpose of this paper is to improve SPARC code quality. We suggest a method of SPARC cod generation using EM tree. Our method is divided into two phases:EM tree building phase and code expansion phase. The EM tree building phase creates the EM tree and code expansion phase translates it into SPARC code. EM tree is designed to pass parameters of a procedure call through register windows. To remove hybrid stack, we extract an additional information from EM code. We improved many disadvantages that arise from code expander in ACK.

• Journal of Korea Multimedia Society
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• v.10 no.9
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• pp.1153-1164
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• 2007

One of the most challenging technical issues in mobile communication for multimedia is Quality of Service (QoS) management of handover calls. This paper proposes a 2-level handover control system to copy with this problem. A 2-level handover control system consists of resource reservation and call admission control modules. The resource reservation module divides the network resource into Hard and Soft reserved resource. The Hard reserved resource is only for the handover calls while the Soft reserved resource is for both the handovers and the new calls. And also, the resource reservation module classifies handovers into primary and secondary handovers based on often they occur. The call admission control module deals with the primary and secondary handover calls in different ways. The new calls can use Soft reserved resource only if there is sufficient amount available in the Hard reserved resource. Proposed system is evaluated using an M/M/c/c queueing model. It is shown that proposed system allows more efficient utilization of network resource without degrading QoS comparing with the legacy handover control systems.

• Database Research
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• v.34 no.3
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• pp.69-85
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• 2018

Many researches proposed federated query engines to perform query on several homogeneous or heterogeneous datasets simultaneously that significantly improve the quality of query results. The existing techniques allow querying only over a few heterogeneous datasets considering the static binding using the non-standard query. However, we observe that a simultaneous system considering the integration of heterogeneous metadata standards can offer better opportunity to generalize the query over any homogeneous and heterogeneous datasets. In this paper, we propose a transparent federated engine (DRAZ) to query over multiple data sources using SPARQL. In our system, we first develop the ontology for a non-RDF metadata standard based on the metadata kernel dictionary elements, which are standardized by the metadata provider. For a given SPARQL query, we translate any triple pattern into an API call to access the dataset of corresponding non-RDF metadata standard. We convert the results of every API call to N-triples and summarize the final results considering all triple patterns. We evaluated our proposed DRAZ using modified Fedbench benchmark queries over heterogeneous metadata standards, such as DCAT and DOI. We observed that DRAZ can achieve 70 to 100 percent correctness of the results despite the unavailability of the JOIN operations.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.1
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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.