# A Cooperative Communication Protocol for QoS Provisioning in IEEE 802.11p/Wave Vehicular Networks
## 3 Related Works  
In [18], the authors presented a position-based routing protocol to reduce the performance degradation by radio obstacles. The algorithm requires global information of the city topology. In [19], the authors proposed a movement-based routing algorithm for VANETs. This algorithm exploits the position and direction of movement of vehicles. The algorithm determines the routing path considering mobility related information such as speed and other movement characteristics of vehicles. In [20], the authors proposed a multi-hop routing protocol for urban area vehicular ad hoc networks without the need of any pre-installed infrastructure. The algorithm introduced a new metric called the expected disconnection degree (EDD) to estimate the quality of a route based on factors such as vehicle position, speed, and trajectory. In [21], the authors proposed a group-based routing protocol to enhance routing consistency. Vehicles are divided into four groups depending on the velocity vector. The routing protocol is considered stable if two vehicles belong to the same group. Otherwise, it is considered unsteady. In [22], the authors proposed a vehicular routing protocol to maintain routing in disconnected vehicular networks. The algorithm uses a carry-and-forward strategy to allow packets to be carried by vehicles in sparse networks for eventual forwarding when another appropriate node enters the broadcast range, thereby allowing packets to be forwarded by the relay in case of sparse networks. The VADD requires a global street map that includes traffic statistics. In [23], the authors proposed a cross-layer position-based delay-aware communication protocol called PROMPT. The PROMPT utilizes position-based source routing based on network traffic statistics collected during propagation of service advertisements of base stations. In [24], the authors proposed a diagonal-intersection-based routing (DIR) protocol for urban vehicular ad hoc networks. The algorithm is a geographic-based routing protocol. According to the geographic routing protocol, source vehicle sends data packet toward the first diagonal intersection, and then the second diagonal intersection,  
Figure 1: The channel structure in the WAVE standard. and so on, until toward the last diagonal intersection, and then reach to the destination vehicle. In [25], the authors proposed a unicast, multi-hop routing protocol based on opportunistic forwarding in an urban environment. The algorithm uses the information about link layer quality regarding SNIR and MAC frame error rate to improve the efficiency of the proposed routing protocol. In [26], the authors proposed a routing protocol for VANETs based on estimated network reliability. The algorithm utilizes an undirected graph representing the street layout. In this graph, the vertices are the curves or intersections in the streets and edges are street segments. In [27], the authors proposed a solution to the support of point-to-point video-streaming over VANETs. The algorithm is a receiving-based solution that uses the vehicle's current location and their future positions estimations to better select relaying nodes. In [28], the authors proposed a multipath solution for video transmission over urban vehicular networks. The algorithm discovers relatively short paths with minimum route coupling effect based on location information. In [29], the authors proposed a contention-based forwarding protocol that dynamically selects the forwarding road segments based on their multi-hop connectivity. The algorithm selects the routing path with high probability to forward the message towards the destination. In [30], the authors proposed a geographical routing protocol to reduce the beacon overhead and to improve the routing efficiency. The algorithm forwards a packet along a street toward an intersection where the routing direction changes.