From Medium Access to Physical Layer: An Integrated DSP Framework for Wireless Packet Networks

第一代和第二代无线网络在提供具有全球覆盖的语音服务方面取得了显著的成功。在这一成功的基础上，第三代和第四代网络的设想更加强调灵活的数据而不是语音服务。这样的基础设施将能够实现先进的和多样化的无线服务，这可能是还没有想象到的。在实现高速无线数据网络中最棘手的技术挑战之一是在无线信道上复用可变比特率数据用户。传统的解决方案，如TDMA、FDMA甚至CDMA都不合适，因为它们坚持面向连接而不是基于分组的无连接哲学。另一方面，随机接入技术提供了所需的灵活性，但在繁忙的业务下遭受严重的吞吐量/延迟惩罚。为了处理预期的多样化的流量混合，新的媒体接入（MAC）计划必须开发。正如NSF 99-68倡议所强调的那样，越来越多的人认为，这种新的解决方案需要打破传统的分层网络设计方法，走向跨多个Layers.The研究的目标是一个跨介质访问和物理层的无线分组网络设计的综合方法。从最近推出的MAC协议（称为NDMA网络分集多址接入），利用MAC级网络资源之间的物理层和MAC层的协同作用，研究人员研究联合冲突解决方案，盲波束成形，并在分组无线电网络的功率控制，展示了大量的吞吐量延迟性能增益超过传统的分层设计的目标。这项研究涉及先进的信号处理，因子分析，优化和建模工具。为了将NDMA概念发展成一个完整的最先进的物理和数据链路层解决方案，正在研究以下具体问题：（i）针对实际SNR的NDMA性能分析，以及针对频率选择性信道的系统设计;（ii）盲和半盲NDMA冲突解决方法的开发和相关性能分析;以及（iii）系统集成问题：联合盲波束形成、冲突解决、功率控制和分组无线电网络中的ARQ设计。该项目还包括一个综合教育部分，促进研究生和本科生在无线通信和网络方面的研究。

First and second generation wireless networks have had a remarkable success in providing voice services with global coverage. Building on this success, third and fourth generation networks are envisioned with more emphasis on flexible data rather than voice services. Such an infrastructure will enable the implementation of advanced and diverse wireless services which are perhaps not yet imagined. One of the thorniest technical challenges in implementing high speed wireless data networks is that of multiplexing variable-bit-rate data users over the wireless channel. Classical solutions like TDMA, FDMA, or even CDMA are not appropriate, since they adhere to a connection-oriented, rather than packet-based, connectionless philosophy. Random access techniques on the other side offer the required flexibility, but suffer from severe throughput/delay penalties under heavy traffic. In order to handle the anticipated diverse traffic mix, novel Medium Access (MAC) schemes have to be developed. As the NSF 99-68 initiative underlines, there is growing consensus that such novel solutions require breaking away from the traditional layered approach to network design, moving towards integrated design across multiple layers.The goal of this research is an integrated approach to wireless packet network design that cuts across the medium access and physical layers. Starting from a recently introduced MAC protocol (termed NDMA for Network Diversity Multiple Access) which utilizes MAC-level network resources to create a synergy between the physical and MAC layers, the investigators study joint collision resolution, blind beamforming, and power control in packet radio networks, with the goal of demonstrating substantial throughput-delay performance gains over traditional layered designs. This research involves advanced signal processing, factor analysis, optimization, and queueing tools. Aimed at developing the NDMA concept into a complete state-of-art physical and data link layer solution, the following specific issues are under investigation: (i)NDMA performance analysis for realistic SNR, and system design for frequency selective channels; (ii)development of blind and semi-blind NDMA collision resolution methods and associated performance analysis; and (iii)system integration issues: joint blind beamforming, collision resolution, power control, and ARQ design in packet radio networks. The project also includes an integrated educational component promoting graduate and undergraduate research in wireless communications and networking.