A method and system to help control CoMP service in a V-RAN arrangement. The load on a cell site's fronthaul network interface between the cell site's RRH and the cell site's BBU is determined. And in response to detecting that the fronthaul load is threshold high, a limit will be imposed on application of CoMP service involving the cell site. For example, in response to detecting that the cell site's fronthaul network interface is threshold highly loaded, (i) the cell site could be made to use decentralized joint processing rather than centralized joint processing, (ii) a lower coverage strength threshold could be imposed as a basis to trigger CoMP service involving the cell site, and/or (iii) the quantity of uplink communication that is subject to CoMP service involving the cell site could be limited.