IEEE ISIT 2020 Asynchronous Polar-Coded Modulation Authors: Jincheng Dai, Kai Niu, and Zhongwei Si Speaker: Jincheng Dai Key Laboratory of Universal Wireless Communications, Ministry of Education Beijing University of Posts and Telecommunications (BUPT) BUPT Confidential and Proprietary
Backgrounds about polar-coded modulation Motivation Transmission scheme of A-PCM Channel polarization transforms in A-PCM Theoretical performance analysis Simulation results analysis and conclusion 6/6/2020 BUPT Confidential and Proprietary 2
Preliminaries about polar-coded modulation From polar coding to polar-coded modulation Polar coding − Polar codes achieve the capacity of binary input symmetric discrete memoryless channels (B-DMCs) under the successive cancellation (SC) decoding when the code length goes to infinity. − The key idea is “channel polarization” which comes from the chain rule of mutual information. − The channel polarization effect lies in the “coding” given by the binary constraint. Polar-coded modulation (PCM) − By considering the dependencies among the bits which are mapped to a single modulation symbol as a special kind of channel transform, the polar-coded modulation (PCM) scheme is derived under the framework of two-stage channel transform, i.e. the modulation partition and the binary partition. − State-of-the-art PCM framework includes two schemes, i.e. the multilevel coding (MLC) [1] and the bit-interleaved coded modulation (BICM) [2], and their corresponding PCM frameworks are referred as the MLC-PCM and the BI-PCM, respectively. [1] U. Wachsmann, R. F. H. Fischer, and J. B. Huber, “ Multilevel codes: theoretical concepts and practical design rules, ” IEEE Trans. Inf. Theory , vol. 45, pp. 1361 – 1391, Jul. 1999. [2] G. Caire, G. Taricco, and E. Biglieri, “ Bit-interleaved coded modulation ” IEEE Trans. Inf. Theory , vol. 44, pp. 927 – 946, May 1998. 6/6/2020 BUPT Confidential and Proprietary 3
Preliminaries about polar-coded modulation Block diagram of PCM frameworks MLC-PCM BI-PCM QAM Gray labeling with QAM SP labeling with N -length parallel demodulation serially demodulation polar code brings weak polarization. brings strong polarization. N -length 2 m -ary mN -length 2 m -ary polar code Interleaver modulation polar code modulation … N -length polar code Stage 2: Stage 1: Stage 2: Stage 1: Bit partition modulation partition Bit partition modulation partition 6/6/2020 BUPT Confidential and Proprietary 4
Preliminaries about polar-coded modulation Some conclusions about PCM MLC-PCM For the 2 m -ary quadrate amplitude modulation (QAM) methods, given N symbols to be transmitted in − one block, the MLC-PCM contains m component polar encoders whose code length is N . − The MLC-PCM is capacity-achieving as N goes to infinity. − For the finite block length, the set-partition (SP) labeling rule should be adopted in QAM constellations to enhance the polarization diversity among the m modulation synthesized subchannels after the sequential partition. BI-PCM − Only one mN -length binary polar coding block is used, after the polar encoding and interleaving, the coded bits are mapped to the N QAM symbols. − Under the finite block length, the Gray labeling rule should be used to minimize the capacity loss during the parallel modulation partition. [1] M. Seidl, A. Schenk, C. Stierstorfer and J. B. Huber, “Polar - Coded Modulation,” IEEE Trans. Commun ., vol. 61, no. 10, pp. 4108 – 4119, Oct. 2013. 6/6/2020 BUPT Confidential and Proprietary 5
Backgrounds about polar-coded modulation Motivation Transmission scheme of A-PCM Channel polarization transforms in A-PCM Theoretical performance analysis Simulation results analysis and conclusion 6/6/2020 BUPT Confidential and Proprietary 6
Asynchronous polar-coded modulation (A-PCM) Motivation The shortages of MLC-PCM − Involves m component polar codes which increase the latency. − Each component code length is N which is much shorter than the code length mN in the BI-PCM. The shortages of BI-PCM − The parallel modulation partition leads to the capacity loss because it does not satisfy the chain rule of mutual information as that in the MLC-PCM. − The QAM with gray labeling used in BI-PCM can well reduce the capacity loss in the MLC-PCM, but the polarization effect among the modulation synthesized subchannels is much inferior to the SP labeling used in MLC-PCM. Summary − The MLC-PCM shows advantages on the SP labeling and no capacity loss, but its component code length is short, that makes the polarization in polar coding is insufficient for finite length N . − The BI-PCM shows advantages on the one mN -length polar code and the lower decoding latency, but its QAM labeling rule should adopt the weak polarization Gray labeling. 6/6/2020 BUPT Confidential and Proprietary 7
