High-Performance Adaptive Receivers for Broadband Multi-User Communications

用于宽带多用户通信的高性能自适应接收机无线信道上的高速通信已经成为未来通信系统的关键特征，部分原因是对信息技术应用的爆炸性兴趣，包括无线传感器网络、移动的可穿戴系统、移动的计算、无线定位（E911）、高速移动互联网和无线信道上的视频传输。在这些应用中对更高信息容量的需求已经促使宽带无线信道的使用，以便提供更宽的带宽和更高的数据速率。这种需求也促使多用户通信方案的发展，以允许用户共享相同的物理信道，从而有助于更高的数据速率。限制这种多用户通信系统性能的一个关键挑战是由耦合通信信道、用户间干扰和信道衰落条件引入的失真。本研究的目的是研究和开发自适应接收机，可以通过调整他们的性能，根据通信环境来对抗这种失真，研究和开发有效的自适应接收机的宽带多用户通信，通过利用空间，数据和模型结构，以减少计算复杂度和提高性能水平。通过这样做，期望所得到的方案将有助于提高数据速率，降低由于训练引起的开销，降低误码率，改善信噪比，并且有助于减轻符号间干扰、用户间干扰和噪声的组合效应，这样的方案将通过允许多个用户以有效的方式共享相同的时隙和频带来增加宽带无线网络的容量。本研究的重点是时域和频域均衡技术，后者越来越受到关注，因为它已被接受为IEEE 802.16标准的无线城域网。这项研究也与其他无线应用有关，例如无线定位（E911），它已成为未来蜂窝系统的重要公共安全组件。这是因为这项工作能够开发增强的自适应技术，这些技术对快速信道衰落、低信噪比条件和严重的多径传播情况具有鲁棒性，所有这些都是E911环境的特征

High-Performance Adaptive Receivers for Broadband Multi-User CommunicationsHigh speed communications over wireless channels has emerged as a key feature of future communications systems due in part to the explosive interest in information technology applications, including wireless sensor networks, mobile wearable systems, mobile computing, wireless location (E911), high-speed mobileinternet, and video transmission over wireless channels. The demand for higher information capacity in these applications has motivated the use of broadband wireless channels in order to provide wider bandwidth and higher data rates. This demand has also motivated the development of multi-user communicationschemes in order to allow users to share the same physical channel; thereby contributing to even higher data rates. A key challenge that limits the performance of such multi-user communications systems is the distortion introduced by the coupled communication channels, by the interference among users and by thechannel fading conditions. This research aims at studying and developing adaptive receivers that can combat such distortions by adapting their performance in accordance to the communications environment.The research studies and develops efficient adaptive receivers for broadband multi-user communications by exploiting spatial, data, and model structures in order to reduce computational complexity and increase performance level. In so doing, it is expected that the resulting schemes will help increase data rates, loweroverhead due to training, lower bit-error-rate, improve signal-to-noise ratio, and help mitigate the ombined effects of inter-symbol interference, inter-user interference, and noise.Such schemes would increase the capacity of broadband wireless networks by allowing multiple users to share the same time slot and frequency band in an efficient manner. This study focuses onboth time-domain and frequency-domain equalization techniques, with the latter receiving increasing attention since it has been accepted as IEEE 802.16 Standard for Wireless Metropolitan AreaNetworks. The research is also relevant to other wireless applications such as wireless location (E911), which has emerged as an essential public safety component of future cellular systems. This is because this work enables the development of enhanced adaptive techniques that are robust to fast channelfading, low signal-to-noise ratio conditions, and severe multipath propagation situations, all of which are characteristic of the E911 environment