| Ka-band,as a type of high-band resource,has attracted more attention in addressing the current situation of congestion in low-band satellite communications.Ka-band,of which frequency range is 27-40 GHz has several advantages,such as a wide available band,large communication capacity,low interference,etc.Therefore,Ka-band has become a research highlight.Channel coding technology is used to decrease the impact of weather and mo-bile attenuation factors on the reliability of satellite communications.Polar codes,a kind of channel coding technology with strong error-correction capability,had few applications in the field of Ka-band satellite communication.In this dissertation,polar codes are applied to the Ka-band satellite communication system for related research.The main research con-tents are as follows:（1）According to the channel characteristics,a Ka-band satellite communication system based on polar codes is proposed in this section.Firstly,the main influencing factors and channel characteristics of the Ka-band satellite channel are analyzed,and simulations are carried out under different shadow fading situations in clear weather.Secondly,polar codes are con-structed by the Monte Carlo method.Through several simulations,we determined that the system has the best bit error rate（BER）performance when using the cyclic redundancy check aided successive cancellation list（CA-SCL）decoding algorithm.Finally,aiming at the sys-tem,the performance improvement of using polar code is analyzed in this section.（2）With the addition of the orthogonal frequency division multiplexing（OFDM）technique,a Polar-OFDM communication system is proposed here.This section reconstructs polar codes and simulations in different shadow fading situations.In the Polar-OFDM communication system,the BER performance is compared with the low density parity check（LDPC）codes under the same conditions which this dissertation calls it LDPC-OFDM system.Besides,this section compares the BER performance with the system without the OFDM technique.（3）The Polar-OFDM satellite communication system integrated with the adaptive modula-tion is simulated in different shadow fading situations.In this section,the BER performance is compared with the LDPC-OFDM system using adaptive modulation under the same con-ditions.The results indicate that,when the BER is 10-4and under different shadow fading situa-tions in clear weather,the system based on polar codes obtains a 2-5.5d B gain compared with the uncoded system.It illustrates that using polar codes in the Ka-band satellite chan-nel is effective and feasible.In the same situation,compared with the system without the OFDM technology,the Polar-OFDM system has a 6-8d B gain when the BER is 10-5.The performance of the Polar-OFDM system is better than the LDPC-OFDM system.With the addition of adaptive modulation,when the BER is 10-5,the Polar-OFDM system obtains a0.2-0.5d B gain compared with the LDPC-OFDM system.This result indicates that the per-formance of polar codes is more robust.In summary,polar codes have certain advantages for ensuring the robustness of satellite communication transmission and have good application prospects in this field. |
