Sheau-Ru Tong

Efficient resource reservation based on communication paradigms for multicast multimedia applications

In modern multimedia applications, heterogeneous hosts may get involved in a complicated multicast communication paradigm. For facilitating the analysis on resource reservation in such an environment, a useful model for describing the multicast communication paradigm, termed the CP graph, is presented in this paper. Based on this model, we develop a set of reservation modeling frameworks, respectively employing the RSVP reservation scheme and a proposed scheme. We prove the proposed scheme is able to achieve more efficient reservation than the RSVP scheme, while incurs very limited information and processing overheads. We simulate two applications: one with a distant learning scenario and the other B2B bargain scenario. The simulation results confirm the effectiveness of our scheme.

A video caching policy for providing differentiated service grades and maximizing system revenue in hierarchical video servers

A video server normally targets at providing abundant bandwidth access and massive storage in supporting large-scale video archival applications. Its performance is sensitive to the deployment of the stored contents. In this paper, we propose a video caching policy for a video server, based on the knowledge of video profiles, namely: access rate, video size and bandwidth, tolerable rejection probability, and rental price. We consider the video server as having a hierarchical architecture which consists of a set of high-speed disk drives located in the front end for caching a subset of videos, and another set of high-capacity tertiary devices located in the back end for archiving the entire video collection. The front-end disks particularly, are organized together by employing a proposed data striping scheme, termed the adaptive striping (AS), which is flexible on heterogeneous disk integration. The proposed policy determines what video set should be cached, and how to arrange them in the front-end disks with two objectives in mind: (1) offering differentiated service grades conforming to the video profiles as well as (2) maximizing the overall system revenue. We simulate the system with various configurations, and the results affirm our effective approach.

Multisource FEC interleaving for mobile P2P streaming

In mobile Peer-to-Peer networks (MP2P), packet losses are usually shown in bursts due to temporary peer failure or mobile channel disruption. This paper investigates how to apply Forward Error Correction (FEC) interleaving to overcome this issue and provide a guaranteed streaming service in MP2P, where a peer usually receives data from a set of heterogeneous peers through heterogeneous links. Some theories are developed for characterizing the problem, which help us to design a simple spiral packet-source allotment algorithm that implements near perfect FEC interleaving among sources with objective of maximizing throughput subject to an application-specific target packet loss rate. The simulation results confirm the superiority of the proposed scheme in aspects of combating burst loss and adaptability to peer/link heterogeneity for offering guaranteed streaming quality with high throughput under MP2P.

Application-layer error resilience for wireless IP-based video broadcasting

Wireless IP-based video broadcast suffers from heavy packet losses caused by multipath fading and interference variations in the wireless channels. This paper addresses this issue by proposing an application-layer error-resilience scheme, called the replicate multiple descriptor coding scheme (RMD). In principle, RMD extends the conventional multiple descriptor transmission strategy with two new features, the selective-frame-based replication and a time-shifted descriptor transmission. We show that with these two features, we are able to exploit the time diversity in a time-sharing channel to mitigate the damage impact and provide more efficient protection for the video. The simulation results confirm that when the packet loss rate is heavy (e.g., 15%–35%), RMD outperforms other schemes in terms of PSNR improved, while only requiring moderate data overheads.

Harmonic DiffServ: provisioning scalable heterogeneous-QoS multicast in DiffServ networks

A scalable quality-of-service (QoS) mechanism, termed harmonic DiffServ, is presented in this paper for supporting many-to-many heterogeneous-QoS multicasts in the DiffServ networks. In principle, it restricts data to be distributed using a limited number of multicast addresses (channels). In order to differentiate traffic with different QoS within a multicast channel, a small number of undefined DS codepoints (DSCP) are reserved for marking packets, and dynamic associations between DSCPs and service types are maintained in output ports of routers. We show that with proper arrangement on the usage of small numbers of multicast addresses and DSCPs, the forwarding information can be effectively shared among senders, which in turn significantly improves the system scalability.

Guaranteeing quality-of-service for delivery of compressed videos based on GOP-aware effective envelopes

Exploitation of the statistical multiplexing gain in the delivery of compressed videos is essential for achieving efficient network resource utilization. This paper proposes an analytical framework based on a GOP-aware effective envelope for guaranteeing statistical quality-of-service (QoS) to an aggregate flow from a class of connections. The GOP-aware effective envelope intends to model more realistic traffic burst by taking the information of individual flows launch time and group-of-picture (GOP) into account With this information, the QoS guarantee is applicable not only to the aggregate flow but also to individual flows. Through numerical experiments, we show that the significant improvement on multiplexing gain can be achieved, particularly, under those cases with short delay bounds and small-to-moderate aggregation scales.

A staggered-channel-cluster approach to support videomulticast handoff in wireless networks

Video multicast handoff in wireless networks is challenged by various impairments, such as high bit-error-rate, connection disruption and asynchronous stream concatenation. We tackle this problem by proposing a two-stage multicast approach, where a video stream is distributed to a group of access routers using a regular IP multicast. Within a local subnet, each access router further replicates and forwards the stream over a cluster of multicast channels by enforcing a staggered transmission schedule. A mobile host subscribes to all these channels and employs a buffer control to recover errors and to build up necessary backlogs. This approach gives us a scalable way to improve the error recovery rate and to smooth out potential stream gaps caused by the handoff. Some theoretical results concerning the buffer requirements for guaranteeing the seamless handoff are derived. The simulation results reveal that a cluster of three multicast channels along with a couple-second-video-clip buffer deployed in each access router and mobile host are capable of achieving satisfactory seamless video multicast handoff in most of the typical network environments.

Efficient Region Layouts for Region-based Video Servers Employing Multi-zone Disks

This paper investigates the implementation of video servers employing multi-zone disks. A multizone disk consists of a set of concentric disk zones with non-uniform storage capacities and data transfer rates. Superimposing a customized region layout on the top of such a disk is essential for facilitating the video server design and improving the disk resource utilization. This paper develops theories concerning the optimal region layouts for implementing the region-based data placement. Based on them, two efficient region layout algorithms are proposed, namely, the free-π scheme and fixed-π scheme. The former can achieve better resource utilization than the latter, but the latter requires a simpler timing control than the former. Extension of the fixed-π scheme to perform the disk striping in a disk array platform is also investigated. A spiral synchronization scheme is proposed to improve the system scalability by alleviating the disk bus congestion problem, caused by variable data transfer rates from individual disks. The analytical results reveal that the proposed schemes can effectively customize region layouts to achieve 85‐99% resource utilization. By considering the region layout together with other design factors, an efficient configuration strategy is proposed for building a cost-effective server subject to the performance requirements of a target application.

A resource reservation protocol for deterministically multiplexing compressed video streams over wide-area networks

In terms of the delivery of compressed videos, two service categories are frequently considered, namely deterministic and statistical services. It is a general belief that the statistical service can achieve more efficient bandwidth utilization than the deterministic one, due to its statistically multiplexed streams. In this paper, however, we investigate the possibility of applying the multiplexing principle in the context of the deterministic service for improving the bandwidth utilization in wide-area networks. We propose a resource reservation protocol and discuss implementation details based on the deterministic multiplexing framework previously proposed by S. Tong (2000).