Abstract
High-order modulations are essential to improve the bandwidth efficiency of communication systems. However, such modulated signals with large envelopes are typically sensitive to the non-linear distortion caused by high power amplifiers (HPAs) in the transponder of satellite channels. In this paper, a new nonequiprobable constellation is designed to combat the non-linear effects of HPAs. We use non-uniformly distributed symbols to construct the appropriate high-order constellation for non-linear satellite channels. The nonequiprobable symbols are generated using the non-linear mapping method, which specifically consists of expansion mapping, symbol decomposition, permutation, and combination. Moreover, the demapping method adapting to the designed nonequiprobable constellation is also discussed. The simulation results show that the proposed scheme has considerable performance improvements compared with the traditional equiprobable constellations over the non-linear satellite channel.
Highlights
As the demand for data volume and spectral efficiency in satellite communications is increasing steadily, the use of high-order modulations has become quite essential [1,2,3]
Due to the non-linear transfer characteristics of the high power amplifiers (HPAs), non-linear distortion is introduced in the form of constellation warping and clustering at the receiver when high-order modulated signals with large envelopes are used for transmission [6,7,8]
This section investigates the bit error rate (BER) comparison of the proposed nonequiprobable constellation, conventional equiprobable 64-quadrature amplitude modulation (QAM) constellation and 64-level amplitude phase shift keying (APSK) constellation which has four concentric rings and each ring consists of 16 points [35]
Summary
As the demand for data volume and spectral efficiency in satellite communications is increasing steadily, the use of high-order modulations has become quite essential [1,2,3]. Due to the non-linear transfer characteristics of the HPA, non-linear distortion is introduced in the form of constellation warping and clustering at the receiver when high-order modulated signals with large envelopes are used for transmission [6,7,8]. The geometric proposals include devising the constellation shape [12], the position, and the separation of the constellation points [13,14]. These methods have high complexity in designing specific high-order constellations. The nonequiprobable constellation can be generated using signal superposition [18], or by combining forward error correction (FEC) with shaping, i.e., shaping before or after FEC
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
