All Analogue Full-duplex Dual-receiver Radio for Wideband Mm-wave Communications

智能手机、平板电脑和笔记本电脑广泛用于多用户视频会议、观看视频和电视、玩视频游戏、下载/上传大文件和应用程序。通过无线网络交换的数据每年都在显著增加，因此需要随着需求而提高数据速度，以满足用户的需求。无线网络设计者和频谱监管者面临着有效的资源规划以满足日益增长的需求的艰巨任务。考虑到频谱限制，提供超高速无线系统只能通过一些突破性的技术来实现。全双工(FD)无线电是一种有可能将速度翻一番的技术，如果计划在毫米波频段，它可以提供巨大的带宽。宽带毫米波FD在HetNet中的巨大好处是众所周知的，包括无线网络中小小区之间非常快的Gbit互操作。基于毫米波MMIC的低成本子系统的可用性，以及用于FD无线电的简单基础设施设置，将使宽带毫米波FD无线电领先于其竞争对手，即工作在多个通道中的复杂低频宽带大规模多输入多输出(MIMO)系统。事实上，基于FD的低成本宽带基础设施网络将对不断寻找廉价解决方案的移动运营商非常有吸引力，以便在地下隧道、大型/高层建筑和繁忙的人口稠密城市地区等复杂环境中提供非常高速的通信覆盖。事实上，可以设想，随着宽带毫米波FD技术的成熟，数百万毫微微蜂窝的宽带毫米波FD无线电将在全球范围内运行，从而确保该技术的贡献者获得可观的收入(数十亿英镑)。FD无线电使用一个频道进行收发，因此自干扰(SI)是其主要问题。在FD无线电中，所需的SI消除(SIC)取决于发射机功率和信号带宽。通常，一个可靠的FD系统需要60分贝到110分贝的SIC。在低频FD无线电中，这种大的抑制通常是在多个阶段实现的；即：在天线系统、接收器前端和具有数字信号处理(DSP)的基带中。假设10%的分数带宽，毫米波载波频率有可能调制几GHz带宽的快速信号；例如：在30 GHz载波上可获得3 GHz带宽。对于如此宽的基带，基于DSP的SIC不是一种选择，因为目前没有用于在小型移动/固定设备中实现的小型化功率敏感的DSP单元来处理几GHz带宽的快速信号。为了消除数字信号处理器的限制，已经提出了几种很有前景的技术来抑制毫米波FD无线电中的SI，但到目前为止，这些技术仍然处于研究阶段，实际结果有限。最近，在EPSRC的资助下，我们开发了一种新的SIC技术，它不需要DSP。在此基础上，我们实现了3.2 GHz微波载波下的窄带(60 MHz)FD无线电。我们的演示器在-5.6dBm的发射功率下实现了81.5dBSIC。我们的新系统的无数字性能归功于一个双接收器架构，消除了对DSP阶段的需要。这一特性预计对于实现所有模拟宽带毫米波FD系统是非常合适/重要的。该方案的新颖性，它区别于并且实际上漂浮在文献中的工作之上，释放了我们新的窄带FD无线电体系结构的潜力，以利用其几个优势，包括模拟基带SIC解决方案(即，没有DSP)和通过发射器和双接收器之间具有高度隔离的三端口双天线系统的自多径反射干扰消除。在这项工作中，我们将测试我们在开发新的双接收器微波FD无线电方面的经验，以实现独特的无DSP宽带毫米波FD无线电。

Smartphones, tablets and laptops are widely used for multi-user video conferencing, watching video and TV, playing video game, downloading/uploading large files and applications. Data exchanged over wireless networks is significantly increasing annually, and hence the data speed needs to be increased with the demand to keep users happy. Radio network designers and spectrum regulators are facing the daunting task of efficient resource planning to meet the growing demand. Considering spectrum limitation, providing ultra-speed wireless systems can only come through some breakthrough technologies. The full-duplex (FD) radio is one technology with the potential to double the speed and if planned at mm-wave bands, it can offer a huge bandwidth.The massive benefits of broadband mm-wave FD in HetNets are well-known including very fast Gbit inter-operation between small cells in wireless networks. The availability of low-cost mm-wave MMIC-based subsystems together with the simple infrastructure setups for FD radios would place broadband mm-wave FD radios ahead of its rival, namely, the complicated low frequency broadband massive multi-input multi-output (MIMO) systems operating in multiple channels. Indeed, the low-cost broadband infra-structure networks based on FD would be very attractive to mobile operators continuously looking for cheap solutions to provide very high-speed communication coverage in complex environments like underground tunnels, large/high-story buildings, and busy densely populated city areas. Indeed, millions of femtocells of wideband mm-wave FD radios can be envisaged to operate worldwide on the mature of the broadband mm-wave FD technology, ensuring substantial revenue (of the order of billions of pounds) for contributors to the technology.A FD radio uses one channel to transceive and hence self-interference (SI) is its major problem. In FD radios, the required SI cancellation (SIC) depends on transmitter power and signal bandwidth. Typically, a SIC of 60 dB to 110 dB is necessary for a reliable FD system. In low frequency FD radios, this large suppression is normally achieved in multiple stages; ie: in antenna system, in receiver front-end, and in baseband with digital signal processing (DSP).Assuming 10% fractional bandwidth, mm-wave carrier frequencies have the potential to modulate fast signals of a few GHz bandwidth; eg: 3 GHz bandwidth becomes available at 30 GHz carrier. For such a wide baseband, the DSP-based SIC cannot be an option, since no miniaturised power conscious DSP unit for implementation in small mobile/fixed devices is available presently to deal with fast signals of a few GHz bandwidth. To remove the DSP constraint, several promising techniques have been proposed to mitigate the SI in mm-wave FD radios, but they are still under research with limited practical results presented so far in the literature.Recently under an EPSRC grant we have developed a new SIC technique free from DSP. Based on this, we demonstrated a narrow band (60 MHz) FD radio at 3.2 GHz microwave carrier. Our demonstrator achieved a total of 81.5 dB SIC at -5.6 dBm transmit power. Our new system owes its digital-free performance to a two-receiver architecture purging the need for the DSP stage. This property is anticipated to be extremely suitable/important for realising all analogue broadband mm-wave FD systems.The novelty of this proposal, distinguishing it from and indeed levitating well above the work in the literature, is unlocking the potential of our new narrow band FD radio architecture to exploit its several advantages including an analogue baseband SIC solution (i.e., free from DSP) and a self-mutipath reflection interference cancellation via a three-port dual antenna system with a high isolation between transmitter and the dual-receiver. In this work we are to put to test our experiences in developing our new dual-receiver microwave FD radio to realise a unique DSP-free broadband mm-wave FD radio.