Wai-Tian Tan

Low-latency wireless video over 802.11 networks using path diversity

Wireless local area networks, such as 802.11b, are becoming wide-spread as they provide simple wireless connectivity and data delivery. This paper examines low-latency (conversational) video communication over 802.11b networks. The challenges to enable low-latency video include overcoming the highly variable delays, losses, and bandwidth of 802.11b wireless networks. To overcome these challenges we (1) employ the H.264/MPEG-4 advanced video coding (AVC) standard for high video compression efficiency and good resilience to losses, (2) use low-latency best-effort transport mechanisms, and (3) exploit the potential path diversity between each mobile client and multiple access points in the infrastructure, where we use multiple paths simultaneously or switch between multiple paths (site selection) as a function of channel characteristics. Our results indicate that the proposed system can provide significant benefits over conventional single access point (single path) systems.

Infrastructure-Based Streaming Media Overlay Networks

Publisher Summary This chapter describes the basic concepts and architecture of a media overlay, which adds resources to an existing network infrastructure to enhance the media capability of the network. A media overlay can enable new media capabilities in the network, while improving the end-user media performance and the system-wide efficiency of the network for both its media and nonmedia traffic. This is achieved by leveraging the underlying resources and existing connectivity provided by the original network, while enhancing it to improve its ability to deliver real-time media to end-users and scaling to support a large number of users. The term “overlay” refers to the approach of adding resources on top of an existing network infrastructure. This has the advantage of leveraging the attributes of the existing infrastructure, such as its existing deployment, widespread connectivity, and built-in network services—domain name services (DNS) and system management.

Path Diversity for Media Streaming: The Use of Multiple Description Coding

Publisher Summary This chapter provides an overview of path diversity of complementary media coding techniques, such as multiple description coding, and of their benefits and uses for improved media streaming. Path diversity is a transmission technique that sends data through two or more paths in a packet-based network. A path diversity system may use multiple paths at the same time or may perform path selection to switch among them. This is in contrast to the conventional approach where all packets are sent over a single path between sender and receiver, and this path does not vary with time under the direct or indirect control of the application. The paths may originate from single or multiple sources. This chapter provides a survey of the benefits, architectures, system design issues, and open problems associated with streaming media delivery using path diversity. The complementary media-coding techniques, such as multiple description coding, are also reviewed in the chapter.