Model-Based Signal Processing for Digital Communications

最近，pi开发了一种使用基于模型的逐符号最大后验（MAP）算法的数字通信信号解调范式。同时，开发了一种实验性物理层无线调制解调器，实现了通信理论中的许多高级算法。本项目利用这些过去的发展成果进行高质量的研究：-为重要的无线数据通信应用开发新的算法；-提供技术来分析这些算法的性能和稳定性；-在实际无线信道上部署和实验新算法，以验证理论并制定更准确的分析信号模型。逐符号MAP解调在各种数字通信应用中都很重要。Turbo码由于其接近容量的性能和相对简单的解调架构，最近引起了人们极大的兴趣。MAP解码在Turbo解码中非常重要，本项目将探索以有原则的方式降低标准Turbo解码复杂性的方法，并探索基于最优MAP解码近似的Turbo解码非迭代技术。另外，MAP解调在无线通信中常用的交错编码系统中是非常重要的。本项目探索用于时变频率平坦和频率选择性衰落信道的软输出算法。特别是，我们正在探索用于时分多址应用的高性能解调器，如IS-136和数字电视。在高容量应用中，干扰抑制的重要性大大增加。该项目将扩展基于模型的MAP范例，使用传统的单天线调制解调器和“时空”调制解调器架构，为存在同信道干扰的信号开发高性能解调器。我们项目的另一个独特之处在于，我们将软输出解调/解码与接收器前端设计（例如，均衡，同步）集成在一个框架中。这种方法对于在低信噪比下工作是必不可少的，这是利用强大代码（例如Turbo代码）所必需的。这个项目的另一个独特之处在于，我们打算比传统尝试更深入地研究生成的算法。该项目将应用复杂的分析技术来分析许多提出的算法的性能和稳定性。这种分析将比单独的模拟研究更深入地了解这些算法的性能。我们还打算实现和现场测试许多提出的算法。我们目前有一个工作的无线调制解调器和新的算法可以添加一个简单的改变软件。这种算法开发、算法分析和算法实现的结合将导致对通信理论特别是无线领域的重要新见解。这种结合的方法也将为学生参与者提供更全面的教育体验。

A demodulation paradigm using model-based symbol-by-symbol maximum a posteriori (MAP) algorithms for digital communication signals has recently been developed by the PIs. In parallel, an experimental physical layer wireless modem has been developed that implements many advanced algorithms from communication theory. This project uses these past developments to produce high quality research to: - Develop new algorithms for important wireless data communication applications; - Produce techniques to analyze the performance and stability of these algorithms,; - Deploy and experiment with new algorithms on realistic wireless channels to verify the theory and to formulate more accurate analytical signal models. Symbol-by-symbol MAP demodulation is important in a wide variety of digital communication applications. Turbo codes have recently sparked significant interest due to their near capacity performance and their relatively simple demodulation architecture. MAP decoding is very important in Turbo decoding and the project will explore methods to reduce complexity of standard Turbo decoding in a principled fashion and explore noniterative techniques for Turbo decoding based on approximations to optimal MAP decoding. Additionally MAP demodulation is very important in interleaved coded systems commonly used in wireless communications. This project explores soft output algorithms for use in time-varying frequency flat and frequency selective fading channels. In particular, we are exploring high performance demodulators for time-division multiple-access applications like IS-136 and for digital television. In high capacity applications, interference suppression has greatly increased in significance. This project will extend the model-based MAP paradigm to develop high performance demodulators for signals in the presence of co-channel interference using both a conventional single antenna modem and ''space-time'' modem architectures. Another unique feature of our project is that we consi der soft output demodulation/decoding in an integrated framework with receiver front-end design (e.g., equalization, synchronization). Such an approach is essential for operating at the low SNR's necessary to take advantage of powerful codes (e.g., Turbo codes). A further unique aspect of this project is that we intend to study the resulting algorithms in a much greater depth than is traditionally attempted. This project will apply sophisticated analytical techniques to analyze the performance and stability of many of the proposed algorithms. This analysis will provide a greater insight into the performance of these algorithms than can be achieved via simulation study alone. We also intend to implement and field test many of the proposed algorithms. We currently have a working wireless modem and new algorithms can be added by a simple change of software. This combination of algorithm development, algorithm analysis, and algorithm implementation will lead to significant new insight into communication theory especially in the wireless area. This combined approach will also provide a more well-rounded educational experience for the student participants.