No abstract

The Datagram Congestion Control Protocol (DCCP) was designed to provide congestion control for unreliable applications, such as voice-over-IP and IPTV. But the current congestion control mechanisms of DCCP do not have the ability to support Quality of Service (QoS) features. This paper aims to design an end-to-end QoS-aware congestion control mechanism for DCCP based on theory. In particular, we design an end-to-end traffic control mechanism to support Real-time Delay Adaptive and Real-time Rate Adaptive applications. The mechanism possesses several provable properties, including friendliness to TCP, stability, and optimality. The experimental results show that the proposed mechanism can provide minimum rate guarantee for real-time applications and maintain a lower packet drop ratio.

No abstract

No abstract

Emergency warning message (EWM) transmission insurance is one of the most interesting topics for Vehicular Cyber-physical System (V-CPS) application. A relatively low transmission requirement should improve EWM's real-time delivery, and however, decrease reliability of packet delivery by its corresponding burst converge-cast, especially under multihop condition. In this paper, based on a series experiments, a clear channel assessment (CCA) threshold ladder selection method is proposed to ensure both real-time and reliability for EWM transmission. The experimental results show that the threshold adjusting method has a positive effect on the delivery rate. With an appropriately diminishing clear channel assessment threshold related to the packet hops, the global dissemination successful rate can be up to 73.5%, and more than 90% of the 1-hop nodes can receive the correct packet. The experiment results provide a practicable method to improve EWM dissemination performance. Index Terms-Inter-vehicle communication, emergency warning message, clear channel assessment, delivery ratio, ladder CCA threshold selection mechanism I. INTRODUCTION With close to a billion vehicles on the road today, and a doubling project over the next 20 years, we face pressing challenges about how to improve efficiency and reliability for the vehicle network to meet vehicle driver's demands in real time collision avoidance. As a result, Vehicular Cyber-Physical System (V-CPS) is put forward to monitor the road conditions via the inter-vehicle communication (IVC) mode. All the road vehicles in object region are considered as nodes, which communicate with each other via Vehicular Ad-Hoc Networks (VANETs). The key point we are interested in this paper is how to ensure the emergency warning message (EWM) delivery in VANETs. To ensure EWM transmission quality, IEEE recently drafted 802.11p/WAVE (Wireless Access in Vehicular Environments) standard, which introduces CCH (common control channel) to disseminate control and warning messages[1]. Vehicles switch their working channel between CCH and SCH (service channel), which used to exchange non-safety-related data in turn.