在过去一段时间内，我专注在以下研究工作上。
I focus on the following interesting topics.

可靠的低功耗无线网络协议 – Dependable Low-Power Wireless Protocols:

With recent technological advancements in sensing and low-power wireless communication, an immense number of Internet of Things (IoT) devices (e.g., smart wristbands with Bluetooth Low Energy and Zigbee indoor temperature sensors, etc.) are changing our life. However, the low-power wireless communication, as one of key technologies, is yet unable to handle practical scenarios where exist unknown (dynamic) radio interference (e.g., the smart wristband near a Wi-Fi router transferring files, or the Bluetooth speaker at a cooking microwave oven, etc.). Most current IoT devices cannot work properly since their communication would be interfered significantly. Simply increasing the radio transmission power would significantly reduce the lifetime of such IoT devices because they are generally powered by batteries. To enable IoT devices to work in real scenarios dependably (i.e., not only reliably but also in time), it is necessary for optimizing the existing low-power wireless communication (as well as protocols). Together with my colleagues, our work [realWSN’18] enables existing low-power wireless sensors to still achieve communication even under a continuous intensive radio interference (e.g., the microwave oven is cooking food with strong heat). In addition, we also proposed and implemented protocols [EWSN’17, EWSN’18, IEEEAccess, EWSN’19, INFOCOM’20, ICNP’20] to make multi-hop networks dependable under dynamic interference (e.g., Wi-Fi devices are exchanging bulk data).

低功耗广域网测试平台 – Testbed for Low-Power Wide Area Networks:

随着SigFox、LoRa以及NB-IoT等远距离无线通信技术的兴起，低功耗广域网已然成为一个炙手可热的话题。无论是低功耗无线通信协议领域的研究者还是物联网工程师，都迫切地需要一个网络测试平台来观察在实际场景下低功耗广域网设备是如何工作的，从而来优化他们的设计。然而，按照传统思想设计的低功耗广域网测试平台会需要大量的基础设施支持（例如以太网、4G通信以及相关的嵌入式观测记录设备等等），这无疑是需要消耗大量的人力财力的，同样也是这样的测试平台并不多见的原因。我和我的同事，以LoRa通信为例，提出了一种无需依赖基础设施（无需任何网络基础设施、无需专有的服务器、无需额外的通信资费、无需额外的嵌入式观测记录设备、甚至无需供电）的低功耗广域网测试平台方案[EWSN’20, EWSN’21, ACM DATA’21]。

The breakthrough of long range communication technology (e.g., SigFox, LoRa, and NB-IoT, etc.) brings a wide attention to Low-Power Wide Area Networks (LPWANs). IoT researchers/builders desire to have a testbed for LPWANs to observe nodes’ behaviors, thereby optimizing their design or fixing bugs. Conventionally, such a testbed for LPWANs requires infrastructures (e.g., a backbone Ethernet, cellular networks, and extra embedded platforms to monitor nodes’ energy consumption, etc.), which means building such a testbed needs for substantial investments of financial and human resources. This is why testbeds for LPWANs are not common. My colleagues and I developed an infrastructure-less testbed for LoRa (no need for network infrastructure, dedicated server, and extra embedded platforms for monitoring, without servicing costs on data traffic, and even without power cables) [EWSN’20, EWSN’21, ACM DATA’21].

低功耗无线通信优化 – Low-Power Wireless Communication Optimization:

低功耗无线通信技术是实现物联网概念中“物物相连”的关键。物联网开发者/研究人员往往可以使用射频收发芯片快速集成此类技术。然而，在享受射频收发芯片为开发工作所带来的便捷的同时，开发者也难以对针对某些应用进行进一步的物理层或者编解码方面的性能优化（因为很多技术细节被隐藏在芯片实现中）。受到软件定义射频（SDR）的启发，我们对现有射频芯片进行了“探索”，通过“巧妙使用”（例如充分利用一些芯片自带的射频自测功能），实现了对低功耗多跳无线网络的吞吐量优化[COMNET]以及对LoRa通信功耗优化[IPSN’22]。

Low-power wireless communication technology is key for achieving the concept of “connecting objects”. IoT researchers/builders can make use of a low-power radio transceiver to integrate such communication technology easily. However, developers are difficult to carry out further optimization on the physical layer or the CoDec to achieve more awesome performance in some specific applications because details are hidden in the chip implementation. Inspired by the thought of software defined radio (SDR), we optimize the throughput of multi-hop all-to-one networks [COMNET] and energy consumption for LoRa [IPSN’22] via some “tricky” operations and even reverse engineerings over existing low-power wireless transceivers.