• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.34S no.4
• /
• pp.1-11
• /
• 1997

In this paper, modeling of the communication channel occupancy characteristics at the base station in the wide area radio trunking syste has been performed. Using the results, mathematical analysis for the switching capacity at the network switch has also been done. Specificatlly, we propose a G/M/m queueing model for the single service area modeling, and analyze changes in call blockingprobabilities accoridng to changes in the burstness characteristics of group paging calls. As a result, we have observe dthat the channel occupancy variations become larger as the burstness characteristics become more apparent, to make the call blocking probability higher. Next, based on the single service area analysis, we have anayzed mathematically the average switching capacity required to serve mobile subscribers for a wide area radio trunking sytem, where multiple switching port assignments are required when the people in the same group are distributed over several base stations. Accordingly, we have observed that the average and the variance of switching channel occupancy are closely related to the mobility characteristics of subscribers, and that we need a netowrk switch having bigger capacity as subscribers show wider distribution. Especially, with the call dropping probability within 0.2%, a switch having about 5 to 6 times bigger can be required, compared with the one when the mobility of subscribers is mostly restricte dto a single service area.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.23 no.7
• /
• pp.1732-1743
• /
• 1998

In this paper, we have proposed a channel assignment shceme for the multiple traffic class environment where the traffic volume varies with time. Our basic idea is to assign radio channels considering the characteristics of each traffic class and mobile speed and change the number of allocated channels for each traffic class according to vaiation of traffic volume. To evalute the perfomance of our proposed algorithms, we conducted analyical and simulation studies. We derived new call blocking probability and hand-off failure probability of the proposed scheme analytically. The simulatioh results show that our proposed algorithms can grantee GOS of each traffic class and provide a fairness between the new call and the hand-off call.

• Proceedings of the Korean Information Science Society Conference
• /
• 1999.10c
• /
• pp.369-374
• /
• 1999

The problem of bandwidth allocation and routing in VP based ATM networks was studied. A priori reservation of resources for VP's reduces the statistical multiplexing gain, resulting in increased Call Blocking Probability (CBP). The focus of this study is on how to reduce CBP by the efficient bandwidth allocation and routing algorithms. Equivalent capacity concept was used to calculate the required bandwidth by the call. and the effect of traffic dispersion was explored to achieve more statistical gain. A cost-effective traffic dispersion routing algorithm, CED, was designed. The algorithm finds the optimal number of dispersion paths for a call, where the gain balances the dispersion cost. Simulation study showed that CED could significantly reduce the CBP.

• The Journal of the Acoustical Society of Korea
• /
• v.22 no.3
• /
• pp.242-249
• /
• 2003

When special voice control application services (VCS) such as voice-controlled web browsing or voice-controlled stock transactions are introduced in cellular systems, a channel quality better than that for ordinary voice communications service (OVS) is necessary in order to keep a suitable grade of VCS. To avoid ai. congestion, calls are normally admitted if there exists a channel-processing resource not occupied by other calls in the base as well as the interference level at the receiver is not higher than a predefined threshold. The threshold is usually 10㏈ noise-rise over the background noise level for voice communications service. When the base admits VCS attempts in exactly the same manner as it handles OVS calls. the same fraction of those will be not successful in taking the channel and then blocked. If the same noise-rise threshold is used as 10 ㏈, however, the admitted VCS calls might suffer from bad channel qualify and finally be dropped. From the user's point of view, the forced termination of ongoing calls is significantly undesirable than blocking new call attempts. When using a lower noise-rise threshold for VCS. on the other hand, the blocking probability of VCS gets higher than that of OVS. In this paper, a call admission policy that gives a priority to VCS is considered in order to reduce the blocking probability and keep an adequate channel quality.

• Proceedings of the Korean Institute of Communication Sciences Conference
• /
• 1987.04a
• /
• pp.79-81
• /
• 1987

The traffic characteristicsof digitalswich network depend on the structure blocking probability, path searching method and etc. This paper presents the study of TDX-1 swicth network traffic capacity by considering some decisive factors such as call processing software, switch network structrure and control schme Conclusively the study shows that the switch network of TDX-1 can handle approximately up to 1650 Erlang.

