Design and Reliability Performance Evaluation of Network Coding Schemes for Lossy Wireless Networks

This thesis investigates lossy wireless networks, which are wireless communication networks consisting of lossy wireless links, where the packet transmission via a lossy wireless link is successful with a certain value of probability. In particular, this thesis analyses all-to-all broadcast in lossy wireless networks, where every node has a native packet to transmit to all other nodes in the network. A challenge of all-to-all broadcast in lossy wireless networks is the reliability, which is defined as the probability that every node in the network successfully obtains a copy of the native packets of all other nodes. In this thesis, two novel network coding schemes are proposed, which are the neighbour network coding scheme and the random neighbour network coding scheme. In the two proposed network coding schemes, a node may perform a bit-wise exclusive or (XOR) operation to combine the native packet of itself and the native packet of its neighbour, called the coding neighbour, into an XOR coded packet. The reliability of all-to-all broadcast under both the proposed network coding schemes is investigated analytically using Markov chains. It is shown that the reliability of all-to-all broadcast can be improved considerably by employing the proposed network coding schemes, compared with non-coded networks with the same link conditions, i.e. same probabilities of successful packet transmission via wireless channels. Further, the proposed schemes take the link conditions of each node into account to maximise the reliability of a given network. To be more precise, the first scheme proposes the optimal coding neighbour selection method while the second scheme introduces a tuning parameter to control the probability that a node performs network coding at each transmission. The observation that channel condition can have a significant impact on the performance of network coding schemes is expected to be applicable to other network coding schemes for lossy wireless networks

High-speed Curve25519 on 8-bit, 16-bit, and 32-bit microcontrollers

Contains fulltext : 147319.pdf (preprint version ) (Open Access

Full-Size High-Security ECC Implementation on MSP430 Microcontrollers

Contains fulltext : 147317.pdf (preprint version ) (Closed access

Efficient E-Cash in Practice: NFC-Based Payments for Public Transportation Systems

Abstract. Near field communication (NFC) is a recent popular technology that will facilitate many aspects of payments with mobile tokens. In the domain of public transportation payment systems electronic payments have many benefits, including improved throughput, new capabilities (congestion-based pricing etc.) and user convenience. A common concern when using electronic payments is that a user’s privacy is sacrificed. However, cryptographic e-cash schemes pro-vide provable guarantees for both security and user privacy. Even though e-cash protocols have been proposed three decades ago, there are relatively few ac-tual implementations, since their computation complexity makes an execution on lightweight devices rather difficult. This paper presents an efficient implemen-tation of Brands [11] and ACL [4] e-cash schemes on an NFC smartphone: the BlackBerry Bold 9900. Due to their efficiency during the spending phase, when compared to other schemes, and the fact that payments can be verified offline, these schemes are especially suited for, but not limited to, use in public trans-port. Additionally, the encoding of validated attributes (e.g. a user’s age range, zip code etc.) is possible in the coins being withdrawn, which allows for addi-tional features such as variable pricing (e.g. reduced fare for senior customers) and privacy-preserving data collection. We present a subtle technique to make use of the ECDHKeyAgreement class that is available in the BlackBerry API (and in the API of other systems) and show how the schemes can be implemented efficiently to satisfy the tight timing imposed by the transportation setting.

MODELLING AND OPTIMIZING OPERATING CONDITIONS OF APPARATUS USED IN PREPARATORY AND SECONDARY PROCESSES OF DRESSING MINERAL RESOURCES

A universal Markovian model describing a series of apparatus, relating to a class of separation characteristics and permitting to consider a number of parameters of the operating conditions of the apparatus has been constructed; an algorithm used for optimizing the apparatus operating conditions has been devised on the basis of the model built. A program for calculating the parameters of the developed model has been worked out by using the experimental data, and methods of solving the problems of predicting and optimizing the operation of the production apparatus in commercial conditions have been developed. The methods and the program have succesfully been tested at solving a series of practical problems associated with the optimization of the operation of commercial apparatus, at selection of structural parameters of new separators, at issue of recommendations concerning the reconstruction of the filtration section and during the investigations of the problems of the dressability of ores of various types and their mixturesAvailable from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio