The immediate problem is to determine the transmit power of the mobile when it first establishes a connection. Until the mobile does not come in contact with the base station, it has no idea of the amount of interference in the system. If it attempts to transmit high power to ensure contact, then it can introduce too much interference. On the other hand, if the mobile transmits less power (not to disturb other mobile connections), the power cannot meet the Eb/N0 as required.