• ETRI Journal
• /
• v.28 no.3
• /
• pp.371-374
• /
• 2006

We propose and analyze a priority queuing scheme that gives priority in the same class of calls according to their total resource requirements (TRRs). The proposed scheme gives a higher priority to the calls that have a lower TRR over the calls that have a higher TRR. The numerical results show that the proposed priority queuing scheme provides better performance than the traditional queuing schemes in call blocking probability.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.12 no.3
• /
• pp.83-88
• /
• 2012

This paper studies the effects of wavelength conversion on self-healing optical networks. We examined the effects of wavelength conversion capability on the backup routing and the spare wavelength utilization. The efficiency of spare wavelength utilization is proportionally increased as the wavelength conversion capability increases, different from the call blocking probability for which about 30% of wavelength conversion capability shows nearly the same performance as full wavelength conversion capability. The spare resource utilization efficiency can be improved by using alternate routing and wavelength assignment algorithms.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.46 no.4
• /
• pp.56-63
• /
• 2009

Resource reservation scheme is effective for better QoS guarantee to handover call for the next generation cellular systems where handover rate highly increases. However, resource reservation for handover call can incur negative impact on the new user admission. In this paper, we propose a random access based adaptive group-wise reservation to effectively reduce dropping rate of handover call, while protecting new local call. In the proposed scheme, target base station divides adaptively future handover users into groups based on the expected handover time, and then does group-wise reservation, where service allocation within each group is done on random access basis. Markov approach is also provided to analyze the performance of the proposed scheme. By computer simulation, it is shown that theoretical analysis on the performance is similar to the simulation results and the proposed reservation scheme outperforms the conventional scheme with respect to dropping probability of handover call.

• The KIPS Transactions:PartC
• /
• v.9C no.3
• /
• pp.385-398
• /
• 2002

To accommodate the increasing number of mobile terminals in the limited radio spectrum, wireless systems have been designed as micro/picocellular architectures for a higher capacity. This reduced coverage area of a cell has caused a higher rate of hand-off events, and the hand-off technology for efficient process becomes a necessity to provide a stable service. Population-based Bandwidth Reservation(PBR) Scheme is proposed to provide prioritized handling for hand-off calls by dynamically adjusting the amount of reserved bandwidth of a cell according to the amount of cellular traffic in its neighboring cells. We analyze the performance of the PBR scheme according to the changes of a fractional parameter, f, which is the ratio of request reservation to the total amount of bandwidth units required for hand-off calls that will occur for the next period. The vague of this parameter, f should be determined based on QoS(Quality of Service) requirement. To meet the requirement the value of Parameter(f) must be able to be adjusted dynamically according to the changing traffic conditions. The best value of f can be determined by a function of the average speed of mobile stations, average call duration, cell size, and so on. This paper considers the average call duration and the cell size according to the speed of mobile stations. Although some difference exists as per speed, in the range of 0.4 $\leq$ f $\leq$ 0.6, Blocking Probability, Dropping Probability and Utilization show the best values.

• Journal of Korea Multimedia Society
• /
• v.6 no.1
• /
• pp.105-113
• /
• 2003

In CDMA cellular system, inefficient Channel assignment for high-speed mobile host increase call blocking probability For it has been method proposed to guarantee QoS upon tn the speed of hierarchical cell that is allocated Queues and dedicated channels of high speed mobile host's speed. In this paper, We allocated the dedicated channel of high-speed handoff In FA (Foreign Agent), only if the receive signal strength of mobile host in current cell that there is low traffic in HA (Home Agent). also, we created new Circular queue LiFA (Limited Foreign Agent) for high-speed handoff call that signal strength is weak in certain FA, and had this High-speed handoff call to be ready for Life time to the new Circular queue LiFA. Thus improve the rate of the forced call termination.