Browsing by Author "Nickerson, Bradford"
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Item A comparison of adjustment methods for the densification of horizontal control networks(University of New Brunswick, 1983) Blue, Malcolm C.; Nickerson, BradfordItem A fault tolerant data structure for Peer-to-Peer range query processing(University of New Brunswick, 2015) Mirikharaji, Zahra; Nickerson, BradfordWe present a fault tolerant dynamic data structure based on a constant-degree Distributed Hash Table called FissionE that supports orthogonal range search in d-dimensional space. A publication algorithm, which distributes data objects among all nodes in the network is described, along with a search algorithm that processes range queries and reports all objects in range to the query issuer. The worst case orthogonal range search cost in our data structure with n nodes is O(log n + m) messages plus reporting cost, where m is the minimum number of nodes intersecting the query. We have proved that in our data structure the cost of reporting data in range to the query issuer is ∑mi=1 ⌈Ki/B⌉ O(log n) ∈ O((K/B + m) log n) messages, where K is the number points in range, Ki is the number of points in range stored in node i, and B is the number of points fitting in one message. Storing d copies of each data objects on d different nodes provides redundancy for our scheme. This redundancy permits completely answering a query in the case of simultaneous failure of d — 1 nodes. Results of our experimental simulation with up to 12,288 nodes show the practical application of our data structure.Item A parallel integrated index for spatio-temporal textual search using Tries(University of New Brunswick, 2019) Arseneau, Yoann S. M.; Nickerson, Bradford; Ray, SuprioThe proliferation of location-enabled devices and the increasing use of social media platforms is producing a deluge of multi-dimensional data. Novel index structures are needed to efficiently process massive amounts of geotagged data, and to promptly answer queries with textual, spatial, and temporal components. Existing approaches to spatio-textual data processing either use separate spatial and textual indices, or a combined index that integrates an inverted index with a tree data structure, such as an R-tree or Quadtree. These approaches, however, do not integrate temporal, spatial, and textual data together. We propose a novel integrated index called Spatio-temporal Textual Interleaved Trie (STILT), which unifies spatial, textual, and temporal components within a single structure. STILT is a multi-dimensional binary-trie-based index that interleaves text, location, and time data in a space-efficient manner. It supports dynamic and parallel indexing as well as concurrent searching. With extensive evaluation we demonstrate that STILT is significantly faster than the state-of-the-art approaches in terms of index construction time and query latency.Item Efficient text search with spatial constraints(University of New Brunswick, 2014) Han, Dan; Nickerson, BradfordThis thesis presents a search engine called TexSpaSearch that can search text documents having associated positions in space. We defined three query types Q 1 ( t) , Q2( t, r) and Q3(p, r) that can search documents with queries containing text t, position p and radius r components. We indexed a sample herbarium database of 40,791 records using a novel R*-tree and suffix tree data structure to achieve efficient text search with spatial data constraints. Significant preprocessing was performed to transform the herbarium database to a form usable by TexSpaSearch. We built unique data structures used to index text with spatial attributes that simultaneously support Ql, Q2 and Q3 queries. This thesis presents a novel approach for simplifying polygon boundaries for packing into R*-tree leaf nodes. Search results are ranked by a novel modified Lucene algorithm that supports free form text indexing in a general way. A novel ranking of Q2 search results combines the text and spatial scores. The architecture of a prototype Java based web application that invokes TexSpaSearch is described. A theoretical analysis shows that TexSpaSearch requires O(A 2lbl) average time for Ql search, where A is the number of single words in the query string t, and llbl is the average length of a subphrase in t. Q2 and Q3 require O ( A 2 Tbf + Z logM Vn + y) and O(logM Vn + y), respectively, where Z is the number of point records in the list P of text search results, Vn is the number of data objects indexed in the R*=tree for n records, M is the maximum number of entries of an internal node in the R*-tree, and y is the number of leaf nodes found in range in a Q3 query. Testing was performed with 20 test Ql queries to compare TexSpaSearch to a Google Search Appliance (GSA) for text search. Results indicate that the GSA is about 45.5 times faster than TexSpaSearch. The same 20 test