Zaishuang Liu

APSK Constellation with Gray Mapping

Amplitude phase shift keying (APSK) constellation is superior to its quadrature amplitude modulation (QAM) counterpart from the mutual information point of view. However, due to the lack of Gray mapping, it introduces high independent demapping loss. In this letter, a special kind of APSK constellations with Gray mapping (Gray-APSK) is proposed, which provides considerable shaping gain compared with the QAM constellations with Gray mapping (Gray-QAM) in both independent and iterative demapping scenarios, as verified by average mutual information analysis and bit error rate simulations.

Irregular Mapping and its Application in Bit-Interleaved LDPC Coded Modulation With Iterative Demapping and Decoding

This paper proposes an irregular mapping technique, where a new labeling searched via modified adaptive binary switch algorithm (ABSA), mixed with a pre-fixed labeling, can provide near-optimal match to a given outer channel code. By using the proposed technique, the bit-interleaved low-density parity-check (LDPC) coded modulation systems with iterative demapping/decoding (BILCM-ID) could achieve near-capacity performance. With a slight modification on the LDPC coded modulation scheme of DVB-T2 standard, the proposed technique can improve the iterative demapping system by exploiting significant iterative gain. The superior performance is verified via extrinsic information transfer (EXIT) chart analysis and bit error rate (BER) simulation.

Efficient Receiver Architecture for LDPC Coded BICM-ID System

The low-density parity-check (LDPC) coded bit-interleaved coded modulation with iterative demapping (BICM-ID) has excellent bit error rate (BER) performance, but with extremely high receiver complexity. This letter proposes a three-stage full-parallel receiver architecture in which each component decoder is separately but simultaneously iteratively decoded. This architecture can make full use of the computing resources and improve the system performance without sacrificing the throughput. Three-dimensional (3-D) extrinsic information transfer (EXIT) analysis and BER simulations are carried out to demonstrate the superiority of the proposed new receiver architecture.

A new look of doping technique in BICM-ID

Doping technique was employed to remove the high error floor in conventional bit-interleaved coded modulation with iterative demapping and decoding (BICM-ID). This paper proposes a new look of the doping technique-BICM-ID with serial concatenated convolutional code (SCCC-BICM-ID). Unlike conventional doping decoding scheme which deems the doping decoder and the demapper as a whole doped demapper, we combine the doping code and the outer convolutional code together to form an SCCC, so that iterative demapping and decoding is performed between the demapper and the SCCC decoder. Extrinsic information transfer (EXIT) chart is used to analyze these two decoding schemes and reveals that they both can achieve near-capacity performance with no penalty of error floor. According to the results of EXIT analysis and BER simulations, SCCC-BICM-ID system can achieve the same or even better performance compared to the doping BICM-ID system with lower decoding complexity.

Improve the performance of LTE Turbo coded modulation by irregular mapping

3GPP long term evolution (LTE) Turbo coded modulation is well-known for its excellent error-control capability. However, its decoding threshold is still a few decibels away from the constellation-constrained capacity. In this paper, an irregular mapping scheme involving labeling search is proposed to improve the performance of the LTE system. The scheme first predetermines one labeling, and then searches the other one via adaptive binary switch algorithm (ABSA), which considerably increases the design freedom and can provide near-optimal match to a given channel code. By applying the scheme to the LTE specification (Release 8), a practical bit-interleaved Turbo coded modulation with iterative demapping and decoding (Turbo-BICM-ID) system is proposed. With a slight modification on the constellation mapping, the scheme can lower the signal-to-noise ratio (SNR) threshold by 0.43~0.48dB at the block error rate (BLER) of 10-2 under different channel conditions.