A method for conducting communications involving a plurality of access nodes (104, 106, 108, 110) using a shared communication medium, the method comprising: sending a message over the shared communication medium from a first access node of the plurality of access nodes (104, 106, 108, 110), the shared communication medium organized to include an allocation of node identification signal space and an allocation of data transmission signal space, the allocation of node identification signal space including a plurality of collision-free node identification segments each having a different location within the allocation of node identification signal space, each of the plurality of access nodes (104, 106, 108, 110) being associated with a unique one of the plurality of collision-free node identification segments, the allocation of data transmission signal space including a data transmission segment, the data transmission segment available for data transmission from two or more of the plurality of access nodes (104, 106, 108, 110), the message including a node identification portion and a data transmission portion; wherein the node identification portion is transmitted in the allocation of node identification signal space, and the node identification portion occupies a collision-free node identification segment that is one of the plurality of collision-free node identification segments; wherein the data transmission portion is transmitted in the allocation of data transmission signal space, and the data transmission portion occupies the data transmission segment; wherein a measure of occupancy of the shared communication medium is based on a number of occupied collision-free node identification segments detected in the allocation of node identification signal space; and wherein, depending on the measure of occupancy of the shared communication medium, the data transmission portion in the allocation of data transmission signal space is processed. sending a message over the shared communication medium from a first access node of the plurality of access nodes (104, 106, 108, 110), the shared communication medium organized to include an allocation of node identification signal space and an allocation of data transmission signal space, the allocation of node identification signal space including a plurality of collision-free node identification segments each having a different location within the allocation of node identification signal space, each of the plurality of access nodes (104, 106, 108, 110) being associated with a unique one of the plurality of collision-free node identification segments, the allocation of data transmission signal space including a data transmission segment, the data transmission segment available for data transmission from two or more of the plurality of access nodes (104, 106, 108, 110), the message including a node identification portion and a data transmission portion; wherein the node identification portion is transmitted in the allocation of node identification signal space, and the node identification portion occupies a collision-free node identification segment that is one of the plurality of collision-free node identification segments; wherein the data transmission portion is transmitted in the allocation of data transmission signal space, and the data transmission portion occupies the data transmission segment; wherein a measure of occupancy of the shared communication medium is based on a number of occupied collision-free node identification segments detected in the allocation of node identification signal space; and wherein, depending on the measure of occupancy of the shared communication medium, the data transmission portion in the allocation of data transmission signal space is processed.