## 2 Related Works  
### Gateway  
Vehicle gateways are the most important technology in autonomous vehicles. Basically, this not only enables communication between the server and the sensor but also leads to a serious accident if the communication environment of an autonomous vehicle becomes unstable. Therefore, researches on automotive gateways in various fields are actively underway. [PERSON] et al. proposed a vehicle gateway (VGW) that is auto-configured by the network and that eases mobility management. Indeed, the high mobility of a vehicle may imply many changes of access points; nevertheless, the connection must not be broken even during these access point changes. The connection to the new access point must be authorized and the VGW authenticated before leaving the communication range of the last access point. It also introduces a knowledge plane. The role of the knowledge plane is to know the environment of the user, to define the better link to use and control the mobility of the VGW introducing also new architecture to securely bind the user to the IP multimedia subsystem (IMS) [2]. [PERSON] et al. examines in detail the various actual arriving orders of gateway messages and analyzes the real-time property of such in-vehicle networks. Worst case response time (WCRT) analysis for gateway-integrated controller area network (CAN) messages has been used. In this study, experimental results for a real message set demonstrates as much as 24% reduction of WCRT, compared with those obtained using the state-of-the-art methods [3]. [PERSON] et al. presents a FlexRay-CAN gateway using a node-mapping method. The provided gateway describes the operating algorithm. In addition, it also solves the problem of having to reload the modified message mapping table on the gateway if the network message ID change and software complexity changes. This gateway solves three problems. First, when the message ID for the network is changed, the gateway must be reloaded with the revised message-mapping table. Second, if the number of messages exchanged is increased in the network, the complexity of the gateway software rapidly increases. In order to overcome these obstacles, this paper presents a FlexRay-CAN gateway using a node-mapping method. A gateway operation algorithm is described, and an experimental evaluation for ID change and software complexity is presented [4]. [PERSON] et al. proposes a gateway framework for in-vehicle networks (IVNs) based on the controller area network (CAN), FlexRay, and Ethernet. The proposed gateway framework is designed to be easy to reuse and verify to reduce development costs and time. The gateway framework can be configured, and its verification environment is automatically generated by a program with a dedicated graphical user interface (GUI). The gateway framework provides state-of-the-art functionalities that include parallel reprogramming, diagnostic routing, network management (NM), dynamic routing update, multiple routing configuration, and security [5]. [PERSON] envisions a vehicular ad hoc network (VANET)-universal mobile telecommunication system (UMTS) integrated network architecture. In this architecture, vehicles are dynamically clustered according to different related metrics. From these clusters, a minimum number of vehicles, equipped with IEEE 802.11p and UTRAN interfaces, are selected as vehicular gateways to link VANET to UMTS. Issues pertaining to gateway selection, gateway advertisement and discovery, and service migration between gateways (i.e., when serving gateways lose their optimality) are all addressed and an adaptive mobile gateway management mechanism is proposed [6]. [PERSON] et al. introduces a new strategy for deploying internet gateways on the roads, together with a novel scheme for data packet routing, in order to allow a vehicle to access the internet via multi-hop communications in a VANET.