Tao Cheng

Tsinghua University, Peping, Beijing, China

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Publications (9)4.33 Total impact

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    ABSTRACT: An augmented data transmission (ADT) scheme for the Digital Television Terrestrial Multimedia Broadcasting (DTMB) systems based on the technique of embedded constellation is proposed in this paper. With the proposed ADT scheme, the transmission rates of receivers with sufficient good channel conditions are increased at the cost of little impact to the performance of legacy receivers, which is verified by AMI analysis and BER simulation. Additional RF spectrum is not required and no additional complexity is introduced to legacy receivers. What's more, the proposed ADT scheme is backward compatible with the existing DTMB system.
    Broadband Multimedia Systems and Broadcasting (BMSB), 2013 IEEE International Symposium on; 01/2013
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    ABSTRACT: The performance degradation of each step from Shannon limit to implementation for the second generation digital video broadcasting - terrestrial (DVB-T2) system is analyzed in this paper, from three aspects: the time-frequency bandwidth loss, imperfect coded modulation scheme, and other implementation issues. The analysis results intuitively show the weak parts that still exist in the DVB-T2 system, and also provide guidelines for system improvement in the future.
    Broadband Multimedia Systems and Broadcasting (BMSB), 2013 IEEE International Symposium on; 01/2013
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    ABSTRACT: 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.
    Wireless Communications and Mobile Computing Conference (IWCMC), 2013 9th International; 01/2013
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    ABSTRACT: 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.
    01/2012;
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    ABSTRACT: In this paper, the bit mapping technique is applied to the low-density parity-check (LDPC) coded modulation system with Gray-APSK constellations for the first time. A multi-grid searching algorithm (MGSA) based on extrinsic information transfer (EXIT) chart analysis is first proposed to optimize the bit mapping distribution, after which a low-complexity bit mapper consisting of a structural bit interleaver and a demultiplexer (DEMUX) is devised. Compared to the LDPC coded QAM system specified in DVB-T2, the proposed APSK system with the optimized DEMUX can achieve up to 0.83dB gain under additive white Gaussian noise (AWGN) channel.
    IEEE Communications Letters 01/2012; 16(6):777-780. · 1.16 Impact Factor
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    ABSTRACT: Due to the unequal error protection (UEP) property of both the irregular low-density parity-check (LDPC) code and the higher-order modulation, bit mapping is proposed as a joint optimization of the LDPC coded-modulation scheme. In this paper, we discuss the bit mapping optimization performed by employing an additional DEMUX following the given bit interleaver, and then apply it to the second generation digital video broadcasting system for cable (DVB-C2). The extrinsic information transfer (EXIT) chart technique is adopted to analyze the influence of bit mapping on the iterative decoding process. Based on the EXIT-chart analysis, an optimization method is proposed to design the DEMUX for performance improvement. As an example, we re-design the DEMUX for the DVB-C2 system with reduced DEMUX width. The superior performance of the optimized DEMUX is verified by the bit error rate (BER) simulation.
    Wireless Communications and Mobile Computing Conference (IWCMC), 2012 8th International; 01/2012
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    ABSTRACT: Powerline communications (PLC) have gained heightened interest in recent years. PLC G3, a newly developed specification for narrowband PLC, uses DBPSK/DQPSK as its modulation to provide a data rate up to 33.4kbps. In this paper, we propose to use 3D-BPSK in PLC G3 to lower the signal-to-noise ratio (SNR) threshold of the system with iterative demapping and decoding (ID). To optimize the performance of ID systems, 3D-BPSK labelings are classified into 33 groups based on the criteria of constellation mapping operators and Hamming-Euclidean distance (HED) spectrum. The optimal labeling is selected through exhaustive searching over the 33 groups by means of curve fitting on extrinsic information transfer (EXIT) chart. Simulation results show that the proposed system can achieve up to 1.0 dB iterative gain under AWGN channel.
    01/2012;
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    ABSTRACT: 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.
    IEEE Transactions on Broadcasting 10/2011; · 2.09 Impact Factor
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    ABSTRACT: In this paper, we focus on the design of bit mapping scheme to improve the error-control performance for the second generation digital video broadcasting-terrestrial (DVB-T2) standard. Generally in the case of low-density parity-check (LDPC)-coded modulation system, the nonuniform bit reliabilities inherent to the high-order modulation and irregular LDPC code imply the mismatch between the decoder and the demodulator. Hence, the bit mapping is plugged between the two modules to match the unequal error protections (UEPs) of different coded bits to different modulation levels. This scheme gives a remarkable performance improvement with no added complexity in the bit-interleaved coded modulation (BICM) system. By performing the curve-fitting on the extrinsic information transfer (EXIT) chart, we propose a DEMUX design methodology to improve the bit mapping scheme. Design examples are given for the DVB-T2 system under the AWGN channel as well as the Rayleigh channel. Simulation results indicate that the proposed DEMUX schemes can even surpass the performance of the DEMUX operation specified in the DVB-T2 standard1.
    IEEE Transactions on Consumer Electronics 01/2011; 57(4):1579-1585. · 1.09 Impact Factor