HAP: a heterogeneous ad hoc protocol

Ad hoc wireless networks are becoming an important infrastructure for developing networking applications due to their decentralized nature, improved scalability as compared to wireless managed networks, minimal configuration and fast deployment. However, such networks show several limitations regarding their capacity and are, in general, impractical for stand alone commercial applications; in fact, such networks are mostly used for emergency applications. However, the features of ad hoc networks can be useful to extend the connectivity of wireless networks, while taking into account node mobility. In this paper we propose a Heterogeneous Ad hoc Protocol (HAP), which aims to extend the connectivity of a wireless networks. HAP is a cross layer protocol that operates on the link, MAC, and network layers, which takes into account the impact of the mobility on each of these layers. The objective of HAP is thus to overcome limitations of existing protocols, especially regarding mobility. HAP can be useful for developing applications in pedestrian and community networks.Peer ReviewedPostprint (published version

Priority diffusion model in lattices and complex networks

We introduce a model for diffusion of two classes of particles ($A$ and $B$) with priority: where both species are present in the same site the motion of $A$'s takes precedence over that of $B$'s. This describes realistic situations in wireless and communication networks. In regular lattices the diffusion of the two species is normal but the $B$ particles are significantly slower, due to the presence of the $A$ particles. From the fraction of sites where the $B$ particles can move freely, which we compute analytically, we derive the diffusion coefficients of the two species. In heterogeneous networks the fraction of sites where $B$ is free decreases exponentially with the degree of the sites. This, coupled with accumulation of particles in high-degree nodes leads to trapping of the low priority particles in scale-free networks.Comment: 5 pages, 3 figure

Achieving Secure and Efficient Cloud Search Services: Cross-Lingual Multi-Keyword Rank Search over Encrypted Cloud Data

Multi-user multi-keyword ranked search scheme in arbitrary language is a novel multi-keyword rank searchable encryption (MRSE) framework based on Paillier Cryptosystem with Threshold Decryption (PCTD). Compared to previous MRSE schemes constructed based on the k-nearest neighbor searcha-ble encryption (KNN-SE) algorithm, it can mitigate some draw-backs and achieve better performance in terms of functionality and efficiency. Additionally, it does not require a predefined keyword set and support keywords in arbitrary languages. However, due to the pattern of exact matching of keywords in the new MRSE scheme, multilingual search is limited to each language and cannot be searched across languages. In this pa-per, we propose a cross-lingual multi-keyword rank search (CLRSE) scheme which eliminates the barrier of languages and achieves semantic extension with using the Open Multilingual Wordnet. Our CLRSE scheme also realizes intelligent and per-sonalized search through flexible keyword and language prefer-ence settings. We evaluate the performance of our scheme in terms of security, functionality, precision and efficiency, via extensive experiments

Libra, a Multi-hop Radio Network Bandwidth Market

Libra is a two-level market which assigns fractional shares of time to the transmitting nodes in local regions of a multi-hop network. In Libra, users are assigned budgets by management and users assign funding to services within their budget limits. The purpose is to prioritize users and also optimize network utilization by preventing source nodes from injecting too much traffic into the network and thereby causing downstream packet loss. All transmitting nodes sell capacity in the region surrounding them, and buy capacity from their neighbors in order to be able to transmit. Streams buy capacity from each of the nodes on their paths, thus streams that cross the same region compete directly for the bandwidth in that region. Prices are adjusted incrementally on both levels