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

• 제어로봇시스템학회:학술대회논문집
• /
• 2005.06a
• /
• pp.1846-1850
• /
• 2005

This paper presents a constrained-based routing (CBR) algorithm called, Dynamic Possible Path per Link (D-PPL) routing algorithm, for MultiProtocol Label Switching (MPLS) networks. In MPLS on-line routing, future traffics are unknown and network resource is limited. Therefore many routing algorithms such as Minimum Hop Algorithm (MHA), Widest Shortest Path (WSP), Dynamic Link Weight (DLW), Minimum Interference Routing Algorithm (MIRA), Profiled-Based Routing (PBR), Possible Path per Link (PPL) and Residual bandwidth integrated - Possible Path per Link (R-PPL) are proposed in order to improve network throughput and reduce rejection probability. MIRA is the first algorithm that introduces interference level avoidance between source-destination node pairs by integrating topology information or address of source-destination node pairs into the routing calculation. From its results, MIRA improves lower rejection probability performance. Nevertheless, MIRA suffer from its high routing complexity which could be considered as NP-Complete problem. In PBR, complexity of on-line routing is reduced comparing to those of MIRA, because link weights are off-line calculated by statistical profile of history traffics. However, because of dynamic of traffic nature, PBR maybe unsuitable for MPLS on-line routing. Also, both PPL and R-PPL routing algorithm we formerly proposed, are algorithms that achieve reduction of interference level among source-destination node pairs, rejection probability and routing complexity. Again, those previously proposed algorithms do not take into account the dynamic nature of traffic load. In fact, future traffics are unknown, but, amount of previous traffic over link can be measured. Therefore, this is the motivation of our proposed algorithm, the D-PPL. The D-PPL algorithm is improved based on the R-PPL routing algorithm by integrating traffic-per-link parameters. The parameters are periodically updated and are dynamically changed depended on current incoming traffic. The D-PPL tries to reserve residual bandwidth to service future request by avoid routing through those high traffic-per-link parameters. We have developed extensive MATLAB simulator to evaluate performance of the D-PPL. From simulation results, the D-PPL improves performance of MPLS on-line routing in terms of rejection probability and total throughput.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
• /
• v.17 no.2 s.58
• /
• pp.38-49
• /
• 2006

In order to increase the spectrum efficiency, recently, there is the number of studies for CR technology. For instance, IEEE 802.22 WRAN(Wireless Regional Area Network) WG considered the CR technology as a solution of WRAN system to serve the high speed internet service(1.5 Mbps down stream and 384 kbps up stream) in 100 km overall coverage and 54 MHz-746 MHz band. Basically, in MAC point of view, the WRAN system have been standardizing based on the IEEE 802.16 MAC layer features such as Data transmission method, QoS provision and Bandwidth request schemes. Additionally, the WRAN system further include CR nature functions such as incumbent user protection, self coexistence which would be importantly considered. Also, the inherent WRAN functions are added such as channel bonding and fractional bandwidth usage. This paper mainly explained frame structure, IU protection, self coexistence which are key functions of WRAN system. Finally, in this paper, we expressed a prospect of IEEE 802.22 WRAN standardization.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.11 no.4
• /
• pp.105-112
• /
• 2011

We propose an adaptive load balancing scheme to transport real-time video streams efficiently in this paper. The playback buffer level of a video requesting client is high or low temporarily in mobile environment. This scheme attempts to allocate more network bandwidth to serve a video request with the lower buffer level preferentially. In this scheme, the amount of network bandwidth is dynamically allocated to the requesting clients according to their playback buffer levels in a distributed mobile system. In order to improve the quality of service and real-time performance of individual video playback, the proposed load balancing scheme tries to maximize the number of frames that are transported successfully to the client prior to their playback times. Fair services can also be provided to all the concurrent clients by making their playback situation more adaptive. The performance of this load balancing scheme is compared with that of other static load balancing scheme through extensive simulation experiments, resulting in the higher ratio of frames transmitted successfully within given deadlines.

