Media Synchronization Control Research Articles

音声・ビデオストリーミングＩＰ伝送のアプリケーションレベルＱｏＳを向上するＷＦＱスケジューラの配置

We investigated how the arrangement of two packet scheduling algorithms (WFQ and FIFO) affects the application—level QoS of an audio—video streaming service over IP networks (typified by IPTV). We ran two computer simulations: (i) only the packet scheduling algorithms were applied, and (ii) both the packet scheduling algorithms and a media synchronization control were applied. Results showed that in case (i), a high application—level QoS with a relatively low delay was achieved when the WFQ was applied to congested nodes and to the node next to the media senders. In case (ii), a high QoS was achieved independently of the arrangement of WFQ nodes only if the bandwidth requirement was satisfied at the congested nodes.

Application-Level and User-Level QoS Assessment of Audio-Video IP Transmission over Cross-Layer Designed Wireless Ad Hoc Networks

SUMMARY This paper performs application-level QoS and user-level QoS assessment of audio-video streaming in cross-layer designed wireless ad hoc networks. In order to achieve high QoS at the user-level, we employ link quality-based routing in the network layer and media synchronization control in the application layer. We adopt three link quality-based routing protocols: OLSR-SS (Signal Strength), AODV-SS ,a ndLQHR (Link Quality-Based Hybrid Routing). OLSR-SS is a proactive routing protocol, while AODV-SS is a reactive one. LQHR is a hybrid protocol, which is a combination of proactive and reactive routing protocols. For applicationlevel QoS assessment, we performed computer simulation with ns-2 where an IEEE 802.11b mesh topology network with 24 nodes was assumed. We also assessed user-level QoS by a subjective experiment with 30 assessors. From the assessment results, we find AODV-SS the best for networks with long inter-node distances, while LQHR outperforms AODV-SS for short inter-node distances. In addition, we also examine characteristics of the three schemes with respect to the application-level QoS in random topology networks.

An Audio-Video Multipath Streaming Scheme for Ad Hoc Networks: The Effect of Node Mobility

SUMMARY This letter studies the effect of node mobility on application-level QoS of audio-video multipath streams in wireless ad hoc networks. The audio-video streams are transmitted with the MultiPath streaming scheme with Media Synchronization control (MPMS), which was previously proposed by the authors. We perform computer simulation with a grid topology network of IEEE 802.11b including two mobile nodes. The simulation results show that MPMS is effective in achieving

分散仮想環境におけるアバタの適応型ＱｏＳ制御方式

We propose an adaptive QoS control scheme for avatars which output voice and video streams in distributed virtual environments. The scheme performs processing load control, traffic control, and media synchronization control on the basis of the processing load of a terminal, the network load, and the importance of avatars. We also illustrate the effectiveness of the scheme by experiment.

An Audio-Video Multipath Streaming Scheme with Media Synchronization Control: Application-Level QoS Assessment in a Wireless Ad Hoc Network

This paper proposes the MultiPath streaming scheme with Media Synchronization control (MPMS) for audio-video transmission in wireless ad hoc networks. In many audio-video streaming applications, media compensate each other from a perceptual point of view. On the basis of this property, we treat the two streams as separate transport streams, and then the source transmits them into two different routes if multiple routes to the destination are available. The multipath transmission disturbs the temporal structure of the streams; in MPMS, the disturbance is remedied by media synchronization control. In order to implement MPMS in this paper, we enhance the existing Dynamic Source Routing (DSR) protocol. We compare the application-level QoS of MPMS and three other schemes for audio-video transmission by simulation with ns-2. In the simulation, we also assess the influence of the multipath transmission on other traffic. The simulation result shows that MPMS is effective in achieving high QoS at the application-level.

A proposal of adaptive protocol relay capability for real‐time media with allowable delay

AbstractIn the video and speech transmission using packets, the media synchronization control is applied, especially in the system for real‐time transmission. In the system containing the media synchronization, the allowable time delay is defined, and the packet after this delay limit is discarded. In protocols such as ARQ (automated repeat request), where the packet retransmission is executed for error correction, if the delay or the error rate of the channel is large, the packet delay is greatly increased when an error occurs. The packet is discarded when the packet delay exceeds the allowable delay, which produces degradation of quality. This paper proposes an adaptive protocol relay system considering the allowable delay, in order to cope with this problem. In the adaptive protocol relay system, the protocol relay is executed at the relay node, when a certain condition for each packet is satisfied. By reducing the time spent in the packet retransmission due to the error, the number of packets that do not arrive at the receiving terminal within the allowable delay is reduced. This paper examines the effect of the protocol relay on the packet discard rate, when the proposed method is used. The condition for the adaptive control at the relay node is also discussed. © 2005 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 88(8): 50–59, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10031

An experiment on media synchronization of MPEG video and voice in a wireless LAN

In this paper, an extension of the MPEG video configuration is carried out for a synchronization scheme, which was previously proposed by the authors for stored media in a wireless LAN. In this scheme, video and voice streams stored separately are interleaved into a single composite stream, and media synchronization control is carried out without distinguishing the media types. Further, as a traffic control method in MPEG video transmission, a four-level temporal resolution control method is treated. In this method, the temporal resolution of the transmitted video is switched among four levels depending on the traffic condition of the network. In order to carry out such control, a method is needed for detecting congestion. To this end, a simple congestion detection scheme is proposed. These schemes have been implemented on a wireless LAN, and experimental transmissions of the MPEG video and voice streams have been carried out. We make a performance comparison between the case with synchronization control and the case without it. We also confirm the effectiveness of the extended media synchronization scheme for the MPEG video transmission. Further, from a comparison of the case with only the media synchronization control and the case with combined use of the dynamic resolution control, it is found that the synchronization quality at heavy loads can be substantially improved by the dynamic resolution control. © 1999 Scripta Technica, Electron Comm Jpn Pt 1, 83(4): 83–92, 2000