• The Journal of the Korea Contents Association
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• v.17 no.3
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• pp.589-595
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• 2017

We present an estimation model for optimal channel capacity required to data traffic transmission. The optimal channel capacity should be calculated in order to satisfy the permitted transmission delay of each wireless data services. Considering the discrete-time operation of digital communication systems and batch arrival of packet-switched traffic for various wireless services, $Geo^x$/G/1 non-preemptive priority queueing model is analyzed. Based on the heuristic interpretation of the mean waiting time, the mean waiting times of various data packets which have the service priority. Using the mean waiting times of service classes, we propose the procedure of determining the optimal channel capacity to satisfy the quality of service requirement of the mean delay of wireless services. We look forward to applying our results to improvement in wireless data services and economic operation of the network facilities.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.1
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• pp.40-45
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• 2007

In this paper, aim to suggest the medical information wireless transmission system to provide the mobility of medical service by means of wireless area network which makes it possible, home or at a long range, to check and oversee the state of patients, and to can out a simulation. The proposed method converts medical information to digital data in an emergency and sends them to mobile terminals such as PDAs to make possible swift first aid. The simulation took advantage of the OFDM transmission method based on IEEE 802.1la in order to send reliable medical information in mobile wireless channel environment, and analyzed the system performance by applying convolution encoding to transmit reliable information in AWGN and 3-ray mobile multipath fading channel environment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.2
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• pp.459-465
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• 2014

Recently, multimedia data transmission becomes important issues in the wireless sensor network. For the multimedia data transmission in wireless sensor network, QoS (Quality of service) is an important factor to determine the system performance. AODV algorithm is one of the widely used algorithm for wireless ad-hoc environment. In AODV, the destination node selects the route with the smallest hop count. Since AODV only considers the hop count, the selected route could have low channel condition, and degrade QoS. In this paper, we propose a modified AODV algorithm that considers the successful transmission rate of each link. The proposed algorithm regards the number of retransmission which can be obtained from the successful transmission rate as the hop count, and applies the modified hop count to AODV. The advantage of the proposed algorithm is that the modified AODV can support QoS without significant change of the conventional algorithm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.8
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• pp.1011-1017
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• 2019

This paper proposes reinforcement learning to solve the node-disjoint path problem which establishes multipath for reliable data transmission in wireless ad-hoc networks. The node-disjoint path problem is a problem of determining a plurality of paths so that the intermediate nodes do not overlap between the source and the destination. In this paper, we propose an optimization method considering transmission distance in a large-scale wireless ad-hoc network using Q-learning in reinforcement learning, one of machine learning. Especially, in order to solve the node-disjoint path problem in a large-scale wireless ad-hoc network, a large amount of computation is required, but the proposed reinforcement learning efficiently obtains appropriate results by learning the path. The performance of the proposed reinforcement learning is evaluated from the viewpoint of transmission distance to establish two node-disjoint paths. From the evaluation results, it showed better performance in the transmission distance compared with the conventional simulated annealing.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.8A
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• pp.858-870
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• 2007

TCP is popular protocol for reliable data delivery in the Internet. In recent years, wireless environments with transmission errors are becoming more common. Therefore, there is significant interest in using TCP over wireless links. Previous works have shown that, unless the protocol is modified, TCP may perform poorly on paths that include a wireless link subject to transmission errors. The reason for this is the implicit assumption in TCP that all packet losses are due to congestion which causes unnecessary reduction of transmission rate when the cause of packet losses are wireless transmission errors. In this paper, we propose a new LDA that monitors the network congestion level using ROTT. And we evaluate the performance of our scheme and compare with TCP Veno, Spike scheme with NS2(Network Simulator 2). In the result of our experiment, our scheme reduces the packet loss misclassification to maximum 55% of other schemes. And the results of another simulation show that our scheme raise its transmission rate with the fairness preserved.

• Journal of IKEEE
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• v.6 no.1 s.10
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• pp.65-71
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• 2002

In this study, we evaluate the reliability of using bluetooth wireless communication method, the industrial, scientific, and medical standards for local wireless communications, in the medical environment. For the study, an ECG measurement system using bluetooth is developed and used in various conditions of medical environment. It is found that the bluetooth communication method has shown a reliable data transmission capability when both transmitter and receiver are positioned in the same room. However, the increase of transmission distance and the existence of a wall prevent the retailable data transmission. Therefore, it is necessary to make sure if reliable data transmission is achieved for individual environments, before we use this technology.

• Journal of the Korea Society of Computer and Information
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• v.17 no.12
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• pp.121-129
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• 2012

In this paper, we proposed WBAN system model to management an application that requires low rate data transfer in IEEE 802.15.4. We have to use different wireless sensor network technology to transfer different date rate and emergency message in medical application service. A suitable system model for WBAN and a WBAN MAC protocol in order to solve these existing system problems are proposed. Firstly, the priority queuing was applied to contention access period, and the system model which could guarantee transmission of a MAC command frame was proposed. Secondly, the MAC frame was newly defined to use the system model which was proposed above. Thirdly, WBAN CSMA/CA back-off algorithm based on data transmission rate was proposed to enhance data throughput and transmission probability of the data frame which does not have priority in the proposed WBAN system. The proposed algorithm is designed to be variable CSMA/CA algorithm parameter, depending on data rate. For the evaluation of WBAN CSMA/CA algorithm, we used Castalia. As a result of the simulation, it is found that the proposed system model can not only relieve loads of data processing, but also probability of collision was decreased.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.6B
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• pp.586-592
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• 2002

In this paper, new channel scheduling algorithms which reduce transmission delay caused by wireless network are proposed in AMC/TDM wireless data communication. The concept of the Proposed algorithms is based on the proportional fairness, M-LWDF, and performance-guaranteeing algorithm proposed by Xin Liu. The proposed algorithm can be applied to QoS guaranteeing services as well as best-effort services. Simulation results show that new algorithm reduced transmission delay upto 11.5% in case of proportional fairness algorithm and also decreased transmission delay unto 9% in case of M-LWBF algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.12B
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• pp.1468-1473
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• 2011

With the proliferation of wireless LAN and smart phones, IP local broadcasting technology has been developed, and the new solution should be studied for error corrupted frames in the wireless broadcasting channel. In push service system using point-to-multi-point connection among broadcasting server and receivers, the technology proposed in this paper provides an effective data broadcasting system by employing frame length adjustment, redundant transmission, and repetitive transmission method.

• Speech Sciences
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• v.11 no.4
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• pp.67-73
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• 2004

Packet loss, jitter, and delay in the Internet are caused mainly by the shortage of network bandwidth. It is due to queuing and routing process in the intermediate nodes of the packet network. In the Internet whose bandwidth is changing very rapidly in time depending on the number of users and data traffic, controlling the peak transmission bit-rate of a VoIP. system depending on the channel condition could be very helpful for making use of the available network bandwidth. Adapting packet size to the channel condition can reduce packet loss to improve the speech quality. It has been shown in [1] that a VoIP system with an AMR speech codec provides better speech quality than VoIP systems with fixed rate speech codecs. With the adaptive codec mode assignment. algorithm proposed in [1], in this paper, we performed the voice transmission experiments using the wireless LAN through the real Internet environment. Experimental results are analyzed and discussed with our findings.