Effective algorithms for video transmission over wireless channels

摘要

New schemes for video transmission over wireless channels are described. Content based approaches for video segmentation and associated resource allocation are proposed. We argue that for transport over wireless channels, different video content requires different form of resource allocation. Content and data dependent FEC/ARQ schemes are used to do adaptive resource allocation after segmentation. FEC based schemes are used to provide class dependent error robustness and a modified ARQ technique is used to provide constrained delay and loss. The approach is compatible with video coding standards such as H.261 and H.263. We use frame-type (extent of intra coding), scene changes, and motion based procedures to provide finer level of control for data segmentation in addition to standard headers and data-type (motion vectors, low and high frequency DCTs) based segmentation. An experimental simulation platform is used to test the objective (SNR) and subjective effectiveness of proposed algorithms. The FEC schemes improve both objective and subjective video quality significantly. An experimental study on the applicability of selective repeat ARQ for one way real time video applications is also presented. We study constraints of using ARQ under display constraints, limited buffering requirements and small initial startups. The proposed ARQ schemes greatly reduce the packet errors, when used along with optimal decoder buffer control and source interleaving. The common theme integrating the study of FEC and ARQ algorithms is the content based resource allocation for wireless video transport.