Turbo Coded Modulation for Partially Coherent Channels

部分相干信道的 Turbo 编码调制

• 批准号: 0098357
• 负责人: Benjamin Belzer
• 金额: --
• 依托单位: Washington State University
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-05-15 至 2004-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0098357&HistoricalAwards=false
• 关键词: Turbo; Coded; Modulation; Partially; Coherent; Turbo; Coded; Modulation; Partially; Coherent

Abstract:This research considers the design of bandwidth efficient coded modulation for partially coherent channels. Such channels occur in practice when coherent receivers are operated at low or moderate signal-to-noise ratios (SNRs), resulting in noisy phase estimates. This happens for example on wireless channels, where multipath fading causes fluctuations in received SNR. This research leverages a recent breakthrough known as turbo coding, wherein the outputs of two or more encoders at the transmitter are iteratively decoded at the receiver, resulting in reliable communication at SNRs within 1 dB of channel capacity. This research integrates phase-tracking error into all aspects of turbo coded modulation design, thereby reducing the required SNR for practical coherent communication systems. The new design techniques stemming from this research will therefore interest not only communication and coding theorists, but also engineers designing practical communication systems.The goal of this research is to develop theoretically based, practical design methods for parallel and serially concatenated turbo coded modulation over partially coherent (PC) channels, including PC additive white Gaussian noise (AWGN) channels, and PC fading channels with and without channel state information (CSI), with and without correlated fading, and with closed-loop and open-loop phase estimation. The investigators study the information capacity of PC channels, and determine capacity-achieving input probability density functions (PDFs) and capacity-optimal constellations for equiprobable and non-equiprobable signaling under average and peak power constraints. Distance metrics based on pairwise symbol error probabilities will be derived for PC fading channels, and iterative decoder performance prediction tools based on union bounds and convergence-region analysis will be developed. The investigators will then study set-partitioning, bits-to-symbol mapping, and code-search procedures for both linear and non-linear recursive convolutional encoders used as constituent codes in concatenated trellis-coded modulation schemes. Finally, shaping code design techniques for turbo coded modulation on power-constrained PC channels will be developed, based on the capacity-achieving PDFs of these channels, which are known to be non-Gaussian. These codes will shape the high-dimensional space of encoder output symbol sequences so that the induced two-dimensional PDF will closely approximate the capacity-optimal input PDF.

摘要：这项研究考虑了部分连贯通道的带宽有效编码调制的设计。当相干接收器以低或中等的信噪比（SNR）运行时，这种通道发生在实践中。例如，在无线通道上发生这种情况，在无线通道中，多径褪色会导致接收的SNR波动。这项研究利用了最近称为涡轮编码的突破，其中在接收器上迭代地解码了两个或多个编码器的输出，从而在通道容量的1 dB以内在SNRS上进行了可靠的通信。这项研究将相跟踪误差集成到涡轮编码调制设计的各个方面，从而减少了实用相干通信系统所需的SNR。因此，由这项研究引起的新设计技术不仅会感兴趣，不仅会引起沟通和编码理论家的关注，而且还会引起工程师的设计实用通信系统。这项研究的目标是开发基于理论上的，实用的设计方法，用于平行和串联的涡轮增压调节，并在包括PC添加剂（PC添加剂）的通道（包括PC添加剂噪声）（包括PC添加剂）通道（包括AWGN）的通道（PC）通道（PC）通道（PC）通道（PC）通道（PC），以及PC的通道（PC）。并且没有相关的褪色，也没有闭环和开环相估计。研究人员研究了PC通道的信息能力，并确定能力调整的输入概率密度函数（PDFS）以及在平均功率和峰值限制下的设备和不可设备的信号传导的容量和不可设备的信号。将根据PC褪色通道得出基于成对符号误差概率的距离指标，并将开发基于联合界限和收敛区域分析的迭代解码器性能预测工具。然后，研究人员将研究固定分区，位对符号映射以及用于线性和非线性递归卷积编码器的代码搜索程序，用于串联的格子编码调制方案中的组成代码。最后，将基于这些频道的能力调整PDF开发针对涡轮构成的PC通道的涡轮编码调制的代码设计技术，这些PDF已知是非高斯的。这些代码将塑造编码器输出符号序列的高维空间，以便诱导的二维PDF将紧密近似于容量最佳的输入PDF。