Performance evaluation of user applications in the ITS scenario: An analytical assessment of the NeMHIP
Introduction
The evolution and deployment of wireless access technologies and the spread of wireless user devices are bringing the anytime–anywhere connectivity concept into a closer reality. Following this idea, the connectivity demand is also reaching new scenarios with specific particularities and requirements like the ITS (Intelligent Transportation Systems) context.
Internet provisioning in the ITS context is not only an end-user demand; a wide scope of applications related to the control and operation of the vehicle such as SCADA (Supervisory Control and Data Acquisition) services could also profit from Internet connectivity. In fact, ITS communication standards are currently being designed to support multiple classes of applications including those that assist in vehicle operation, and Internet-based applications (European Telecommunications Standards Institute, 2010). Moreover, Internet-based applications are considered to be beneficial for safety and fundamental for non-safety purposes (Baldessari et al., 2007). Therefore, the ITS communication architecture should not only focus on the needs of the communications of the vehicle, but also on the demands of users onboard.
Due to the mobile nature of the vehicle, its mobility has to be managed in order to provide continuous communications and reachability to the nodes onboard. Recently, several ITS standardisation bodies like the ETSI (European Telecommunications Standards Institute, 2010) and the ISO (International Standardization for Organization, 2010) have chosen the NEtwork MObility Basic Support (NEMO BS) protocol (Devarapalli et al., 2005) as the solution to manage the mobility of mobile networks to provide transparent session continuity to the onboard equipment. However, the NEMO BS protocol still presents shortcomings like suboptimal routing which leads to worsen the performance of not only signalling exchanges but also of data services. On the other hand, NEMO BS relies on IPsec to provide security, which has been demonstrated to be insufficient (Jung et al., 2004, Petrescu et al., 2004).
If network mobility management signalling exchanges are not secured, consequences like the breakage of ongoing communications as a result of attacks to the integrity of those messages; prevention from establishing new communications with nodes onboard due to notifying a fake IP address; or exhaustion of the resources of a victim point of attachment as a result of improperly notifying its IP address could happen. Therefore, the network mobility management should ensure security properties. Furthermore, in NEMO BS no attention is given to the end-to-end data protection. Although data protection could be achieved by other security provisioning protocols like TLS, this solution results in having two separated security frameworks, which is translated into a need of cross layer information. Additionally, as a result of handovers, vulnerabilities related to the changes in the security support of the different wireless access technologies are prone to occur. Therefore, the security solution has also to answer to the particularities of the mobile scenario, overcoming its vulnerabilities. In such a scenario, besides securing the network mobility management, services to be deployed in the ITS context should be secured. Services related to the operation and control of the vehicle involve the exchange of sensitive data, hence, a high level of security has to be ensured for this type of services. On the other hand, security properties like confidentiality are desirable also to end-user services. Furthermore, as there are certain applications that exchange personal user data, these data should also be protected. That is, end-user services should be provided assuring security and privacy in order to have acceptability of the deployed communication services. Last but not least, legal concerns also apply in the ITS scenario where legal liability related issues are a common reality, so, security properties like integrity are also demanded. Therefore, there is a wide scope of motivations that point that a strong security support in the ITS context is demanded.
Apart from the security related issues, the introduction of a network mobility management protocol should not prevent from not fulfilling service QoS requirements. Therefore, the network mobility management protocol itself should not worsen the performance of applications while it has to ensure the required security level in this scenario.
In this paper we present the NeMHIP, a new secure and efficient network mobility management protocol based on the Host Identity Protocol (HIP). NeMHIP ensures the required security level for the ITS context, not only for the mobility management itself, but also for the data services to be deployed in this context. As the impact of the introduction of security services in the performance of the applications should be bearable, the performance of the VoIP application when the NeMHIP is present has been evaluated by means of analytical modelling. More precisely, we demonstrate that the introduction of the NeMHIP results in a negligible end-to-end delay and packet loss of the VoIP service. Consequently, based on the obtained results, we can conclude that the introduction of the NeMHIP in the ITS context does not lead to worsen the QoS requirements. Accordingly, the introduction of end-to-end security services by means of the NeMHIP still enables to fulfil the performance requirements of the applications. Hence, the commonly known trade-off between security and performance is successfully achieved by our protocol.
The rest of the paper is organised as follows. Section 2 presents the related work to show the motivation of our work while Section 3 introduces the NeMHIP. The analytical models utilised in this analysis are presented in Section 4, as well as the most relevant results are shown. Section 5 presents concluding remarks.
Section snippets
Background
Currently, MIPv6 (Johnson et al., 2004) based NEMO solution (Devarapalli et al., 2005), NEMO BS, defined by the IETF NEMO Working Group is considered the most outstanding protocol to provide NEMO support. It provides session continuity to every node located inside a moving network as the network moves, allowing also be every node onboard reachable. The NEMO BS protocol is based on MIPv6 and runs on the network layer; thus it inherits network layer basic procedures.
A network mobility management
The NeMHIP
The NeMHIP has been designed to ensure security properties not only to the network mobility management procedures but also to the end-to-end data exchanges. In addition, the required security level in the ITS context is maintained while the efficiency is ensured. In order to do so, the MR is in charge of managing the mobility of the entire network as well as it triggers a procedure to renew the end-to-end keys which does not require end-to-end exchanges when a mobility event takes place. This
Analytical performance evaluation
This section presents the analytical models that have been defined to study the performance of user applications and the most relevant results obtained. More precisely and due to its stringent QoS requirements, we have focused on the VoIP application to study the feasibility of the NeMHIP to be deployed in the ITS context. The key performance parameters that have been studied are VoIP end-to-end packet delay and VoIP packet loss.
Conclusions
Internet connectivity while travelling is a flourishing market that should be addressed by means of the introduction of new protocols and technologies that aim at covering the particular necessities and demands of the ITS scenario. Moreover, not only travellers will profit from the Internet connectivity, which will allow the deployment of a wide scope of services, but also services in charge of controlling the operation of the vehicle as well as safety services will benefit from Internet
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