دانلود رایگان مقاله یونی کاست پویا: مسیریابی مولتی هاپ اطلاعات محور برای شبکه ادهاک سیار

Abstract

Information-centric networking (ICN) offers new perspectives on mobile ad-hoc communication because routing is based on names but not on endpoint identifiers. Since every content object has a unique name and is signed, authentic content can be stored and cached by any node. If connectivity to a content source breaks, it is not necessarily required to build a new path to the same source but content can also be retrieved from a closer node that provides the same content copy. For example, in case of collisions, retransmissions do not need to be performed over the entire path but due to caching only over the link where the collision occurred. Furthermore, multiple requests can be aggregated to improve scalability of wireless multi-hop communication. In this work, we base our investigations on Content-Centric Networking (CCN), which is a popular ICN architecture. While related works in wireless CCN communication are based on broadcast communication exclusively, we show that this is not needed for efficient mobile ad-hoc communication. With Dynamic Unicast requesters can build unicast paths to content sources after they have been identified via broadcast. We have implemented Dynamic Unicast in CCNx, which provides a reference implementation of the CCN concepts, and performed extensive evaluations in diverse mobile scenarios using NS3-DCE, the direct code execution framework for the NS3 network simulator. Our evaluations show that Dynamic Unicast can result in more efficient communication than broadcast communication, but still supports all CCN advantages such as caching, scalability and implicit content discovery.

7. Conclusions and future work

We have explored information-centric routing in mobile and wireless ad-hoc networks. While broadcast is beneficial to quickly find a content source, it is not required to perform all message transmissions via broadcast. Instead, Dynamic Unicast enables requesters to retrieve content from the same content source until it becomes unavailable. We have described two forwarding strategies for Dynamic Unicast as well as an optional Content Request Tracker to enable one broadcast transmission instead of multiple independent unicast transmissions. All mechanisms have been implemented in the CCNx framework and evaluated using NS3-DCE. Evaluations have shown that CCN can effectively improve scalability of wireless communication because multiple requests can be aggregated and content can be retrieved from caches such that only a fraction of requests needs to be forwarded to content sources. Dynamic Unicast results in significantly shorter content retrieval times and fewer Data transmissions than broadcast for high content densities, but surprisingly it performed also better than broadcast for low content densities. As future work, adaptive Interest lifetimes based on round-trip times may help to detect path breaks quicker and, thus, improve performance of Dynamic Unicast in case of high mobility. Furthermore, the usage of different MAC protocols can be investigated such as IEEE 802.11p for vehicular networks or new MAC protocol designs tailored for information-centric wireless communication.