Non-Linear Linear Distortion Cancellation and Symbol-Based Symbol Based Equalization in Satellite Forward Links
Abstract: In this paper, a low-complexity complexity symbol-based symbol based equalizer that performs non-linear non distortion cancellation is proposed for application at the user terminal in the DVBDVB S2X satellite forward link. The channel is comprehensively modeled, including the non-linear travelling wave tube amplifier characteristics, the input input-multiplexing and output-multiplexing multiplexing filter responses at the satellite transponder, and the phase noise at the user terminal, according to the very-small very small aperture terminal reference scenario. Two detectors detectors in the cancellation loop are considered, comparing the packet-error error rate (PER) performance of simple maximum likelihood demodulation with hard decision to soft information exchange with low-density parity-check check decoder, and showing only marginal improvement i with the latter solution. The PER performance is compared against a number of pre predistortion techniques at the transmitter, such as dynamic data pre-distortion, pre successive data pre-distortion, distortion, and static data pre pre-distortion. distortion. The novel receiver demonstrates emonstrates superior performance even with one iteration of distortion cancellation, while the joint application of successive data pre-distortion pre and iterative symbol-based based equalization shows up to 4.95-dB 4.95 dB energy efficiency gain for 32-level level amplitude and phase-shift keying (32-APSK). APSK). The computational complexity is also evaluated. The improved receiver is particularly suitable for