Adaptive Systems for Equalization of Wireless Multiple Access Comunication Channels

9811095穷移动电话和数据传输的无线系统目前正经历非常迅速的发展，因为最近的国际协议在无线电频谱中开辟了新的区域供这些服务使用。这些新系统，即所谓的第三代无线系统，将整合相当大的信号处理智能，以提供多媒体等先进服务。为了优化这些服务的可用带宽并提供最大的灵活性，许多这样的系统将作为多址系统运行，其中信道带宽在随机访问的基础上由许多用户共享，使用诸如码分多址（CDMIA）信令等协议。此外，为了支持这些服务中固有的高数据速率，比特率与带宽的比率将被推到极限。一般来说，无线信道可能是非常不友好的通信媒介。物理缺陷，如多址干扰、同信道干扰、多径传输、幅度衰减以及带宽有限导致的色散，都使通过无线信道可靠、快速地传输数据变得困难。此外，由用户移动性和上述移动渠道的随机访问性质所产生的动态性放大了这些损害的影响，并使它们更难以改善。这些困难的解决方案在于使用先进的自适应系统来执行先进的信号处理功能，本提案解决了这些解决方案。具体而言，我们计划考虑多址无线信道自适应均衡领域的三个一般研究问题：联合自适应均衡和多用户检测的最佳方法；联合自适应均衡和多用户检测的自适应线性和非线性方法在编码信道上联合自适应均衡和多用户检测的迭代方法。通过解决这些研究问题，我们可以回答有关无线多址信道均衡的关键问题。特别是，对最佳方法的考虑将建立基线结果，从而可以作为其他方法的基准。此外，通过考虑低复杂性的自适应线性和非线性方法，我们可以发展对机制的理解，通过这种机制，适应性可以对手头的问题产生影响。能够在可处理的环境中检查适应的动态。最后，通过考虑迭代和其他自适应非线性方法，我们可以寻求自适应技术，可以接近通过其他两个领域的分析结果建立的理想-高性能和低复杂性。为了实现这些目标，有必要采用一种新的方法来解决这些问题，特别是综合来自不同领域的技术。因此，这项研究将作为三家机构（ALGOREX, Inc.， Cornell University和Princeton University）的联合项目进行，汇集了均衡、干扰抑制和自适应系统设计领域的大量独立专业知识，以促进必要的思想综合。* * *

9811095PoorWireless systems for mobile telephony and data transmission are currently undergoing very rapid development due to recent international agreements opening new regions in the radio spectrum to such services. These new systems, so-called third-generation wireless systems, will incorporate considerable signal-processiilg intelligence in order to provide advanced services such as multimedia. In order to make optimal use of available bandwidth for these services and to provide maximal flexibility, many such systems will operate as multiple-access systems, in which channel bandwidth is shared my many users on a random-access basis using protocols such as code division multipleaccess (CDMIA) signaling. Moreover, in order to support the high data rates inherent in such services, ratios of bit rates to bandwidths will be pushed to their limits. In general, wireless channels can be be very hostile media through which to communicate. Physical impairments such as multiple-access interference, co-channel interference, multipath transmission, amplitude fading, and dispersion due to limited bandwidth, all contribute to make it difficult to transmit data reliably and quickly through wireless channels. Moreover, the dynamism resulting from user mobility and the above-noted random-access nature of mobile channels, amplify the effects of these impairments, and make them much more difficult to ameliorate. Solutions to these difficulties lie in the use ofadvanced adaptive systems to perform advanced signal processing functions, and this proposal addresses such solutions.Specifically, we plan to consider three general research problems within the area of adaptive equalization of multiple-access wireless channels: optimal methods for joint adaptive equalization and multiuser detection; adaptive linear and nonlinear methods for joint adaptive equalization and multiuser detection; and iterative methods for joint adaptive equalization and multiuser detection on coded channels. By addressing these research issues we can answer key questions about the equalization of wireless multiple-access channels. In particular, the consideration of optimal methods will establish baseline results by which other methods can be benchmarked. Furthermore, by considering low complexity adaptive linear and nonlinear methods, we can develop an understanding of mechanisms by which adaptivity can brought to bear on the problem at hand, and moreoever we. can examine the dynamics of adaptation in a tractable setting. And, finally, by consideration of iterative, and other adaptive nonlinear methods, we can seek adaptive techniques that can approach the ideals - of high performance and low complexity - established via the analytical results of the two other areas. In order to accomplish these goals, it is necessary to take a novel approach to these problems, and in particular to synthesize technologies from disparate areas. Consequently, this studv will be conducted as a joint project among three institutions - ALGOREX, Inc., Cornell University, and Princeton University - bringing together considerable separate expertise in the fields of equalization, interference suppression, and adaptive system design to facilitate the necessary synthesis of ideas. ***