Apparatus, and an associated method, for facilitating communication of data in a packet radio communication system to effectuate a packet communication service in which packet data is communicated at a variable, selectable rate. A detector embodied at an RLP layer detects channel allocations and channel reaollcations, granted to the mobile station to effectuate the data communication service. A report is generated at the RLP layer and forwarded to the TCP layer. At the TCP layer, selection is made of the TCP window to match the rate at which data is provided to the RLP layer to the rate, based upon the channel allocations provided to the mobile station, at which the data is communicated therefrom.