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Owing to the escalating social and commercial interest on location-based services (LBS), research and development of indoor positioning systems (IPS) have been extended. Since the global navigation satellite system (GNSS) is not available at indoors, IPS research has been focused with alternative wireless technologies. Among them, Wi-Fi and Bluetooth Low Energy (BLE) have been widely used. In this paper, we discuss the RSS features of Wi-Fi and BLE measured under uniform conditions. Then, we show the typical weighted k-nearest neighbor (Wk-NN) fingerprinting positioning using Wi-Fi and BLE beacon individually for the IPS application. In addition, we propose a hybrid Wk-NN fingerprinting employing both BLE and Wi-Fi signals. The experiments were performed through real field deployments. The obtained results show that distance estimation and fingerprinting positioning accuracy using BLE is moderately better than Wi-Fi under identical AP deployment and signal attenuation condition. In addition, the proposed hybrid method shows better location accuracy compared to the BLE beacon and Wi-Fi when used individually.

The Angle-of-Arrival (AOA) has a variety of applications in civilian and military wireless communication fields. Due to the rapid development of the location-based service (LBS) industry, the importance of the AOA estimation technique has increased. Although a large antenna array is necessary to estimate accurate AOA information of many signals, the computational complexity of conventional AOA estimation algorithms, such as Multiple Signal Classification (MUSIC), is dramatically increased. In this paper, we propose a cascade AOA estimation algorithm employing CAPON and Beamspace MUSIC, based on a flexible (on/off) antenna array. First, this approach roughly finds AOA groups, including several signal AOAs using CAPON, by applying some of the antenna elements. Then, it estimates each signal AOA in the estimated AOA groups using Beamspace MUSIC by applying the full size of the antenna array. In addition to extremely low computational complexity, the proposed algorithm also has similar estimation performance to that of MUSIC. In particular, the proposed cascade AOA estimation algorithm is highly efficient when employing a massive antenna array. Representative computer simulation examples are provided to illustrate the AOA estimation performance of the proposed technique.

With the rise of new radio technologies, resource sharing mechanism has become a promising technique to achieve better system performance. Recently, the Fractional frequency reuse (FFR) method has gained more popularity to mitigate intra-cell interference generated by device-to-device (D2D) multicast communications into the traditional cellular networks. In this paper, we propose a weighted bipartite matching mechanism to accommodate the user’s satisfaction. Then, we formulate an optimization problem to maximize system throughput and satisfaction rate while guaranteeing the quality of service (QoS) of both cellular users and D2D multicast users. Simulation results show that the optimal system throughput is obtained by the proposed scheme and D2D multicast communication shows its effectiveness in maximizing overall system throughput, resource allocation satisfaction rate and spectrum efficiency.

In this paper, we discuss on the device-to-device (D2D) communication to fulfill the exponentially growing demands of the high data rate services. Multicast D2D communication is envisioned as a promising solution due to its advantages of high data rates and high spectrum efficiency. However, integrating D2D communication severely degrades the quality of service (QoS) of the network. To improve the QoS, we formulate a self-organizing resource allocation scheme using a stochastic algorithm for multicast D2D communication. Using the proposed algorithm, each uplink cellular resource can be simultaneously reused by the active D2D users in a network. Theoretical analysis and simulation results validate the proposed scheme.

The Global Positioning System (GPS) is designed to accurately estimate the location information of objects, using signals from at least four GPS satellites. When the high-power interference signals exist, the GPS receiver does not have the proper estimation performance. In this case, we need to enhance the desired GPS signals and to efficiently suppress interference signals. For this purpose, the adaptive beamformer based on the angle-of-arrival (AOA) is widely employed, but the AOA information of the GPS signal is not easily estimated. After conventional despreading, GPS AOA can be estimated using various AOA estimation algorithms such as Multiple Signal Classification (MUSIC), but the estimated result includes not only GPS AOA but also interference AOA at the high-power interference environment. In this paper, we propose a GPS AOA estimation algorithm, based on the composite despreader and the null despreader for multiple GPS signals. The AOA estimation result based on the composite despreading output includes AOAs of GPS and interference signals, and that based on the null despreading output includes only AOAs of interference signals. In order to determine GPS AOAs, we finally compare two results. The proposed algorithm efficiently estimates multiple GPS AOAs at a time, unlike the conventional technique.

