INSTITUTE FOR TELECOMMUNICATIONS RESEARCH
B3G/4G Workshop Seoul 2006B3G/4G Workshop Seoul 2006
November 2006November 2006
Nonlinear Mitigation for Two Carrier TransmissionNonlinear Mitigation for Two Carrier Transmission
International Workshop for B3G/4G Satellite Communications
INSTITUTE FOR TELECOMMUNICATIONS RESEARCH
B3G/4G Workshop Seoul 2006B3G/4G Workshop Seoul 2006
November 2006November 2006
Nonlinear Mitigation for Two Carrier TransmissionNonlinear Mitigation for Two Carrier Transmission
Presentation Overview
Joint research between ITR from University of South Australia and ETRI, South Korea
Project description and problem statement
TWTA characterisation
Iterative ISI cancellation process for two carriers
Summary of performance results
INSTITUTE FOR TELECOMMUNICATIONS RESEARCH
B3G/4G Workshop Seoul 2006B3G/4G Workshop Seoul 2006
November 2006November 2006
Nonlinear Mitigation for Two Carrier TransmissionNonlinear Mitigation for Two Carrier Transmission
Regenerative Satellite Model
INSTITUTE FOR TELECOMMUNICATIONS RESEARCH
B3G/4G Workshop Seoul 2006B3G/4G Workshop Seoul 2006
November 2006November 2006
Nonlinear Mitigation for Two Carrier TransmissionNonlinear Mitigation for Two Carrier Transmission
Satellite Transmission Model
INSTITUTE FOR TELECOMMUNICATIONS RESEARCH
B3G/4G Workshop Seoul 2006B3G/4G Workshop Seoul 2006
November 2006November 2006
Nonlinear Mitigation for Two Carrier TransmissionNonlinear Mitigation for Two Carrier Transmission
Transmission Model Summary
Multiple uplink TDMA channels
Regenerative satellite model, including onboard switch
Two high rate TDM downlink carriers per transponder
Mitigation technique has knowledge of both data streams and nonlinear characteristics of the TWTA
Investigate an optimum mitigation technique
INSTITUTE FOR TELECOMMUNICATIONS RESEARCH
B3G/4G Workshop Seoul 2006B3G/4G Workshop Seoul 2006
November 2006November 2006
Nonlinear Mitigation for Two Carrier TransmissionNonlinear Mitigation for Two Carrier Transmission
Measured TWTA Characteristics
AM/AM Characteristic AM/PM Characteristic
INSTITUTE FOR TELECOMMUNICATIONS RESEARCH
B3G/4G Workshop Seoul 2006B3G/4G Workshop Seoul 2006
November 2006November 2006
Nonlinear Mitigation for Two Carrier TransmissionNonlinear Mitigation for Two Carrier Transmission
TWTA AM/AM and AM/PM Functions
Fit a piecewise polynomial to the characteristics with the following Fit a piecewise polynomial to the characteristics with the following constraints:constraints:
• Both AM/AM and AM/PM pass through the originBoth AM/AM and AM/PM pass through the origin• Extension of the curves past the measured dataExtension of the curves past the measured data• No discontinuities at breakpoints and first derivative continuousNo discontinuities at breakpoints and first derivative continuous• AM/AM polynomial contains only odd coefficientsAM/AM polynomial contains only odd coefficients• AM/PM polynomial contains only even coefficientsAM/PM polynomial contains only even coefficients
188.1;14751.01639.1
188.10.1;8.63592.580.3
0.1;25.005.185.105.2753
753
rr
rrrr
rrrrr
rA
3.1;75.1964.17
3.1;1171176228180105 12108642
rr
rrrrrrrr
INSTITUTE FOR TELECOMMUNICATIONS RESEARCH
B3G/4G Workshop Seoul 2006B3G/4G Workshop Seoul 2006
November 2006November 2006
Nonlinear Mitigation for Two Carrier TransmissionNonlinear Mitigation for Two Carrier Transmission
Polynomial Approximations
TWTA AM/AMTWTA AM/AM TWTA AM/PMTWTA AM/PM
INSTITUTE FOR TELECOMMUNICATIONS RESEARCH
B3G/4G Workshop Seoul 2006B3G/4G Workshop Seoul 2006
November 2006November 2006
Nonlinear Mitigation for Two Carrier TransmissionNonlinear Mitigation for Two Carrier Transmission
Simulation Scenarios
Three models for the nonlinearity are considered for comparison purposes:Three models for the nonlinearity are considered for comparison purposes:
•Original nonlinear characteristicsOriginal nonlinear characteristics
•Clipped nonlinear characteristicsClipped nonlinear characteristics
•Ideal linearised modelIdeal linearised model
0.1;34.36
0.1;1171176228180105 12108642
r
rrrrrrrr
0.1;0.1
0.1;25.005.185.105.2 753
r
rrrrrrA
Clipped Nonlinear:Clipped Nonlinear:
INSTITUTE FOR TELECOMMUNICATIONS RESEARCH
B3G/4G Workshop Seoul 2006B3G/4G Workshop Seoul 2006
November 2006November 2006
Nonlinear Mitigation for Two Carrier TransmissionNonlinear Mitigation for Two Carrier Transmission
Three Simulation Scenarios
0.1;0.1
0.1;
r
rrrA
Ideal Linearised:Ideal Linearised:
0r
INSTITUTE FOR TELECOMMUNICATIONS RESEARCH
B3G/4G Workshop Seoul 2006B3G/4G Workshop Seoul 2006
November 2006November 2006
Nonlinear Mitigation for Two Carrier TransmissionNonlinear Mitigation for Two Carrier Transmission
Iterative ISI Cancellationfor each block of 8196 symbols
for each of 10 iterations
construct the transmitted two carrier signal
simulate the nonlinear distortion
for each of the two carriers
determine the ISI, , for each received symbol
subtract from each transmitted symbol
end for
end for
end forwhere = 0.1
INSTITUTE FOR TELECOMMUNICATIONS RESEARCH
B3G/4G Workshop Seoul 2006B3G/4G Workshop Seoul 2006
November 2006November 2006
Nonlinear Mitigation for Two Carrier TransmissionNonlinear Mitigation for Two Carrier Transmission
Total Degradation Overall performance through the nonlinear amplifier
Output power Output distortion components
dBdBOdBD
Assume two QPSK carriers of the same bandwidth and same power level
Performance results are for uncoded at a BER of 10-1 which loosely corresponds to error free transmission for rate ½ QPSK turbo coded systems
INSTITUTE FOR TELECOMMUNICATIONS RESEARCH
B3G/4G Workshop Seoul 2006B3G/4G Workshop Seoul 2006
November 2006November 2006
Nonlinear Mitigation for Two Carrier TransmissionNonlinear Mitigation for Two Carrier Transmission
Performance Results
INSTITUTE FOR TELECOMMUNICATIONS RESEARCH
B3G/4G Workshop Seoul 2006B3G/4G Workshop Seoul 2006
November 2006November 2006
Nonlinear Mitigation for Two Carrier TransmissionNonlinear Mitigation for Two Carrier Transmission
Conclusions Mitigation technique for the combined nonlinearity and
memory Iterative predistortion technique using data
predistortion Better results and less complexity than signal
predistortion Can be extended to OFDM systems