Cross-layer performance effects of path coupling in wireless ad hoc networks: Power and throughput implications of IEEE 802.11 MAC

Path coupling is defined as the media access contention between nodes distributed along node disjoint paths. It is caused by the broadcast nature of wireless communications. In this paper the cross-layer problem of path coupling is characterized and analyzed based upon the characteristics of the DCF of IEEE 802.11. Path coupling involves MAC-layer interactions that impact the performance of network-layer paths that are otherwise disjoint. These interactions are shown to have significant impact on energy efficiency, throughput and delay. Analytical models are developed to demonstrate the asymptotic throughput and power characteristics of coupled and non-coupled paths. These models are validated using simulation. The performance analysis of energy consumption and queuing characteristics at the network-layer due to MAC-layer interactions are also studied via simulation. Results demonstrate how path degrades performance, thus, supporting the need for the control of cross-layer interactions and methodologies for cross-layer optimization.