Underlaying Device-to-device (D2D) communication is intimated as an encouraging technology for the next generation cellular network, where nearby devices can directly communicate to one another abstaining the evolved nodeB (eNB). In this paper, we propose a resource sharing mechanism which employs for multiple D2D communications by sharing a single cellular link simultaneously. In order to minimize the interference caused by multiple D2D pairs while sharing single cellular link at a time, we propose a metaheuristic algorithm based on the comprehensive interference minimization with reference to an uplink cellular network. The simulation results demonstrate that the proposed algorithm attains efficient performance compared with basic schemes.

Using the radio wave, RFID(: Radio Frequency IDentification) wirelessly transmits the unique information saved in a tag attached on the specific object. In the construction area, the trend in using RFID for managing the input and inventory of the construction materials is upward. General management systems for the construction materials have only a function of identifying the tag attached on the construction materials, but the management system with a function of identifying and managing the location information of the construction materials employing RFID, for reusing it, is not actively developed. For the efficient reuse of the construction materials, in this paper, we propose the RFID system with a function of estimating and saving the location information of the specific construction materials, based on the estimated distances between the particular subs and reader. The proposed system consists of RFID reader, distance estimate, communication, and memory units.

Due to the global warming, the restriction for emitting the green-house gas is strengthened and a main ingredient of the green-house gas is carbon dioxide (). In order to reduce the amount of , the low-carbon and long-life of the construction and the construction materials management system based on the radio frequency identification (RFID) technique have been actively studied in the construction field. The conventional construction management system based on RFID only focuses on the study and experiment for managing the used amount and location of the construction materials in the construction stage, but it does not consider the study for the status management system for the recycling materials in the construction stage or the building deactivation. In this paper, we propose the effective RFID system for managing the status of the construction materials during the construction stage or the building deactivation. Employing RFID with the frequency of 900MHz, the proposed system consists of the reader unit, communication unit, and memory unit, and its tags are attached in the surface or inside of the construction materials.

Device-to-Device (D2D) communication provides high data rate requirements within the available access network and is viewed as a promising solution for the increasing mobile data traffic. D2D communication carries out direct communication for users located in close proximity to each other, without passing through the eNB. However, integration of D2D communication in cellular network introduces technical challenges like interference among cellular users and D2D pairs, and D2D pairs and eNB for the uplink cellular system which deteriorates the system performance. In this paper, we propose a distance-based throughput optimization method for D2D communications in a sectored multicell system using fractional frequency reuse (FFR) method. The simulation results show that our proposed scheme significantly improves system performance by mitigating interference.

Wireless sensor networks are being deployed in different event monitoring applications where the location of a source node might indicate information such as the presence of valuable asset or person, the behavior of an event etc. Thus, strong location privacy preservation technique is always preferred by the sensor system. Although the content is secured with different encryption techniques, open wireless channel allows an adversary to analyze traffic patterns, trace back and locate the source node. To achieve source-location privacy, several techniques based on flooding, random walk and dummy traffic transmission are proposed for WSN. In this paper, we propose a new routing method that randomly forwards a packet towards the sink such that an adversary will find difficult in tracing the source location. We evaluate privacy of our proposed method in terms of success rate of an adversary. The simulation results show proposed routing strategy is better in preserving privacy.

