Throughput maximization using cross-layer design in wireless sensor networks

In this paper, a cross-layer-based sensor node selection scheme in a cooperative network with equally spatially correlated channels is proposed. The equally correlated model can be used as a worst-case benchmark or as a rough approximation by assuming equal correlation coefficients for all channels. By considering the physical and link layer characteristics, one or multiple sensor nodes are selected to maximize the link layer throughput. Based on the channel characteristics, the best performance is achieved by using one cooperative sensor node in poor links and multiple relays/sensors in high quality links. The performance of the proposed scheme is compared with the capacity-based scheme and considerable improvement in performance is achieved in both correlated and uncorrelated channels. The proposed scheme is examined for both decode-and-forward (DF) and amplify-and-forward (AF) relaying, and also for relay selection and subcarrier allocation in an orthogonal-frequency-division multiplexing (OFDM)-based systems. In all cases, the cross-layer technique is shown to offer significant improvement relative to physical-layer optimization techniques.