Reducing wireless multi-hop delay via RSU re-routing in vehicular wireless networks

Vehicular wireless networks offer wireless multi-hop communications between vehicles and roadside units (RSUs). To reduce deployment cost, the distance between two RSUs could be long; that is, the communications between an RSU and a vehicle may be carried out through multi-hops among intermediate vehicles. When a vehicle is driven from one RSU to another, the wireless multi-hop delay becomes more serious as the number of multi-hop relays increases. The wireless multi-hop delay is critical for some emergency service. For instance, in a traffic accident, when a patient was sent to the hospital by ambulance, the life information of the patient must be transmitted to the hospital on time through the multi-hop wireless network. If the ambulance is moved from one RSU to another, the wireless multi-hop delay becomes more and more serious as the ambulance is closing to another RSU. In this paper, we propose an RSU re-routing strategy that dynamically alters multi-hop communications until the best RSU with the shortest path using location information is found. Moreover, we compare the proposed strategy with the existing strategy in terms of broadcasting costs, re-routing delay, and wireless multi-hop delay of data transmission. Performance results show that the proposed strategy can reduce the wireless multi-hop delay significantly.