Radio-frequency identification (RFID) is a tracking technology that enables immediate automatic object identification and rapid data sharing for a wide variety of modern applications using radio waves for data transmission from a tag to a reader. RFID is already well established in technical areas, and many companies have developed corresponding standards and measurement techniques. In the construction industry, effective monitoring of materials and equipment is an important task, and RFID helps to improve monitoring and controlling capabilities, in addition to enabling automation for construction projects. However, on construction sites, there are many tagged objects and multiple RFID tags that may interfere with each other’s communications. This reduces the reliability and efficiency of the RFID system. In this paper, we propose an anti-collision algorithm for communication between multiple tags and a reader. In order to suppress interference signals from multiple neighboring tags, the proposed algorithm employs the time-division (TD) technique, where tags in the interrogation zone are assigned a specific time slot so that at every instance in time, a reader communicates with tags using the specific time slot. We present representative computer simulation examples to illustrate the performance of the proposed anti-collision technique for multiple RFID tags.

D printer is based on an additive manufacturing technology, which helps in creating the three-dimensional object using a 3D drawing. It is used in various fields, because it prints out a variety of three-dimensional products in a short period of time. In this paper, we consider a technique using the FDM(Fused Deposition Modeling) method by dissolving the ABS(Acrylonitrile Butadiene Styrene) resin among a diversity of printing technique and materials. This kind of the 3D printer prints out a product in high temperature and cools down it. In this process, a flection phenomenon is occurred according to the size of the printing product and the surrounding environment. Conventional methods for mitigating this phenomenon maintain the temperature at the optimum level, but they require using additional devices. In order to minimize the flection phenomenon in 3D printing products without additional devices, in this paper, we propose a noble technique, which creates holes on suitable positions when they are designed by 3D drawing tools. Also, we suggest mathematical model for the proposed method, and measure and analyse a printing output using a proposed technique.

요 약차량 운행 시 주의분산으로 인한 자동차 사고가 증가 하고 있는데, 주의분산 행동은 전방 주시율, 차로 유지능력, 위험상황별 반응시간의 세 가지 항목에 대해 영향을 미친다. 많은 운전자들이 운행 중 라디오를 청취하게 되는데, 지역의 경계를 넘어가는 경우 특정 방송국의 라디오를 계속 청취하기 위해 라디오의 주파수를 변경하여야 한다. 이 과정에서 운전자의 주의분산이 발생하여 교통사고 발생 가능성이 높아지게 된다. 특히 고속도로에서는 빠른 속도로 차량이 주행하므로 사고의 위험이 더욱 높아지게 된다. 차량 운행 시 라디오 조작으로 인한 사고의 위험성을 줄이기 위해 본 논문에서는 각 방송국의 표준 라디오 주파수를 데이터베이스(D/B : date base)에 저장하고, 특정 지역의 경계에서 내비게이션으로부터 얻은 차량의 위치정보를 이용하여 변경된 지역의 라디오 주파수를 결정한 후, 기존의 주파수와 새로운 주파수를 이용하는 신호 중 수신율이 양호한 주파수를 선택하는 알고리즘을 제안한다. 양호한 수신율을 가지는 주파수를 선택하기 위해 두 주파수에 대한 신호의 신호-대-잡음비(SNR : signal-to-noise ratio)를 기준으로 사용한다. ABSTRACT

Radio frequency identification (RFID) is an important and essential components of ubiquitous computing, with the development of wireless communication technologies and mobile computing environment. Recently, RFID becomes the mainstream application that helps fast handling and uniquely identifying the physical objects. It utilizes the electromagnetic energy for data transmission from a tag to a reader in the presence of arbitrary interference and noise. In order to employ the portable mobile RFID reader, a tag-collision problem between two or more adjacent tags should be considered. In this paper, we present the operation of RFID system in which numerous tags are present in the interrogation zone of a single reader at the same time. Since there may exist a number of tagged objects in the narrow area, multiple RFID tags may interfere each other, caused to degrade the data reliability and efficiency of the RFID system. In order to suppress interference signals from multiple neighboring tags, we present an application of Gold code for RFID communication system, which uses spread spectrum technique. In this RFID system, data bits are spreaded in each tags with the unique Gold code and the spreaded data bits are despreaded in the reader with the same Gold code. The performance analysis of the considered RFID anti-collision system is illustrated via computer simulation examples.

