document title / titre du document TRP W ORK PLAN ... - emits - ESA

TRP Work Plan 2005-2007
Description of Activities
TEC-SB/7935/dc
12/Feb/09
TRP Reference:
T501-12ET
Study of Enhanced digital transmission techniques for Broadband Satellite Digital
Title:
Transmissions
Advanced digital techniques can be envisaged making use of dynamic signal pre-distortion at the modulator side combined
with adaptive non-linear equalizer at the receiver in order to compensate both the amplitude and the ISI (Inter-Symbol
Interference) distortions caused by the channel non-linearity. If digital pre-compensation and equalization techniques are
used, the optimum operating point in terms of Baud rate may be shifted towards greater value of Bs/Bf while output back-off
reduced. This is particularly true if higher order modulations (such as 8PSK, 16/32-APSK) currently proposed by DVB-S2 are
adopted. Efficiency gains in the order of 2 dB in terms of power efficiency and 20-30% in spectral efficiency are expected with
affordable implementation complexity. A further step is represented modulation schemes with constant envelope like M-ary
CPM (Continuous Phase Modulation) signals and re-assessment of their suitability to broadband satellite communications. In
particular, their energy and spectral efficiency on linear channel shall be investigated and compared to more classical linear
band-limited M-QAM modulations. Performance shall also be investigated for typical non-linear satellite channels to show the
performance gain of these signals. New coding schemes employing CPM signals shall also be studied. Carrier and timing
synchronization techniques that are able to work at the very low operative SNR of typical satellite transmissions in presence of
powerful coding schemes, shall be studied and optimised. Overall coded modulation performance over typical satellite
nonlinear channels shall be finally estimated through an accurate end-to-end simulator. Finally implementation complexity
issues for the demodulator and decoder shall be analysed and CPM complexity shall be compared with current state-of the art
M-QAM demodulator/decoders. This is a key issue as in the past adoption of CPM schemes was often discarded for
high-speed applications because of the lack of maturity of digital signal processing technologies. The activity shall include: 1.
technical report trading off different equalization techniques for the specific application showing the proposed innovative
techniques as well as their performance results assessed through analysis and computer simulations; 2. the description and
the performance of the selected coded modulation scheme over the linear and non-linear channel; 3. the gain w.r.t the more
classical modulations shall also be assessed; 4. the description and the performance of the carrier and symbol timing
synchronizers suitable for the selected modulation scheme for both the forward and the return channel; 4. an in-depth
assessment of the equalizer complexity and feasibility study for the selected application scenarios; 5. a software package in
MATLAB or C/C++ implementing the overall system simulation including the channel distortion elements (IMUX/OMUX and
power amplifiers) and modulators and demodulators with the proposed innovative techniques.
Deliverables:
Technical report. Selected modulation scheme description/performance/feasibility study; SW (MATLAB or C/C++).
Current TRL: TRL1 Target TRL: TRL2-3 Application Need/Date: TRL5 by 2008-2009
Application/Mission: Telecom Contract Duration: 18 months
SW Clause : - Dossier0 Ref.: T-7923
Consistency with Harmonisation
Roadmap and Conclusions:
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