Guobin (Jacky)  Shen

Jianfei  Cai

Multimedia Networking

We present a novel active queue management (AQM) technique to demonstrate the efficacy of practically harnessing the predictive utility of SSR indications for improved video communication. We consider a network within which corrupted packets are relayed over multiple hops, but a certain percentage of packets needs to be dropped at an intermediate node due to congestion. We propose an AQM technique, survival of the fittest (SOTF), to be employed at the relay node, within which we use packet state information, available from SSR indications and checksums, to drop packets with the highest corruption levels. On the basis of actual 802.11b measurements we show that such a side information (SI) aware processing within the network can provide significant performance benefits over an SI-unaware scheme, random queue management (RQM), which is forced to randomly discard packets. With trace-based simulations, we show the utility of the proposed AQM technique in improving the error recovery performance of cross-layer FEC schemes. Finally, with the help of H.264-based video simulations these improvements are shown to translate into a significant improvement in video quality.

Shirish S. Karande

Kiran Misra

Hayder Radha

Survival of the Fittest: An Active Queue Management Technique for Noisy Packet Flows

The popularity of multimedia streaming services via wireless networks presents major challenges in the management of network bandwidth. One challenge is to quickly and precisely estimate the available bandwidth for the decision of streaming rates of layered and scalable multimedia services. Previous studies based on wired networks are too burdensome to be applied to multimedia applications in wireless networks. In this paper, a new method, IdleGap, is suggested to estimate the available bandwidth of a wireless LAN based on the information from a low layer in the protocol stack. We use a network simulation tool, NS-2, to evaluate our new method with various ranges of cross-traffic and observation times. Our simulation results show that IdleGap accurately estimates the available bandwidth for all ranges of cross-traffic (100 Kbps <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mo>&#x223C;</mml:mo></mml:math> 1 Mbps) with a very short observation time of 10 seconds.

Heung Ki Lee

Varrian  Hall

Ki Hwan Yum

Kyoung Ill Kim

Eun Jung Kim

Bandwidth Estimation in Wireless Lans for Multimedia Streaming Services

MIMO-OFDM is a promising technique for the broadband wireless communication system. In this paper, we propose a novel scheme that integrates multiple-description coding (MDC), error-resilient video coding, and unequal error protection strategy with hybrid space-time coding structure for robust video transmission over MIMO-OFDM system. The proposed MDC coder generates multiple bitstreams of equal importance which are very suitable for multiple-antennas system. Furthermore, according to the contribution to the reconstructed video quality, we apply unequal error protection strategy using BLAST and STBC space-time codes for each video bitstream. Experimental results have demonstrated that the proposed scheme can be an excellent alternative to achieve desired tradeoff between the reconstructed video quality and the transmission efficiency.

Haifeng Zheng

Congchong Ru

Chang Wen Chen

Lun Yu

Video Transmission over MIMO-OFDM System: MDC and Space-Time Coding-Based Approaches

As a recently emerging service, multiview video provides a new viewing experience with a high degree of freedom. However, due to the huge data amounts transferred, multiview video&#39;s delivery remains a daunting challenge. In this paper, we propose a multiview video-streaming system based on IP multicast. It can support a large number of users while still maintaining a high degree of interactivity and low bandwidth consumption. Based on a careful user study, we have developed two schemes: one is for automatic delivery and the other for on-demand delivery. In automatic delivery, a server periodically
multicasts special effect snapshots at a certain time interval. In on-demand delivery, the server delivers the snapshots based on distribution of user requests. We conducted extensive experiments and user-experience studies to evaluate the proposed system&#39;s performance, and found that it provides satisfying multiview video service
for users on a large scale.

Jian-Guang  Lou

Hua  Cai

Jiang  Li

Interactive Multiview Video Delivery Based on IP Multicast

Transmissions over unreliable networks, for example, wireless, can lead to packet loss. An area that has received limited research attention is how to tailor multimedia information taking into account the way packets are lost. We provide a
brief overview of our research on designing a 3D perceptual quality metric integrating two important factors, resolution of texture and resolution of mesh, which control transmission bandwidth, followed by a suggestion on alternative strategies for packet 3D transmission of both texture and mesh. These strategies are then compared with respect to
preserving 3D perceptual quality under packet loss in ad hoc wireless networks. Experiments are conducted to study how buffer size, sending rate, sending intervals, and packet size can affect loss in unreliable channels. A model for
estimating the optimal packet size is then proposed. We derive the optimal number of packets based on this model, and relate the theoretical derivations to actual network data.

