• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.5
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• pp.1049-1068
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• 2011

In this paper a simple and effective call admission control (CAC) scheme is proposed for the emerging interleave-division multiple-access (IDMA) systems, supporting a variety of traffic types and offering different quality of service (QoS) requirements and priority levels. The proposed scheme is signal-to-interference-plus-noise ratio (SINR) evolution based CAC (SE-CAC). The key idea behind the scheme is to take advantage of the SINR evolution technique in the process of making admission decisions, which is developed from the effective chip-by-chip (CBC) multi-user detection (MUD) process in IDMA systems. By virtue of this semi-analytical technique, the MUD efficiency can be estimated accurately. Additionally, the computational complexity can be considerably reduced. These features make the scheme highly suitable for IDMA systems, which can combat intra-cell interference efficiently with simple CBC MUD. Analysis and simulation results show that compared to the traditional CAC scheme considering MUD efficiency as a constant, the proposed SE-CAC scheme can guarantee high power efficiency and throughput for multimedia traffic even in heavy load conditions, illustrating the high efficiency of CBC MUD. Furthermore, based on the SINR evolution, the SE-CAC can make accurate estimation of available resource considering the effect of MUD, leading to low outage probability as well as low blocking and dropping probability.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.7
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• pp.680-695
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• 1991

In this paper, the conditions on the number of required copies of a self-routing network with and without extra stages in back-to-back manner are presented respectively for a nonblocking $Multi-Log_2N$ multiconnection network. Actually the obained results hold regardless of connection patterns, i.e., whether a network deploys on-to-one connections or multiconnections. Thus open problems on the nonblocking condition for a multi $Multi-Log_2N$ multiconnection network are solved. Interestingly some of the given formulas comprise the Benes network and the Canto network as a special case repectively. A novel switching system architecture deploying a distributed calls-distribution algorithm is provided to design a nonblocking $Multi-Log_2N$ photonic switching network using a directional coupler. And a directional couplex based call holding demultiplexer is introduced to hold a call until blocking disappears in a switching network and let it enter to a network, provided that the number of switching networks is less than that of required switching networks for a nonblocking $Multi-Log_2N$ network.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.7
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• pp.714-719
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• 2011

This paper proposes a scheme for distributed load balancing in mobile communication networks based on supervisory control framework. Using load information exchanged with neighboring cells, the "supervisors" that reside in the base stations distribute load among cells by controlling handover parameters in a distributed manner. The supervisors are designed so that the load difference among neighboring cells are kept under a pre-defined value. Results from systematic analysis and simulation indicate that our scheme effectively balances traffic load among cells and reduces call blocking rate of the overloaded cells.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.38-41
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• 1998

Due to the increasing demand to multimedia services over wireless communication network, LMDS(Local Multipoint Distribution Service) has been proposed as an alternate approach for broadband wireless access network. But LMDS, Which uses the mmwavelength radio spectrum, has been limited for unknown microwave frequency characteristics. In this paper, we analyze the parameters related to the system design on 28GHz frequency: Propagation path loss and rainfall attenuation. Based on these analytical results, the proper cell size in Korea is determined. We also analyze the bit error rate and frame loss rate for various kinds of digital modulation schemes(QAM 4, 16, 64, 256). Finally, we apply to ㅍ service to evaluate a call blocking rate, efficiency and channel capacity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.3
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• pp.360-371
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• 1993

Flood search algorithm is known to be an effective routing mechanism for tactical application, since it provides high degree of survivability and robustness. But it is known that it has significant drawbacks with respect to the network efficiency [1]. We consider a tactical circuit-switched grid network with a maximum of four links and two priority classes of voice traffic, Using the minimum first-derivative length (MFDL) path, we improve the blocking probability performance of the circuit-switched network without increasing the call set-up time and processor loading of the algorithm.

• The Journal of Information Technology
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• v.4 no.3
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• pp.65-75
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• 2001

Code-division multiple access has been widely accepted as the major multiple access scheme in mobile communication systems. Wide-band CDMA and its hybrid associate time-division CDMA are key elements in the mobile communication. Since 10 years ago, there has been enormous research activity in analysis of the capacity of these CDMA-based systems. Recently, upgrading service, high quality and the different service classes in radio resource allocation has recently increased. This paper presents an overview of Radio Resource Allocation on the CDMA-based systems that are flexible, support traffic services, minimize call blocking rate and have acceptable radio resource utilization.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.1098-1100
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• 2002

Inter-RNC(radio network controller) and inter-BSC(base station center) hard handovers involve rerouting. Thus additional delay time for the new bearer setup and reroute determination should be considered. For theses kinds of handovers we propose a new scheme and coined it as ICHP(Inter-Cluster Handover Prediction). When a call approaches a boundary cell of a cluster, ICHP prepares for the handover by performing resource reservations and reroute computation in advance. Performance analysis shows that ICHP provides faster handover and that it lowers the blocking probability.

• Journal of the Korean Society of Industry Convergence
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• v.6 no.4
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• pp.401-404
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• 2003

In most resource reservation strategies, which give higher priorities to handoff calls over new calls, new calls are often blocked even though there is plenty of available reserved resource. This causes inefficient resource utilization, especially when there are not so many handoff attempts. In this paper, we propose a new reservationstrategy called soft reservation in which new calls can be allocated to the reserved resource while maintaining the QoS of handoff acceptable. Using an M/M/c/c queuing model, we can see that the proposed strategy provides better performance than the conventional reservation strategy in terms of blocking probability of new call and dropping probability of handoff calls.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.1
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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.

• Journal of the Korea Society for Simulation
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• v.13 no.3
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• pp.31-41
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• 2004

In this paper, we consider the strategy of Universal Mobile Telecommunication System (UMTS) and Wireless Local Area Network (WLAN) internetworking that provide the seamless vertical handover for mobile nodes. We propose Mobility Anchor Points (MAP) based UMTS/WLAN internetworking architecture to support the vertical handover. Also, on integrated UMTS/WLAN networks, we propose a vertical handover scheme that avoids the call blocking caused by the network resource shortage. We provide the numerical analysis to investigate the performance evaluation to the proposed scheme and compare the proposed scheme with the existing scheme.