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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.

The ever-growing mobile station (MS) localization technologies provide an increasingly important role in all aspects of the wireless cellular systems and Internet of Things (IoT). The accurate MS location information is the basis in connection of different devices in IoT. The MS localization techniques based on time of arrival (TOA) trilateration algorithm, which determines the location of MS using an intersection point of three circles based on distances between MS and base stations (BS) and coordinates of BSs, have been actively studied. In general, the distance between the MS and BS is calculated by counting the number of delay samples or measuring the power of the received signal. Since the estimated distance (radius of a circle) between MS and BS is commonly increased, three circles may not meet at a single point, resulting in the estimation error of MS localization. In order to improve this problem, in this paper, we propose the hybrid TOA trilateration algorithm based on the line intersection algorithm for the general case for intersection of three circles and the comparison approach of intersection distances for the specific case where a small circle is located inside the area of two large circles. The line intersection algorithm has an excellent location estimation performance in the general case, but it does not work in the specific case. The comparison approach of intersection distances has good performance only for the specific case. In addition, we propose the mode selection algorithm to efficiently select a proper mode between the general and specific cases. The representative computer simulation examples are provided to verify the localization performance of the proposed algorithm.

In this paper, we present an efficient architecture of the adaptive beamforming satellite system based on the planar (square) array antenna. It is consisted of an Angle-of-Arrival (AOA) estimator for estimating AOAs of signals, an adaptive beamformer for suppressing interference signals and enhancing the desired signals, a signal processing & D/B unit for saving and processing data obtained from the received signal, and a transmission beamformer for transmitting signal information. Also, we provide computer simulation results to evaluate the performance of the presented system with different sizes of the square antenna array.

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.

The time-of-arrival (TOA) trilateration may have the serious estimation error, when three circles do not intersect at single point. In this paper, we classify all possible error cases of estimating the location of the mobile station (MS). In addition, we propose the individual estimation algorithms for each case, which are employed with a hybrid form.

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

On poly and single crystalline Cu substrates, the graphene was synthesized by chemical vapor deposition(CVD). Optical microscopic images which were not possible to show the detailed characterization of graphene growth were adjusted and analyzed using image analyzing software. As a result it was possible to show the detailed growth mechanism of graphene by utilizing the image analysis. Nucleation of graphene on Cu grain boundary and its growth behavior into Cu grain are shown. In addition, the movement of graphene grain boundary interacting with Cu grain boundary and pinholes during growth was illustrated in detail, and the cause and result are discussed as a result of those interactions.

위치 추정 기술 (LDT, Location Detection Technology)은 자원관리 및 통신 서비스의 품질을 향상시키기 위한 무선통신 분야에서 사용되고 있는 LBS(Location Based Service)의 핵심기술 중 하나이다. 이동국(MS, mobile station)의 위치는 세 개의 기지국(BS, base station)들의 좌표와 이동국과 기지국들 사이의 거리에 상응하는 반지름에 기초한 세 개의 원들에 기반한 도래시간(TOA, Time of Arrival)기법을 사용하여 추정된다. 삼각변 측량법을 이용하여 정확한 이동국의 위치를 추정하기 위해서는 세 개의 원들이 한 점에서 만나야 하는데, 이동국과 기지국의 거리를 추정하기 위한 시간지연 개수와 전송 주파수에 따라 원들의 반지름이 증가하여 세 개의 원들이 한 점에서 만나지 못하는 경우들이 발생한다. 반지름이 증가된 세 개의 원들은 여섯 개의 교점을 가지게 되고 이 교점들 중 세 개의 교점들이 특정 이동국의 좌표에 가까이 위치하게 된다. 본 논문에서는 여섯 개의 전체 교점들 중에서 세 개의 내부 교점들을 선택하는 TOA 삼각변 측량법을 위한 최단 거리 알고리즘을 제안한다. 제안된 방법은 여섯 개의 교점들 중 이동국의 좌표와 가장 가까운 세 개의 교점을 선택하고, 선택된 교점들의 평균 좌표를 특정 이동국의 위치로 결정한다. 제안된 알고리즘의 성능은 컴퓨터 시뮬레이션 예를 통해 확인된다.

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.

