ITR: Design of Novel Receiver Algorithms for OFDM Incorporating Realistic Indoor Channel Modeling

由于移动的通信和因特网领域的快速增长，对通信服务的爆炸性需求已经产生并将继续产生宽带有线/无线通信领域的大量研究工作。为了适应未来的应用需求，系统必须设计成能够对未知的和可能时变的信道参数进行联合均衡、检测、解码和估计，同时保持合理的复杂度（和低成本）。基于这些需求，并以一个OFDM Mindoor无线系统为设计实例，本课题主要研究了两个方向：第一个方向是设计迭代、联合均衡、检测和译码的接收机算法，以解决上述关键问题;调查开始确定一个强大的模型，包括所有的OFDM传输系统的特色。OFDM系统中的数据检测问题可以归结为一个二维数据检测问题，该问题存在局部的、二维码间干扰、非线性失真以及未知的时变参数。然后，我们确定快速，联合数据检测和信道估计方案，这些方案被用作强大的自适应迭代检测接收机的构建块。与整个迭代接收器不同，这些子块在精确定义的意义上是最优的，并且可以以相对于数据序列长度小于指数的复杂度来实现。第二个方向是发展一个统一的框架来分析自适应迭代算法的瞬态和稳态行为。在所提出的研究中，接收器被假定为没有明确的知识的信道参数，除了他们的统计描述。收敛到无差错传输所需的最小信噪比，以及导频和编码符号中功率的最佳分配，是研究各种自适应迭代接收机架构的一些问题。关于室内环境的传播建模，本文所采用的方法与经典方法直接不同，经典方法包括测量或完善的射线跟踪技术。特别是，超快速算法的电磁问题的数值解的开发。这些算法的结果几乎exactsolutions，可以评估的复杂性相媲美的不准确的射线跟踪技术。

The explosive demand for communication services, fueled by therapid growth in the areas of mobile communications and theInternet, has generated and will continue to generate immenseresearch efforts in the area of wideband wired/wirelesscommunications. To accommodate the demanding future applications,systems must be designed to perform joint equalization, detection,decoding and estimation of the unknown and possibly time varyingchannel parameters, while maintaining reasonable complexity (andlow cost). Motivated by these requirements, and using an OFDMindoor wireless system as a design example, two main directionsare investigated in this project.In the first direction, receiver algorithms are designed foriterative, joint equalization, detection and decoding, thataddress the critical issues mentioned above. The investigationstarts by identifying a powerful model that encompasses all thesalient features of the OFDM transmission system. Data detectionin OFDM is then stated as a problem of two-dimensional (2D) datadetection in the presence of localized, 2D intersymbolinterference, non-linear distortion, and unknown and time varyingparameters. We then identify fast, joint data detection andchannel estimation schemes which are utilized as building blocksfor powerful adaptive iterative detection receivers. Unlike theentire iterative receiver, these sub-blocks are optimal in aprecisely defined sense, and can be implemented withless-than-exponential complexity with respect to the data sequencelength.The second direction is the development of a unified framework forthe analysis of the transient and steady-state behavior ofadaptive iterative algorithms. In the proposed study, the receiveris assumed to have no explicit knowledge about the channelparameters, other than their statistical description. The minimumsignal-to-noise ratio required for convergence to error-freetransmission, and the optimal allocation of power in pilot andcoded symbols, are some of the issues that are investigated for awide variety of adaptive iterative receiver architectures.Regarding propagation modeling for the indoor environment, theapproach followed herein is a direct divergence from the classicalapproaches that include either measurements, or thewell-established ray-tracing techniques. In particular, ultra-fastalgorithms for the numerical solution of the electromagneticproblem are developed. These algorithms result in almost exactsolutions that can be evaluated with complexity comparable to theless accurate ray-tracing techniques.