Consider a data communication system $($transmitter $-$ receiver$).$ To transmit, the transmitter groups n data packets $($from the MAC layer$)$ before transmitting $($that group$)$ over the physical medium. At the receiver, these groups of packets are received, deaggregated and the packets are processed $($serevidor$)$ individually. If the packet processing speed is lower than the packet arrival speed, the packets are stored in a buffer $($queue$)$ to be processed $($as soon as the processor becomes free$)$ in a FIFO $($first$-$in first$-$out$)$ scheme. The storage space can be considered sufficiently large so that there are no losses. The evolution of the packet processing system at the receiver is given by the following rules: