Recent technology advances in multimedia communication have ushered in a new era of personal communication. Users can ubiquitously access the Internet via various mobile devices. For the mobile devices featured with l...
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Recent technology advances in multimedia communication have ushered in a new era of personal communication. Users can ubiquitously access the Internet via various mobile devices. For the mobile devices featured with lower bandwidth network connectivity, transcoding can be used to reduce the object size by lowering the quality of a multimedia object. In view of the monolithic transcoders which only provide transcoding services and have limited performances due to the unknown data types and protocols in the prior research, we propose the architecture of versatile transcoding proxy (VTP). Based on the concept of the agent system, the VTP architecture can accept and execute the transcoding preference script provided by the client or the server to transform the corresponding data or protocol according to the user's specification. In order to enhance the effectiveness of the VTP architecture, we adopt the concept of dynamic cache categories and propose the scheme Maximum Profit Replacement with Dynamic Cache Categories (DCC-MPR). Based on the weighted transcoding graph, scheme DCC-MPR performs cache replacement according to the content in the caching candidate set, which is generated by the concept of dynamic programming, The experimental results show that the proposed architecture VTP and the corresponding scheme DCC-MPR have better performances in many aspects compared to the conventional transcoding proxy systems.
Traditional caching technology is not applicable to cache video streaming objects over heterogeneous networking environments. The popularity of mobile devices in the heterogeneous networking environments make the acce...
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Traditional caching technology is not applicable to cache video streaming objects over heterogeneous networking environments. The popularity of mobile devices in the heterogeneous networking environments make the access of Internet content become a common phenomenon. To support different mobile devices in the heterogeneity networking environments, a transcoding proxy is used to transcode different versions of the streaming videos according to clients' requests. In this paper, we propose a weighted caching replace strategy for video streaming objects over heterogeneous networking environments. A new caching algorithm with static weight transcoding graph and dynamic caching relation tree is introduced. The proposed algorithm is compared with LRU, LFU, CP and PF cache algorithms in three parts: hit ratio, byte hit ratio, and average transmission delay. Experimental results show that the proposed algorithm outperforms than traditional LRU, LFU, CP and PF cache algorithms. (C) 2010 Elsevier Ltd. All rights reserved.
Most research works in transcoding proxies in mobile computing environments are on the basis of the traditional client-server architecture and do not employ the data broadcast technique. In addition, the issues of QoS...
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Most research works in transcoding proxies in mobile computing environments are on the basis of the traditional client-server architecture and do not employ the data broadcast technique. In addition, the issues of QoS provision and energy conservation are also not addressed in the prior studies. In view of this, we design in this paper a QoS-aware and energy-conserving transcoding proxy by utilizing the on-demand broadcasting technique. We first propose a QoS-aware and energy-conserving transcoding proxy architecture, abbreviated as QETP, and model it as a queuing network consisting of three queues. By analyzing the queuing network, three lemmas are derived to estimate the load of these queues. We then propose a version decision policy and a service admission control scheme to provide QoS in QETP. The derived lemmas are used to guide the execution of the proposed version decision policy and service admission control scheme to achieve the given QoS requirement. In addition, we also propose a data indexing method to reduce the power consumption of clients. To measure the performance of the proposed architecture, three experiments are conducted. Experimental results show that the average access time reduction of the proposed scheme over the traditional client-server architecture ranges from 45 percent to 75 percent. Experimental results also show that the proposed scheme is more scalable than the traditional client-server architecture and is able to effectively control the system load to attain the given QoS requirements. In addition, the proposed scheme is able to greatly reduce the average tuning time of clients at the cost of a slight increase ( around 5 percent in our experiments) in average access time.
Finding replacement candidates for accommodating a new object is an important research issue in web caching. Due to the new emerging factors in the transcoding proxy and the aggregate effect of caching multiple versio...
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Finding replacement candidates for accommodating a new object is an important research issue in web caching. Due to the new emerging factors in the transcoding proxy and the aggregate effect of caching multiple versions of the same multimedia object, this problem becomes more important and complex as audio and video applications have proliferated over the Internet, especially in the environment of mobile computing systems. This paper addresses coordinated cache replacement in transcoding proxies. First, we propose an original model which determines cache replacement candidates on all candidate nodes in a coordinated fashion with the objective of minimizing the total cost loss for linear topology. We formulate this problem as an optimization problem and present a low-cost optimal solution for deciding cache replacement candidates. Second, we extend this problem to solve the same problem for tree networks. Finally, we conduct extensive simulations to evaluate the performance of our solutions by comparing with existing models.
transcoding is a promising technology that allows systems to effect a quality-versus-size tradeoff on multimedia objects. As audio and video applications have proliferated on the Internet, caching in transcoding proxi...
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transcoding is a promising technology that allows systems to effect a quality-versus-size tradeoff on multimedia objects. As audio and video applications have proliferated on the Internet, caching in transcoding proxies has become an important technique for improving network performance, especially in mobile networks. This article addresses the problem of coordinated enroute multimedia object caching in transcoding proxies for tree networks. We formulate this problem as an optimization problem based on our proposed model, in which multimedia object caching decisions are made on all enroute caches along the routing path by integrating both object placement and replacement policies and cache status information along the routing path of a request is used to determine the optimal locations for caching multiple versions of the same multimedia object. We propose an optimal solution using dynamic programming to compute the optimal locations. We also extend this solution to solve the same problem for several constrained cases, including constraints on the cost gain per node and on the number of versions to be placed. Our model is evaluated on different performance metrics through extensive simulation experiments. The implementation results show that our model significantly outperforms existing models that consider Web caching in transcoding proxies either on a single path or at individual nodes.
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