[show abstract][hide abstract] ABSTRACT: 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.
Multimedia and Expo (ICME), 2011 IEEE International Conference on; 08/2011
[show abstract][hide abstract] ABSTRACT: The proxy server is generally deployed for accessing streaming server in order to serve amount of domain's clients on Internet simultaneously. For continuous media (CM) services, in order to decrease the initial delay when a user request a VoD service, the proxy stores two kinds of segments: prefix and suffix; former one means the beginning segments of a video, which are allocated in advanced for decreasing initial delay, and latter one means the following segments, which are stored temporally for sharing segments between amount of users. Therefore, the study proposes an adaptive suffix-window scheme, which is able to dynamically schedule the storage allocation for suffix window in response to gain the optimal performance. The experimental results show that the proposed scheme significantly increases the number of served clients and improves the performance of proxy storage utilization when the client owns limited buffer.
The 13th International Conference on Network-Based Information Systems, NBiS 2010, Takayama, Gifu, Japan, 14-16 September 2010; 01/2010
[show abstract][hide abstract] ABSTRACT: Video streaming has been challenged by the best-effort service provided by the Internet. It is known that temporary traffic congestion may trigger the "traffic sawtooth" phenomenon of TCP and makes it inefficient in offering stable high-bandwidth transmission for video streaming. To address this issue, this paper proposes a segment-based flow control, called the adaptive TCP trunking (ATCP+). In principle, a video is transmitted in terms of a sequence of video segments. Each segment is then equally divided into several sub-segments and transmitted over distinct TCP connections in parallel. The size of sub-segment (or the number of TCP connections) is dynamically adaptive to the network conditions with the objective of stabilizing link throughput for a video stream. We implement ATCP+ with the HTTP 1.1 protocol. Practical experiments indicate that the proposed scheme is able to achieve a stable link throughput (e.g., 1.5Mbps) for a video stream under various network conditions.
Proceedings of the International Conference on Wireless Communications and Mobile Computing: Connecting the World Wirelessly, IWCMC 2009, Leipzig, Germany, June 21-24, 2009; 01/2009
[show abstract][hide abstract] ABSTRACT: This paper studies the buffer control issues that are related to supporting a seamless stream handoff in a WLAN environment that employs simulcast streaming. We analyze the impacts of the handoff disruption period and inter-AR synchronization variance. We also derive theoretical results that concern how a seamless stream handoff can be guaranteed in terms of the minimum buffer and backlog requirements. Based on the results, an MH-controlled-AR-pushed buffer control scheme is proposed and its cooperation with FMIPv6 is also discussed. The simulation results confirm the effectiveness of our scheme. In general, the deployment of a few-hundred-millisecond video-clip buffer in ARs and MHs is sufficient to achieve the seamless stream handoff most of the time, subject to fairly relaxed constraints of the inter-AR synchronization variance (ranging plusmn 150 ms) and handoff disruption period (around 50 ms).
IEEE Transactions on Wireless Communications 02/2008; · 2.42 Impact Factor
[show abstract][hide abstract] ABSTRACT: 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.
Proceedings of the 2008 IEEE International Conference on Multimedia and Expo, ICME 2008, June 23-26 2008, Hannover, Germany; 01/2008
[show abstract][hide abstract] ABSTRACT: The Differentiated Service (DiffServ) has been considered as a scalable approach to provide class-based quality-of-service (QoS) control in Internet. However, the direct implant of DiffServ in IP multicast shows some limitations on supporting a multicast session exhibiting QoS heterogeneity. Also IP multicast by itself has to maintain a large amount of the session-based forwarding information and potentially causes another routing scalability problem in routers. In this paper, we therefore propose a novel adaptation framework, termed harmonic DiffServ, to solve the QoS heterogeneity and routing scalability problems at the same time. In principle, (1) multicast trees are clustered and aggregated into a given number of multicast sessions, and (2) within each multicast session, packets are further marked by a set of undefined DSCPs which lead packets to specific QoS treatments in each router in a way that the respective QoS requirements of multicast trees are realized properly. We propose a heuristic clustering scheme and based on it, two DSCP encoding schemes, namely, the fixed encoding (FE) and the dynamic encoding (DE). Extensive simulations based on different network configurations are conducted. The simulated result reveals that our schemes can effectively reduce the forwarding information and achieve excellent scalability in terms of the number of multicast sessions and DSCP in use. And DE always consumes less number of DSCP than FE at the cost of slightly more computation and control overheads.
[show abstract][hide abstract] ABSTRACT: This paper considers a scenario of broadcasting stream media over a mobile multicast networking environment, where a server employs the wired Internet multicast to replicate and distribute stream media to a set of access points (APs), from which mobile hosts (MHs) intercept the stream through wireless unicast links. An analytical framework is introduced for characterizing the traffic dependency between AP and MH by taking into account the issues impacting the seamless stream handoff (e.g., AP out-of-synch, handoff latency and path-setup delay). Based on it, a proactive hot-zone flow control scheme is proposed, which employs a simple threshold-based policy for regulating the traffic flow between AP and MH prior to handoff. The simulation results reveal that the proposed scheme can significantly reduce the playback hiccups while consuming limited buffer space, compared with the one without any special attention. Particularly, deployment of a few-second-video-length buffer in AP and MH is capable of achieving the seamless stream handoff most of the time subject to fairly loose constraints of the AP synch error (ranging ±3 sec) and handoff latency (around 1 second).
Multimedia and Expo, 2005. ICME 2005. IEEE International Conference on; 08/2005
[show abstract][hide abstract] ABSTRACT: 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.
IEEE Transactions on Broadcasting 10/2004; · 2.09 Impact Factor
[show abstract][hide abstract] ABSTRACT: 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.
[show abstract][hide abstract] ABSTRACT: This paper investigates the implementation of video servers employing multi-zone disks. A multi-zone 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.
[show abstract][hide abstract] ABSTRACT: The significant frame size variability exhibited in the compressed videos imposes a great challenge on network delivery. In this paper we propose an efficient flow control scheme, employed in the peer stations (i.e., servers and clients), for delivery of prestored compressed videos in a video-on-demand (VOD) system. This scheme resorts to an off-line analysis on the video frame sizes and server properties for figuring out the necessary buffer space and network bandwidth. The server platform of particular interest obeys a cycle-based data-block retrieval discipline, which is an essential technique to reduce the disk seek time for leveraging the disk throughput for supporting a large number of concurrent video accesses. Such a discipline is taken into account here to guarantee smooth delivery of variable-bit-rate videos. In run-time a server-driven control model is in use, where a server performs the primary flow control task, without relying on any feedback from clients. The scheme has been implemented in our prototype VOD system to support both unicast- and multicast communication paradigms under an RSVP-enabled network.
IEEE Transactions on Multimedia 10/2003; · 1.75 Impact Factor
[show abstract][hide abstract] ABSTRACT: 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.
Multimedia and Expo, 2003. ICME '03. Proceedings. 2003 International Conference on; 08/2003
[show abstract][hide abstract] ABSTRACT: 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 flow's 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.
Multimedia and Expo, 2002. ICME '02. Proceedings. 2002 IEEE International Conference on; 02/2002
[show abstract][hide abstract] ABSTRACT: 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.
Multimedia Software Engineering, 2000. Proceedings. International Symposium on; 02/2000