Prioritized data synchronization with applications

We are interested on the problem of synchronizing data on two distinct devices with differed priorities using minimum communication. A variety of distributed sys- tems require communication efficient and prioritized synchronization, for example, where the bandwidth is limited or certain information is more time sensitive than others. Our particular approach, P-CPI, involving the interactive synchronization of prioritized data, is efficient both in communication and computation. This protocol sports some desirable features, including (i) communication and computational com- plexity primarily tied to the number of di erences between the hosts rather than the amount of the data overall and (ii) a memoryless fast restart after interruption. We provide a novel analysis of this protocol, with proved high-probability performance bound and fast-restart in logarithmic time. We also provide an empirical model for predicting the probability of complete synchronization as a function of time and symmetric differences. We then consider two applications of our core algorithm. The first is a string reconciliation protocol, for which we propose a novel algorithm with online time com- plexity that is linear in the size of the string. Our experimental results show that our string reconciliation protocol can potentially outperform existing synchroniza- tion tools such like rsync in some cases. We also look into the benefit brought by our algorithm to delay-tolerant networks(DTNs). We propose an optimized DTN routing protocol with P-CPI implemented as middleware. As a proof of concept, we demonstrate improved delivery rate, reduced metadata and reduced average delay

Key-value storage system synchronization in peer-to-peer environments

Data synchronization is the problem of bringing multiple versions of the same data on different remote devices to the most up to date version. This thesis looks into the particular problem of key-value storage systems synchronization between mobile devices in a peer-to-peer environment. In this research, we describe, implement and evaluate a new key-value storage system synchronization algorithm using a 2-phase approach, combining approximate synchronization in the first phase and exact synchronization in the second phase. The 2-phase architecture helps the algorithm achieve considerable boost in performance in all three major criteria of a data synchronization algorithm, namely synchronization time, processing time and communication cost, while still being suitable to operate in a peer-to-peer environment. The performance increase makes it feasible to employ database synchronization technique in a wider range of mobile applications, especially those operating on a slow peer-to-peer network

High-Precision Measurement of Sine and Pulse Reference Signals using Software-Defined Radio

This paper addresses simultaneous, high-precision measurement and analysis of generic reference signals by using inexpensive commercial off-the-shelf Software Defined Radio hardware. Sine reference signals are digitally down-converted to baseband for the analysis of phase deviations. Hereby, we compare the precision of the fixed-point hardware Digital Signal Processing chain with a custom Single Instruction Multiple Data (SIMD) x86 floating-point implementation. Pulse reference signals are analyzed by a software trigger that precisely locates the time where the slope passes a certain threshold. The measurement system is implemented and verified using the Universal Software Radio Peripheral (USRP) N210 by Ettus Research LLC. Applying standard 10 MHz and 1 PPS reference signals for testing, a measurement precision (standard deviation) of 0.36 ps and 16.6 ps is obtained, respectively. In connection with standard PC hardware, the system allows long-term acquisition and storage of measurement data over several weeks. A comparison is given to the Dual Mixer Time Difference (DMTD) and Time Interval Counter (TIC), which are state-of-the-art measurement methods for sine and pulse signal analysis, respectively. Furthermore, we show that our proposed USRP-based approach outperforms measurements with a high-grade Digital Sampling Oscilloscope.Comment: 10 pages, 15 figures, and 4 table

Practical Target-Based Synchronization Strategies for Immutable Time-Series Data Tables

As the Internet of Things and industrial monitoring of utilities grow, efficiently synchronizing immutable time-series data streams between databases becomes a pressing issue. Extracting data from critical production databases demands careful consideration of the stress imposed on the machines, so synchronization strategies are required to minimize the transfer of duplicate data and the load imposed on remote sources. Literature on the synchronization problem is generalized to arbitrary tables and does not consider the characteristics of time-series data streams, so research was required to investigate methods to quickly synchronize source and target time-series data tables. This thesis examines immutable time-series scenarios and synchronization strategies to answer the following question: given several scenarios, which target-based immutable time-series synchronization strategies best optimize run-time, bandwidth, and accuracy? The strategies explored in this research are implemented into the Meerschaum system, a project intended to leverage these time-series concepts for production deployments. As a practical demonstration, these strategies are used to continuously cache Clemson University’s utilities data

Reconciling Graphs and Sets of Sets

We explore a generalization of set reconciliation, where the goal is to reconcile sets of sets. Alice and Bob each have a parent set consisting of $s$ child sets, each containing at most $h$ elements from a universe of size $u$. They want to reconcile their sets of sets in a scenario where the total number of differences between all of their child sets (under the minimum difference matching between their child sets) is $d$. We give several algorithms for this problem, and discuss applications to reconciliation problems on graphs, databases, and collections of documents. We specifically focus on graph reconciliation, providing protocols based on set of sets reconciliation for random graphs from $G(n,p)$ and for forests of rooted trees

Scalable string reconciliation by recursive content-dependent shingling

We consider the problem of reconciling similar strings in a distributed system. Specifically, we are interested in performing this reconciliation in an efficient manner, minimizing the communication cost. Our problem applies to several types of large-scale distributed networks, file synchronization utilities, and any system that manages the consistency of string encoded ordered data. We present the novel Recursive Content-Dependent Shingling (RCDS) protocol that can handle large strings and has the communication complexity that scales with the edit distance between the reconciling strings. Also, we provide analysis, experimental results, and comparisons to existing synchronization software such as the Rsync utility with an implementation of our protocol.2019-12-03T00:00:00

SARHA – Development of a Sensor-Augmented GPS/EGNOS/Galileo Receiver for Urban and Indoor Environments

The main objective of the project ‘SARHA - Sensor-Augmented EGNOS/Galileo Receiver for Handheld Applications in Urban and Indoor Environments’ is the development of a modern satellite navigation receiver with autonomous sensor augmentation. Additionally, the hybrid navigation system will be enhanced by a transponder capable of receiving absolute position updates from transmitters installed inside buildings. The transponder will allow the SARHA system to significantly increase reliability and accuracy of the positioning solutions indoors. The hybrid navigation software is split up into two parts. The first one will be implemented directly on the GPS receiver, whereas the second part will run on a microcontroller. Thus, a small, low-performance microcontroller can be used, representing the first step towards the reduction of size, weight and power consumption of the mobile system. This paper provides an overview on personal mobility and typical applications related to the system, describes the system architecture and the hybrid navigation software in detail. Furthermore, emphasis is laid on a comparison of different step detection algorithms, showing their advantages and disadvantages. Based on the Galileo signal definition, additional analysis set up to explore the signal characteristics in comparison to the GPS signals, are provided. Improvements due to the Galileo signal availability in urban and indoor environments are assessed and will later ensure seamless integration of enhanced technologies into the continuous developments