A method and a device relating to a scheduling mechanism in a base station in a WCDMA system are disclosed. The mechanism enables the base station to rapidly adapt to users momentary traffic demands and to interference variations, a dynamical adjustable margin is proposed in this invention. The adjustment is based on the RoT measurement in a cell. To fully use the resource in a cell, the RoT can be targeted to be as closer to the RoTmax as possible however without exceed the limit. The scheduler is preferably set to schedule as high a rate or as many users as possible to fill up the available RoT. The margin which is reserved for the neighboring cell load and external interference is decreased step by step as long as the RoT measurement is below a threshold under RoTmax. Whenever the RoT measurement exceeds the threshold, the margin is increased by one step.