  In this paper, we investigate how Joint Communication And Sensing (JCAS) can
be used to improve the Inertial Measurement Unit (IMU)- based tracking accuracy
of eXtended Reality (XR) Head-Mounted Displays (HMDs). Such tracking is used
when optical and InfraRed (IR) tracking is lost, and its lack of accuracy can
lead to disruption of the user experience. In particular, we analyze the impact
of using doppler-based speed estimation to aid the accelerometer-based position
estimation, and Angle of Arrival (AoA) estimation to aid the gyroscope-based
orientation estimation. Although less accurate than IMUs for short times in
fact, the JCAS based methods require one fewer integration step, making the
tracking more sustainable over time. Based on the proposed model, we conclude
that at least in the case of the position estimate, introducing JCAS can make
long lasting optical/IR tracking losses more sustainable.
