An adaptive retry-limit scheme for real-time IEEE 802.11 based wireless industrial networks

Being reliable and real-time, are the two most challenging requirements of wireless industrial networks due to the shared, error-prone and non-deterministic behaviour of wireless communication medium. Retry-Limit (RL) parameter of IEEE 802.11 standard directly effects on the packet reliability, whereas other parameters mostly effect on packet delay. In this paper, at first the delay-reliability trade-off in wireless industrial networks based on IEEE 802.11 standard, utilizing Enhanced Distributed Channel Access (EDCA) at Medium Access Control (MAC) layer has been studied. Then a simple adaptive retry-limit scheme to minimize packet delay while satisfying the required reliability at low signal to noise ratios (SNR's) is proposed.