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Presenter: Dr. Hamid Gharavi - Information Technology Lab, Advanced Network Technologies Division, National Institute of Standards and Technology, Gaithersburg, Maryland
Supervisor:

Date: Fri, December 12, 2003
Time: 14:30:00 - 15:30:00
Place: EOW 430

ABSTRACT

Abstract

In this talk we present methods for the transmission of real-time video information over a mobile ad-hoc network. An experimental cellular based mobile ad-hoc network architecture has been developed to assess the quality of video when transported in real-time over multihop mobile channels. The mobile cellular network consists of a number of mobile base nodes (MBNs) and their associated mobile slave nodes (MSNs). In this architecture, the participating Mobile Slave Nodes (MSNs) communicate with each other via their respective Mobile Base Nodes (MBNs) in an ad-hoc manner. For network implementation, IEEE 802.11 Wireless LAN (WLAN) has been deployed. In this network only the MBNs are classified as ad-hoc routers, therefore IP packets received by one MBN from its MSN cannot be directly routed to another MBN. This has been solved with a tunneling technique that allows communication between the MBNs in an ad-hoc mode. The network has been primarily applied to the transmission of RTP/UDP/IP packets using the emerging H.264 video coding standard. To improve the quality of the received video against bursts of packet drops, we also present a frame synchronized RTP-based Forward Error Correction (FEC) streaming strategy as well as a frame synchronized redundant packet transmission scheme for lossy recovery of missing packets. As the network topology in ad-hoc network environments is expected to change drastically, we present a cross-layer feedback control mechanism that can allow the transmitting node to dynamically adjust to the multihop network characteristics. In this presentation we will discuss the design aspects of the proposed network and the quality of the received signal in real-time.