• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.3B
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• pp.204-211
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• 2012

Wireless Mesh Network (WMN) has drawn much attention due to wide service coverage with low system cost. However, WMN suffers from high bit error rate, which provides different link capacity among wireless mesh routers. The conventional routing metrics select the path based on link quality. The link with the best quality is preferred as the data transmission path, and they becomes the bottleneck links, which leads to network performance degradation. In this paper, we propose a routing metric that considers the available bandwidth and the number of nodes suffering congestion in the path. Through computer simulations, we verified that the proposed routing metric outperforms the existing routing metrics in terms of average transmission delay, packet loss, system throughput.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.9B
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• pp.838-847
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• 2006

In order to support multiple multimedia streaming services in home networks, many critical issues must be considered. In addition, handling the shortage of network bandwidth is one of the most significant and complicated issues. In this paper, real-time bandwidth management service is suggested as a solution to the problem regarding the IEEE1394-based home network. In order to handle the shortage of network bandwidth and to enhance the bus utilization rate, the proposed service combines two methods. First, the bus bandwidth management function determines the state of the network bandwidth and restores the residual bandwidth, which is excessively occupied by a streaming service, to the available free bandwidth. Second, the Isochronous Streaming (IS) Scheduler manages all streaming services according to priority. In order to test the proposed service, we implemented a prototype steaming management middleware and evaluated it by using the IEEE1394 network test-bed.

• Journal of Internet Computing and Services
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• v.8 no.4
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• pp.41-49
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• 2007

Ethernet passive optical network(EPON) is the next-generation technology for supporting services of high-quality at low-cost. In the EPON, all optical network units(ONUs) have to share a limited uplink channel for upstream data. In order to satisfy bandwidth demands of users on high-capacity local access networks(LANs), the optical line terminal(OLT) efficiently divides and allocates time slots of uplink channel to all ONUs. We discuss previous schemes for dynamic bandwidth allocation(DBA), such as interleaved polling with adaptive cycle time(IPACT) and sliding cycle time(SLICT). In this paper, dynamic right sizing of maximum-windows(DRSM), as a novel bandwidth allocation service, is proposed for more effective and efficient time slot allocation of the uplink channel. DRSM which is based on past information of bandwidth allocated by OLT calculates maximum available bandwidth and dynamically alters the maximum window size for the next ONU. This scheme does not only exert every effort to meet bandwidth demands of ONUs with the possible scope, it also seeks fairness of bandwidth allocation among ONUs.

• Journal of Korea Multimedia Society
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• v.17 no.4
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• pp.526-534
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• 2014

Most of the multiplayer games available online are based on a client-server architecture because this architecture gives better administration control to the game providers than peer-to-peer architecture. In this architecture, the server is responsible for all the communication between the connected clients. The weakness of this architecture is its bandwidth requirement and scalability. Peer-to-peer architectures have then been proposed to solve these issues. In this paper, we propose a hybrid client-server architecture in which the game state is partially shared by the mobile terminal to achieve consistency among different players. Like a peer-to-peer architecture, this architecture uses client-side capacities to reduce bandwidth requirements for the server and improves consistency in wireless networks. Client events have different timeliness and consistency requirements according to their nature in the game world. These requirements lead to tasks with different priorities on CPU processing. In the proposed architecture, either the server or the client applies consistency mechanism according to the priority level. Simulation experiments show that the bandwidth of the server in this architecture is smaller than that of the client-server architecture. As a result, the server in the proposed architecture can accommodate more clients with enhancing the scalability.

• Journal of Drive and Control
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• v.14 no.2
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• pp.1-8
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• 2017

The spool displacement of a directional control valve can be considered as the standard signal for the measurement of its bandwidth frequency. When the spool displacement is not available, the metering-orifice system is suggested in this study as an alternative way to measure the - 3 dB amplitude-ratio bandwidth frequency of the hydraulic directional-control valve. The amplitude ratio of the metering-orifice pressure can be adjusted to equal that of the spool displacement through the controlling of the metering-orifice opening area. A series of experiments were conducted to verify the effectiveness of the metering-orifice system. The metering orifice was confirmed as adequate for the measurement of the - 3 dB amplitude-ratio bandwidth frequency.

• The KIPS Transactions:PartC
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• v.15C no.2
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• pp.111-118
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• 2008

A wireless router is a device which allows several wireless clients to share an internet line using NAT (Network Address Translation). In a school or a small office environment where many clients use multiple wireless routers, a client may select any one of wireless routers so that most clients can be clustered to a small set of the wireless routers. In such a case, there exists load unbalancing problem between clients and wireless routers. One of its result is that clients using the busiest router get poor service. The other is that the resource utilization of the whole wireless routers becomes very low. In order to resolve the problems, we propose a load sharing scheme to maximize network bandwidth utilization based on SSID(Service Set IDentifier) hiding. The proposed scheme keeps checking the available bandwidth of all the possible wireless routers in a time interval and select the most available one. If a new client appears, the most available router is visible to him or her whereas the others are not visible. This is handled by SSID hiding in the proposed scheme. We implemented the proposed scheme with ASUS WL 500G wireless router and performed experiments. Experimental results show the bandwidth utilization improvement compared to the existing method.

