Wireless sensing is an exciting new research area which can benefit a large spectrum of disciplines including elderly care, HCI, environment monitoring, and disaster response. The key difference between wireless sensing and traditional sensor-based sensing is that the target does not need to be equipped with any sensors and the wireless signal itself is utilized to sense the context information of humans. The rationale behind wireless sensing is that wireless signals vary with human movement. For instance, when a person moves in a room covered by WiFi, the WiFi signal reflected from this person varies with his/her movement. By analyzing the signal variation, the motion information such as target moving speed and respiration rate can be obtained. The contact-free and sensor-free nature of wireless sensing makes it particularly appealing in challenging scenarios such as pandemic and disaster survivor detection. During the COVID-19 pandemic, it is preferred that the patients' respiration rates can be monitored in a contact-free manner through walls. In disasters such as building collapse where the survivors do not have any sensors with them, wireless sensing can be crucial in detecting their presence and saving lives. % While promising in many aspects, there are several critical issues that hinder wireless sensing from being widely deployed in real-life scenarios. % critical issues still exist. These issues include (1) very limited sensing range due to the intrinsic nature of employing weak reflection signals for sensing; (2) strong interference from other objects in the environment; and (3) severe degradation of sensing performance in the presence of ongoing communication function of wireless technologies. This thesis explores the exciting opportunity of employing LoRa~--~the emerging wireless protocol designed for IoT device connections~--~to realize long-range wide-area wireless sensing. This thesis addresses these fundamental issues by making the following contributions. First, we adopt a chirp concentration scheme which fully exploits the property of LoRa chirp to improve the signal power and accordingly boost the sensing range. Second, to mitigate the impact of interference, we propose the concept of ``virtual fence'' to constrain sensing only within the area of interest. The location and size of virtual fence can be flexibly controlled in software to meet the requirements of different applications. Finally, to make LoRa-based wireless sensing work in the presence of ongoing communication, we propose to employ the reversed chirp, i.e., downchirp, for sensing and keep the original upchirp for communication. This design smartly leverages the orthogonality between downchirp and upchirp to address the issue of communication interference on sensing. While the upchirp-downchirp design can remove most of the interference, we further adopt a novel chirp rotation method to deal with the remaining power leakage interference from upchirp to downchip, enhancing the sensing performance.