This read-write value sets the initial contention-resolution back-off window, expressed as a power of 2, that a subscriber unit uses when it first attempts to transmit an initial ranging request, with a value of 16 at the headend signaling that a proprietary adaptive algorithm is used instead. Admins tune this to control how much random delay SUs introduce before their first ranging attempt, which affects contention on a busy upstream. For example, on a heavily loaded upstream where many new SUs are trying to range simultaneously, an admin might raise cwdIfUpChannelRangBackoffStart to reduce collisions during initial ranging.