Back-Channel Communication Embedded in Standard Compliant Wireless Packets

在现代物联网（IoT）应用中，无线通信通常是整体功耗的主导因素。因此，实现节能的无线通信是延长超低功耗（ULP）物联网设备寿命并最终实现仅由收集的环境能源供电的永久运行的最关键问题。该计划为超低功耗设备提供了创新的“反向信道”通信技术，这些设备由于其极其有限的功率预算而无法负担基于标准WiFi或蓝牙低功耗（BLE）的无线通信。 反向信道通信的概念将使通过现有WiFi或BLE网络互连异构ULP IoT设备成为可能，即使这些ULP IoT设备无法解码常规WiFi或BLE消息。此外，WiFi和BLE标准兼容节点将受益于反向信道技术，以在不采用专有唤醒信号发射机和/或专用信道资源的情况下显著增强它们的功率效率。新的概念，如WiFi-on-demand，取代传统的始终在线的WiFi接入点，可以实现拟议的研究成果。该计划的结果将以Web应用程序和软件包的形式传播，以便学生，研究人员和行业专家可以利用嵌入无处不在的WiFi和/或BLE标准数据包中的反向信道通信概念探索其他应用。所提出的研究可以直接影响下一个无线标准化，以采用更灵活的分组结构来丰富反向信道通信的用例。所提出的嵌入在WiFi和BLE消息中的反向信道信令具有独特的属性，这些属性易于被仅消耗10 s微功耗的ULP接收器检测到。所提出的方案消除了对用于嵌入式反向信道信号传输的专用发射机硬件或专用信道资源的需要。相反，仔细排序的数据比特流将从已经部署的WiFi和BLE基础设施生成反向信道消息，而无需任何硬件修改。这种WiFi和BLE反向信道通信在各种调制格式中是可行的，这些调制格式可以由非WiFi/非BLE IoT设备容易地解码。该研究计划将演示多种类型的ULP反向通道接收器集成电路（IC），包括RF和模拟前端以及基带信号处理。一个完整的ULP唤醒方案将通过制造的反向通道接收器IC与商用现成的WiFi和BLE设备进行交互来演示。IC设计目标是实现比商用低功耗WiFi接收器低1/1000倍的功耗，比商用蓝牙接收器低1/200倍的功耗。将提出广义反向信道通信框架以将反向信道用例扩展到WiFi和BLE标准之外。

In modern Internet-of-Things (IoT) applications, wireless communication is typically the dominant factor in overall power consumption. Enabling energy-efficient wireless communication, therefore, is the most critical issue to prolong the lifespan of ultra-low power (ULP) IoT devices and eventually realize perpetual operation only powered by harvested ambient energy. This program presents innovative "back-channel" communication techniques for ultra-low power devices, which could not afford standard WiFi or Bluetooth Low Energy (BLE) based wireless communication due to their extremely limited power budget. The concept of back-channel communication will make it possible to interconnect heterogeneous ULP IoT devices through existing WiFi or BLE networks even if these ULP IoT devices are incapable of decoding regular WiFi or BLE messages. In addition, WiFi and BLE standard compliant nodes will benefit from the back-channel technique to significantly enhance their power efficiency without employing a proprietary wakeup signal transmitter and/or dedicated channel resources. Novel concepts such as WiFi-on-demand, replacing conventional always-on WiFi Access Points, can be realized by the outcomes of the proposed research. The results of this program will be disseminated in the form of Web applications and software packages so that students, researchers and industry experts can explore other applications utilizing the concept of back-channel communication embedded in ubiquitous WiFi and/or BLE standard packets. The proposed research could make direct impact on the next wireless standardization to adopt more flexible packet structures to enrich use-cases of back-channel communication.The proposed back-channel signaling embedded in WiFi and BLE messages has unique properties that are easily detectable by ULP receivers consuming only 10s of micro-Watts or even less. The proposed scheme eliminates the need for specialized transmitter hardware or dedicated channel resources for embedded back-channel signal transmission. Instead, carefully sequenced data bit streams will generate back-channel messages from already-deployed WiFi and BLE infrastructure without any hardware modification. This WiFi and BLE back-channel communication is feasible in various modulation formats that are easily decodable by non-WiFi / non-BLE IoT devices. This research program will demonstrate multiple types of ULP back-channel receiver integrated circuits (ICs) that include the RF and analog frontend as well as the baseband signal processing. A complete ULP wakeup scheme will be demonstrated with fabricated back-channel receiver ICs interacting with commercial off-the-shelf WiFi and BLE devices. The IC design goal is to achieve 1/1000x lower power consumption than a commercial low-power WiFi receiver and 1/200x lower power than a commercial Bluetooth receiver. A generalized back-channel communication framework will be proposed to expand the back-channel use cases beyond WiFi and BLE standards.