Data Communication And Computer Networks Prakash C Gupta Pdf 157 ((NEW))
Many methods have been proposed for data encryption. A four-image encryption scheme has been proposed by Yu et al. based on the computer-generated hologram, quaternion fresnel transforms (QFST), and two-dimensional (2D) logistic-adjusted-sine map (LASM). This innovative technology considerably decreases the key data sent to the receiver for decryption, making it more promising to be stored and transmitted . In order to secure cloud data storage and its delivery to authorized users, a hierarchal identity-based cryptography method has been proposed by Kaushik et al. to assure that a malicious attacker or CSP does not change for its benefit .
data communication and computer networks prakash c gupta pdf 157
Currently, there are two main types of communication technologies used for V2X: Dedicated Short Range Communication (DSRC) and Long Term Evolution for V2X (LTE-V2X). The DSRC system consists of a series of IEEE and SAE standards . At the physical layer and the medium access control (MAC) layer, DSRC uses the 802.11p protocol , which simplifies authentication, associated processes, and data transmission before sending data, enabling vehicles to broadcast relevant security information directly to neighboring vehicles and pedestrians. The network architecture and security protocols are defined in IEEE 1609 WAVE [7,8,9]. At the application layer, SAE J2735  defines the message format used for communication, and the J2945/x family of standards defines various scenarios of V2X communication and its performance requirements. LTE-V2X is a wireless communication technology for V2X with high data rate and controlled QoS [11,12], which is based on the evolution of LTE mobile communication technology defined by 3GPP, including two kinds of working modes of cellular communication (Uu) and direct communication (PC5) [13,14,15,16]. The Uu mode uses the existing LTE cellular network to implement V2V communication by forwarding (shown in Figure 1a), and the PC5 mode is similar to the DSRC, enabling direct communication between vehicles (shown in Figure 1b) [17,18]. Additionally, the PC5 interface has been enhanced in many aspects to accommodate exchanges of rapidly changing dynamic information (position, speed, driving direction, etc.) and future advanced V2X services (automatic driving, vehicle platooning, sensor sharing, etc.) .
The cloud service platform not only faces the problems of traditional network cloud platforms, but also has a weak identity authentication problem caused by the principle of mutual trust in V2X communications . Whether the data in the cloud will be leaked is a major problem . Moreover, the V2X cloud platform contains data about vehicles, roads, and pedestrians. If these data are leaked, they could cause significant losses. Owing to the high-speed mobility of vehicles, identity authentication and establishing a trusted connection with the cloud is a difficult problem. How to identify false data uploaded by an attacker and how to uniformly manage different types of data uploaded by different vehicles are also challenges faced by the cloud platform .
Because of its wireless transmission properties, the V2X network is particularly vulnerable to attacks. Therefore, communication security is very important. The security attributes include authentication, availability, data integrity, confidentiality, non-repudiation, real-time constraints, and attacks against these security attributes are as follows [30,36,37,38,39]:
There are many problems in the Internet of Vehicles, which seriously hinder the development of vehicle networking technology and commercialization. Firstly, in special scenarios such as intersections or traffic jams, the density of vehicles is very large. The sheer number of users puts tremendous pressure on wireless communications, so it easily causes communication congestion . Secondly, the vehicle has the characteristics of high mobility and rapidly changing network topology , which brings great difficulties to data transmission, routing, etc . For example, two vehicles traveling in opposite directions will drive out of communication range within a few seconds. These communications have the requirement of low latency and high reliability for the Internet of Vehicles . Finally, how to design and develop a good application is also an important issue for the Internet of Vehicles . Before developing an application, developers need to spend a lot of time trying to determine the application scenarios. In addition, how to ensure the safety and effectiveness of an application is also an important issue .
Internet of Vehicles is a new cross-industry thing involving many industries such as automotive, communications, transportation, etc. As the name implies, V2X needs to connect all vehicles together, so the interconnection and interoperability are important attributes . In the Internet of Vehicles, if a vehicle cannot understand the data sent by another vehicle with different brand, it will cause the lack of the information, and greatly reduce the meaning of V2X. Besides it may also lead to serious accidents resulting in unnecessary loss. At present, countries in which the V2X is growing up have been developing communication standards to help vehicles and other transportation participants to communicate unimpeded. These standards can also achieve understanding between different brands of vehicles and different intelligent transportation infrastructures, to ensure interconnection and interoperability of the V2X.
