I. Introduction
Vehicular ad hoc networks have been widely researched, especially for real-time multimedia applications. The successful market penetration for video streaming services in VANET is mostly due to fast development of multimedia devices such as tablets and smartphones. However, fast mobility and intermittent connectivity in VANET lead low QoE experiences when using fixed bit rate video services [1] [2]. To fully utilize the dynamically changed bandwidth and improve the QoE for mobile users, dynamic adaptive streaming (DAS) technology is introduced to deliver video content with different bit rates according to the available bandwidth. But DAS technology requires several versions of a same video content, which greatly reduces the utilization rate for content caches with a specific bit rate. In this situation, the Scalable Video Coding (SVC), a extension of the H.264/AVC standard, has been introduced to the DAS framework (SVC-DAS) to improve the system performance. In SVC-DAS, each video chunk is encoded into one base layer and several enhancement layers. And the mobile users adaptively select the enhancement layers of content to playback according to the receiver buffers and network conditions. Thanks to the layered structure of SVC, the caching efficiency can be greatly improved and the already received content can be easily upgraded to a higher quality version [3] [4].