• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.5A
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• pp.387-393
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• 2007

In this paper, we propose the load control procedure for WiBro system in order to keep the data traffic throughput maximum. The transmitter at a mobile terminal can estimate maximum available power for each user and then the maximum number of subchannels can be calculated considering the total available power. The data traffic throughput and the total throughput (the sum of signaling traffic and data traffic throughput) are considered. As the number of bandwidth requests per frame increases, the data traffic throughput can significantly decrease. Therefore, the load control procedure is indispensible to maintain the data throughput at the maximum level. So, we propose the load control procedure to prevent data traffic throughput from decreasing and evaluate the proposed procedure through the computer simulation under the multi-user environment. The maximum throughput can be maintained by applying the proposed procedure.

• Journal of the Korea Society of Computer and Information
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• v.9 no.2
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• pp.41-48
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• 2004

Access control protocol have verified security of external mobile terminal that access to inner information sever at Ubiquitous ages. In this paper, I would design for If Access Control Protocol of considering operation time when make cipher digital signature. Public key are used Individual identification number that issued from certify communication company, and cipher algorithm are used ECDSA definition factor for generation and verification of digital signature and it used Elliptic Curve with over 160 bit Key. Also, Access control operate on If level that designed IPv6 frame architecture. I would conclude that IP Access Control Protocol have verified security and improved performance in operation time more 4 times than before protocols when through the communication of use cipher digital signature for authentication and verification.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.4
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• pp.406-412
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• 2019

In this paper, we propose two algorithms for classifying services with similar delay characteristics into three classes and allocating radio resources according to priority in LTE-A system where H2H and M2M services coexist. The first is to allocate resources from the higher priority class to the lower priority class, and each class gives priority to H2H over M2M, and the other is to give priority to H2H regardless of delay characteristics except for the class with the highest priority. The RA success probability was analyzed according to the access rate(${\alpha}$) of M2M devices in each class. In comparison with the conventional systems, it was improved from 0.5 to 0.52 for ${\alpha}_{2M}=0.05$ in two classes. In the three classes, the success probability was slightly increased from 0.5 to 0.57 for ${\alpha}_{2M}={\alpha}_{3M}=1$ and from 0.5 to 0.58 for ${\alpha}_{2M}=0.5$ and ${\alpha}_{3M}=0.1$. Although 6 services are considered in the proposed scheme, the RA success probability is almost similar to the previous scheme because the average arrival rate of H2H of each class is set to the same.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.177-181
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• 2004

It is as research about embodiment of MAC algorithm that is point of wireless LAN technology that is radio skill that is receiving present head of a family footlights, and embodied MAC that is algorithm that control modem Rf and host interface to level that existent common use radio AP and send-receive of high speed are available that embody function that is presented to IEEE 802.11 specs using H/W and S/W. When embody actually, tested module that embody actually using module modem and RF part because test is impossible after have common use product. Also, module that embody actually designed, and is expected to be utilized in radio LAN system construction of high speed late considering CRC and FCS ewer on channel.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.5
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• pp.1080-1086
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• 2014

In this paper, we analyze the tradeoff performance of a consensus algorithm when it is applied to the CSMA/CA-based distributed wireless network. The consensus algorithm has a faster convergence speed as the number of cooperating neighbors increases, but the transmission delay on the wireless network increases due to access collisions as the number of cooperating neighbors increases. Therefore, there exists a tradeoff relationship between these two performances and so there exists an optimal number of cooperating neighbors that minimizes the consensus time. The result for the optimal number of neighbors according to the number of nodes that participate in the consensus shows that it is optimal for all nodes to cooperate together in the small-scale network but it is optimal to limit the number of neighbors to a fixed value in the large-scale network with nodes greater than a certain value.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.549-552
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• 2005

Multiple wireless devices in wired and wireless heterogeneous networks communicate with counterparts via a single access point (AP). In this case, the AP becomes a bottleneck of the network, therefore buffer overflows occur frequently and result in TCP performance degradation. In this paper, a new algorithm that prevents buffer overflows at AP and enhances TCP fairness is proposed. Depending on the buffer usage of AP, the new algorithm adaptively controls each TCP senders' transmission rate, prevents buffer overflows and thus guarantees improved TCP fairness. It is proved that the algorithm makes better of TCP throughput and fairness by preventing buffer overflows.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.8
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• pp.735-742
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• 2016

The Low-Rate WPAN is a short range wireless networking technology characterized by low-rate, low-power, low complexity and low-cost. The LR-WPAN controls wireless channel access among network devices based on the contention-based CSMA/CA algorithm. Therefore, frame collisions may take place at any time, leading to the severe degradation of network performance. This paper proposes a new algorithm that changes back-off periods adaptively in the CSMA/CA process depending on network conditions, resulting in the reduction of frame collisions. Throughout extensive simulations, it turns out that varying the back-off periods dynamically shows better performance than maintaining the fixed back-off periods.

• Journal of Software Assessment and Valuation
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• v.16 no.1
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• pp.89-94
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• 2020

In this paper, we propose a software algorithm that can configure n-key roll-over that detects all keys without limitation on the number of pressed keys in the dynamic scanning detection of a keyboard composed of a matrix. The proposed algorithm uses the timer interrupt of the microcontroller for computer keyboard control, so that a constant and accurate detection interval can be obtained, and an accurate debounce time can be provided. In order to confirm the effectiveness of the proposed algorithm, a microcontroller was connected to a toy keyboard constructed in the form of a clavier and experiments were conducted. As a result of the experiment, it was confirmed that detection of all keys was performed accurately regardless of the number of keys pressed.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.1
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• pp.72-78
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• 2006

Distributed generation (DG) systems go to intentional islanding operation to back up private emergency loads when the main grid is out of electric power. Conventional utility interactive inverters normally operated in current control mode in DG system must change their operation mode into voltage control mode to ensure stable voltage source to the emergency loads when intentional islanding operation occurs. During the transfer between current control mode and voltage control mode, serious transient problem may occur on the output terminal voltage of the utility interactive inverter. This paper proposes reasonal inverter topology and its control algorithm for seamless transfer of DG systems in intentional islanding operation. Filter design guide line and data for a LCL filter that is appropriate for the proposed control algorithm are also presented by the authors.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.1B
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• pp.42-48
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• 2002

In broadband wireless networks, the effective meeting of the QoS guarantees may strongly depend on the Contention Resolution Algorithm used in the uplink contention period. The time it takes a station to transmit a successful request to the base station, or request delay, must be kept low even during periods of high contention. If a request suffers many collisions, it cannot rely on the preemptive scheduler to receive low access delays. However, the conventional collision resolution algorithm has a problem that all collided stations are treated equally regardless of their delay from previous contention periods. Some requests may have very long request delay caused by continuous collisions. In this paper, we propose an adaptive collision resolution algorithm for fast random access in broadband wireless networks. The design goal is to provide quick access to the request with a high number of collisions. To do this, the proposed algorithm separates the whole contention region into multiple sub regions and permits access through each sub region only to the requests with equal number of collisions. The sub region is adaptively created according to the feedback information of previous random access. By simulation, the proposed algorithm can improve the performance in terms of throughput, random delay and complementary distribution of random delay by its ability to isolate higher priorities from lower ones. We can notice the algorithm provides efficiency and random access delay in random access environment.