Seamless handover in industrial WLAN using IEEE 802.11k

In the era of increasing connectivity driven by IoT and CPS concepts, wireless networks are gaining importance in industrial applications. One of their obvious benefits is the support of mobile clients. In complex network infrastructures consisting of many access points, roaming becomes an important aspect because many applications rely on realtime communication and therefore need seamless handover between access points. In IEEE 802.11 WLANs, however, the roaming today is mostly reactive, i.e., a connection is kept as long as the quality of the link provides the possibility to transmit data. If the quality decreases too much the connection is lost, and the client must scan the wireless channels and look for a new access point in order to establish a new connection. The scanning procedure typically takes a long time and thus prohibits seamless roaming. This paper investigates a simple, proactive roaming method using the IEEE 802.11k standard to collect information about the wireless environment prior to roaming. Actual handover is then based on an assessment of the signal strength (RSSI). Experimental results show that the proposed method can reduce the handover time by a factor 30.