queries were combined with a Q2 query radius r = 5, 50 and 500m. Results indicate Q2 queries are 22.8 times slower than Ql queries. For testing Q3 queries, 15 points were chosen in 15 different N .B. counties. The average Tc, T 8 and Te values of 191.5ms, 3603.2ms and 4183.9ms are given in the Q3 test, respectively, and the average value of Npt + Npl is 1313.4.Item Estimating the safety function response time for wireless control systems(University of New Brunswick, 2015) Guerra, Victoria; Nickerson, BradfordSafety function response time (SFRT) is a metric for safety-critical automation systems defined in the IEC 61784-3-3 standard for single input and single output systems communicating over wired technologies. This thesis proposes a model to estimate the SFRT for multiple input and multiple output feedback control systems communicating over the IEEE 802.15.4e wireless medium access control standard designed for process automation. The wireless SFRT model provides equations for the worst case delay time and watchdog timer of participating network entities, including wireless communication channels. Thirty-nine on board, wired and wireless control experiments using real devices were carried out to evaluate control performance, and the applicability of the wireless SFRT model. The estimated SFRT for the wired implementation is 38.2 ms. For the wireless experiments, the best SFRT obtained was 655.4 ms with no acceptable packet loss. The wireless implementation failed to provide successful control on 15 of the 21 experiments.Item Exploring an IPv6 protocol for mobile sensor network communication(University of New Brunswick, 2013) Zhang, Weiqi; Nickerson, BradfordThis research explores IPv6 in mobile wireless sensor networks (WSNs). An indoor WSN mobile sensor network testbed of length 24 m was built and used for mobile WSN testing. The test network enabled the use of one or two moving nodes and six stationary nodes. TelosB sensor nodes were used for testing. The thesis presents a detailed explaination of sending and receiving User Datagram Protocol (UDP) packets using the IPv6 Low Power Wireless Area Network (6LoWPAN) software stack in the Berkeley Low power Internet Protocol (BLIP) implementation of Tiny0S 2.1.1 and 2.1.2. A Java based Web application called WSNWeb was built that displays real-time route topology changes and sensor data. The data is updated in a log file, and used to compute packet loss and determine the number of route topology changes. We created 35 test cases, 15 with two moving nodes, and 20 with one moving node. On a test track, model train velocities between 0.076 m/s and 0.376 m/s were used, with three different routing table update periods (RTUPs) of 60 s, 6 s, and 0.6 s. The results show that the one moving node 0.6 seconds RTUP has significantly higher packet loss (up to 1.4% compared to 0.16%) over a five hour test compared to RTUPs of 60 s and 6 s. The two moving nodes test shows that RTUP of 0.6 s still has a higher packet loss compared to RTUPs of 6 sand 60 s.Item Global Positioning System differential positioning simulationsDavidson, Derek; Delikaraoglou, Demitris; Langley, Richard; Nickerson, Bradford; Vanicek, Petr; Wells, DavidItem Global Positioning System differential positioning simulationsDavidson, Derek; Delikaraoglou, Demitris; Langley, Richard; Nickerson, Bradford; Vanicek, Petr; Wells, DavidItem Indoor localization supporting smartphone advertising(University of New Brunswick, 2016) Seo, Amy; Nickerson, Bradford; Song, WeiThis thesis presents an indoor advertising server called Adaptive Real-Time Advertising Server (ARTAS) that provides advertisements to customer smartphones walking inside a retail store. Ultra-wideband (UWB) systems installed in the retail store locate the tag carried by the customer. ARTAS reads position data from UWB systems, and ranks advertisements based on the customer's position. Ranked advertisements are then sent to the customer smartphone. ARTAS was tested under line-of-sight (LOS) and non-line-of-sight (NLOS) environments with 2 experiments carried out for each environment. A simulated store with 25 advertising zones, and a simulated customer walking with a smartphone were used to carry out the tests. ARTAS system variables including position update and advertisement rates, advertisement delay, minimum advertising area radius, and time scale factor were changed for 18 test cases to determine variables giving better advertisement ranking. These experiments demonstrate that for LOS experiments, correct advertisements are top ranked 44.4% to 48.6% of the time, while for a NLOS environment correct advertisements are top ranked only 33.3% to 35.7% of the time. If the ranking order is ignored, then correct advertisements are ranked 64.1% to 68.3% of the time for a LOS environment, and 50% to 51.6% for a NLOS environment. A second technique (called the next zone method) used advertisements