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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 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.

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 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.

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.