• Journal of Digital Contents Society
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• v.9 no.3
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• pp.433-439
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• 2008

A moving picture in online game is one of major ways to advertise online games, which gives a lot of help in playing game. In this case, a moving picture is compressed to variable bit rate for efficient storage use and network resource efficiency. Adaptable bandwidth allocation technique builds a transmission plan of a game moving picture. And, then some frames are discarded when transmission rate by the transmission plan is larger than available transmission rate, until transmission rate satisfies available transmission rate. Thus, performance evaluation factors in adaptable bandwidth allocation technique may be dependent on discarding order of a frame which transmission rate is much influenced. In this paper, in order to show the performance, a CBA algorithm, an MCBA algorithm, an MVBA algorithm, [6] and [7] algorithm were applied to a transmission plan in the adaptable band width allocation technique using various frame discard methods and performance evaluation factors were compared in among smoothing algorithms.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.1B
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• pp.64-72
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• 2004

Multiprotocol Label Switching (MPLS) has been developed as a key technology to enhance the reliability, manageability and overall quality of service of core If networks with connection-oriented tunnel LSP and traffic engineering such as constraint-based routing, explicit routing, and restoration. In this paper, we propose a control bandwidth borrowing scheme that maximizes the utilization of tunnel LSPs or physical links by an extension to the RSVP-TE label distribution protocol. MPLS-based core switching network and VPN services rely on the establishment of connection-oriented tunneled LSPs that are configured or predefined by network management systems. The mechanism of network management system varies from (i) a relatively static LSP establishment accounting, to (ii) a dynamic QoS routing mechanisms. With the use of hierarchical LSPs, the extra bandwidth that is unused by the trunk (outer) LSPs should be fully allocated to their constituent end-to-end user traffic (inner) LSPs in order to maximize their utilization. In order to find out the unused extra bandwidth in tunnel LSP or physical link and redistribute these resources to constituent LSPs, we expend the functionality of RSVP-TE and the found unused extra bandwidth is redistributed with a weight-based recursive redistribution scheme. By the extended RSVP-TE and proposed recursive redistributed scheme, we could achieve the instantaneous maximized utilization of tunnel LSP or physical link suffering from the potential under-utilization problem and guarantee the end-to-end QoS requirements. With the proposed scheme, network manager can manage more effectively the extra available bandwidth of hierarchical LSPs and maximize the instantaneous utilization of the tunneled LSP resources.

• Journal of Drive and Control
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• v.15 no.4
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• pp.1-10
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• 2018

Spool displacement of a direction control valve is the standard signal to measure the bandwidth frequency of the direction control valve. When the spool displacement signal is not available, it is suggested in this study to use the metering hydraulic line as an alternative way to measure - 90 degree phase bandwidth frequency of the hydraulic direction control valve. Dynamics of the hydraulic line is composed of inertia, capacitance, and friction effects. The effect of oil inertia is dominant in common hydraulic line dynamics and the line dynamics is close to a derivative action in a range of high frequency; such as a range of bandwidth frequency of common directional control valves. Phase difference between spool displacement and line load pressure is nearly constant as a valve close to 90 degree. If phase difference is compensated from the phase between valve input and pressure, compensated phase may be almost same as the phase of spool displacement that is a standard signal to measure phase bandwidth frequency of the directional control valve. A series of experiments were conducted to examine the possibility of using line pressure in to measure phase bandwidth frequency of a directional control valve. Phase bandwidth frequency could be measured with relatively high precision based on metering hydraulic line technique and it reveals consistent results even when valve input, oil temperature, and supply pressure change.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.11a
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• pp.89-92
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• 2003

대규모 네트워크 망인 인터넷을 통한 실시간 멀티미디어 데이터 전송에 있어 다양한 수신자들의 요구를 충족시키기 위해 공유 대역폭(shared bandwidth)을 공정하게 사용해야 한다. 그러나, 공유 대역폭을 공정하게만 사용하기 때문에 혼잡이 발생할 경우 가용대역폭(available bandwidth)을 효율적으로 사용할 수 있는 기법이 필요하게 되었다. 이에 본 논문에서는 최상위 레이어의 손실률에 따른 패킷에 우선순위(priority)를 부여하여 패킷(Packet)을 선택 제거함으로써 혼잡이 발생하지 않는 세션에서는 공유 대역폭을 보다 효율적으로 사용할 수 있는 알고리즘을 제안한다. 실험결과, 제안하는 알고리즘이 기존기법 보다 공유 대역폭을 효율적으로 사용할 수 있었다.