RFID (Radio Frequency Identification), which is a kind of the electronic tag, is a wireless access device using the radio frequency for recognizing the ID information. It has a variety of application such as the bus card, gate access card, distribution industry, and management of construction materials. The performance and size of RFID depend on the penetrability, recognition ratio, memory size, multi tag recognition, external pollution dust, and exterior impact, and RFID requires the packaging to protect itself considered above factors. Recently, RFID is diversely employed to effectively manage construction materials and the RFID packaging, which is robust to the external impact, is required to attach RFID on construction materials. In this paper, we propose the construction material RFID packaging designed to be robust for the external impact and to be practicable for change of the broken RFID. For the change of RFID, we separate the cast and body of the packaging. Also, we present the detail drawing for the proposed construction material RFID packaging and implement the performance evaluation of the packaging manufactured using 3D printer.

Tire Pressure Monitoring System (TPMS) is an auxiliary safety system for recognizing the condition of tires based on the pressure and temperature data transmitted from the sensor unit installed on a tire of the vehicle. Using TPMS, a driver can frequently check the state of tires and it aids to maintain the optimum running condition of the vehicle. Since TPMS must utilize the wireless communication technique to transmit data from a sensor unit to a signal processing unit installed in the vehicle, it suffers from interference signals caused by various external electrical or electronic devices. In order to suppress high-power interference signals, we employ beamforming techniques based on the uniform linear antenna array. As the number of the antennas is increased, the performance of the interference suppression is improved. However, there is the limit of the number of antennas, installed in the center of a vehicle, because of its size. In this paper, we compare and analyze the performance of the beamformer, when reducing the interelement spacing of antennas, to increase the number of the receiving antennas. For the performance analysis of the beamformers, we consider the switching beamformer and minimum-variance distortionless-response (MVDR) beamformer for TPMS, recently proposed.

Wireless Body Area Network (WBAN) is a special purpose sensor application network which can be applied for applications relating to the health care. WBAN should support immediate and reliable data transmission for medical service during an emergency situation. Hence this paper proposes a new MAC superframe structure which can handle emergency data as well as a regular periodic data at the time of emergency. Simulation result shows low latency and increased throughput of the proposed superframe.

There has been an upward trend in the requirement of indoor positioning systems using bluetooth low energy (BLE), Wi-Fi, and visible light communication. In order to realize the indoor positioning with these communication systems, techniques such as fingerprinting, trilateration, and triangulation have been widely studied. Even though fingerprinting has been chosen as a representative approach in many literatures, it is known as tedious and time consuming method due to the long-time location learning phase. Therefore, the fingerprinting is expected to be integrated with other methods to enhance the location accuracy and reduce the location estimation procedures. In this work, we discuss one of these methods used for indoor positioning, i.e., weighted centroid localization (WCL) using received signal strength indicator (RSSI) observed from neighboring BLE beacons. The WCL is evaluated in our testbed building and analyzed to configure its parameters for indoor positioning.

A TPMS(Tire Pressure Monitoring System) is a wireless communication system designed to monitor the pressure and temperature of pneumatic tires of a vehicle. In order to provide the aid in protecting a driver, this system reports tire pressure information to the driver of the vehicle. Since the wireless communication technique should be employed to transmit the TPMS data from each tire to signal processing unit in the vehicle, it suffers from interference signals from external electrical or electronics equipments. In this paper, we propose the TPMS interference cancellation technique based on GSC(Generalized Sidelobe Canceler), which does not have only the excellent performance like MVDR(Minimum-Variance-Distortionless-Response) but also has the low computational complexity comparing with MVDR. The performance of interference suppression is conformed by computer simulation examples.