Asynchronous polar-coded modulation (A-PCM) Motivation Can we combine the advantages of Q Q MLC-PCM and BI-PCM? 1001 0011 1011 0001 1001 0011 1011 0001 − SP labeled QAM. 0111 1101 0101 1111 0111 1101 0101 1111 − One mN -length polar encoder/decoder. I I 1010 0000 1000 0010 1010 0000 1000 0010 − Parallel modulation partition is adopted. − The strongest channel polarization effect 0100 1110 0110 1100 0100 1110 0110 1100 Q Q among the modulation synthesized 1001 0011 1011 0001 1001 0011 1011 0001 subchannels with no capacity loss. Key idea 0111 1101 0101 1111 0111 1101 0101 1111 I I − Change the synchronous superposition 1010 0000 1000 0010 1010 0000 1000 0010 mode among the bit streams to the asynchronous mode. 0100 1110 0110 1100 0100 1110 0110 1100 − Introduce the spatial-coupling idea to form the modulated frame. 6/6/2020 BUPT Confidential and Proprietary 8
Asynchronous polar-coded modulation (A-PCM) Key idea of A-PCM Why the “well - polarized” SP labeling cannot be used for BI -PCM? The existing PCM frameworks are indeed the synchronous schemes where the N transmitted 2 m -ary − symbols in each frame come from one coded block. Hence, the interference among the modulation bit streams is severe. − The parallel modulation partition in BI-PCM leads to capacity loss which makes the “well - polarized” SP labeling in MLC-PCM cannot be used. A-PCM combines the advantages of MLC-PCM and BI-PCM We propose an asynchronous PCM (A-PCM) framework, where the N transmitted 2 m -ary symbols in − each frame comes from m different coded blocks. − The coded bits in one block are asynchronously transmitted within m frames, and various coded blocks form the spatial coupled structure. − Although the parallel demodulation in BICM scheme is used, the previous m − 1 decoded blocks will mitigate the interference among the modulation bit streams so that the SP labeling can be used with no capacity loss during the parallel modulation partition. 6/6/2020 BUPT Confidential and Proprietary 9
Backgrounds about polar-coded modulation Motivation Transmission scheme of A-PCM Channel polarization transforms in A-PCM Theoretical performance analysis Simulation results analysis and conclusion 6/6/2020 BUPT Confidential and Proprietary 10
A-PCM transmission scheme Transmission scheme − Only one mN -length polar encoder is utilized for one block, and m coded blocks are superposed as the spatial-coupled structure. − The coded bits in each block is divided to m segments, and each segment is mapped to different frames and different bits. Nested structure The capacity distribution is the same of polar codes as that with SP labeling in MLC-PCM. Polar Coded Blocks ... ... ... in BI-PCM ... t + Bit-4 Bit-1 in the ( 3)-th frame 4 3 t + Bit-3 Bit-2 in the ( 2)-th frame 2 t + Bit-2 1 Bit-3 in the ( 1)-th frame Modulation to one frame Bit-1 Bit-4 in the -th frame t 2-ary 4-ary 8-ary 16-ary 16-ary 16-ary 16-ary 16-ary ... 1 2 3 4 Transmitted Frames 6/6/2020 BUPT Confidential and Proprietary 11
A-PCM transmission scheme Transmission scheme Polar Coded Blocks ... ... ... Q ... 1001 0011 1011 0001 Bit-4 0 4 0111 1101 0101 1111 0 3 Bit-3 0 2 I 1010 0000 1000 0010 Bit-2 0/1 1 Modulation to one frame 0100 1110 0110 1100 Bit-1 2-ary 4-ary 8-ary 16-ary 16-ary 16-ary 16-ary 16-ary ... 1 2 3 4 Transmitted Frames No interference! Equivalent to a 2-ary modulation. 6/6/2020 BUPT Confidential and Proprietary 12
A-PCM transmission scheme Transmission scheme Polar Coded Blocks ... ... ... Q 1001 0011 1011 0001 ... Bit-4 0 4 0111 1101 0101 1111 0 3 Bit-3 I 0/1 2 1010 0000 1000 0010 Bit-2 0/1 1 Modulation to one frame 0100 1110 0110 1100 Bit-1 2-ary 4-ary 8-ary 16-ary 16-ary 16-ary 16-ary 16-ary ... 1 2 3 4 Transmitted Frames Due to interference mitigation, the parallel demodulation in this frame is equivalent to the serial demodulation in MLC-PCM. 6/6/2020 BUPT Confidential and Proprietary 13
A-PCM transmission scheme Transmission scheme Polar Coded Blocks ... ... ... Q 1001 0011 1011 0001 ... Bit-4 0 4 0111 1101 0101 1111 0/1 3 Bit-3 I 0/1 2 1010 0000 1000 0010 Bit-2 0/1 1 Modulation to one frame 0100 1110 0110 1100 Bit-1 2-ary 4-ary 8-ary 16-ary 16-ary 16-ary 16-ary 16-ary ... 1 2 3 4 Transmitted Frames 6/6/2020 BUPT Confidential and Proprietary 14
Recommend
More recommend
