The document describes a satellite communication system that uses Wavelet Filtered Multi-tone (WFMT) modulation to provide advantages over traditional QPSK modulation. WFMT modulation has a lower peak-to-average ratio, allows for a programmable spectrum, and can compensate for distortions from the satellite transponder and multipath propagation in urban environments. It provides similar energy efficiency to QPSK and multipath immunity comparable to OFDM. Simulation results show the WFMT spectrum meets requirements and has a higher tolerance for delay than existing systems.

1. SATELLITE COMMUNICATION SYSTEM
based on WFMT Technology
09-Dec-11 VIO CONCEPT Ltd. 1

2. PROJECT OBJECTIVE
 The Project describes Satellite Communication System
( SCS) intended for connection of the mobile devices in
Urban areas.
 The developed SCS uses the Wavelet Filtered Multi-tone
(WFMT) modulation proposed by author of this project.
 WFMT modulation has several advantages before QPSK
that common used in Satellite communications.
• Low Peak-to-Average Ratio of WFMT signal (typical < 2 dB).
• Programmable spectrum by changing form of the wavelets.
• Compensation of phase and amplitude distortions inserted by
satellite transponder.
• Compensation of distortions inserted by multipath propagation of
the electromagnetics waves in the urban area.
 WFMT modulation has the same energy efficiency as
single carrier QPSK modulation and the same immunity
to multipath as multicarrier OFDM modulation.

3. Multipath propagation in Urban area
Common mode QPSK
Satellite signal can not
be received in the moving
car in this area.
WFMT based satellite
signal can be received
without errors.

4. Typical measured values of RMS delay spread
( Satellite – Ground channel)
Environment Freq.(MHz) RMS Delay Spread Notes
Urban 910 1300 ns avg., 3500 ns max New York
Urban 892 10-25 us worst case San Franc.
Suburban 910 200-310 ns typical case Average
Suburban 910 1960-2110 ns extreme case Average
Country 910 120 ns typical case Average
Country 910 750 ns worst case Average
Max. available RMS delay spread for different systems.
SYSTEM MODULATION Symbol Max . available
length RMS delay spread
Wi-MAX OFDM 102.9 us 4.5 us
Satellite (old) QPSK 60 ns 30 ns
Satellite (WFMT) Wavelet QPSK 1 us 1.7 us

5. BACKGROUND
 The bandwidth efficient methods of modulation for
aircraft and space communication were developed and
regulated by NASA.
 Space Frequency Coordination Group (SFCG) approved
an RF mask recommendation 17-2 in 1998, last revision
21-2 in 2002.
 SFCG rec. 17-2/21-2 becomes NASA policy for missions
to meet CCSDS Rec. 2.4.17A, 2.4.17B, and 2.4.18,
approved 2001, contains specifications for Offset
Quadrature Shift Keying (OQPSK)-type modulations:
Gaussian Minimum Shift Keying (GMSK), Filtered-
OQPSK, Shaped-OQPSK (S-OQPSK), Feher QPSK-
Type B (FQPSK-B) and also higher-order coded
modulations, i.e. 8-PSK TCM at 2.0, 2.25, 2.5, and 2.75
bits/symbol/Hz.
 These modulations all conform to the SFCG mask.

6. SFCG MASK for Satellite channel

7. FILTERED OQPSK SPECTRUM
(current Satellite communication system )

8. WFMT MULTI-QPSK SPECTRUM
( VDSL system)

9. WFMT based QPSK SPECTRUM
(Satellite communication system)
WFMT

10. MATLAB SIMULATION
 OUTPUT SPECTRUM of Wavelet based QPSK Modulator
txSignal -60, rxSignal, Noise -140
Power Spectrum Magnitude (dB)
-60
-80
-100
-120
-140
0.1 0.15 0.2 0.25
Frequency

11. WFMT based QPSK MODULATOR
(Satellite communications system)
0 /127T t127
t126
0
a4
a3
a2
a1
a0
IFFT W)t(
a1
128 point
P/S
a2
a3
a4
0
Sub-channel
Sub-channel
Wavelet
Wavelet
t1
0 0 t0
Sub-channel wavelet
spectrum
a2 a1 a0 a1 a2
a3 a3
T
a4 a4
t
f
0 /1T /127T
fc

12. WFMT based QPSK DEMODULATOR
(Satellite communications system)
t127 /127T 0
t126
0
FFT
S/P 128 point
W)t(D
0
+ + + +
t1
t0 0 0 a4 a3 a2 a1 a0
D Sub-channel
Sub-channel
modulated Wavelet t127 /127T 0
Wavelet Equalizer
t126 0 eq1
eq2
eq3
eq4
eq5
T S/P
FFT
eq6
128 point
demodulator
^
W)t( eq7
eq8
Information eq9
0
Demodulation of Wavelets t1
t0 0 0
+ + + +
a3 a2 a1 a0
a4
Prototype wavelet
a0 spectrum a a1
a1 2
a2 a3
a3
a4 a4
demodulator
f
0 /127T
/1T
Information
Demodulation & Equalization
of Wavelet

13. Parameters of Wavelet QPSK modulation
versus standard QPSK and OFDM
Parameter Wavelet QPSK QPSK OFDM NOTES
Channel Bandwidth 35 MHz 35 MHz 35 MHz
Data Rate ( max) 32 Mbps 32 Mbps 32 Mbps
Peak-to-Average Ratio 1~2 dB 1~2 dB 12 dB
FFT size 64 - 2048
Symbol duration 1 us 60 ns 70.6 us
Max. available multipath delay spread 1.7 us 30 ns 2.2 us
Cyclic prefix duration 3.5 us no 4.6 us
Satellite transponder RF power (peak) ~ 10 W ~ 10 W ~ 160 W
Complexly of Transmitter Medium Low Medium
Complexity of Receiver High Low Medium
Immunity to phase noise and carrier High High Low
frequency offset
Immunity to narrowband interference High Low High
Immunity to Doppler effect High Medium Low
Rejection of adjacent channel High Medium Low