A TPMS is a wireless communication system designed to monitor its condition inside the pneumatic tires on various types of vehicles. These systems report the tire pressure information to the driver of the vehicle. While wireless communications is used to transmit the measurement data from TPMS sensors to a central processing unit in the vehicle, it suffers from the various interferences such as sensors of each tire or outside electrical equipments. Based on the conventional beamformer, a switching beamforming technique is proposed to minimize the interference and efficiently receive valid data. Moreover, in order to minimize the interference and reduce power consumption for communication, a system with unique Gold Code is presented for each tire. The performance of interference suppression is illustrated by computer simulations.

In this paper, we propose an advanced partial encryption of watermarking and scrambling using the magnitude information of Modifed Discrete Cosine Transform (MDCT). In MPEG-1/Audio Layer III (MP3), the magnitude and phase information of modified discrete cosine transform (MDCT) coefficients is encrypted. The proposed method uses both watermarking and scrambling, and aims at protecting the contents against eavesdropping and moreover against illegal mass distribution after descrambled. Experimental results show that the proposed method can achieve higher security and less computational complexity by reusing the MDCT coefficients obtained in MP3.

The Global Positioning System (GPS) utilizes low-power spread-spectrum signals and thus is vulnerable to various types of high-power interference sources. It requires at least four satellites for estimating three-dimensional user positions and the receiver clock bias. In this paper, we propose a blind adaptive GPS receiver that is based on a new despreader and the one-stage constant modulus (CM) array. The despreader consists of a conventional GPS despreader and a so-called null despreader, which together modify the received signal so that the CM array can extract the GPS signal of interest. The beamformer not only rejects jammers and extracts the GPS signal of interest without explicit direction-of-arrival (DOA) information of any of the signals but also it has a low computational complexity compared with conventional techniques, such as minimum-variance distortionless-response (MVDR) beamforming. As a conventional despreader can recover only one GPS signal, multiple despreaders are usually required for separating multiple GPS signals. We also explore an extension of the proposed null despreader to detect multiple GPS signals. Computer simulation examples are presented to illustrate the performance of the receiver for different types of jammer signals. Copyright © 2010 John Wiley & Sons, Ltd.

This paper describes a method for achieving highway lane differentiation without requiring expensive global navigation receivers in every vehicle. Accurate lane identification can be used to optimize transportation network safety, by improving a vehicle's ability to avoid collision and to safely complete lane- change maneuvers. Using a cooperative technique, each vehicle communicates with road infrastructure and nearby connected vehicles to achieve sub-meter lane identification. We assume that a small subset of vehicles have high-accuracy GPS localization, which we refer to as probe vehicles. Other vehicles use location information from the probe vehicles and fixed infrastructure anchors to improve their position estimates.

Radio-frequency identification (RFID) communication system known as auto-id has experienced tremendous growth worldwide, considering as a flexible mechanism for identification of objects. Degradation of data transmission due to external interference and interference of RFID system itself (tags and reader collision) is one of the most important factors to restrict the development of the RFID system and has a direct bearing on the performance of the whole system. In order to eliminate the tag collision problem in an RFID system variety of different anti-collision algorithms have been proposed by many researchers for the successful adoption of RFID on a massive scale. Synthesizing much anti-collision algorithm and conducting in-depth analysis, we propose a new combined primary digital transmission technique based on time division (TD) and gold code to efficiently suppress tag-to-tag interference.

The global positioning system (GPS) was designed to provide location estimates for various civilian and military applications using at least four satellites. Since GPS signals have a low signal-to-noise ratio (SNR), they also have a low signal-to-jammer ratio so that the accuracy of location estimates is influenced by cochannel interference and intentional jammers. We propose a low-complexity blind adaptive receiver that is based on a novel modified despreader and the constant modulus (CM) array. This system is capable of nulling directional interference and capturing the GPS signal of interest without requiring explicit angle-of-arrival (AOA) information. We also consider the multiple satellite problem and extend the proposed receiver to capture several GPS signals of interest. Representative computer simulation examples are presented to illustrate the performance of the multicomponent system for the suppression of different jammer types.

