Presented herein are techniques for assigning Ultra-Wideband (UWB) anchors for client ranging. A control device can monitor UWB ranging between a mobile device and a primary anchor. In response to determining that a signal strength between the mobile device and the primary anchor is below a threshold, the control device can identify anchors for which the mobile device has had a signal strength above the threshold during a period of time, and select one of the anchors as a new primary anchor for the mobile device. For example, the control device can select the new primary anchor based on a relative collision tolerance mapping for the new primary anchor and at least one other anchor within a UWB range of the new primary anchor. The control device can send a command causing UWB ranging to be performed between the mobile device and the new primary anchor.