• Title/Summary/Keyword: radio map

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Optimal Fingerprint Data Filtering Model for Location Based Services (위치기반 서비스 강화를 위한 최적 데이터 필터링 기법 및 측위 시스템 적용 모델)

  • Jung, Jun;Kim, Jae-Hoon
    • Korean Management Science Review
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    • v.29 no.2
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    • pp.79-90
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    • 2012
  • Focusing on the rapid market penetration of smart phones, the importance of LBS (Location Based Service) is drastically increased. However, traditional GPS method has critical weakness caused by limited availability, such as indoor environment. WPS is newly attractive method as a widely applicable positioning method. In WPS, RSSI (Received Signal Strength Indication) data of all Wi-Fi APs (Access Point) are measured and stored into a huge database. The stored RSSI data in database make single radio fingerprint map. By the radio fingerprint map, we can estimate the actual position of target point. The essential factor of radio fingerprint database is data integrity of RSSI. Because of millions of APs in urban area, RSSI measurement data are seriously contaminated. Therefore, we present the unified filtering method for RSSI measurement data. As the results of filtering, we can show the effectiveness of suggested method in practical positioning system of mobile operator.

Indoor Network Map Matching by Hidden Markov Model (은닉 마르코프 모델을 이용한 실내 네트워크 맵 매칭)

  • Kim, Tae Hoon;Li, Ki-Joune
    • Spatial Information Research
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    • v.23 no.3
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    • pp.1-10
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    • 2015
  • Due to recent improvement of various sensor technologies, indoor positioning becomes available. However, Indoor positioning technologies by Wi-Fi radio map and acceleration sensor and digital campus still have a certain level of errors and a number of researches have been done to increase the positioning accuracy of the indoor positioning. If we could provide a room level accuracy, indoor location based services with current indoor positioning methods such as Wi-Fi radio map and acceleration sensors would be possible. In this paper, we propose an indoor map matching method to provide a room level accuracy based on hidden markov model.

Butterfly Log-MAP Decoding Algorithm

  • Hou, Jia;Lee, Moon Ho;Kim, Chang Joo
    • Journal of Communications and Networks
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    • v.6 no.3
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    • pp.209-215
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    • 2004
  • In this paper, a butterfly Log-MAP decoding algorithm for turbo code is proposed. Different from the conventional turbo decoder, we derived a generalized formula to calculate the log-likelihood ratio (LLR) and drew a modified butterfly states diagram in 8-states systematic turbo coded system. By comparing the complexity of conventional implementations, the proposed algorithm can efficiently reduce both the computations and work units without bit error ratio (BER) performance degradation.

A Study on Map Building of Mobile Robot Using RFID Technology and Ultrasonic Sensor (초음파센서와 RFID 시스템을 이용한 이동로봇의 맵 빌딩에 관한 연구)

  • Lee, Do-Kyoung;Im, Jae-Sung;Kim, Sang-Bong
    • Journal of Institute of Control, Robotics and Systems
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    • v.16 no.3
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    • pp.239-244
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    • 2010
  • This paper is to present map building of mobile robot using RFID (Radio Frequency Identification) technology and ultrasonic sensor. For mobile robot to perform map building, the mobile robot needs its localization and accurate driving in space. In this reason, firstly, kinematic modeling of mobile robot under non-holonomic constrains is introduced. Secondly, based on this modeling, a tracking controller is designed for tracking a given path based on backstepping method using Lyapunov function. The Lyapunov function is also introduced for proving the stability of the designed tracking controller. Thirdly, 2D map building is performed by RFID system, mobile robot system and ultrasonic sensors. The RFID mobile robot system is composed of DC motor, encoder, ultra sonic sensor, digital compass, RFID receiver and RFID antenna. Finally, the path tracking simulation results and map building experimental results are presented to show the effectiveness of the designed controller.

Efficient Indoor Location Estimation using Multidimensional Indexes in Wireless Networks

  • Jun, Bong-Gi
    • International Journal of Contents
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    • v.5 no.2
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    • pp.59-63
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    • 2009
  • Since it is hard to use GPS for tracking mobile user in indoor environments, much research has focused on techniques using existing wireless local area network infrastructure. Signal strength received at a fixed location is not constant, so fingerprinting approach which use pattern matching is popular. But this approach has to pay additional costs to determine user location. This paper proposes a new approach to find user's location efficiently using an index scheme. After analyzing characteristics of RF signals, the paper suggests the data processing method how the signal strength values for each of the access points are recorded in a radio map. To reduce computational cost during the location determination phase, multidimensional indexes for radio map with the important information which is the order of the strongest access points are used.

