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

• Journal of Advanced Navigation Technology
• /
• v.13 no.6
• /
• pp.901-906
• /
• 2009

This paper proposes a call admission control(CAC) method for wireless networks, which is based on the upper bound of a possibility distribution of handoff calls dropping rates. The possibility distribution is estimated in a fuzzy inference and a learning algorithm in neural network. The learning algorithm is considered for tuning the membership functions(then parts)of fuzzy rules for the inference. The fuzzy inference method is based on a weighted average of fuzzy sets. The proposed method can avoid estimating excessively large handoff calls dropping rates, and makes possibile self-compensation in real time for the case where the estimated values are smaller than real values. So this method makes secure CAC, thereby guaranteeing the allowed CDR. From simulation studies we show that the estimation performance for the upper bound of call dropping rate is good, and then handoff call dropping rates in CAC are able to be sustained below user's desired value.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.42 no.12
• /
• pp.85-94
• /
• 2005

In this thesis, we propose a Speed Accommodation Priority Algorithm Scheme(SPAS) and Traffic Control Model Scheme (TCMS) to satisfy a desired handoff dropping probability and to reduce the blocking probability of new calls using mobility characteristics and handoff rate in mobile communication networks. The guard channels below threshold can guarantee the Quality of Service(QoS) in terms of the request handoff dropping probability and the guard channels above the threshold can be used to handle high priority new calls and high priority handoff calls. When the ratio of the handoff call arrival rate is less then the ratio of the new call arrival rate, the proposed method can guarantee the new call better than the previous guard channel scheme.

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

• 전자공학회논문지 IE
• /
• v.45 no.3
• /
• pp.50-55
• /
• 2008

In CDMA system, the number of mobile stations which can be served simultaneously in a base station is limited by the amount of total interference received. 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 considering the number of mobile station being served and dynamically assigned by taking account of the blocking rate of new calls and the dropping rate of handoff calls. Also, there is reserved resource for handoff call. We analyze the performance of system according to reserved resource by a simulation study. The more a resource reserved, the less it is the dropping rate of handoff.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.25 no.9A
• /
• pp.1282-1289
• /
• 2000

In this paper we propose a Fractional Channel Reservation (FCS) scheme to satisfy a desired handoof dropping probability and to reduce the blocking probability of new calls using mobility characteristics and incoming handoff rate in mobile communication networks. When the ratio of the handoff call arrival rate is less then the ratio of the new call arrival rete, the proposed scheme is capable of determining the number of the guard channels which can guarantee the Quality of Service(QoS) in terms of the request handoff dropping probability and allocating dynamically the wireless channels the new calls according to the rest of the guard channels to reduce the new call blocking probability. Also we perform mathematical analysis and simulation to evaluate the performance of proposed scheme and compare to conventional guard channel scheme in terms of dropping probability blocking probability and the utilization efficiency of wireless channels.

• Journal of Advanced Navigation Technology
• /
• v.16 no.5
• /
• pp.794-800
• /
• 2012

In this paper, we propose a scheme for improving not only the utilization of frequency bands in the guard channel scheme but also the dropping rate of cognitive radio user in the wireless cognitive radio-based cellular network. The proposed scheme enables cognitive radio users to utilize the guard channel for servicing only handoff calls in normal times, but cognitive radio users must vacate the frequency channel when handoff call appearing. At this time our scheme ensures their seamless services for cognitive radio users, by predicting handoff call's appearance by MMOSPRED (Multi-Media One Step Prediction) method and then reserving the demanded channels for spectrum handoff calls. Our simulations show that our scheme performs better than other schemes; GCS(Guard Channel Scheme) and a scheme without prediction in terms of cognitive users call's dropping rate and resource utilization efficiency.

• Journal of Advanced Navigation Technology
• /
• v.23 no.4
• /
• pp.322-327
• /
• 2019

In this paper, we propose first a scheme of grouping spectrum holes that are created in the multiple channels of primary users, and then by using the scheme we enhance quality of service (QoS) of wideband cognitive radio users in cellular cognitive radio networks. In our scheme, spectrum holes created in each primary channel are predicted by Wiener prediction process, and then the predicted spectrum holes happened in the same time are grouped into a group. The wideband cognitive radio users explore the group of spectrum holes to improve their QoS. Simulation results show that their handoff calls dropping rate and initial calls blocking rate are significantly reduced in our scheme, compared to those in the single primary channel.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.25 no.12B
• /
• pp.2109-2119
• /
• 2000

In this paper, the Packet CDMA Reservation ALOHA protocol is proposed to support the multi-traffic services such as voice and videophone services with handoff calls, high-rate data and low-rate data services efficiently on the multi-rate transmission in uplink cellular systems. The frame structure, composed of the access slot and the transmission slot, and the proposed access permission probability based on the estimated number of contending users for each service are presented to reduce MAI. The assured priority to the voice and the videophone handoff calls is given through higher access permission probability. And through the proposed code assignment scheme, the voice service can be provided without the voice packet dropping probability in the CDMA/PRMA protocols. The code reservation is allowed to the voice and the videophone services. The low-rate data service uses the available codes during the silent periods of voice calls and the remaining codes in the codes assigned to the voice service to utilize codes efficiently. The high-rate data service uses the assigned codes to the high-rate data service and the remaining codes in the codes assigned to the videophone service. Using the Markov-chain subsystem model for each service including the handoff calls in uplink cellular systems, the steady-state performances are simulated and analyzed. After a round of tests for the examples, through the proposed code assignment scheme and the access permission probability, the Packet CDMA Reservation ALOHA protocol can guarantee the priority and the constant QoS for the handoff calls even at large number of contending users. Also, the data services are integrated efficiently on the multi-rate transmission.

• Journal of Korea Multimedia Society
• /
• v.7 no.5
• /
• pp.737-743
• /
• 2004

In this paper, we propose the call control scheme that can improve the capacity of the wireless system for the non-uniform traffic load distribution and the multiple types of services in multiple cells CDMA system. The number of mobile stations that can be served simultaneously in a base station is limited by the amount of total interference received in CDMA system. Further, the average number of mobile stations in each cell may not be uniformly distributed. Considering this factors, the call admission control scheme using the effective bandwidth concept is adapted in this paper. Thus, the bandwidth for a new call can be varied dynamically for reducing the blocking rate of new calls and the dropping rate of handoff calls. The suggested call control scheme is experimented through a simulation by dynamically assigning the bandwidth to new and handoff calls. The simulation results show that the proposed call control scheme can accommodate more mobile stations than the other methods in multiple cells environment.