Collaborative Research: EARS: Broadband Mobile Wireless Access Using mm-Waves Bands Beyond 100 GHz

无线通信对我们的生活质量和经济的重要性怎么强调都不为过。虽然网络运营商和研究人员已经做了大量的工作来提高现有网络的容量，但迫切需要探索新的选择来支持指数级增长的无线互联网流量。这项研究将研究毫米波频段的全新频谱，该频谱可以为移动用户提供千兆链路，使网络运营商能够以优雅的方式扩展容量。到目前为止，毫米波通信主要局限于点对点链路或固定终端的短距离通信。在移动通信中使用毫米波无线电需要对电路、天线、封装、系统和协议进行彻底的重新思考和共同设计。这项研究将探索120 GHz毫米波电路和系统的设计，使大型无线电阵列能够在相对较长的距离（数百米）上以非常高的数据速率（10 Gbps）进行通信。与100ghz以下的研究相比，这一领域相对未被探索，只有大约12个工作收发器的演示。研究团队将研究系统和电路架构，以支持波束形成、波束零化、多用户MIMO（多输入多输出），通过空间滤波和抑制干扰实现有效的频谱再利用。新型电路设计概念将采用28纳米CMOS（互补金属氧化物硅）技术和GaN（氮化镓）晶体管进行原型设计，以实现高功率传输。当波形具有较高的峰值平均比（平均效率为2%）时，当今的毫米波发射机效率极低，而所提出的发射机架构将使输出功率和效率提高一个数量级。在CMOS中实现的毫米波系统的范围，特别是在不使用镜头的情况下，也将从几米增加到数百米。这项研究将使5G蜂窝及其他应用能够利用完全未开发的频谱。提出的合作研究项目的技术目标是专注于电路和系统级硬件平台的实现，该硬件平台可以研究最佳波束形成和波束零（干扰消除），同时允许对100ghz以上室内和室外信道的传播特性进行实际测量。具体来说，PI， co-PI和一组研究人员将设计和实现收发器的关键构建模块，以实现100 GHz以上通信的测量和表征。该项目涉及待调查的四个主要重点领域。第一个重点领域将侧重于发射器电路设计和集成挑战，并探索用于CMOS MIMO应用的硅基功率放大器的技术限制，特别是100 GHz以上。第二个重点将提供有关GaN晶体管与CMOS集成的见解，以允许用于数字信号处理和波形整形的高密度逻辑，以及用于发电的高击穿电压GaN器件。第三个重点将集中在天线和系统架构上，以支持波束形成，特别关注解决有关LO（本振）产生和分布的问题，并找到在大型阵列中最小化功耗的最佳配置。最后的推进领域将重点研究在其他推进领域开发的子模块的系统级集成挑战，以生产120GHz收发器。

The importance of wireless communication on the quality of our lives and on our economy cannot be overstated. While network operators and researchers have done a tremendous job to improve the capacity of existing networks, there is a strong need to explore new options to support the exponentially growing wireless Internet traffic. This research will investigate a completely new spectrum in the mm-wave band that could enable Gigabit links for mobile users, allowing network operators to expand capacity in a graceful manner. Up to now, mm-wave communication has been mostly limited to either point-to-point links or to short-range communication for fixed terminals. Using mm-wave radios for mobile communication requires a complete rethinking and co-design of the circuits, antennas, packages, and systems and protocols. This research will explore the design of mm-wave circuits and systems at 120 GHz, enabling large arrays of radios to communicate with very high data rates ( 10 Gbps) over relatively long ranges (hundreds of meters). Compared to research below 100 GHz, this area is relatively unexplored, with only about a dozen demonstrations of working transceivers. The research team will investigate system and circuit architectures to support beam forming, beam nulling, multi-user MIMO (multiple-input multiple-output), allowing efficient spectrum re-use through spatial filtering and interference rejection. Novel circuit design concepts will be prototyped in 28 nm CMOS (Complementary Metal-Oxide Silicon) technology along with GaN (Gallium Nitride) transistors for high power transmission. Today's mm-wave transmitters are extremely inefficient when the waveform has a high peak to average ratio (2% average efficiency), whereas the proposed transmitter architectures will increase both the output power and efficiency by an order of magnitude. The range of mm-wave systems realized in CMOS, particularly without the use of lens, will also be increased from a few meters to hundreds of meters. This research will enable the exploitation of completely untapped spectrum for 5G cellular and beyond applications.The technical objective of the proposed collaborative research project is to focus on circuit and system level realization of a hardware platform that can enable the study of optimal beam forming and beam nulling (interference cancellation), while allowing practical measurements to be carried out on the propagation characteristics of indoor and outdoor channels above 100 GHz. Specifically, the PI, co-PI and a team of researchers will design and implement key building blocks for the transceiver to enable measurement and characterization of communication above 100 GHz. This project involves four main thrust areas to be investigated. The first thrust area will focus on transmitter circuit design and integration challenges and explore technology limits for silicon-based power amplifiers for MIMO applications in CMOS, especially above 100 GHz. The second thrust will provide insight regarding the integration of GaN transistors with CMOS to allow for high-density logic for digital signal processing and waveform shaping, and high breakdown voltage GaN devices for power generation. The third thrust will focus on antenna and system architectures to support beam forming with special attention to solving problems regarding LO (local oscillator) generation and distribution and finding the optimal configuration to minimize power consumption in a large array. The final thrust area will focus on investigating system level integration challenges from the sub-modules developed in the other thrust areas to produce a 120GHz transceiver.