Dynamic Path Reconfiguration Among Hybrid FSO/RF Nodes

To increase the availability of free space network (FSO) networks, the optical link is provided with a redundant backup network, such as RF, to form a hybrid network. The immediate switching from FSO to RF in hybrid networks leads to suboptimal utilization of FSO network. In this work, a network of hybrid nodes, where each node is equipped with multiple transceivers and has multiple associations with other nodes of the network is proposed. Alternate FSO paths are established and prioritized through these multiple associations via intermediate nodes. On the loss of an active FSO link, path reconfiguration takes place, and the FSO path next in priority is utilized. Thus, communication can be maintained in the optical domain for a longer period, and efficiency is increased. A hardware testbed with four hybrid nodes having multiple IR transceivers to establish optical links was constructed to validate proof of concept. Dynamic path reconfiguration in the optical domain was demonstrated in the testbed by blocking different transceivers of the nodes. We measure network performance in terms of end-to-end delay along alternative FSO paths. Results show how the proposed path reconfiguration algorithm can provide performance improvement in hybrid networks.