Access delay for nodes with finite buffers in IEEE 802.15.4 beacon enabled PAN with uplink transmissions

In this work we analyze the performance of a personal area network operating under the IEEE Standard 802.15.4 in the beacon enabled mode, and derive the probability distribution of packet access delay and calculate the throughput. We assume that the network is operating in non-saturation mode and that the nodes have finite buffers. We model the operation of the PAN using the theory of discrete time Markov chains and M/G/1/K queues. The model considers acknowledged uplink transmission and includes the impact of different parameters such as packet arrival rate, number of stations, station's buffer size, packet size, and inactive period between the beacons. The model also captures the problem of congestion at the beginning of the superframe due to multiple transmissions being delayed from the previous superframe, and we propose a correction to the standard in order to avoid this problem. In order to achieve acceptable access delays and small blocking probability at the buffer (which has to be small), PAN must be operated at throughput less than 50%, which can be achieved by restricting the number of the nodes in the PAN, or by reducing the packet arrival rates at the nodes.