دانلود رایگان مقاله سرویس تحریک شده عملیات چند کانالی برای ارتباطات وابسته به رسانه یابرندگر

Abstract

We present a novel approach for multi-channel operation (MCO) in vehicular communication systems, which allows for efficient utilization of the available bandwidth by asynchronous channel switching and enables dynamic service provisioning and usage by means of service advertisements. The proposed solution – Service-Actuated Multi-Channel Operation (SAMCO) – provides a logic that controls the prioritization of services and the timing of channel switching. It takes into account users preferences to decide on the consumption of a particular service if several concurrent services are available. SAMCO employs a novel channel load estimation scheme that, in addition to measuring the load on the channel at the physical layer, exploits the information contained in service advertisements. We perform simulations and use platooning as an example of a service with particularly stringent requirements to show that SAMCO can support service prioritization, continuity of service for high-priority services, and graceful degradation for low-priority services. Furthermore, by limiting the admission to services in high load scenarios, we show that SAMCO effectively controls the channel load and thereby complements congestion control mechanisms. Finally, we discuss the extensions needed in currently standardized solutions to implement SAMCO.

6. Conclusions

We presented SAMCO, a new scheme for multi-channel operation in a decentralized network with vehicle-to-vehicle and vehicle-to-infrastructure communication for safety and traffic effi- ciency applications. Instead of high spectrum utilization as the primary objective, the design of SAMCO specifically addresses service priorities and user preferences. Relying on the flexible framework in the IEEE 1609.4 standard [6] and the MCO support in the architecture of the simTD field trial [7], our simulation-based study has shown that the proposed scheme effectively supports service prioritization, continuity of service for high-priority services, and graceful degradation for low-priority services. While the initial deployment of vehicular communication systems expected in the next few years does not make use of MCO, with a growing equipment rate in vehicles and an increasing number of applications, MCO will become an important system feature. In particular, as a relevant and representative use case for automated driving, platooning has very high requirements on uninterrupted operation (same applies to other low-latency, highreliability applications such as lane merging, C-ACC, etc. [23]). For scenarios with platooning in the presence of lower-priority services, our simulation-based performance evaluation has also given an indication about the number of platoons that can be supported in a MCO-enabled system. We have also shown that SAMCO reduces the load on the wireless channels, thereby contributing to data congestion control at the service level, and efficiently reduces the number of channel switching operations. To enable SAMCO in the light of current standardization efforts in EU and the U.S., the main requirements are related to: (i) the information provided in service advertisements; and (ii) application prioritization. Specifically, SAMCO will yield better results the more of the optional information is contained in SAMs: (i) service channel that the node plans to use for the service, (ii) channel load information, (iii) frequency of messages sent by the service (by service provider, user, or both), (iv) message size, and (v) expected duration of the service. To that end, part of the future work is to provide input to standardization bodies on the required information fields in SAMs to enable more efficient channel switching. In terms of application priorities, SAMCO can make use of the application identifiers used in the existing standards, such as Provider Service Identifier (PS-ID) in the IEEE 1609 stack and the Application ID (A-ID) in the ETSI protocol stack.