Turbo equalization based on joint Gaussian, SIC-MMSE and LMMSE for nonlinear satellite channels
- 51 Downloads
The nonlinear distortion of wideband signal due to the filtering and efficiently operated high power amplifiers limits the performance of satellite communications. Volterra series can be used to describe the nonlinear satellite channels effectively. Most existing equalizers simply ignore the nonlinear terms or treat all the nonlinear combinations of symbols as interference. In this study, by properly exploiting information from nonlinear terms, we propose three turbo equalizers for nonlinear satellite channels, namely, joint Gaussian (JG), soft interference cancellation-minimum mean square error (SIC-MMSE) and linear minimum mean square error (LMMSE) equalizers. In JG and SIC-MMSE-based equalizers, both the linear and nonlinear terms that contain the symbol of interest are considered as desired signals. Accordingly, the required statistics are calculated based on the a priori probabilities of coded bits from output of channel decoder. For LMMSE-based equalizer, we propose to calculate the extrinsic information from output of equalizer by excluding the prior information in both the linear and nonlinear terms. Simulation results demonstrate that the proposed equalizers significantly outperform the method which ignores the presence of nonlinear interferences. Moreover, the nonlinear terms that contain the symbol of interest can be exploited to further improve the performance of turbo equalization.
Keywordsnonlinear satellite channel turbo equalization joint Gaussian soft interference cancellation-minimum mean square error (SIC-MMSE) linear minimum mean square error (LMMSE)
This work was supported by National Natural Science Foundation of China (Grant Nos. 61471037, 61571041).
- 6.Malone J, Wickert J. Practical Volterra equalizers for wideband satellite communications with TWTA nonlinearities. In: Proceedings of Digital Signal Processing Workshop and IEEE Signal Processing Education Workshop, Sedona, 2011. 48–53Google Scholar
- 7.Deleu T, Horlin F, Dervin M. Turbo-equalization of the remaining interference in a pre-distorted non-linear satellite channel. In: Proceedings of IEEE International Conference on Acoustics, Speech and Signal Processing, Florence, 2014. 1946–1950Google Scholar
- 25.Liu L, Leung W, Ping L. Simple iterative chip-by-chip multiuser detection for CDMA systems. In: Proceedings of IEEE Vehicular Technology Conference, Jeju Island, 2003. 2157–2161Google Scholar
- 30.Burnet C E, Cowley W G. Performance analysis of turbo equalization for nonlinear channels. In: Proceedings of International Symposium on Information Theory, Adelaide, 2005. 2026–2030Google Scholar
- 31.Ampeliotis D, Rontogiannis A, Berberidis K et al. Turbo equalization of non-linear satellite channels using soft interference cancellation. Adv Sat Mobile Syst, 2008, 124: 289–292Google Scholar
- 32.Benammar B, Thomas N, Poulliat C, et al. On linear MMSE based turbo-equalization of nonlinear volterra channels. In: Proceedings of IEEE International Conference on Acoustics, Speech, and Signal Processing, Vancouver, 2013. 4703–4707Google Scholar