Claudio Palestini

LTE adaptation for mobile broadband satellite networks

One of the key factors for the successful deployment of mobile satellite systems in 4G networks is the maximization of the technology commonalities with the terrestrial systems. An effective way of achieving this objective consists in considering the terrestrial radio interface as the baseline for the satellite radio interface. Since the 3GPP Long Term Evolution (LTE) standard will be one of the main players in the 4G scenario, along with other emerging technologies, such as mobile WiMAX; this paper analyzes the possible applicability of the 3GPP LTE interface to satellite transmission, presenting several enabling techniques for this adaptation. In particular, we propose the introduction of an inter-TTI interleaving technique that exploits the existing H-ARQ facilities provided by the LTE physical layer, the use of PAPR reduction techniques to increase the resilience of the OFDM waveform to non linear distortion, and the design of the sequences for Random Access, taking into account the requirements deriving from the large round trip times. The outcomes of this analysis show that, with the required proposed enablers, it is possible to reuse the existing terrestrial air interface to transmit over the satellite link.

Robust Code Acquisition in the Presence of BOC Modulation for Future Galileo Receivers

The problem of code acquisition for the Galileo system is investigated in this paper. The effect of non-ideal sampling on the binary offset carrier (BOC) modulated signal is evaluated and a novel detection scheme, identified as Quadribranch, is proposed. Detection performance is investigated by analysis and simulations taking into account frequency errors and non ideal sampling with actual Galileo signals. The notable result is that Quadribranch is able to improve performance in terms of detection probability and mean acquisition time, and, differently from the conventional approach, allows to achieve robust code acquisition without oversampling.

Impact of high-end receivers in a peer-to-peer cooperative localization system

This paper introduces the concept of peer-to-peer cooperation as an aiding technique in GNSS positioning and addresses the impact of the presence of professional receivers in the network. The impact of their higher accuracy is evaluated for the cases of both GNSS-data only and hybrid data exchange. Kalman Filters are considered as the data fusion engine.

Hierarchical code acquisition for dual band GNSS receivers

This paper tackles the problem of fast acquisition for dual band GNSS receiver. In particular, a novel technique is proposed based on the exploitation of the hierarchical structure of the Galileo E1 and E5 Open Service signals. The new procedure is based on the information exchange between the acquisition blocks of the two bands, and on the reduction of the uncertainty region in one band when the signal in the other one is already acquired. Numerical evaluation shows that the proposed method allows to achieve good performance in terms of Mean Acquisition Time with respect to classical stand alone acquisition while guaranteeing at the same time a significant complexity reduction.

Integrated NAV-COM Systems: Assisted Code Acquisition and Interference Mitigation

In this paper, the problem of code acquisition for global navigation satellite systems (GNSS) is investigated in the presence of interference. A low-complexity interference mitigation technique is proposed to combat the effect of interference, which offers the potential for improved performance especially when high power jammers affect the reception. For practical implementation, an integrated navigation-communication network architecture is proposed, composed by an assistance network to aid code synchronization and an interference management system, augmenting the GNSS local component to enhance the system quality of service. Accordingly, an overall assistance network is proposed to estimate the interference characteristics and broadcast them to conventional terminals along with a rough time and frequency reference to improve code acquisition performance. Analytical and simulated results are provided, in the presence of binary offset carrier (BOC) modulation, showing the clear potential of assistance GNSS to significantly improve performance and reduce terminal complexity at the same time.

Cross-Band Aided Code Acquisition in Dual-Band GNSS Receivers

The problem of fast code acquisition in dual-band Galileo receivers is tackled. The proposed techniques exploit the Galileo E1 and E5 Open Service signals structure, implementing a cross-band aiding approach that yields mutual assistance in code synchronization adopting a master/slave configuration. The schemes are analyzed in terms of mean acquisition time (MAT) introducing the procedure flow-graph and overall mean acquisition time (OMAT). Numerical evaluation shows enhanced OMAT performance w.r.t. autonomous dual-band acquisition, guaranteeing complexity reduction.

Direct sequence spectrum spreading techniques for next generation mobile broadband satellite services

The recently approved mobile version of the Digital Video Broadcasting Return Channel via Satellite (DVB-RCS+M) foresees the use of direct sequence spectrum spreading (DS-SS) in the forward link. The addition of a spreading mode, on top of the conventional time division signaling structure of the fixed DVB-S2, allows in fact for the efficient extension of DVB-S2 to mobile terminals with small aperture antennas operating in Ku (11–14 GHz) and Ka (20–30 GHz) bands. Spectrum spreading has been introduced to augment the received energy without increasing the transmitted power density, which is limited by regulatory constraints, and to enhance the waveform resilience to co-channel interference. In this paper, we report on the design and assessment of the DS-SS technique that we carried out for its inclusion in the DVB-RCS+M standard. In particular, by comparing the physical layer performance of the spread and nonspread modes in the specific DVB-RCS+M mobile scenarios, we show that the proposed DS-SS technique has no impact on the DVB-RCS+M data detection performance, while satisfying the requirements on interference resilience and received energy augmentation. In order to deal with the acquisition issues raised by the introduction of the DS-SS technique, we then propose and evaluate several synchronization sub-systems able to deal with the specific impairments of the mobile satellite scenarios, that is, large frequency offsets, phase noise, link obstructions, etc. Finally, a possible implementation of the DS-SS technique that fully accommodates the reuse of the specific hardware compatible with conventional DVB-S2 is also reported. Copyright

An insider view on tracking loops: A novel ultra-tight GNSS/INS hybridization approach

This paper tackles the issue of increasing GNSS receivers reliability by presenting a novel ultra-tight integration scheme identified as Gaussian AUtocorrelation Scaled Sum (GAUSS). This hybridization approach is based on the concept that a completely artificial autocorrelation peak, generated starting from the information provided by the inertial sensors can be fused non-coherently into the received signal autocorrelation function to enhance the receiver robustness in harsh conditions as in the presence of interferers and multipath.

A performance and complexity optimization of joint code and frame synchronization for DVB-S2/RCS mobile

This paper analyzes the possibility to perform joint frame synchronization and code acquisition for the DVB-RCS mobile system. Since the standard foresees the adoption of Direct Sequence Spread Spectrum techniques, novel detectors able to cope with the scenario at hand are proposed. Comparison in terms of Mean Acquisition Time and complexity are carried out, and the best solution in terms of performance / complexity tradeoff is identified.

The Single Frequency Satellite Network Concept: Multiple Beams for Unified Coverage

This paper investigates the concept of Single Frequency Satellite Networks (SFSNs), whereby multiple satellite beams that have no form of mutual phase coherence are unified through baseband signal processing to achieve uniform coverage across wide areas. We present a realistic application scenario and its link budget analysis, which allows to highlight the advantages with respect to a classic single beam approach. Our technique is based on the use of orthogonal frequency division multiplexing and on the creation of synthetic multipath at the gateway, realizing a form of delay diversity. The synthetic power delay profile is beam specific, and it is the key instrument that allows to avoid destructive interference amongst the signals transmitted from the multiple beams. The main benefit is that homogeneous coverage is guaranteed with a generic multi-beam antenna, that can be easily reconfigured according to traffic and service needs.