A system for transmitting data packets includes at least one access point and at least one terminal. The access point receives data packets transmitted by the terminal in compliance with a multiple access protocol including carrier detection, and transmits to the terminal at least the width of the contention window that the terminal is to observe for transmitting a packet. The transmitted packets are coded using an erasure code and the access point is further adapted to decode the received packets. The system may be applied to networks such as WLANs.