• Journal of the Korea Society of Computer and Information
• /
• v.16 no.10
• /
• pp.147-153
• /
• 2011

In this paper, we present a new video management technique using forward timeline to efficiently store and delete the videos on a local server. The proposed method is based on capturing the changing preference of the videos according to recentness, frequency, and playback length of the requested videos. For this purpose, we utilize the forward timeline which represents the time area within a number of predefined intervals. The local server periodically measures time popularity and request segment of all videos. Based on the measured data, time popularity and request segment, the local server calculates the mean time popularity and mean request segment of a video using forward timeline. Using mean time popularity and mean request segment of video, we estimate the ranking and allocated storage space of a video. The ranking represents the priority of deletion when the storage area of local server is running out of space and the allocated storage space means the maximum size of storage space to be allocated to a video. In addition, we propose an efficient storage space partitioning technique in order to stably store videos and present a time based free-up storage space technique using the expected variation of video data in order for avoiding the overflow on a local server in advance. The simulation results show that the proposed method performs better than other methods in terms of hit rate and number of deletion. Therefore, our video management technique for local server provides the lowest user start-up latency and the highest bandwidth saving significantly.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.8A
• /
• pp.937-941
• /
• 2004

In this paper, we propose a efficient multicast routing algorithm in the wire/wireless integrated environment. Through simulations and comparing to another multicast algorithm, we reach a conclusion is that the routing algorithm can simply and dynamically adjusts the construction of multicast tree with little delay and the most reducible bandwidth resources.

• Proceedings of the IEEK Conference
• /
• 2001.06c
• /
• pp.125-128
• /
• 2001

Nowadays, Internet users are widespread internationally. Fallowing the users requirements, server has to transfer real-time multimedia data to many clients. Multicast can significantly reduce the system overhead and the network resource waste, so it supports efficient mechanism when server has to transfer same data to many clients. We can deliver multimedia data transfer in real-time using Patching Algorithm which has no delay for service request. And multicast algorithm can support different network bandwidth using Receiver driven Layered Multicast under heterogeneous environment network. The purpose of this paper is to suggest an algorithm that can create new multicast group adequately and transfer real-time multimedia data efficiently under heterogeneous environment.

• Proceedings of the IEEK Conference
• /
• 2000.06a
• /
• pp.131-134
• /
• 2000

Only MAC protocol can satisfy the service quality of the request of bandwidth, delay time, and cell loss at the same time and it is because MAC protocol provides mobile terminal an environment to use channel evenly and effectively This Paper has been adapted Mobile ATM Standardization of ETSI in maximum and used not only for practicing in-band signal to a priority order but also to the next reserved slot assignment of the dynamic frame. Also, by accepting VBR traffic more adaptively, the effectiveness of transmission channel has been maximized as well, and these are compared with the old way of it and analyzed to confirm the effectiveness.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.33 no.4B
• /
• pp.215-223
• /
• 2008

Retransmission signals from relays to destination when the destination fails to decode received signal from the source in Automatic Repeat Request (ARQ) protocol make the destination receive signals more reliably. With using omni -direction antenna in the practical system, in communication range of both the source antenna and the destination antenna, there are some relays that can be used to transmit signal to the destination. However, using all relays to transmit signal consume power and bandwidth. In this paper, we propose a new protocol in which the best relays are chosen based on threshold of distance from the source to the relay and the relay to the destination when the relays use decode- and forward (DF) protocol. Simulation results prove the efficiency of the protocol when we compare using only the best relays with using all relays to transmit signal to the destination.

• The Transactions of the Korea Information Processing Society
• /
• v.7 no.6
• /
• pp.1932-1940
• /
• 2000

We must solve problems caused by mobile computing environments for supporting efficient mobile computing services. The problem is the use of wireless medium having high error rates and low bandwidth, and the sudden network disconnection to reduce the power consumption of a mobile host and the cost of the network connection. For these problems, we proposed the architecture of the partial connection manager and designed and implemented that in this paper. In particular, The partial connection manager creates the limited number of mobile agents according to priority and sends them in parallel to server systems and combines results of them process rapidly the user request. By applying the proposed partial connection manager to the mobile computing services called cybermarket, we knew that the mobile agent technique could be suited to the mobile computing environment and overcome the partial connection problem caused by eh mobile computing environment.