Multihop Wireless Networks: Opportunistic Routing

7.6 CodePlay: a Live Multimedia Streaming Scheme for VANETs Based on SLNC

In this section, we study the cooperative broadcast of live multimedia streams (LMS) in VANETs. We present CodePlay, a distributed live multimedia streaming scheme in VANETs based on SLNC. We should note that, unlike general popular content distribution services in VANETs in the last section where the main goal is high average downloading rate, LMS services require not only a high average streaming rate but also demand that the streaming rate keep stable for the purpose of smooth playback. LMS services are also different from nonlive streaming services such as video-on-demand, where various vehicles may be interested in different contents and those contents are not closely related to the real world's time. For LMS services, the streaming contents are usually generated as time progresses and are only useful to vehicles within a short period of time, for example several seconds to tens of seconds. However, these time constraints are usually not as tight as those of real-time services, like intelligent collision avoidance, which usually require a delay smaller than hundreds of milliseconds.

In addition to a stable and high streaming rate for smooth playback and short service delivery delay, LMS also needs high bandwidth efficiency for better coexistence with other competing services. In a dynamic and lossy VANET, the biggest challenge to providing satisfiable LMS services is how to achieve the above multiple ...