Multihop IEEE 802.15.4 Wireless Networks With Finite Node Buffers: Markov Chain-Based Analysis

In this paper, we propose a Markov chain-based analytical framework for modeling the behavior of the medium access control (MAC) protocol in IEEE 802.15.4 wireless sensor networks. Two scenarios are of interest. First, we consider networks where the sensor nodes communicate directly to the network coordinator. Then, we consider scenarios where sensor nodes communicate to the coordinator through an intermediate relay node, which forwards the packets received from the sources (i.e., the sensors). In both scenarios, no acknowledgment messages are used to confirm successful data packet deliveries, and communications are beaconed (i.e., they rely on synchronization packets denoted as "beacons"). In all considered scenarios, our focus is on networks where the relay and the source nodes have finite queues (denoted as buffers) to store data packets. Network performace is characterized in terms of aggregate network throughput and packet delivery delay. Our results show a very good agreement between the proposed analytical model and realistic ns-2 simulation results. In particular, the impact of the buffer size is accurately taken into account in our model.