Performance evaluation of information retrieval schemes for multi-attribute queries in DTNs

Abstract

Abstract-Mobile nodes in some challenging network scenarios suffer from intermittent connectivity and frequent partitions e.g. battlefield and disaster recovery scenarios. Disruption Tolerant Network (DTN) technologies are designed to enable nodes in such environments to communicate with one another. In an earlier work, we studied information retrieval schemes for singleattribute queries in DTNs. Our schemes disseminate replicated data copies and queries to local-neighborhood. However, data items often have multiple attributes and not every node can be trusted to store replicated data or queries. Thus, in this paper, we study the scenario where the queries have multiple attributes. In addition, we compare the effectiveness of using opportunistically encountered nodes or specially deployed index and storage points (ISPs) for storing replicated data items or indices of the data items. Specifically, we conduct extensive simulation studies to evaluate three information retrieval schemes namely (a) the Predetermined ISP advertisement (PISA) scheme where ISPs advertise indices of data items with attribute values that fall within some pre-determined ranges, (b) the Opportunistic Regular Node Advertisement with Index Duplication (ORNA-ID) scheme which uses opportunistically encountered nodes for advertising replicated indices, and (c) the Opportunistic Regular Node Advertisement with Data Duplication (ORNA-DD) scheme which uses opportunistically encountered nodes for storing replicated data items. Our results indicate that the ORNA-ID scheme and the PISA scheme achieve similar performance. This shows that either architecture can be used. In addition, the ORNA-DD scheme provides 91% more query success rate and 128% more overall success rate in the sparsest network scenario (40 nodes distributed over 4000x4000m 2 ).Index Terms-disruption tolerant networking, content-based routing, multi-attribute queries, information retrieval.

Secure data retrieval system (SEDAR) for DTNs

“…A publisher can publish data items and store replicated copies of the data items at nodes it encounters opportunistically or at specifically deployed storage nodes called the index and storage point (ISP)s [21]. In [9], we describe how a publisher can use a friendliness metric to select more popular nodes to store its data items.…”

“…In [9], we describe how a publisher can use a friendliness metric to select more popular nodes to store its data items. Our simulation results [3], [9], [21] indicate that distributed storage of replicated data items improve the query success rate and query response time in extreme networks. Query performance results using specially deployed storage nodes called ISPs are also provided in [21].…”

“…Our simulation results [3], [9], [21] indicate that distributed storage of replicated data items improve the query success rate and query response time in extreme networks. Query performance results using specially deployed storage nodes called ISPs are also provided in [21]. Each storage node (including the publisher) also periodically broadcasts a data bloom filter advertising the data items that it currently stores.…”