A communication method in a communication network comprising a plurality of nodes, at least one node comprising a plurality of traffic queues for serving data traffic at different priorities, each traffic queue being associated with a respective queue backoff value computed from respective queue contention parameters having first and second values in, respectively, a first and a second contention modes, obtaining quality of service requirements of data stored in a traffic queue of the node; checking whether the quality of service requirements can be fulfilled when accessing the communication channel using the second contention mode; if the requirements cannot be fulfilled as the result of the checking, disabling access to resource units provided by the other node within one or more transmission opportunities granted to the other node on the communication channel; and transmitting data stored in the traffic queue using the first contention mode.