The time of arrival (TOA) trilateration, which is one of the representative localization algorithms, estimates the location of the mobile station (MS) based on the received signals from at least three base stations (BS). The MS location is determined at a single intersecting point of three circles with radiuses corresponding to distances between MS and BSs and centers corresponding to BS's coordinates. In general, three estimated circles may not meet at a single point, causing the location estimation error, because the distance between MS and BS is usually estimated by counting the number of delay samples, which it should be an integer but it is not originally integer, and it may be slightly increased. In this paper, we present the advanced TOA trilateration algorithms for solving the above problem, such as the line intersection algorithm, which has good performance in the general case, and the comparison approach of intersection distances which has good performance in the specific case where one relatively small circle is located inside the area of two large circles. In addition, we analytically prove that the comparison approach of intersection distances in the specific case has better performance for estimating the MS location than that of the line intersection algorithm.

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.

Recently, permanent magnet type linear synchronous motors have been used as a driving source of transportation systems, to satisfy requirements such as speeding up of transportation systems and also to simplify maintenance. The authors' laboratory has proposed a stationary discontinuous armature PM-LSM in which the armature is engaged only when accelerated and decelerated operation is necessary, in order to resolve the problem of higher costs, when PM-LSM is used with long-distance transportation systems in factories. However, the stationary discontinuous armature PM-LSM contains the outlet edges which always exist as a result of the discontinuous arrangement of the armature. These edges become a problem, because the cogging force that they exert influences the controllability of the motor. This paper presents the results of an experimental examination and three-dimensional numerical analysis by the finite element method of the cogging force exerted by the outlet edge. Moreover, we modified the permanent magnet on the mover to decrease the cogging force at the outlet edge, and the results are examined using three-dimensional numerical analysis by the finite element method.

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 TOA trilateration method decides the location of MS using an intersection point of three circles with centers corresponding three base station (BS) coordinates and radius based on the distance between MS and three BSs. Since the distance between BS and MS is generally estimated counting the number of time delay samples, the estimated distances are slightly increased and three circles may not intersect at a point. In this paper, we introduce the shortest distance and line intersection algorithms for improving conventional TOA trilateration method to resolve above problem. Also, the mathematic analysis is provided to indicate the relation between both algorithms.

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.

A sparse reconfigurable adaptive filter (SRAF) for a photonic switch consists of a large number of input and output delays, sparse reconfigurable connections, and adaptive weights. Recently, it was shown that a modified system-based (MSB) algorithm for the SRAF is more efficient than conventional algorithms such as previously introduced cross-correlation-based (CCB) and system-based (SB) approaches. In this paper, we propose a connection constraint for the MSB algorithm that chooses the most effective elements among the entire connection matrix. The proposed method allows any input to be connected to any output with an arbitrary weight, and is more efficient than the approaches mentioned above due to its reduced computational complexity. We provide a computer simulation example to demonstrate the performance of the connection-constraint algorithm for a system identification application.

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.

Adaptive algorithms can be an important component of a sparse reconfigurable adaptive filter (SRAF) for photonic switches. In this paper, we propose a modified system-based (MSB) algorithm that not only has good performance for white and non-white input signals, but also has a reduced computational complexity compared with conventional approaches such as the previous cross-correlation-based (CCB) and system-based (SB) algorithms. In order to improve the convergence rate of the system, the MSB algorithm separately updates each row or column of the switch weight matrix. We also consider a specific structure for the intermediate desired signals, and present a computer simulation example to demonstrate the performance of the proposed SRAF algorithm for a system identification application.

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 multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) is one of core technologies for the third generation (3G) and fourth generation (4G) communication systems. The efficient channel estimation scheme with relatively low estimation error is required for the MIMO-OFDM communication system. In this paper, we propose a channel estimation scheme based on the adaptive algorithm such as the least-mean-square (LMS) and a preamble signal architecture considering the guard subcarrier, which is suitable to MIMO-OFDM. The proposed algorithm which estimates channels in the time-domain has not only the low channel estimation error but the low peak-to-average power (PAPR) comparing to conventional techniques such as the least-square (LS). Computer simulation results are provided to illustrate the performance of the proposed algorithm for the channel estimation.

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.