from the customer's current and predicted next advertising zones to compute the number of correctly shown advertisements. Using the next zone method, top ranked advertisements are shown correctly 59.2% to 62.7% of the time for the LOS environment, and 41.2% to 42.9% of the time for the NLOS environment.Item Indoor real-time positioning using Ultra-Wideband technology(University of New Brunswick, 2015) Yavari, Mohammadreza; Nickerson, BradfordThis thesis investigates the capability of Ultra-Wide Band (UWB) communication technology to be used for indoor real-time positioning. The integration of an inertial measurement unit (IMU) to increase positioning accuracy was also evaluated. We designed and implemented a novel evaluation method for positioning systems that compares each of the position estimates with the ground truth position at the same moment. We experimentally verified the accuracy of an UWB positioning system in line-of-sight (LOS) conditions to be, on average, 10.97 cm for a robot moving at around 0.16 m/s on a track of length 6.7 m. In the case of non-line-of-sight (NLOS) conditions, accuracy on a track of length 9.7 m for the same moving robot was, on average, 58.47 cm. Data fusion of IMU and UWB measurements using an extended Kalman filter increased average positioning accuracy to 51.96 cm, an 18.8% increase over UWB measurements alone, in NLOS conditions. In LOS conditions, we observed that data fusion of IMU and UWB measurements decreases the average positioning accuracy (from 10.97 cm to 14.17 cm) compared to use of UWB only position estimation.Item Industrial wireless control using ultra-wideband radio(University of New Brunswick, 2017) M. King, Daniel; Nickerson, Bradford; Song, WeiItem Position estimation of nodes moving in a wireless sensor network(University of New Brunswick, 2014) Zhou, Lingchen; Nickerson, BradfordThis thesis investigates the use of measured radio signal strength indicator (RSSI) in wireless sensor networks (WSNs) to provide an estimated distance. Estimated distances are arrived at using experimental calibration of a free space model to find the best free space model exponent and transmission power level over distances up to 7.78 m. We use these distances to estimate the position of a moving wireless sensor node. A new application called MobiPos for indoor distance determination using TelosB module has been developed and tested. In our MobiPos application, the moving node collects RSSI values from TestFtsp messages sent by up to eight stationary nodes. The moving node, in turn, collects valid RSSI observations from the same set, and formulates a special MULTI RSSI message that is sent to a stationary gateway node. The gateway node collects and time stamps received MULTI RSSI messages for post processing using a least squares position estimation process. We experimentally verified our research on a 23.92 m long mobile wireless sensor network testbed with up to six stationary nodes and one moving node. With an average velocity of 0.19 m/s, and 131 received MULTI RSSI messages over a test period of 127 seconds , we found that 64 observation sets (49%) converged with reasonable position estimates compared to approximate true positions. The average position difference for these 64 estimated positions compared to their approximate true positions was 5.03 m.Item Simulator for adaptive multimedia transmission over wireless networks(University of New Brunswick, 2013) Li, Xiaojing; Song, Wei; Nickerson, BradfordMany simulation tools (e.g., NS-2) have been developed to examine the operations and the quality of service (QoS) of different networks, but they cannot demonstrate the visual and auditory impact of network properties on multimedia traffic. This thesis presents a wireless adaptive multimedia simulator (WAMS) that can demonstrate such effects. WAMS uses a compact graphical user interface (GUI) to present the real-time packet delay with the playback of the streaming media over a typical wireless physical channel using IEEE 802.11-based medium access control (MAC). Rate adaptation is also supported to address channel variation. WAMS demonstrates the visual and auditory effects of a variety of factors such as traffic load, fading errors, and rate adaptation. We also carried out tests on user-perceived quality of experience (QoE) with 54 test cases comprising 3 videos, 2 audio clips, and 1 combined video and audio clip produced by WAMS. Ten people (assessors) viewed and listened to these clips and compared them to the original multimedia according to a five-point impairment measure. We find that the subjective QoE is quite sensitive to audio/video content although consistent with objective QoS metrics. Statistical difference of means tests show that the video with slower motion and fewer colours is likely to offer a better delay tolerance, and the audio is less sensitive to the bit error probability (BEP) than the video.