Space-Time Coding for Wireless Communications

无线通信中的空时编码Michael P.Fitz和Urbashi Mitra建议9980616，俄亥俄州州立大学本研究将扩展信道编码公式的天线通信系统的技术水平。 最近的研究表明，如果在发射机和接收机都使用多个天线，无线通信系统的容量可以大大增加。 此外，实现这种增益的一种方法是在传输的扩频序列中引入时间和空间上的受控冗余（编码），这是常规方案。 这一领域的研究仍然是相当新的和几个关键问题领域需要解决。 例如，寻找空时码的计算有效方法是必要的。通常情况下，无线信道是时变的，并且不可能总是对信道条件进行很好的估计，因此评估空时码的鲁棒性是有价值的. 一个相关的项目是考虑空时编码和解码方法与设计用于估计信道和其他关键通信参数的算法的相互作用。 Turbo码是近年来出现的一种具有接近香农容量的强有力的编码，因此本文将研究Turbo码的空时推广。 最后，由于目前空时编码的研究主要是针对窄带时分多址系统的，因此我们也要考虑宽带码分多址系统的空时码设计和译码器设计。第一个研究重点将集中在空时网格码的改进搜索技术的发展和分析。 当前用于搜索空时网格码的距离谱的方法在计算上可能是昂贵的。 将探讨减少错误状态网格的大小的方法以及减少复杂性的网格搜索方案。下一个重点是在现实的信道条件下，评估的鲁棒性的空时码。 此外，将考虑用于参数信道的空时编码。 因此，受约束的信道的不确定性将存在和代码的设计，这样的scenaries.The第三个研究重点将是空时Turbo码作为一种方法，以实现各种信道条件下的鲁棒性。 Turbo编码方案的类随机结构有望减轻码结构和信道特性之间可能的相互作用。CDMA信道的空时码设计将在第四个研究重点中进行研究。 CDMA信号具有较大的维数，因此空时码的设计不同于单用户系统。 此外，CDMA信号在多径信道中将导致不同的最佳码设计。最后的研究课题将考虑接收机设计的背景下，空时编码。 也就是说，空时编码和调制的信道估计和同步将被研究。 将设计利用空时码特性的算法。 此外，性能依赖于准确的信道估计和同步将进行分析。

Space-Time Coding for Wireless CommunicationsMichael P. Fitz and Urbashi MitraProposal 9980616,The Ohio State University This research will extend the state of the art in channel coding formulti-antenna communication systems. It has recently been shown thatthe capacity of a wireless communications system can be greatlyincreased if multiple antennae are used both at the transmitter and thereceiver. Furthermore, a method for achieving such gains is tointroduce controlled redundancy (coding) in the transmitted datasequence spatially as well as temporally, which is the conventionalscheme. This area of research is still quite new and several keyproblem areas need to be addressed. For example, computationallyefficient methods for finding space-time codes are necessary. Typically, the wireless channel is time-varying and it is not alwayspossible to achieve good estimates of the channel conditions; thusevaluating the robustness of space-time codes is of value. A relatedproject is to consider the interplay of space-time coding and decodingmethods with algorithms designed to estimate the channel and other keycommunication parameters. Turbo codes have recently emerged aspowerful codes for achieving near Shannon capacity, thus space-timegeneralizations of such codes will be studied. Finally, much of thecurrent work on space-time coding is for narrowband time divisionmultiple access systems, thus we shall consider space-time code designand decoder design for wideband code-division multiple-access systemsas well. The first research thrust will focus on the development and analysisof improved search techniques for space-time trellis codes. Current methods for searching the distance spectrum of space-time trellis codes can be computationally expensive. Methods for reducing the size of the error state trellis coupled with reduced complexity trellis search schemeswill be explored. The next focus is on evaluating the robustness of space-timecodes under realistic channel conditions. In addition, space-time coding for parametric channels will be considered. Thus, constrained channel uncertainty will exist and code designs for such scenarios will be developed.The third research focus will be on space-time turbo codes as one method to achieve robustness to a variety of channel conditions. The random--like structure of turbo coded schemes hold some promise of mitigating the possible interactions between the code structure and the channel characteristics.Space-time code designs for CDMA channels will be investigated in the fourth research thrust. CDMA signals have a larger dimensionality andthus the space-time code design is different from that for single-user systems. In addition, CDMA signals in a multipath channel will result in different optimal code designs. The final research topic will consider receiver designs in the context of space-time coding. That is, channel estimation and synchronization for space-time coding and modulation willbe investigated. Algorithms which exploit the properties of space-timecodes will be designed. In addition, the performance dependence on accuratechannel estimates and synchronization will be analyzed.