# 5G V2X System-Level Architecture of 5 GCAR Project
## 4 Detailed Analysis of Selected Features
### Location-Aware Scheduling  
Prior works on scheduling for vehicular environments mainly focused on guaranteeing low-latency and reliable communications, which requires additional efforts compared to legacy environments due to vehicles' mobility. The work in [21] defines a scheduling algorithm running at the RSU based on the definition of a weight taking into consideration channel conditions, vehicle speeds and vehicle and/or data priority. A more detailed list of works on this topic can be found in [22], where the listed works in literature mainly consider that data to be delivered to vehicles are \"local\". This means that data received by the vehicles will be immediately used once upon reception as they contain information (e.g., positions and speeds of other vehicles) relevant to the area where vehicles are moving in that specific time interval. As considered in 5 GCAR, V2X applications deal with geographical data but in some cases (e.g., HD map dissemination) such data might be generated and available before the vehicle approaches the target area. This means that the network should take into account the geographical area of the data when scheduling data delivery, i.e., potentially data transfer can be \"relaxed\" in this case to avoid congestion in the network. Considering this aspect of \"relaxed\" or low-priority file transfer, one solution that has been considered relies on adapting the file delivery window to reduce congestion. From this point of view, the most relevant example is represented by TCP_LEDBAT [23] that has been introduced with the goal to provide a \"less than best-effort\" service delivery for applications that have loose constraints in terms of data delivery deadlines or throughput. Although such approaches represent a valid solution to deliver low-priority content (e.g., software updates) and might potentially enable a reduction in the cost of delivery, they do not take into consideration time or spatial deadline aspects for file delivery. This aspect is of primary importance for some V2X services (e.g., HD map download) where data content should be delivered before the vehicle enters the geographical area the file refers to. The location-aware scheduling is an enhanced network procedure designed within 5 GCAR to efficiently manage the transfer of messages with associated spatial/time deadlines. When mapping a certain service to a certain QoS, the location-aware scheduling considers location information, with regards to both vehicle location information (e.g., expected or planned trajectory) and service location information (e.g., area of relevance of a certain message). This is to take into account the requirements that should be interpreted in terms of geographical region (e.g., the vehicle should receive/transmit the message before entering/leaving a certain area) instead of absolute latency budget. Having this in mind, the transfer of the message could be optimized considering the spatial (or time) deadlines of the message, jointly with the vehicle status information (position, speed, etc.). The location-aware  
Figure 7: An example of a V2X service negotiation applied to a file transfer service. scheduling then enables a dynamic adaptation of QoS parameters taking into consideration additional V2X service information instead of using static QoS mapping. In the remainder of this section, we consider a high definition (HD) map acquisition use case, where different messages (layers 1-2 and layer 3) have different areas of relevance, meaning that such messages should be received before entering the associated relevance areas (Figure 8). In addition to the relevance area, additional information can be associated with a message such as the message size. From Figure 8, two different latency budgets for message reception can be extrapolated for delivering layers 1-2 and layers 3, considering the speed of the vehicle and its distance from the relevance areas.