Research On Key Technologies Of Polar Coded Modulation

In practical communication systems,the two most important measurements are reliability and effectiveness.Adopting the channel code can improve the reliability of communication systems.Polar code has been firstly proved to achieve the capacity in the binary input discrete memoryless symmetric channel.Once put forward,it has received many attentions from the academics and industry.The information transmission rate can be used to reflect the effectiveness of communication systems.When the bandwidth is limited,the high-dimensional modulation is needed to promote the information transmission rate.Applying the high-dimensional modulation to the polar code can contribute to promoting its practical application.This thesis mainly studies the key technologies of the polar coded modulation and includes the following three aspects of innovative work.I Research on the construction theory in the polar coded modulationThis thesis designs the high-performance construction methods for the polar coded modulation in the AWGN(Additive White Gaussian Noise)channel and Rayleigh fading channel.1)In the AWGN channel,this thesis firstly finds and demonstrates the partial orders between the polarized bit channels in the polar coded modulation.Based on the partial orders,it is found that the binary expansion of the index for the polarized bit channel can be considered as two parts,corresponding to the modulation transformation and the polarization transformation.Based on the above property,this thesis proposes a general metric to measure the reliability of the polarized bit channels.Then the offline construction method can provide a high performance in the polar coded modulation.2)In view of the Rayleigh fading channel,this thesis firstly obtains the equivalent BIAWGN(Binary Input AWGN)channel based on the mutual information equivalence principle.After that,the Gaussian approximation is performed to construct the polar code in the binary-input Rayleigh fading channel.In order to further reduce the construction complexity,this thesis derives the analytical expression of the noise variance based on the minimum difference entropy principle.Finnaly,the mutual information equivalence algorithm is extended to the polar coded modulation schemes in the Rayleigh fading channel.Ⅱ Research on the joint optimization in the polar coded modulationIn sight of the joint optimization between the polar code and the modulation,this thesis designs the performance evaluation method and the optimization method for the APSK(Amplitude Phase Shift Keying)constellations in the polar coded modulation.Besides,this thesis proposes the DBIPCM(Delayed Bit Interleaved Polar Coded Modulation)architecture and the corresponding optimization method for the constellation mapping.1)The APSK constellation is widely used in the nonlinear channel due to its low PAPR(Peak to Average Power Ratio).In order to promote the application of polar coded modulation,this thesis studies the joint optimization of the APSK constellation and the polar code.In the BIPCM(Bit Interleaved Polar Coded Modulation)architecture,this thesis proposes the CBP(Cumulative Bhattacharyya Parameter)and derive its upper bound UBC(Upper Bound of CBP)to evaluate the polarization effect of the APSK constellation.Based on the proposed metrics,the configuration is optimized for the APSK constellation.In order to further improve the performance,the APSK constellation is applied to the MLC-PCM(Multilevel Coding Polar Coded Modulation)architecture and the second order moment of the mutual information for the modulated bit channels is proposed to meaure the polarization effect of the APSK constellation.Based on this,we provide the general SSP(Semi Set Partitioning)mapping way and optimize the configuration of the APSK constellation.2)In the BIPCM architecture,the performance is limited due to the information loss.In order to overcome the problem,this thesis proposes the DBIPCM architecture and the corresponding optimization method for the constellation mapping.In the DBIPCM architecture,the bit delay module is introduced in the transmitter and multistage demodulation is adopted in the receiver.In contrast to the BIPCM,the Gray mapping is not the best one in the DBIPCM.By considering the polar code as a general concatenated code,the variance of the input mutual information for the outer codes is used to measure the polarization effect for the constellation with different mapping ways in the DBIPCM.The result shows that SP(Set Partitioning)mapping shows more significant polarization effect and adapts to the DBIPCM.Ⅲ Research on the constellation shaping in the polar code modulationThe regular constellation will result in a loss for the mutual information compared to the Shannon channel capacity.Based on this issue,this thesis proposes two types of constellation shaping methods to promote the performance in the polar coded modulation.1)The first type is probabilistic shaping.This thesis proposes the shaping polar coded modulation architecture and its corresponding probabilistic shaping method.In the probabilistic shaping,we adopt the many-to-one mapping to realize the nonequiprobable constellations.Besides,this thesis provides the corresponding optimized method for the constellation mapping based on the unequal probability distribution.2)Different from the probabilistic shaping,the constellation points have the same probability distribution and the position is unevenly distributed in the geometric shaping.In this thesis,the geometric shaping proposed by the preecessors is applied to the polar coded modulation.Moreover,the BSA(Binary Switching Algorithm)algorithm is used to search the mapping way with more significant polarization effect in terms of the UBC.