Back-Channel Communication Embedded in Standard Compliant Wireless Packets

在现代物联网(IoT)应用中，无线通信通常是总体功耗的主导因素。因此，实现高能效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量供电的永久运行的最关键问题。该计划为超低功率设备提供了创新的“反向通道”通信技术，由于其极其有限的功率预算，这些设备无法负担基于标准WiFi或蓝牙低能量(BLE)的无线通信。反向通道通信的概念将使通过现有WiFi或BLE网络互连异类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，符合WiFi和BLE标准的节点将受益于反向信道技术，以显著提高其功率效率，而无需使用专有唤醒信号发射器和/或专用信道资源。通过拟议的研究成果，可以实现新的概念，如按需WiFi，取代传统的始终在线的WiFi接入点。该计划的结果将以网络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无处不在的WiFi和/或BLE标准包中嵌入的反向通道通信概念来探索其他应用程序。该研究可能对下一步的无线标准化产生直接影响，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特性，这些特性很容易被仅消耗10s微瓦甚至更少的ULP接收机检测到。所提出的方案不需要专门的发射机硬件或专用的信道资源来进行嵌入式反向信道信号传输。相反，经过仔细排序的数据比特流将从已经部署的WiFi和BLE基础设施生成反向通道消息，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下都是可行的，这些调制格式很容易被非WiFi/非BLE物联网设备解码。该研究项目将演示多种类型的ULP反向通道接收器集成电路(IC)，其中包括射频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与商业现成的WiFi和BLE设备进行交互来演示。该IC的设计目标是实现比商用低功耗WiFi接收器低1/1000的功耗和比商用蓝牙接收器低1/200的功耗。将提出一个通用的反向通道通信框架，以将反向通道的用例扩展到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.