Bandwidth Efficient Multiple Access (BEMA) Communications

该项目将探索一种名为带宽高效多址（BEMA）的新型多址技术的潜力，该技术可提供比TDMA、FDMA和CDMA等知名多址策略更高的频谱效率。主要的重点是实现BEMA时只使用单用户编解码器（而不是多用户编解码器，因为人们对多用户编解码器知之甚少）作为子系统。潜在的应用是无线室内和个人通信。BEMA的核心将是实现多用户均衡和信号设计功能的信号处理算法，通过将这两个主题结合起来。将系统地发展同步和异步多址信道的多用户决策反馈均衡理论。在多用户均衡器的延迟和复杂度约束下，寻求具有相关波形的高斯多址信道容量区域的顶点或近最优点。结合均衡和连续译码，研究了分频多址的推广。将获得确定用户均衡和解码顺序的算法，将量化多用户决策反馈检测的错误传播效应，并将寻求编码系统决策反馈接收器的错误指数特征。信号设计的重点将是通过决策反馈接收器获得每个用户在功率和速率（服务质量）约束下形成容量区域的签名波形，从而最大限度地减少带宽。

This project will explore the potential of a new multiple access technique called Bandwidth Efficient Multiple Access (BEMA) in offering higher spectral efficiencies than the well-known multiaccess strategies such as TDMA, FDMA, and CDMA. The primary emphasis is to realize BEMA with the use of only single-user codecs (and not multiuser codecs about which too little is known) as subsystems. Potential applications are in wireless indoor and personal communications. At the heart of BEMA will be signal processing algorithms that realize the functions of multiuser equalization and signal design by taking a combined approach to those two subjects. A systematic development of a theory of multiuser decision feeedback equalization for synchronous and asynchronous multiple-access channels will be undertaken. The achievement of vertices or near-optimal points in the capacity regions of Gaussian multiple-access channels with correlated waveforms will be sought under latency and complexity constraints on the multiuser equalizers. Generalizations of Rate-Splitting Multiple Access by combining equalization and successive decoding will be considered. Algorithms that determine the order in which users are to be equalized and decoded will be obtained, error propagation effects for multiuser decision feedback detection will be quantified, and a characterization of error exponents for decision feedback receivers for coded systems will be sought. The focus in signal design will be to obtain signature waveforms that shape the capacity region under power and rate (quality of service) constraints to be achieved for each user via decision feedback receivers so as to minimize bandwidth.