# Semantic Distributed Data for Vehicular Networks Using the Inter-Planetary File System
## 4 Differences between a Static P2P Network and a Vehicular P2P Network  
IPFS has been designed and it is being extensively used to create static P2P networks. However, this paper is considering the application of this P2P technology to vehicular networks. The main differences between a moving vehicle and a static computer are those related to the technologies used in the physical and data link layers. IPFS, notwithstanding, uses standard IP networking, which makes it largely independent from the lower layers. Any node that provides IPv4 or IPv6 connectivity, and supports TCP or QUIC connections, can use IPFS and its P2P services. IPFS will have to use vehicle to anything (V2X) communications to interact with the rest of the vehicles and RSUs. Multiple network services are bound to coexist in the same vehicular network with different requirements in terms of priority, bandwidth, and latency. 5G will promote the communication capabilities to the next level, and provide a long-term roadmap for the enhancement of V2X communications. In the next deployment phase of ITS, environmental sensing will play a new role, in which all vehicles and the cloud share information about detected objects. This will enable vehicles to recognize obstacles hidden to their own sensors. This cooperative awareness will also permit semi-automated reactions, such as automatic braking for vulnerable road users' (VRUs) protection and cooperative adaptive cruise control (C-ACC). These next phase services will require C-V2X connectivity, leveraging an associated Internet connection with a cloud service for cooperative knowledge sharing, and intelligent agents capable of collecting valid information, exchanging it with other peers, and making final decisions based on the processed data. One of the major improvements provided by 5G networks is network slicing [40], an advanced networking solution that allows the creation of flexible and differentiated services on top of a common network infrastructure. Given that the communication between RSUs is expected to be more reliable and it permits higher throughput than vehicle to RSU connections, it seems reasonable to derive most of the traffic load to this static part of the network. With IPFS, this can be achieved by limiting the number of simultaneous connections established by vehicles, and prioritizing vehicle-to-RSU requests. Vehicles, especially while moving, would have to limit themselves to realize short content requests to nearby RSUs. Meanwhile, RSUs, fixed and capable of using high speed connections, would try to keep a large number of connections with other RSUs. Thanks to these connections, they would be able to detect changes in the data published by other RSUs, and get copies of all these data. The moment a vehicle establishes a connection with any RSU of the network, the vehicle would have immediate access to all the data published by nearby RSUs, without the need for establishing additional connections to other RSUs. In some rare cases, the vehicle could need to retrieve information that is not available in the already connected RSU. In this case, the IPFS distributed search algorithm returns the address of the nearest node that has a copy of the requested content. The vehicle has two options: establish a new connection with the indicated node, or use the already established connection as a relay, one of the advanced features of IPFS. By using a RSU as relay, the vehicle can get indirect access to all the nodes connected to that RSU. In summary, the proposed semantic network is a hybrid network--part static, part mobile. The P2P network with IPFS would take advantage of the high speed and stability of the fixed connections between the multiple RSUs of the network. The RSUs would use these connections to share and distribute the semantic content. This part of the P2P network would have the properties and convenience of an static P2P network built using IPFS. The vehicles, however, have the limitations of a mobile and wireless connectivity.