دانلود رایگان مقاله بازیابی محتوای اطلاعات محور برای شبکه تحمل پذیر تاخیر

Abstract

The shift from host-centric to information-centric networking (ICN) promises seamless communication in mobile networks. However, most existing works either consider well-connected networks with high node density or introduce modifications to ICN message processing for delay-tolerant networking (DTN). In this work, we present agent-based content retrieval, which provides information-centric DTN support as an application module without modifications to ICN message processing. This enables flexible interoperability in changing environments. If no content source can be found via wireless multi-hop routing, requesters may exploit the mobility of neighbor nodes (called agents) by delegating content retrieval to them. Agents that receive a delegation and move closer to content sources can retrieve data and return it back to requesters. We show that agent-based content retrieval may be even more efficient in scenarios where multi-hop communication is possible. Furthermore, we show that broadcast communication may not be necessarily the best option since dynamic unicast requests have little overhead and can better exploit short contact times between nodes (no broadcast delays required for duplicate suppression).

7. Conclusions

We have described agent-based content retrieval (ACR) and showed that delay-tolerance in information-centric networks (ICN) can be supported without modifications to ICN message processing. This enables seamless operation in well-connected and disruptive networks. Furthermore, we have shown that mobile ICN communication does not require all messages to be transmitted via broadcast. Dynamic Unicast (DU) has resulted in faster content retrieval times than broadcast for slow and high node velocities (up to a certain path length). Symmetric Interest-Data forwarding paths have not been identified as limitation because Data messages are returned within milliseconds, i..e, the topology has not changed much. We have seen that node mobility is not necessarily a disadvantage for wireless communication and ICN provides the means to exploit it. While multi-hop communication is faster with high node densities, ACR is superior in low and intermediate node densities where multi-hop communication does not work or results in frequent disruptions. Furthermore, ACR is beneficial for large file sizes and works well even under high mobility, where it can be combined with one-hop DU. Although, in our scenarios, agents had to return to the requester to deliver content, agent delegation and content delivery can also be at different locations as long as both locations can communicate and coordinate with each other. With our approach, multi-hop DU and ACR can be combined. A requester could initially try to retrieve content via multi-hop communication and only delegate retrieval to agents if nothing has been found. Because all messages are stored in the same ICN message format, requesters could also retrieve (via multiple hops) content from agents, which were delegated by other requesters. However, concrete mechanisms to combine multi-hop DU with ACR under dynamic (time varying) network condition are still a subject for more investigations.