| Summary: | 碩士 === 國立中央大學 === 電機工程研究所 === 87 === Asymmetric Digital Subscriber Line (ADSL) has been considered as the next-generation transmission technology for high-speed data access applications. In current ADSL standard, the discrete multitone modulation (DMT) technique has adopted as the line code of transmission. The combination of DMT modulation with forward error correction (FEC) coding techniques result in high-performance transceiver for a variety of high-speed applications. The coding scheme in a DMT-based ADSL system is a concatenated code, where a four-dimensional 16-state Trellis-coded modulation (4-D TCM) is used as an inner code, and an interleaved Reed-Solomon (RS) code is used as an outer code. Theoretically, the use of the concatenated code has a coding gain over 5.0 dB at bit error rate (BER) of 10-7.
In this thesis, we focus on the design of encoder/decoder for Wei's 4-D TCM. The use of 4-D TCM can improve the transmission performance, however, the hardware complexity of the encoder/decoder for 4-D TCM is more complicated than the one of conventional TCM. In practical design, we first verify the decoding process by computer simulation. Then, detailed VLSI structures for the major blocks in the 4-D TCM encoder/ decoder are designed. Finally, based on the designed architectures, we implement the design by using Avanti 0.35 Standard Cell. The simulation results show that it can meet the specification of ADSL system.
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