Irene Cheng

Lihang Ying

Anup Basu

Packet-Loss Modeling for Perceptually Optimized 3D Transmission

We propose a system design for delivery of immersive communications to mobile wireless devices based on a distributed proxy model. It is demonstrated that this architecture addresses key technical challenges for the delivery of these services, 
that is, constraints on link capacity and power consumption in mobile devices. However, additional complexity is introduced with respect to application layer mobility management. The paper proposes three possible methods for updating proxy assignments in response to mobility management and compares the performance of these methods.

Mehran Dowlatshahi

Farzad Safaei

System Architecture and Mobility Management for Mobile Immersive Communications

This paper describes a scalable video
streaming system based on JPEG2000 with various
modes of streaming. A core function of the proposed
system is a low-complexity transcoding technique that
adapts the quality and resolution of the scene based on
available bandwidth. One key feature of this technique
that is important for surveillance applications is that
interesting regions of the scene are assigned higher quality
than background regions. To cope with varying network
conditions, we also present a rate control algorithm that
adaptively transcodes stored JPEG2000 frames. The
proposed algorithm is designed to improve overall quality
over a uniform rate control method by increasing
bandwidth utilization, while satisfying buffer constraints
and maintaining consistent quality over time. Simulation
results confirm the effectiveness of the proposed system
and rate control algorithm in terms of both objective
measures and subjective evaluation. Complexity is also
evaluated.

Anthony  Vetro

Derek  Schwenke

Toshihiko  Hata

Naoki  Kuwahara

Scalable Video Streaming Based on JPEG2000 Transcoding with Adaptive Rate Control

Despite the fact that global multicast is still not possible in today&#x27;s Internet, many local networks are already multicast-capable (the so-called multicast &#x201C;islands&#x201D;). However, most application-layer multicast (ALM) protocols for streaming have not taken advantage of the underlying IP multicast capability. As IP multicast is more efficient, it would be beneficial if ALM can take advantage of such capability in building overlay trees. In this paper, we propose a fully distributed protocol called scalable island multicast (SIM), which effectively integrates IP multicast and ALM. Hosts in SIM first
form an overlay tree using a scalable protocol. They then detect IP multicast islands and employ IP multicast whenever possible.
We study the key issues in the design, including overlay tree construction, island management, and system resilience. Through simulations on Internet-like topologies, we show that SIM achieves lower end-to-end delay, lower link stress, and lower resource usage than traditional ALM protocols.

Xing Jin

Kan-Leung Cheng

S.-H. Gary Chan

Scalable Island Multicast for Peer-to-Peer Streaming

We address the problem of delay-constrained streaming of multimedia
packets over dynamic bandwidth channels. Efficient streaming
solutions generally rely on the knowledge of the channel bandwidth,
in order to select the media packets to be transmitted, according to
their sending time. However, the streaming server usually cannot
have a perfect knowledge of the channel bandwidth, and important
packets may be lost due to late arrival, if the scheduling is based
on an over-estimated bandwidth. Robust media streaming techniques
should take into account the mismatch between the values of the
actual channel bandwidth and its estimation at the server. We
address this rate prediction mismatch by media scheduling with a
conservative delay, which provides a safety margin for the packet
delivery, even in the presence of unpredicted bandwidth variations.
We formulate an optimization problem whose goal is to obtain the
optimal value for the conservative delay to be used in the
scheduling process, given the network model and the actual playback
delay imposed by the client. We eventually propose a simple
alternative to the computation of the scheduling delay, which is
effective in real-time streaming scenarios. Our streaming method
proves to be robust against channel prediction errors, and performs
better than other robustness mechanisms based on frame reordering
strategies.

Dan Jurca

Pascal Frossard

Packet Media Streaming with Imprecise Rate Estimation

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