###### Abstract  
Large volume content dissemination is pursued by the growing number of high quality applications for Vehicular Ad hoc NETworks(VANETs), e.g., the live road surveillance service and the video-based overtaking assistant service. For the highly dynamical vehicular network topology, beacon-less routing protocols have been proven to be efficient in achieving a balance between the system performance and the control overhead. However, to the authors' best knowledge, the routing design for large volume content has not been well considered in the previous work, which will introduce new challenges, e.g., the enhanced connectivity requirement for a radio link. In this paper, a link Lifetime-aware Beacon-less Routing Protocol (LBRP) is designed for large volume content delivery in VANETs. Each vehicle makes the forwarding decision based on the message header information and its current state, including the speed and position information. A semi-Markov process analytical model is proposed to evaluate the expected delay in constructing one routing path for LBRP. Simulations show that the proposed LBRP scheme outperforms the traditional dissemination protocols in providing a low end-to-end delay. The analytical model is shown to exhibit a good match on the delay estimation with Monte Carlo simulations, as well. beacon-less; end-to-end delay; link lifetime; vehicular ad hoc networks (VANETs) +
Footnote †: journal: Sensors  
[PERSON], [PERSON], [PERSON], mobile video streaming has increased 70% per year recently and will take about 70% of the total network traffic by 2018 [2]. Since videos have much larger data volume compared to periodical safety beacons with tens of bytes, a more durable transmission path should be constructed to disseminate this content in VANETs. An open question is how to support large volume content delivery services between vehicles. For VANETs, a dynamically-changing topology is one distinct difference from other networks. Many researchers preferred designing beacon-less routing protocol for VANETs because of its low overhead on the routing decision process [3; 4; 5]. While a beacon-less routing protocol can reduce the wireless service cost in neighbors' information maintenance, it will introduce delay in the neighbors competition for serving as the next-hop relay. The delay problem might be more serious in transmitting large volume content, where more than one link connection needs to be established before completing the whole dissemination process. As delay appears in each round of the backbone nodes' competition process, a more durable routing path is pursued to reduce the number of routing path construction phases. Therefore, the link lifetime should be taken into consideration on the routing protocol design for large volume content dissemination. The traditional routing protocol always tried to extend the one-hop transmission range for reducing the end-to-end delay [3; 4; 5; 6], leaving the path lifetime out of consideration. However, for large volume content delivery, the end-to-end path will need being re-built one or more times with high probability during the data download. Therefore, the lifetime of the constructed routing path will be crucial for the integrated content completion time. For obtaining a durable path, the designed routing protocol should increase the link lifetime and reduce the number of links for the constructed routing path, which is the core target for this paper. In this paper, a link Lifetime-aware Beacon-less Routing Protocol (LBRP) is proposed and analyzed for large volume content dissemination in multi-hop VANETs. The LBRP protocol consists of four parts, including the SOurceVehicle (SOV) finding process, the SOV decision process, the Backbone Vehicle (BV) selection process and the BV re-selection process. Instead of periodically exchanging the beacon messages, each vehicle makes the forwarding decision based on the message header information and its current state, including the speed and position information.