HaLow: Registering thousands of low-power sensors in smart cities

Abstract

IEEE 802.11ah working group (WG) introduced Wi-Fi HaLow (or simply HaLow which is a marketing name of Wi-Fi for low-power devices) as a revision of the long-range Wi-Fi technology for the Internet of Things (IoT) applications in smart cities. Such applications often involve thousands of wireless devices (typically sensors and actuators) connected to a shared wireless channel. Channel access for these thousands of IoT devices significantly affects the performance of the network. Several mechanisms have been proposed to register thousands of low-power sensors and actuators by handling the contention between them. Two of which known as the centralized authentication control (CAC) and the distributed authentication control (DAC), aimed to address the contention reduction during the link set-up process in HaLow. In HaLow, a link set-up process requires much more interests from the researchers because the access point (AP) knows nothing about the connected devices and the mean of control at these stations is very limited. DAC is a self-adaptive device authentication mechanism, whereas CAC requires an algorithm to dynamically control critical parameters, such as transmission slots and channel access period. However, the existing IoT devices registration mechanism in HaLow is based on carrier-sense multiple access with collision avoidance (CSMA/CA), which is not very efficient for the registration of large-scale IoT devices due to its limited binary exponential contention mechanism. In this chapter, we explain both of the device authentication mechanisms, i.e. CAC and DAC, in detail. Later, we discuss one of the authentication mechanism known as hybrid slotted-CSMA/CA-time-division multiple access (TDMA) (HSCT) as our case study that is proposed to overcome the aforementioned issues in current authentication techniques. The HSCT mechanism allows IoT systems in smart cities to register thousands of low-power IoT devices (sensors and actuators). This chapter also comes up with the analyses of the access period in a single HSCT time slot. © The Institution of Engineering and Technology 2020.