Our team is building a function testing system which extends the HIL methods. The system uses communication devices instead of the network simulator. The architecture is shown in Figure 5, including the V2X simulation platform, V2X communication module, GNSS simulator, channel interference unit, and CAN bus simulator. The V2X simulation platform performs application scenario simulation, test cases management, test result analysis, etc. It is used to generate dynamic simulation data of the vehicle, such as vehicle speed, position, distance between vehicles, obstacles, traffic scenes, etc., and manages the entire test activity. The V2X simulation platform generates a virtual traffic scenario based on the test cases. The scenario includes a host vehicle (HV) and at least one remote vehicle (RV). The host vehicle refers to the vehicle under test in this scenario, and the RV is used to assist the HV to trigger applications. The V2X simulation platform is connected to the V2X communication module through an Ethernet interface or similar to control the transceiver behavior of the V2X communication module. It also interconnects with the GNSS simulator and the CAN bus simulator through a serial or similar port, and sends the simulation data to the V2X communication module and the device under test. The V2X communication module is used to simulate a RV in a virtual traffic scenario to generate application messages such as a basic safety message (BSM), and then sends it to a device under test through the channel interference unit. Meanwhile, the V2X communication module can also receive application messages sent by the device under test. We have two methods to obtain the application messages of the V2X communication module. One involves the V2X simulation platform directly generating application messages and sending them to the V2X communication module, as shown in Figure 5a. The second involves the V2X communication module generating corresponding application messages according to the simulation data from the GNSS simulator and the CAN bus simulator, as shown in Figure 5b. The channel interference unit simulates the communication environment, such as signal attenuation, interference, and so on. The device under test is used to simulate the HV in a virtual traffic scenario and runs V2X applications relying on simulation data. If the application is triggered, the device under test will generate a control action or warning information, which will be fed back to the V2X simulation platform through the CAN bus simulator. At this time, the HV will perform actions such as braking and issuing a warning, in the virtual traffic scenario.
Function Test System Architecture. (a) the V2X simulation platform directly generates application messages and sends them to the V2X communication module; (b) the V2X communication module generates corresponding application messages according to the simulation data from the GNSS simulator and the CAN bus simulator.
Now we have built a performance test-bed for black-box testing. The architecture of the test-bed is shown in Figure 6. The test system consists of three parts, including UEs (also referred to as user equipment, including the UE under test and the peer UE for simulating the process of transmission), the evolved core network (i.e., the MME/S-GW in Figure 6), and the evolved UMTS terrestrial radio access network (E-UTRAN). The channel simulator is used to simulate wireless channel propagation over the PC5 communication link. Network testers or other testing tools (such as test software developed by the device provider) are responsible for managing the testing process and receiving testing data. The UEs can connect with the E-UTRAN system through the TD-LTE air interface (i.e., the Uu interface). The system can test sidelink basic transmission under Mode4 and Mode3, and IOT test of RRC protocol performance. Based on the timestamps and packet numbers in the packet header, the transmission delays and packet delivery success rates of the packets are measured.
The scenarios are the basis of the system and can be virtual, real or mixed. The virtual scenarios are used in the simulators to build the virtual testing environment. The real scenarios mean that the tests will be done in a field. We can use the real-world data to build the scenarios or map virtual objects to real scenarios which we call the mixed scenarios. One or more testing objects will be put into those scenarios. The communication connects all entities in the scenarios. The communication between virtual entities can be simulated by tools such as NS-3. But the communication between a virtual entity and a real entity is hard to handle. We can map the virtual entity to another real entity to transmit data in the real world or map the real entity into the virtual scenery to communicate with a simulator. Thus the communication has only two types: the virtual or the real. We also divided the applications into two types: virtual or real. The virtual application is the algorithm driven by a simulator in the virtual scenarios which can increase the integrity of the scenarios. The real application is one driven in a real device which is usually used as the background object.