The global positioning system (GPS) is a one-way satellite-based navigation system employing spread-spectrum techniques that is widely used for commercial and military applications. Although the very low signal-to-noise ratio (SNR) is handled by the large spreading gain, GPS is susceptible to high-power interference signals and various types of jammers. We propose multicomponent receiver architectures for GPS interference suppression. A conventional antenna system is first considered which utilizes a minimum-variance distortionless-response (MVDR) beam former and assumes that the GPS signal angle of arrival (AOA) and the antenna model are known at the receiver. However, this receiver is sensitive to AOA estimation errors and can have a high computational complexity. This sensitivity problem is eliminated by a multicomponent system based on a multistage matched filter (MF). Since this MF receiver also has a high computational complexity because the jammer AOAs must be estimated, we introduce a blind interference canceler based on the constant modulus (CM) array that is insensitive to AOA estimation errors and has a low computational complexity. Computer simulations are provided to illustrate the performance of the various systems for interference suppression in example signal scenarios.

The time of arrival trilateration method is one of the representative algorithms for the location detection technology, which estimates the location of mobile station (MS) at a unique intersection point of three circles with radiuses corresponding to distances between MS and base stations (BSs) and centers corresponding to coordinates of BSs. However, there may be serious estimation errors, when they do not meet at a point because the estimated radiuses of them are increased. The solutions for reducing the estimation position error in the main case of meeting three circles with the extended radius have been recently provided as the shortest distance algorithm and the line intersection algorithm. In general, they have good performance for the location estimation, but they may have serious errors in some cases. In this paper, we propose the efficient location estimation algorithm for the specific case of two large circles and one relatively small circle, which is located in the area of two large circles. In this case, there are six intersections in total based on the three extended circles and a small circle has four intersections with two large circles. The proposed approach compares four distances based on four neighboring intersections and selects the shortest one. Finally, it determines the averaged coordinate of two intersections corresponding to the shortest distance, as the location of MS. The location-estimating performance of the proposed algorithm is illustrated by the computer simulation example.

The Tire Pressure Monitoring System (TPMS) displays the state of a tire on a display to inform a driver of the relevant information, by means of a sensor installed on the tire of the vehicle. When the data measured from the tire are wirelessly transmitted to a receiving antenna located in the center of the vehicle, the exact transmission of data is affected by the interference from various external electronic and electrical devices. In this paper, we suggest a minimum variance distortionless response (MVDR) beamformer based on the angle-of-arrival (AOA) vector for suppressing external interference and receiving accurate data. Although the MVDR beamformer effectively suppresses the interference, it has high computational complexity because of the calculation of an autocorrelation matrix. In order to address this issue, we also suggest a generalized sidelobe canceler (GSC) beamformer which does not have the same performance of the interference suppression to MVDR but also has low computational complexity. Since the signal from each tire can cause interference to others, we consider utilizing a unique Gold Code to each tire to minimize intertire interference and reduce power consumption of a battery installed in each tire.

The interference suppression technique is one of core techniques for the wireless sensor communications. In this paper, we focus on the Tire Pressure Monitoring System (TPMS) interference suppression among the wireless sensor communication techniques. The TPMS is an auxiliary safety device for measuring pressure and temperature, wirelessly transmitting the data to the central processing unit (CPU) of a vehicle and displaying the state of a tire on a display to inform a driver of the relevant information, by means of a sensor installed on the tire of the vehicle. When the data measured from the tire are wirelessly transmitted to a receiving antenna located in the center of the vehicle, exact transmission of data is affected by the interference from various external electronic and electrical devices. In this paper we suggest a minimum-variance distortionless-response (MVDR) beamformer based on the angle-of-arrival (AOA) vector for suppressing external interference and receiving accurate data. Although the MVDR beamformer effectively suppresses the interference, it has high computational complexity because of calculation of an auto-correlation matrix. In order to address this issue, we also suggest a generalized sidelobe canceler (GSC) beamformer which does not have the similar performance of the interference suppression to MVDR, but also has low computational complexity. Since the signal from each tire can cause interference to others, we consider utilizing a unique Gold Code to each tire to minimize inter-tire interference and reduce power consumption of a battery installed in each tire. The performance of the proposed interference suppression technique is verified through computer simulation.

