Multi-gateway Data Predistortion for Non-linear Satellite Channels

in IEEE Transactions on Communications (2015), 63(10), 3789-3802

Generalized direct predistortion with adaptive crest factor reduction control

in Proceedings of ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing (2015), 2015-August

Efficient power amplification is inherently a non linear operation that introduces unwanted interference in the amplified signal. Strong inter-symbol interference is generated when the amplifier non ... [more ▼]

Efficient power amplification is inherently a non linear operation that introduces unwanted interference in the amplified signal. Strong inter-symbol interference is generated when the amplifier non linearity is combined with channel memory effects. Further, signals with very high peak to average power ratio, typical of multiple carrier systems, are even more sensitive to the non linearities resulting in severe distortion effects. Signal pre-clipping (crest factor reduction) and predistortion are conventional countermeasure techniques to reduce the generated non linear distortion and improve power and spectral efficiency. In this work, novel optimization methods for predistortion and pre-clipping are analytically derived for a general non-linear communication channel with memory. A combined architecture in which crest factor reduction is followed by signal predistortion is proposed and the parameters are estimated resorting to iterative algorithms based on least squares method. Performance evaluation of the estimation techniques shows the effectiveness of the derived algorithms and significant gain compared to previously known methods. © 2015 IEEE. [less ▲]

A MIMO Symbol Rate Signal Digital Predistorter for Nonlinear Multicarrier Satellite Channels

in IET Communications (2015), 9(15), 20532059

A digital predistortion (DPD) scheme is presented for non-linear distortion mitigation in multi-carrier satellite communication channels. The proposed DPD has a multiple-input multiple-output architecture ... [more ▼]

A digital predistortion (DPD) scheme is presented for non-linear distortion mitigation in multi-carrier satellite communication channels. The proposed DPD has a multiple-input multiple-output architecture similar to data DPD schemes. However, it enhances the mitigation performance of data DPDs using a multi-rate processing algorithm to achieve spectrum broadening of non-linear operators. Compared to single carrier (single-input single-output) signal (waveform) DPD schemes, the proposed DPD has lower digital processing rate reducing the required hardware cost of the predistorter. The proposed DPD outperforms, in total degradation, both data and signal DPD schemes. Further, it performs closest to a channel bound described by an ideally mitigated channel with limited maximum output power. [less ▲]

Performance Analysis of Fractionally Spaced Equalization in Non-linear Multicarrier Satellite Channels

in Proceedings of 32nd AIAA International Communications Satellite Systems Conference (ICSSC), (2014, August 05)

Joint amplification of multiple carriers with a single wideband high power amplifier (HPA) has been considered towards reusing the satellite resources among multiple links to reduce the mission cost. The ... [more ▼]

Joint amplification of multiple carriers with a single wideband high power amplifier (HPA) has been considered towards reusing the satellite resources among multiple links to reduce the mission cost. The non-linear characteristic of the HPA, especially near saturation, coupled with the on-board IMUX/ OMUX filters result in non-linear adjacent carrier interference (ACI) and inter-symbol interference (ISI) during multicarrier power amplification. To benefit from the advantages of multicarrier transmissions, on-ground techniques to mitigate the non-linear distortions need to be devised. These techniques include predistortion at the transmitter and equalization at the receiver. Several works have considered the use of multicarrier predistortion along with single carrier equalization. A symbol synchronous equalizer, while being simple to implement, may not necessarily provide for the optimum linear filter. Towards improving the performance, fractionally spaced equalizers (FSE) have been considered. Such receivers are shown to provide enhanced performance by effectively compensating for the group delay distortions. The objective of this work is to consider the use of FSE in the context of multicarrier transmissions over non-linear channels and illustrate their performance enhancements [less ▲]

Carrier Rate Optimization on the Return Link of Interactive Mobile Satellite Networks

in European Wireless 2014; 20th European Wireless Conference; Proceedings of (2014, May)

Emerging interactive satellite applications demand highly efficient transmission schemes. Narrow-band satellite return channels for mobile users have peculiar characteristics that make the optimal user ... [more ▼]

Emerging interactive satellite applications demand highly efficient transmission schemes. Narrow-band satellite return channels for mobile users have peculiar characteristics that make the optimal user-rate determination a hard problem. Carrier rate enhancement can only be enabled by increasing the user bandwidth and by the application of highly efficient coding schemes. However, with the system bandwidth held constant, gains from increased user bandwidth can be offset by interference from an adjacent user channels. Additional interference is caused by spurious emissions from adjacent channels; these arise from the spectral regrowth caused by the user terminal power amplifier when operated in high-efficiency region. On the other hand, efficient amplification is mandatory to achieve the required signal to noise ratio at the receiver. In this work we propose a combination of transmitter and receiver techniques to improve the user-rate while controlling the user power efficiency. [less ▲]

Non-parametric data predistortion for non-linear channels with memory

in Acoustics, Speech and Signal Processing (ICASSP), 2013 IEEE International Conference on (2013, May 26)

With the growing application of high order modulation techniques, the mitigation of the non-linear distortions introduced by the power amplification, has become a major issue in telecommunication. More ... [more ▼]

With the growing application of high order modulation techniques, the mitigation of the non-linear distortions introduced by the power amplification, has become a major issue in telecommunication. More sophisticated techniques to counteract the strong generated interferences need to be investigated in order to achieve the desired power and spectral efficiency. This work proposes a novel approach for the definition of a transmitter technique (predistortion) that outperforms the standard methods with respect to both performance and efficiency. [less ▲]

Multicarrier Digital Pre-distortion/ Equalization Techniques for Non-linear Satellite Channels

in Proceedings of 30th AIAA International Communications Satellite Systems Conference (ICSSC), (2012)