  IoT devices are in general considered to be straightforward to use. However,
we find that there are a number of situations where the usability becomes poor.
The situations include but not limited to the followings: 1) when initializing
an IoT device, 2) when trying to control an IoT device which is initialized and
registered by another person, and 3) when trying to control an IoT device out
of many of the same type. We tackle these situations by proposing a new
association-free communication method, QuickTalk. QuickTalk lets a user device
such as a smartphone pinpoint and activate an IoT device with the help of an IR
transmitter and communicate with the pinpointed IoT device through the
broadcast channel of WiFi. By the nature of its association-free communication,
QuickTalk allows a user device to immediately give a command to a specific IoT
device in proximity even when the IoT device is uninitialized, unregistered to
the control interface of the user, or registered but being physically confused
with others. Our experiments of QuickTalk implemented on Raspberry Pi 2 devices
show that the end-to-end delay of QuickTalk is upper bounded by 2.5 seconds and
its median is only about 0.74 seconds. We further confirm that even when an IoT
device has ongoing data sessions, QuickTalk can still establish a reliable
communication channel to the IoT device with little impact to the ongoing
sessions.
