Wongwirat, Olarn

Preferred name

Wongwirat, Olarn

Alternative Name

Wongwirat, O.

Wongwirat, Olam

Main Affiliation

School of Information Technology

olarn.wo@kmitl.ac.th

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Moving average based adaptive buffer for haptic media synchronization in telehaptics
(2005-11-16)
Wongwirat, Olarn
;
Ohara, Shigeyuki
Telehaptics Is involved with varions aspects of teleoperation applications. The problem of telehaptics of our concern In teleoperation is a delay variation on networks, or jitter delay. To solve the delay variation problem, a method of synchronization is required. This paper proposes the adaptive buffering control method for haptic media synchronization. The adaptive mechanism employs a moving average smoothing technique to calculate an expected delay in accordance with the delay variations resulting from the network traffics. Then, the expected delay is used to adjust the buffer size under a specified threshold. The idea of haptic media synchronization using a fixed buffer approach from our previous work is first carried out in the paper. Then, the proposed adaptive buffering control approach is explored in detail, including the methods to select the number of spans and to specify the threshold of adaptation. In addition, performance of the synchronization is verified by measuring the loss rate of haptic sequences for comparison between the fixed and adaptive buffering control approaches. According to the results, the adaptive buffer can preserve the loss of haptic sequences better than the fixed buffer approach when performing over the local, regional, and long distance network links under specified traffic conditions. ©2005 IEEE.
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An adaptive buffer control using moving average smoothing technique for haptic media synchronization
(2005-11-30)
Wongwirat, Olarn
;
Ohara, Shigeyuki
;
Chotikakamthorn, Nopporn
This paper proposes an adaptive buffering control method for haptic media synchronization in networked virtual environments based telehaptics. The adaptive mechanism employs a moving average smoothing technique to calculate an average delay for buffering adjustment under a specified threshold. The mechanism of haptic media synchronization using a fixed buffering approach from our previous work is carried out in the paper. Then, the proposed adaptive buffering control scheme is described, including the methods to select the number of spans and the specified threshold. Performance of the synchronization is verified by measuring a loss rate of haptic sequences at the remote process of both buffering approaches for comparison. The performance results express that, in the local and regional link networks with moderate and high traffic conditions, the adaptive buffer can preserve the loss better than the fixed buffer. © 2005 IEEE.
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Performance evaluation of traffic congestion for multiple-lock checking algorithm in distributed share virtual environment applications
(2001-12-01)
Wongwirat, Olarn
;
Sathitwiriyawong, Chanboon
;
Ohara, Shigeyuki
Multiple-lock checking algorithm has been studied and developed to support simultaneous access of shared resources, or objects, by logical processes of applications in distributed shared virtual environment for two years. Its purpose is to provide synchronization among the logical processes in networked virtual environment where users' applications can interact with each other in the shared environment. There are two main factors effecting performance of the multiple-lock checking mechanism in the distributed share virtual environment application, which are network delay and traffic. The former factor has been issued in our previous work. This paper verifies the traffic congestion on local network (LAN) that is generated by the number of logical processes. The effect of increased traffic to the performance of multiple-lock checking algorithm when accessing the shared object in the shared virtual environment application is also investigated. Simulation results show that utilization of the local network to support the locking mechanism for non-competition case is insignificant comparing with the number of logical processes. The locking time for distinct logical processes is constant and below 100 μs at lower 60% workload condition. Finally, the multiple-lock checking algorithm can perform efficiently on the LAN with no traffic affecting the performance.
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Bounded delay performance analysis for distributed multimedia applications under shared virtual environment
(2000-01-01)
Wongwirat, Olarn
;
Makhanov, Stanislav S.
;
Ohara, Shigeyuki
Distributed multimedia applications can be characterized into two types of interaction, nonconversation and conversation, which discrete media and continuous media data are involved respectively. The two applications types have distinct requirement in terms of delay to support interactive services, particularly under shared virtual environment. For conversational interactive type application which continuous media is mainly focused, a limited delay is required for achieving real-time service guarantees and for maintaining temporal relationship, or synchronization. In this paper, we apply the internet delay model to the conversational type application for distributed multimedia data under shared virtual environment on the internet to analyze the performance of the bounded delay value. The simulation results show the delay variation of continuous multimedia data apparently at the clients and a server under dynamic case consideration which represents the delay characteristic of the application on the internet.
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Performance evaluation of compromised synchronization control mechanism for distributed virtual environment (DVE)
(2005-12-01)
Wongwirat, Olarn
;
Ohara, Shigeyuki
Synchronization in a distributed virtual environment (DVE) involves mechanisms to ensure a consistent view of a virtual world for all participants. Most applications in the DVE are related to collaborative activities that include non-contention and contention cases. Using transmission of update messages is suitable enough to support synchronization for only non-contention activity. The contention activity requires an additional mechanism to control accessing a common object for synchronization. In this paper, we present the compromised synchronization control mechanism to support both non-contention and contention activities. The mechanism employs frequent update event and multiple-lock checking to control the synchronization. Frequent update event is used to support a dynamic virtual world for non-contention activity. Multiple-lock checking is embedded to ensure consistency when accessing the common object is required simultaneously for the contention event. Performance measurement of the compromised synchronization is provided by simulation in terms of locking time, sampling event, number of logical processes, and traffic tolerance. Prototype application is also implemented to compare the result in a small scale level. Based on the simulation and experimental results, the compromised sychronization control mechanism is capable to support up to 100 participants for the non-contention activity. It provides a good performance of supporting the contention activity in a small scale. The mechanism is considered suitable for collaborative application where contention is considered a critical event. © Springer-Verlag London Limited 2005.

Wongwirat, Olarn

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