Performance Analysis of Transmitter-Side Cooperation–Receiver-Side-Relaying Schemes for Heterogeneous Sensor Networks (original) (raw)

2008, IEEE Transactions on Vehicular Technology

In this paper, we present two physical layer cooperative protocols for heterogeneous sensor networks. There is one cooperator near the transmitter and a second cooperator (as a relay) near the receiver. Although the focus is on heterogeneous sensor networks, the methods can be applied to homogeneous sensor networks as well. Analytical and simulation results show that, under an additive white Gaussian noise channel assumption for the links between the transmitter and its partner and between the receiver and its partner, the proposed protocols achieve a diversity order of three or four by using the amplify-and-forward cooperation strategy and maximal ratio combining in the receiver. In addition, the proposed methods outperform the noncooperative single-hop transmission in the clustered heterogeneous sensor network and save a considerable amount of energy relative to the noncooperative transmission. Index Terms-Amplify-and-forward (AF) cooperation, cooperative diversity, heterogeneous sensor networks, maximal ratio combining. I. INTRODUCTION S ENSOR networks are composed of a large number of nodes that sense certain phenomena in the area of interest and communicate their observations to other nodes or a central base station, such as a cluster head or a gateway for further processing. Due to the large number of sensing nodes and their computing and communication capabilities, many different applications for the home, military, habitat monitoring, and healthcare industry have become possible (for more details, see [1] and references therein). Sensor networks are categorized as homogeneous and heterogeneous networks [2], [3]. In a homogeneous sensor network, the sensor nodes are identical in terms of computing, sensing and communication capabilities, and power supplies, whereas, in a heterogeneous sensor network, the nodes have different capabilities and/or power supplies [2]. In a homogeneous sensor network, data can be relayed using a multihop transmission or a cluster-based transmission. For example, in a data gathering application, multihop links are utilized to relay information to a sink, which is the ultimate destination of the data. In the clusterbased transmission, the cluster head gathers the information