Assisted Global Navigation Satellite Systems: An Enabling Technology for High Demanding Location-Based Services

[110316.EG Anno 2011, non 2010

On the Role of Stratolites as Local Elements of EGNOS and Galileo

The use of High Altitude Platforms (HAPs) assupport infrastructure for communications is becoming a relevant topic ofinterest for the research activities on future generation systems. In particular, due to their privileged position (stratosphere), these infrastructures are potentially able to yield advantages in the provision of navigation and positioning services: they can exploit the best features of both satellite-based and terrestrial augmentation systems for GlobalNavigation Satellite System (GNSS). Starting from the results presented in [5], in this note it is described how the Stratolite system [2] can be integrated with the EGNOS [6] systemincreasing the overall navigation performances at the user leve

Automatic Object Detection on SAR Images for UAV-HALE Surveillance Systems

This paper deals with the automatic detection of Objects of Interest (OOIs) in SAR (Synthetic Aperture Radar) still images. A particular scenario in which a Light-SAR is part of the payload for HALE (High Altitude Long Endurance) platform, named Heliplat, currently under development at the Politecnico di Torino. This unmanned, solar powered aeronautical vehicle is especially tailored for operations at altitudes between 15 and 25 Km with a potential endurance of weeks to months. It could provide a wide range of potential applications within telecommunication and remote sensing: in this paper a particular surveillance application, the reconnaissance over sea regions, has been focused

Multiple DLL architecture for multipath recovery in navigation receivers

Smce the Selective Availability was turned off, one of the major error sources in GNSS user positioning is represented by the deleterious superimposition of the same SIS due to obstruction and ground reflections (multipath). Such an ermr component is the most critical in case of urban (or indoor) navigation due to the high density of possible scatterers around the receiver. In this paper, a multiple Delay Lock Loop (DLL) architecture for navigation receivers, which is derived from the philosophy of the RAKE receiver for communication, is proposed. In this sense, it is quite diITerent from common multipath rejection techniques almady proposed, where the multipath is not tracked. Simulation mults of the innovative scheme highlight the increased performance with respect to common multipath rejection techniques

Assisted Global Navigation Satellite Systems: An Enabling Technology for High Demanding Location-Based Services

[110316.EG Anno 2011, non 2010

On the use of Galileo SIS and Cellular signals for identification of an hybrid positioning system

Mobile emergency calls need accurate automatic location information. At the present time, several emergency calls are unserved due to the absence of sufficient location information. Regulamentory recommendations and the necessity of providing added value services are driving towards the design of mobile user terminals with improved capabilities, and able to match suitable accuracy requirements. In this paper the positioning accuracy improvement by means of a joint use of Global Navigation Satellite Systems and measurements from Base Transceiver Stations of the cellular network is discussed. A theoretical framework is derived and simulation results are shown in order to demonstrate the performance improvement with respect to pure cellular location techniques

A Hybrid Positioning Algorithm for Cellular Radio Networks by using a Common Rake Receiver Architecture

The development of context-aware services is strongly pushing the integration of positioning capabilities in personal communication terminals, with particular attention to third generation systems (UMTS). On the otlher hand, the synergy between comunication and positioning can be of aid for this latter easing the acquisition and tracking of weak signals, and improving performance. In order to provide the user of reliable positioning solutions a suitable receiver dealing both with navigation and communication signal is reqpired. In this paper, a new hybrid positioning algorithm and a joint receiver structure able to receive and process signals broadcast from both navigation satellite systems and cellular radio networks, is presented, discussing the impact on the joint receive

The Stratolite concept: Design of a Stratospheric Pseudo-satellite for Galileo

The development of the Galileo program is currently dealing with the definition of the local elements in order to complete the overall system architecture. The design of original systems, different and improved with respect to the traditional local segments of GPS may enrich Galileo of additional features providing added value to the system. In this paper, we propose a novel local area augmentation system based on the use of stratospheric High Altitude Platforms (HAPs), unmanned aircraft performing long endurance operation at an altitude of about 20 km. Several aeronautical projects developed in different research laboratories around the world demonstrate that the design of a "near eternal airplane" is a feasible task, and that such aircrafts will be delivered in a near future at affordable costs [1][2]. For these reasons HAPs are candidate to host payload for the provision of communications services over large regions, playing the role of very small satellites almost stationary and near to the ground with respect to low Earth orbit spacecrafts. This paper discusses the use of HAPs for the provision of augmentation signals for Galileo (aerial transponder for local differential corrections), and introduces the concept of stratolite (stratospheric-pseudo-satellite), as an aerial pseudo satellite able to provide differential corrections modulated over a satellite-like signal. The main topics of the system concept definition are discussed in order to demonstrate the feasibility of a payload providing navigation services and the expected advantage

Linear subcodes of turbo codes with improved distance spectra

Abstract—In this correspondence, we present a technique for generation of linear subcodes of a given turbo code with better distance spectrum than the original mother turbo code, via an iterative process of trace-bit injection which minimallyr educes code rate, followed byselecti ve puncturing that allows recoveryof the rate loss incurred during the trace-bit injection. The technique allows for asymptotic performance improvement of any linear turbo code. In effect, we trim the distance spectrum of a turbo code via elimination of the lowdistance and/or high multiplicitycodew ords from the output space of the code. To this end, we perform a greedyminimization of a cost function closelyr elated to the asymptotic bit error probability (or frame error probability) of the code. This improves the performance of the code everywhere, but its main impact is a reduction in the error floor of the turbo code which is important for delayconstrained applications employing short interleavers