INSTITUTE FOR TELECOMMUNICATIONS RESEARCH B3G/4G Workshop Seoul 2006 November 2006 Nonlinear Mitigation for Two Carrier Transmission International Workshop for B3G/4G Satellite Communications

INSTITUTE FOR TELECOMMUNICATIONS RESEARCH B3G/4G Workshop Seoul 2006 November 2006 Nonlinear Mitigation for Two Carrier Transmission Presentation Overview l Joint research between ITR from University of South Australia and ETRI, South Korea l Project description and problem statement l TWTA characterisation l Iterative ISI cancellation process for two carriers l Summary of performance results

INSTITUTE FOR TELECOMMUNICATIONS RESEARCH B3G/4G Workshop Seoul 2006 November 2006 Nonlinear Mitigation for Two Carrier Transmission Regenerative Satellite Model

INSTITUTE FOR TELECOMMUNICATIONS RESEARCH B3G/4G Workshop Seoul 2006 November 2006 Nonlinear Mitigation for Two Carrier Transmission Satellite Transmission Model

INSTITUTE FOR TELECOMMUNICATIONS RESEARCH B3G/4G Workshop Seoul 2006 November 2006 Nonlinear Mitigation for Two Carrier Transmission Transmission Model Summary l Multiple uplink TDMA channels l Regenerative satellite model, including onboard switch l Two high rate TDM downlink carriers per transponder l Mitigation technique has knowledge of both data streams and nonlinear characteristics of the TWTA l Investigate an optimum mitigation technique

INSTITUTE FOR TELECOMMUNICATIONS RESEARCH B3G/4G Workshop Seoul 2006 November 2006 Nonlinear Mitigation for Two Carrier Transmission Measured TWTA Characteristics AM/AM CharacteristicAM/PM Characteristic

INSTITUTE FOR TELECOMMUNICATIONS RESEARCH B3G/4G Workshop Seoul 2006 November 2006 Nonlinear Mitigation for Two Carrier Transmission TWTA AM/AM and AM/PM Functions Fit a piecewise polynomial to the characteristics with the following constraints: Both AM/AM and AM/PM pass through the origin Both AM/AM and AM/PM pass through the origin Extension of the curves past the measured data Extension of the curves past the measured data No discontinuities at breakpoints and first derivative continuous No discontinuities at breakpoints and first derivative continuous AM/AM polynomial contains only odd coefficients AM/AM polynomial contains only odd coefficients AM/PM polynomial contains only even coefficients AM/PM polynomial contains only even coefficients

INSTITUTE FOR TELECOMMUNICATIONS RESEARCH B3G/4G Workshop Seoul 2006 November 2006 Nonlinear Mitigation for Two Carrier Transmission Polynomial Approximations TWTA AM/AM TWTA AM/PM

INSTITUTE FOR TELECOMMUNICATIONS RESEARCH B3G/4G Workshop Seoul 2006 November 2006 Nonlinear Mitigation for Two Carrier Transmission Simulation Scenarios 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 Clipped Nonlinear:

INSTITUTE FOR TELECOMMUNICATIONS RESEARCH B3G/4G Workshop Seoul 2006 November 2006 Nonlinear Mitigation for Two Carrier Transmission Three Simulation Scenarios Ideal Linearised:

INSTITUTE FOR TELECOMMUNICATIONS RESEARCH B3G/4G Workshop Seoul 2006 November 2006 Nonlinear Mitigation for Two Carrier Transmission Iterative ISI Cancellation for 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 where = 0.1

INSTITUTE FOR TELECOMMUNICATIONS RESEARCH B3G/4G Workshop Seoul 2006 November 2006 Nonlinear Mitigation for Two Carrier Transmission Total Degradation l Overall performance through the nonlinear amplifier u Output power u Output distortion components l Assume two QPSK carriers of the same bandwidth and same power level l Performance results are for uncoded at a BER of which loosely corresponds to error free transmission for rate ½ QPSK turbo coded systems

INSTITUTE FOR TELECOMMUNICATIONS RESEARCH B3G/4G Workshop Seoul 2006 November 2006 Nonlinear Mitigation for Two Carrier Transmission Performance Results

INSTITUTE FOR TELECOMMUNICATIONS RESEARCH B3G/4G Workshop Seoul 2006 November 2006 Nonlinear Mitigation for Two Carrier Transmission Conclusions l Mitigation technique for the combined nonlinearity and memory l Iterative predistortion technique using data predistortion l Better results and less complexity than signal predistortion l Can be extended to OFDM systems