On connectivity of wireless ultraviolet networks

Non-line-of-sight optical communication can be enabled by modulating signals into an UV carrier and then transmitting them through an atmospheric scattering channel. This paper investigates some connectivity issues for such UV communication networks. We discuss k-connectivity in a multiuser interference environment. Compared with the studied case without considering multiuser interference in which more users bring higher probability of k-connectivity, a large number of noncoordinated users cause higher interference and limit the network performance. Thus, node density should be carefully designed in accordance with network configurations. Four typical scenarios are discussed, depending on whether each node transmitter is capable of adjusting its pointing angle and tracking a target receiver. They lead to different link losses and consequently the network k-connectivity properties. One of the cases simplifying the transceiver design for adjustable pointing is also illustrated, where each node is equipped with multiple transmitters to be activated via electronic on/off switching. The number of transmitters on a single node then becomes another critical parameter whose effect on k-connectivity is studied. These results will provide a guideline for system and network designers.