Markov Chain-based performance analysis of multihop IEEE 802.15.4 wireless networks
Performance evaluation (Print)
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 networks. Two scenarios are of interest. First, we consider networks where the (sensor) nodes communicate directly to the network coordinator (the final sink). Then, we consider cluster-tree (CT) scenarios where the sources communicate to the coordinator through a series of intermediate relay, which forward the received packets and
... not generate traffic on their own. 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 cases, our focus is on networks where the sources and the relays have finite queues (denoted as buffers) to store data packets. The network performance is evaluated in terms of aggregate network throughput and packet delivery delay. The performance predicted by the proposed analytical framework is in very good agreement with realistic ns-2 simulation results. In this paper, we combine the theory of Discrete Time Markov Chains (DTMCs), considered in  , and the theory of Geo/G/1/L queues  , in order to derive a DTMC-based analytical model for an IEEE 802.15.4 network, which takes into account the presence of buffers (and their sizes) at the sources and the relays. More specifically, given a group (a "cluster") of nodes with the same characteristics, we focus on one of them, denoted as tagged node, using an approach similar to that followed in [8, 9] for single-hop networks. This underlies the assumptions that all nodes behave, on average, in the same way and, therefore, characterizing the behavior of one of them is sufficient. Moreover, our framework can be applied for evaluating the performance of multihop networks with arbitrarily complex topologies (e.g., CT networks), where the relays may contend the shared medium access to the sources. Our Markov chain-based framework allows to evaluate the aggregate network throughput and the packet delivery delay. 1 Due to the approximations needed to make the multihop analysis tractable, in the 1-hop case our more general model is slightly less accurate than other, such as those proposed in     , expressly designed only for these specific scenarios. However, the performance predicted by our analytical model is in very good agreement with the results obtained through extensive (and realistic) ns-2 simulations. This paper is structured as follows. In Section 2, we briefly discuss about the huge literature body on performance analysis of IEEE 802.15.4 networks. In Section 3, we provide the reader with a quick overview of the IEEE 802.15.4 standard. Section 4 contains the derivation of the novel analytical models for the considered networking schemes: we start from single-hop networks to end with generic CT networks with buffers at the nodes. In Section 5, numerical results obtained with the proposed analytical models are shown and their very good agreement with realistic ns-2 simulation results is discussed. Finally, concluding remarks are given in Section 6.