Math @ Duke

Publications [#319405] of Henry Pfister
Papers Published
 Hou, J; Siegel, PH; Milstein, LB; Pfister, HD, CapacityApproaching BandwidthEfficient Coded Modulation Schemes Based on LowDensity ParityCheck Codes,
Ieee Transactions on Information Theory, vol. 49 no. 9
(September, 2003),
pp. 21412155+2322, Institute of Electrical and Electronics Engineers (IEEE) [doi]
(last updated on 2019/07/23)
Abstract: We design multilevel coding (MLC) and bitinterleaved coded modulation (BICM) schemes based on lowdensity paritycheck (LDPC) codes. The analysis and optimization of the LDPC component codes for the MLC and BICM schemes are complicated because, in general, the equivalent binaryinput component channels are not necessarily symmetric. To overcome this obstacle, we deploy two different approaches: one based on independent and identically distributed (i.i.d.) channel adapters and the other based on coset codes. By incorporating i.i.d. channel adapters, we can force the symmetry of each binaryinput component channel. By considering coset codes, we extend the concentration theorem based on previous work by Richardson et al. and Kavčić et al. We also discuss the relation between the systems based on the two approaches and show that they indeed have the same expected decoder behavior. Next, we jointly optimize the code rates and degree distribution pairs of the LDPC component codes for the MLC scheme. The optimized irregular LDPC codes at each level of MLC with multistage decoding (MSD) are able to perform well at signaltonoise ratios (SNR) very close to the capacity of the additive white Gaussian noise (AWGN) channel. We also show that the optimized BICM scheme can approach the parallel independent decoding (PID) capacity as closely as does the MLC/PID scheme. Simulations with very large codeword length verify the accuracy of the analytical results. Finally, we compare the simulated performance of these coded modulation schemes at finite codeword lengths, and consider the results from the perspective of a random coding exponent analysis.


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