دانلود رایگان مقاله پروتکل مسیریابی کیفیت جهت جریان ویدئو برای شبکه های تلفن همراه

Abstract

One of the major challenges for the transmission of time-sensitive data like video over mobile ad-hoc networks (MANETs) is the deployment of an end-to-end QoS support mechanism. Therefore, several approaches and enhancements have been proposed concerning the routing protocols. In this paper we propose a new QoS routing protocol based on AODV (named AQA-AODV), which creates routes according to application QoS requirements. We have introduced link and path available bandwidth estimation mechanisms and an adaptive scheme that can provide feedback to the source node about the current network state, to allow the application to appropriately adjust the transmission rate. In the same way, we propose a route recovery approach into the AQA-AODV protocol, which provides a mechanism to detect the link failures in a route and re-establish the connections taking into account the conditions of QoS that have been established during the previous route discovery phase. The simulation results reveal performance improvements in terms of packet delay, number of link failures and connection setup latency while we make more efficient use of the available bandwidth than other protocols like AODV and QAODV. In terms of video transmission, the obtained results prove that the combined use of AQA-AODV and the scalable video coding provides an efficient platform for supporting rate-adaptive video streaming.

7. Conclusions

A novel QoS-aware routing protocol (AQA-AODV) is proposed in this paper for carrying out time-sensitive communications over mo- bile ad hoc networks. We also proposed an adaptive method to ex- ploit the layered scheme of SVC using the QoS parameters provided by AQA-AODV. This cross-layer method allows video source to ad- just the bit rate of the video source adding or removing SVC lay- ers from the original video stream based on the estimation of the available bandwidth. The integration of AQA-AODV and SVC pro- vides a suitable system for supporting a network-adaptive strategy where video stream can be adapted avoiding network congestion and achieving a significantly improvement in the quality of the trans- mitted video. AQA-AODV incorporates a novel two-step process for estimating the available bandwidth of a route between source and destination node. In the first step, local bandwidth estimation is es- timated in each node and, in the second step, it is performed a pre- diction of the consumed bandwidth that take into consideration the interference between packets of the same flow. In addition, we pro- posed a route recovery mechanism into AQA-AODV, which tries to re- 1068 establish connection to destination after a link failure, with the QoS conditions that had been negotiated during the initial route discovery phase.