Ultra Wideband Communications based on Massive MIMO and Multi-mode Antennas Suitable for Mobile Handheld Devices

DFG优先级计划1655 （SPP 1655）的目标是移动互联网接入的峰值数据速率达到100gbps或更高。在我们对SPP 1655的贡献中，我们专注于移动受限的室内场景，其中部署了低成本低复杂性的微型消费电子设备，如平板电脑和智能手机。在无线通信要求超高数据速率的背景下，超宽带技术是实现目标数据速率最有前途的技术。当只考虑6-8.5 GHz的频率范围时，欧盟国家定义的EIRP掩码具有显著的最大值，至少需要40 bps/Hz的频谱效率。在我们的跨学科（微波工程/基带处理）方法中，我们结合了我们在以下领域的专业知识：实现极高吞吐量的系统架构，实现千兆无线系统的复杂性降低和节能范例，超宽带系统的基带处理算法，以及无线100 Gbps系统性能参数的研究。SPP 1655第一阶段引入的关键概念是结合先进基带处理的多模天线设计，称为多模大规模MIMO。这个概念适用于微型设备，以及接入点阵列。在第一阶段，实现了基于典型机箱矩形形状的最多5个端口的用户终端多模天线，以及适合接入点的11x11x4=484端口的天线阵列。一个重要的结果是，我们的系统方案的可行性可以证明，无论是从微波工程的角度，还是从基带处理的角度。然而，也可以观察到一些瓶颈：在全超宽带宽上可用的模式数量有限，限制了上行链路上的流数量，从而限制了数据速率。在第二阶段，我们的目标是扩展和优化所提出的概念。这项工作的动机是在第一阶段获得的见解。值得注意的是，将探讨多用户场景，以确定以给定数据速率为给定数量的用户提供服务所需的硬件。对于用户终端，在微波/基带联合优化方法中，将研究当所有模式必须服务于整个带宽的限制被取消时，可能提高的w.r.t.吞吐量。特别地，附加模式对信道容量的影响将被研究。关于接入点，减小天线元件的尺寸及其间距是主要关注的问题。对于典型的信道条件，这将启用预定义的模拟波束形成模式，以减少数字波束形成优化的处理复杂性。在此基础上，对多用户多流发射波束形成进行了研究。

The DFG priority program 1655 (SPP 1655) targets at peak data rates of 100 Gbps and beyond for mobile internet access. In our contribution to SPP 1655, we focus on the indoor scenario with limited mobility, where low-cost low-complexity miniature consumer electronic devices like tablets and smartphones are deployed. In the context of ultra-high data rates for wireless communications, ultra-wideband technology is the most promising technique to achieve the target data rate. When considering only the frequency range from 6-8.5 GHz, where the EIRP mask defined for EU countries has a significant maximum, a spectral efficiency of at least 40 bps/Hz is necessary. In our interdisciplinary (microwave engineering/baseband processing) approach we combine our expertise in the following areas: System architectures enabling extremely high throughput, realization of paradigms for complexity reduction and energy saving of gigabit wireless systems, algorithms for baseband processing in ultra-wideband systems, and investigation of performance parameters of wireless 100 Gbps systems.The key concept introduced in the first phase of SPP 1655 is a multi-mode antenna design in conjunction with advanced baseband processing, dubbed multi-mode massive MIMO. This concept is suitable for miniature devices, as well as for access point arrays. In the first phase, both a user terminal multi-mode antenna with up to five ports based on the rectangular shape of a typical chassis as well as an antenna array with 11x11x4=484 ports suitable for access points has been implemented and characterized. One important outcome is that the feasibility of our system proposal could be proven, both from a microwave engineering as well as from a baseband processing point of view. However, also some bottlenecks could be observed: The limited number of modes that is available over the full ultra-wide bandwidth restricts the number of streams on the uplink and hence limits the data rate.In the second phase, we aim at extensions and optimizations of the proposed concept. This work is motivated by insights obtained during the first phase. Notably, multi-user scenarios will be explored to determine the required hardware to serve a given number of users with a given data rate. Concerning the user terminal, in a joint microwave/baseband optimization approach the possible improvements w.r.t. throughput will be investigated when the restriction that all modes must serve the entire bandwidth is dropped. Particularly, the effect of the additional modes on the channel capacity will be studied. Concerning the access point, a reduction of the size of the antenna elements as well as their spacing is of main concern. For typical channel conditions, this shall enable pre-defined analogue beamforming patterns in order to reduce the processing complexity of the digital beamforming optimization. Furthermore, multi-user multi-stream transmit beamforming will be studied in this context.