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

Abstract 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 © 2009 John Wiley & Sons, Ltd.