The Tire Pressure Monitoring System (TPMS) is a wireless communication system designed to monitor the condition of a vehicle tire, based on the transmitted data from the tire sensor. This system reports the tire pressure or temperature information of tires to a driver. While wireless communications is used to transmit the measurement data from TPMS sensors to a central processing unit in the vehicle, it suffers from various interferences such as signal of each tire sensors or outside electrical equipments. In this paper, we propose a switching beamformer based on the conventional beamformer to suppress the outside interference signals and to efficiently receive effective data. In order to suppress interferences due to sensors of each tire and to save the power consumption for the communication, we assign the unique gold code to each tire. Moreover, we propose the data architecture of the duplex wireless communication for the TPMS to maximize the power efficiency of the battery. The performance of the proposed system is illustrated by computer simulations.

The Global Positioning System (GPS) is one of the core technologies for the Location Based Service (LBS), and has various applications from the leisure business to the military. LBS requires accurate location information of an object, which GPS estimates using at least four satellites. In order to enhance the GPS signal quality, angle-of-arrival (AOA) information is required, but these are difficult to estimate because the system operates with a low signal-to-noise ratio (SNR) and in the presence of high-power interference. In this paper, we explore an extension of a recently proposed GPS AOA estimation technique based on a modified despreader for multiple GPS signals. Since the extended estimator does not require a singular value decomposition (SVD), unlike conventional AOA estimation algorithms such as Multiple Signal Classification (MUSIC), it has a relatively low computational complexity. Also, this technique does not need to choose the GPS AOAs from all estimated AOAs because those of the interference signals are not estimated. We demonstrate the performance of the GPS AOA estimation algorithm for multiple satellites via a computer simulation example.

The Global Positioning System (GPS) is designed to estimate the locations of users or objects, and has a variety of civilian and military applications. Although angles-of-arrival (AOAs) may be required to enhance the desired GPS signals, it is difficult to estimate explicit AOA information because a GPS signal has a low power relative to the noise level. In this paper, we propose a GPS AOA estimation method based on a modified despreader and the constant modulus (CM) array cost function. This technique has a low computational complexity compared with other AOA estimation methods, such as the Multiple Signal Classification (MUSIC) algorithm, because it does not require a singular value decomposition (SVD). It also has good estimation performance in low signal-to-noise ratio (SNR) environments.

The Global Positioning System (GPS) requires at least four satellites to achieve the best accuracy for location estimation. Since a conventional despreader can recover only one GPS signal, multiple despreaders are usually required for separating multiple GPS signals. In this paper, we explore an extension of a recently proposed GPS receiver that consists of a conventional despreader and a so-called null despreader, along with the multistage constant modulus (CM) array, to detect multiple GPS signals. This system does not require explicit direction-of-arrival (DOA) information about the GPS signals in order to reject directional interference. We present a computer simulation example to illustrate the jammer suppression performance of the proposed system for multiple GPS signals

The Global Positioning System (GPS) utilizes low- power spread-spectrum signals and thus is vulnerable to various types of high-power interference sources. In this paper, we propose a blind adaptive GPS receiver that is based on a new despreader and the one-stage constant modulus (CM) array. The despreader consists of a conventional GPS despreader and a so- called null despreader which together modify the received signal so that the CM array can extract the GPS signal of interest. The beamformer rejects jammers without explicit direction-of- arrival (DOA) information of any of the signals. A computer simulation example is presented to illustrate the performance of the proposed receiver for different types of jammer signals.

