EDCA delay analysis of spatial diversity in IEEE 802.11-based real-time wireless sensor and actuator networks

Reliability and packet delay, are the two most challenging parameters of wireless sensor and actuator networks (WSAN). In this paper, saturation delay characteristics of Multiple Input Multiple Output (MIMO)-enabled IEEE 802.11 technology utilizing Enhanced Distributed Channel Access (EDCA) at Medium Access Control (MAC) and a simple Spatial-Diversity (SD) scheme in PHYsical (PHY) layer has been thoroughly analysed. Results show that due to the low Signal to Noise Ratio (SNR) in WSAN environment, simple modulation schemes with lower spectral efficiency have better delay and reliability performance. Otherwise, the delay will be highly sensitive to SNR, packet payload, number of competing nodes and other parameters.