Mixerless RF Transceivers for Wireless Communication

无线通信领域在过去二十年中出现了爆炸性增长，同时通信技术及其应用也出现了增长。这种新的增长一直在推动对数据速率指数级增长的需求。鉴于当今的技术和当前关于无线传输的知识，如果数据速率大幅增加，现有的无线通信系统和技术将不能满足需求。为了应对这一挑战，增加用户带宽被认为是未来无线基础设施的潜在解决方案。为了在一组高度使用的不连续频段中提供所需的带宽，需要先进的无线通信系统。这些系统要求多标准和运营商聚合功能更具普遍性、移动性、灵活性和安全性。这就要求开发软件定义的、可重构的、宽带的和认知的收发信机。传统的收发机射频(RF)前端架构是基于模拟的，因此很难重新配置，并且容易受到噪声、非线性和硬件损伤的影响。此外，在频率转换中使用基于开关的混频器会产生大量杂散和谐波，需要使用不可配置、频率限制和笨重的射频滤波器仔细过滤掉这些杂散和谐波，这限制了这些收发器的灵活性和可重构性。一种更有吸引力的替代方案是将设计转移到数字领域和/或避免在频率转换中使用混频器和滤波器。这项拟议的研究是一项研究计划的一部分，该计划旨在为能够在宽带中操作并可随意重新配置的先进通信系统开发创新的可重新配置的射频收发机。在这项拟议的研究中，将从两个不同的层面研究适用于多频段和多标准应用的创新的高度可积、可重构和宽带发射机体系结构：*(I)开发新的发射机体系结构。该架构采用数字控制的“无混频”上变频拓扑。*(Ii)将研究用于系统行为建模和数字预失真的新模型和算法，以减轻这些拓扑结构中的非线性和模拟缺陷。*所提出的数字控制和线性化发射机体系结构有望具有高可积分性、可重构性和低成本的巨大潜力，这使得它们成为未来无线电系统和泛在网络的一个有趣的解决方案。**

The explosive growth occurring in the past two decades in the wireless communication sector has, by association, seen a growth in communication technology and its applications. This new growth has been driving the need for an exponential increase in data rates. Given today's technology and current knowledge about wireless transmission, if data rates were to substantially increase, current wireless communication systems and techniques will not be able to handle the demand. To cope with this challenge, the increase in user bandwidths has been considered as a potential solution for future wireless infrastructure. In order to provide the required bandwidth in a highly used set of discontinuous frequency bands, advanced wireless communication systems are needed. These systems require multi-standard and carrier aggregation capabilities to be more ubiquitous, mobile, agile, and secure. This calls for the development of software-defined, reconfigurable, wideband and cognitive transceivers. Conventional transceiver radio frequency (RF) front-end architectures are analog-based and therefore are hard to reconfigure and are prone to noise, nonlinearity and hardware impairments. In addition, the use of switching-based mixers in frequency conversion generate a large amount of spurs and harmonics that need to be filtered out carefully using non-configurable, frequency limiting and bulky RF filters, which limit the agility and reconfigurability of these transceivers. A more compelling alternative is to move the design to digital domain and/or to avoid the use of mixers and filters in frequency conversion. The proposed research is part of a research program that aims at developing innovative reconfigurable RF transceivers for advanced communication systems that are able to operate in wideband and to be reconfigured at will. In this proposed research, innovative highly integrable, reconfigurable and wideband transmitter architectures suitable for multi-band and multi-standard applications will be investigated at two different levels: ***(i) New transmitter architectures will be developed. This architecture uses digitally controlled "mixerless" frequency up-conversion topologies. Without the use of analog RF filters, the proposed topology will be able to operate over wide frequency bands and therefore can be configured at will for different standards.***(ii) New models and algorithms for system behavioural modeling and digital predistortion will be investigated in order to mitigate the nonlinearity and analog imperfections in these topologies.***The proposed digitally controlled and linearized transmitter architectures are expected to have great potential of high integrability, reconfigurability and low cost, which make them an interesting solution for future radio systems and ubiquitous networks.**