Performance of low-density parity-check (LDPC) coded OFDM systems
Performance of low-density parity-check (LDPC) coded OFDM systems
复制标题
低密度奇偶校验 (LDPC) 编码 OFDM 系统的性能
DOI：
10.1109/icc.2002.997138
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
T. Ohtsuki
中科院分区：
文献类型：
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作者：
H. Futaki;T. Ohtsuki
正交频分复用（OFDM）对于多路径环境中的高比特率数据传输来说是一种非常有吸引力的技术。许多纠错码已应用于 OFDM。近年来，LDPC码引起了广泛关注。 LDPC码的性能非常接近香农极限，具有实用的解码复杂度。我们提出了采用 BPSK 的 LDPC 编码 OFDM (LDPC-COFDM) 系统，并表明 LDPC 码可有效改善多径环境中 OFDM 的误码率 (BER)（参见 Futaki, H. 和 Ohtsuki, T., IEEE VTC2001 秋季，第 1 卷，第 82-6 页，2001）。 LDPC 码可以使用称为和积算法或置信传播的概率传播算法进行解码。为了阐明 LDPC-COFDM 系统中的迭代解码特性，我们首先研究解码算法停止处的迭代次数的分布。在移动通信中，多级调制因其高带宽效率而受到青睐。然而，如何将LDPC码应用于多级调制的OFDM系统尚未明确。我们提出了一种使用 M-PSK 的 LDPC-COFDM 系统解码算法。通过仿真，我们表明 LDPC-COFDM 系统在 AWGN 和频率选择性衰落信道上通过少量迭代即可实现良好的误码率性能。我们确认采用 M-PSK 的 LDPC-COFDM 系统算法可以正常工作。
Orthogonal frequency division multiplexing (OFDM) is a very attractive technique for high-bit-rate data transmission in multipath environments. Many error-correcting codes have been applied to OFDM. Recently, LDPC codes have attracted much attention. The performance of LDPC codes is very close to the Shannon limit, with practical decoding complexity. We proposed LDPC coded OFDM (LDPC-COFDM) systems with BPSK and showed that the LDPC codes are effective in improving the bit error rate (BER) of OFDM in multipath environments (see Futaki, H. and Ohtsuki, T., IEEE VTC2001 fall, vol.1, p.82-6, 2001). LDPC codes can be decoded using a probability propagation algorithm known as the sum-product algorithm or belief propagation. To clarify iterative decoding properties in LDPC-COFDM systems, we first investigate the distribution of the number of iterations where the decoding algorithm stops. In mobile communications, multilevel modulation is preferred for high bandwidth efficiency. However, it has not been clarified how to apply LDPC codes to OFDM systems with multilevel modulation. We propose a decoding algorithm for the LDPC-COFDM systems with M-PSK. By simulation, we show that LDPC-COFDM systems achieve good error rate performance with a small number of iterations on both AWGN and frequency-selective fading channels. We confirm that the algorithm for LDPC-COFDM systems with M-PSK work correctly.