Inter-category Map: Building Cognition Network of General Customers through Big Data Mining

  • Song, Gil-Young;Cheon, Youngjoon;Lee, Kihwang;Park, Kyung Min;Rim, Hae-Chang
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.8 no.2
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    • pp.583-600
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    • 2014
  • Social media is considered a valuable platform for gathering and analyzing the collective and subconscious opinions of people in Internet and mobile environments, where they express, explicitly and implicitly, their daily preferences for brands and products. Extracting and tracking the various attitudes and concerns that people express through social media could enable us to categorize brands and decipher individuals' cognitive decision-making structure in their choice of brands. We investigate the cognitive network structure of consumers by building an inter-category map through the mining of big data. In so doing, we create an improved online recommendation model. Building on economic sociology theory, we suggest a framework for revealing collective preference by analyzing the patterns of brand names that users frequently mention in the online public sphere. We expect that our study will be useful for those conducting theoretical research on digital marketing strategies and doing practical work on branding strategies.

A Study on Improving Indoor Positioning Accuracy Using Map Matching Algorithm (맵 매칭 알고리즘을 이용한 실내 위치 추정 정확도 개선에 대한 연구)

  • Kwangjae Sung
    • Journal of the Semiconductor & Display Technology
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    • v.22 no.2
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    • pp.50-55
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    • 2023
  • Due to the unavailability of global positioning system (GPS) indoors, various indoor pedestrian positioning methods have been designed to estimate the position of the user using received signal strength (RSS) measurements from radio beacons, such as wireless fidelity (WiFi) access points and Bluetooth low energy (BLE) beacons. In indoor environments, radio-frequency (RF) signals are unpredictable and change over space and time because of multipath associated with reflection and refraction, shadow fading caused by obstacles, and interference among different devices using the same frequencies. Therefore, the outliers in the positional information obtained from the indoor positioning method based on RSS measurements occur often. For this reason, the performance of the positioning method can be degraded by the characteristics of the RF signal. To resolve this issue, a map-matching (MM) algorithm based on maximum probability (MP) estimation is applied to the indoor positioning method in this study. The MM algorithm locates the aberrant position of the user estimated by the positioning method within the limits of the adjacent pedestrian passages. Empirical experiments show that the positioning method can achieve higher positioning accuracy by leveraging the MM algorithm.

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Radio environment maps: The survey of construction methods

  • Pesko, Marko;Javornik, Tomaz;Kosir, Andrej;Stular, Mitja;Mohorcic, Mihael
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.8 no.11
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    • pp.3789-3809
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    • 2014
  • Radio environment maps (REMs) and geolocation database represent an important source of information for the operation of cognitive radio networks, replacing or complementing spectrum sensing information. This paper provides a survey of methods for constructing the radio frequency layer of radio environment map (RF-REM) using distributed measurements of the signal levels at a given frequency in space and time. The signal level measurements can be obtained from fixed or mobile devices capable of sensing radio environment and sending this information to the REM. The signal measurements are complemented with information already stored in different REM content layers. The combined information is applied for estimation of the RF-REM layer. The RF-REM construction methods are compared, and their advantages and disadvantages with respect to the spatial distribution of signal measurements and computational complexity is given. This survey also indicates possible directions of further research in indirect RF-REM construction methods. It emphasizes that accurate RF-REM construction methods should in the best case support operation with random and clustered signal measurements, their operation should not be affected by measurements outliers, and it must estimate signal levels comparably on all RF-REM locations with moderate computational effort.

Location Estimation of Satellite Radio Interferer Using CAF Map (CAF Map을 이용한 위성전파 혼신원의 위치추적)

  • Kang, Chul-Gyu;Oh, Chang-Heon
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2011.05a
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    • pp.718-721
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    • 2011
  • In this paper, cross ambiguity function map is proposed to estimate the location of a unknown interferer which emits the harmful radio in the satellite communication network. To estimate the interferer, a time difference between received radio signals at earth stations and a frequency difference caused by the movement of interferers or receiving earth stations are calculated. Therefore, cross ambiguity function is used to calculate that values. The calculating process of the time and the frequency differences using cross ambiguity function is operated at every designated time then the correlation values between the time and frequency are calculated. After calcuation, the final location of the harmful interferer is estimated. From the simulation results, about 800 m distance error is occurred at 10~4 dB of $E_b/N_0$ and about 13 km distance errer is occurred at -20 dB of $E_b/N_0$.

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Mapping USN Route by Integrating Multiple Spatial Parameters into Radio Propagation Model (다중 공간변수와 전파예측 모델을 통합한 USN 중계 경로망도 제작)

  • Kim, Jin-Taek;Um, Jung-Sup
    • Journal of Korea Spatial Information System Society
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    • v.10 no.1
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    • pp.51-63
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    • 2008
  • Previous studies for routing In USN (Ubiquitous Sensor Networks) appear to be unreliable due to the dependence on non-spatial data and the lack of map overlay analysis. Multiple spatial parameters and radio propagation modeling techniques were integrated to derive RSSI (Received Signal Strength Indicator) value between route nodes and produce a highly reliable path map. It was possible to identify area-wide patterns of USN route subject to many different Influences (e.g. the specific effects of radio blocking factors such as the visible area, road area, cell duplicated area, and building density), which cannot be acquired by traditional non-spatial modeling. The quantitative evidence concerning the USN route for individual cell as well as entire study area would be utilized as major tools to visualize paths in real-time and to select alternative path when failure or audition of route node occurs.

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