• Journal of Korea Multimedia Society
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• v.8 no.12
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• pp.1597-1604
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• 2005

Recursive Patching is an efficient multicast technique for large-scale video on demand systems and recursively shares existing video streams with asynchronous clients. When Recursive Patching initiates a transition stream, it always makes a transition stream have additional data for the worst future request. In order to share a VOD server's limited network bandwidth efficiently, this paper proposes Practical Patching that removes the unnecessary data included in the transition stream. The proposed Practical Patching dynamically expands ongoing transition streams when a new request actually arrives at the server. As a result, the transition streams never have unnecessary data. Simulation result confirmed that the proposed technique is better than Recursive Patching in terms of service latency and defection rate.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.3-4
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• 2008

We propose an efficient uplink bandwidth request-allocation algorithm for variable-rate real-time service in IEEE 802.11 broadband wireless access networks. By introducing a notion of target delay under the framework of dual feedback, the proposed algorithm can assure the desired level of QoS while minimizing wastage of bandwidth allocation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.3A
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• pp.223-232
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• 2004

In this paper we propose the hierarchical-based dynamic bandwidth allocation algorithm for multi-class services in Ethernet-PON. The proposed algorithm consists of the high level scheduler in OLT and the low level scheduler in ONU. The hierarchical architecture is able to provide scalability and resource efficiency in Ethernet-PON which has the distributed nature of the scheduling domain, with queues and the scheduler located at a large distance from each other. We also propose three dynamic bandwidth allocation algorithms for the low level scheduler: Proportional Allocation algorithm, Maximum Request First Allocation (MRFA) algorithm and High Priority First Allocation (HPFA) algorithm. We implement the Ethernet-PON standardized in the IEEE 802,3ah using OPNET. We also evaluate and analyze the performance for the proposed algorithms in terms of channel utilization, queuing delay and the amount of remainder.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.10
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• pp.89-94
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• 2003

Passive Optical Network(PON) architecture is a very simple. However media access protocol is necessary to the PON because the ONUs should share a channel in the upsteam direction. We propose the design of dynamic bandwidth allocation algorithm for improved bandwidth utilization in the broad bandwidth access network that uses Ethernet PON. The object of our study shall be to decrease a unused remainder bandwidth of granted timeslot for a upstream traffic transmission. We propose that OLT notifies ONU of maximum transmission window during discovery and ONU request a amount under maximum transmission window after it checks a frame length. We confirm that the proposed algorithm shown improving performance from bandwidth utilization and queueing delay point of view through the simulation result.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.2
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• pp.17-23
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• 2000

Wireless link has high bit error rate compared with wired link and many users share this limited bandwidth. So it needs more powerful error control code and efficient media access control(MAC) to provide multimedia service reliably. In this paper we proposed efficient MAC frame format based on TDMA using mini-slot for request access. The number of mini-slots is variable based on the result of collision in the previous frame. This dynamic allocation of request mini-slots helps resolve the contention situation quickly and avoids the waste of bandwidth that may occur when there are several unneeded request mini-slots. The simulation results are also presented in terms of channel utilization, call blocking probability and cell transmission delay for mixed traffic environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.11B
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• pp.972-984
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• 2003

In this paper, new on-line routing algorithms with a bandwidth constraint are proposed. The proposed algorithms may be used for a dynamic LSP setup in MPLS network. We extend the WSP algorithm, the SWP algorithm and a utilization-based routing algorithm into the proposed algorithms by slightly modified K-shortest loopless path algorithms. The performances such as accepted bandwidth, accepted request number and average path length of the proposed and the previous algorithms are evaluated through extensive simulations. All simulations are conducted under the condition that any node can be an ingress or egress node for a LSP setup. The simulation results show that the proposed algorithms have the good performances in most cases in comparison to the previous algorithms. Under the heavy load condition, the algorithms based on the minimum hop path perform better than any other algorithms.

• Proceedings of the Optical Society of Korea Conference
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• 2006.07a
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• pp.355-356
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• 2006

• Journal of Korea Multimedia Society
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• v.13 no.3
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• pp.349-358
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• 2010

Adaptability is an important issue in video streaming over mobile environments, since the clients may request videos with great differences in their workload. In this paper, we propose the issues in limited bandwidth scheduling for efficient MPEG-4 video stream transmission over a mobile or wireless network. In the phase of admission control, the amount of bandwidth allocated to serve a video request is the mean bandwidth requirement of its requested video. The dynamic allocation of bandwidth in the phase of scheduling depends on the playback buffer levels of the clients with an objective to make it more adaptive to the playback situation of individual clients. In the proposed RTA scheduling protocol, more bandwidth may be allocated temporarily to the client whose buffer level is low. By employing the buffer level based scheduling policy, this protocol attempts to maximize the real-time performance of individual playback while minimizing the impact of transient overloading. Extensive simulation experiments have been performed to investigate the performance characteristics of the RTA protocol as comparing with BSBA protocol. This RTA protocol shows the better performance by transferring more frames than BSBA protocol.Computer simulations reveals that the standard deviation of the bit rate error of the proposed scheme is 50% less than that of the conventional method.

• Journal of Information Technology Services
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• v.8 no.1
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• pp.179-192
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• 2009

In wireless environments, it is very effective to introduce a data broadcast system for providing a number of clients with mobile data services. In particular, an efficient broadcast scheduling and a caching strategy are very important for performance of data broadcast systems in wireless environments which have such inherent restrictions as low bandwidth, frequent disconnections, and short battery life. In this paper, we present a data broadcast scheduling strategy using bit vectors to cope with dynamic request patterns of clients. In addition, we also propose an efficient caching strategy, 2FWT, that takes characteristics of the broadcast scheduling strategy into account. Finally, we evaluate performance of the data broadcast system. According to the results, the proposed system generally shows better performance than others.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.699-700
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• 2014

This paper proposes a new dynamic wavelength and bandwidth allocation algorithm for TWDM PON (time and wavelength division multiplexed passive optical network) which consists of an OLT (optical line termination) and multiple ONU (optical network unit). The proposed algorithm dynamically limits the number of the upstream wavelengths based on the request amount of ONUs to save power.