The Global Positioning System (GPS) utilizes low-power spread-spectrum signals which are vulnerable to many kinds of high-power interference signals and jammers. We propose a low-complexity blind adaptive receiver that is based on a novel modified despreader and the one-stage constant modulus (CM) array. This system is capable of nulling directional interference and capturing the GPS signal of interest without requiring explicit angle-of-arrival (AOA) information. Computer simulations are provided to illustrate the performance of the multicomponent receiver for a combination of different types of jamming signals.

A nonblocking photonic switch can be used to implement a tapped delay line with a large number of coefficients and a wide range of time delays. In this paper, we present a sparse reconfigurable adaptive filter (SRAF) based on a photonic switch with an input/output connection architecture that can be represented by a matrix of adaptive weights. This unique parallel structure can be reconfigured in an adaptive manner to implement a sparse filter impulse response for a variety of applications. The appropriate choice of time delays is determined from a cross-correlation function between the filter input and a desired response signal that depends on the particular application. A computer simulation example illustrates the performance of the algorithm for modeling a bandpass filter characteristic.

The Global Positioning System (GPS) was designed to provide location estimates for various civilian and military applications using at least four satellites. Since GPS signals have a low signal-to-noise ratio, they also have a low signal-to-jammer ratio, and thus the accuracy of these estimates is influenced by cochannel interference and intentional jammers. In this paper, we explore an extension of a recently proposed blind multicomponent jammer rejection system, which is based on a modified despreader, to extract multiple GPS signals. This extended system also operates blindly to null directional interference and capture all GPS signals of interest without requiring explicit knowledge of their angles-of-arrival. A representative computer simulation example is presented Io illustrate the performance of the multicomponent system for the suppression of different jammer types.

The Global Positioning System (GPS) is a satellite-based navigation network employing spread-spectrum techniques that is widely used for commercial and military applications. Although the large spreading gain of GPS allows for operation in very low signal-to-noise ratio environments, the received signals are vulnerable to various types of narrowband and wideband interference. In this paper, we propose a blind multi-component adaptive receiver based on the constant modulus (CM) array that cancels the high-power interference and recovers the GPS signal of interest without using a priori direction-of-arrival information or training data. The performance of the system at the output of each component is illustrated via computer simulations for an example signal scenario. Expressions for the output signal-to-interference-plus-noise ratio are also provided in order to investigate the steady-state properties of the system.

The Global Positioning System (GPS) is a one-way satellite communication system that is widely used for both civilian and military applications. Because of the relatively low power of the received signals, GPS is highly susceptible to a variety of intentional and unintentional interferers. In this paper we examine a multistage space-time adaptive-processor (STAP) that is used to improve the detection capability of a GPS receiver for a wide range of jamming scenarios. Depending on the type of interference, the stages incorporate structures such as a notch filter, a beamformer and a blind linear interference canceler. Computer simulations are provided to illustrate the performance of the multistage receiver for wideband and narrowband interferers.

The location determination technology (LDT) is one of the core techniques for the location-based services (LBS) which has various applications, including a mobile robot, for the modern wireless communication system. The time of arrival (TOA), which is a kind of LDTs based on the cellular network, estimates the location of the specific user or object using a trilateration method based on the received signals from three base stations (BS). The true location of a mobile station (MS) is determined based on an intersection point of three circles with the radius corresponding to the distance between each BS to MS. Since the TOA method estimates the distance between BS and MS using the number of time delay, these three circles should not generally meet at a point and the performance of the location detection should be degraded in this case. In order to overcome this problem, we propose the mobile location detection algorithm based on a line intersection of the TOA geometry. In the case of those three circles do not meet at a point; in general, there are six intersection points and three lines which connect two intersection points. In this paper, we determine an intersection point of three lines as the location of a MS. The computer simulation example is provided to illustrate the location detection performance of the proposed algorithm.