An adaptive rate and coding scheme for MIMO-enabled IEEE 802.11-based Soft-Real-Time wireless sensor and actuator networks

Being reliable and real-time, are the two most challenging requirements of wireless sensor and actuator networks (WSAN) due to the shared, error-prone and nondeterministic behaviour of wireless communication medium. In this paper, an adaptive data-rate and space-time coding (STC) scheme has been proposed for the IEEE 802.11-based Soft-Real-Time WSAN´s utilizing Enhanced Distributed Channel Access (EDCA) at Medium Access Control (MAC) and Multiple-Input Multiple-Output (MIMO) transceivers at PHYsical (PHY) layer, with the target of minimizing average and/or maximum packet delay. Using this technique, delay and reliability have considerably been improved compared with traditional IEEE 802.11 stations, especially in dense networks and/or environments with vast range of Signal to Noise Ratio (SNR) variation.