Tham khảo tài liệu 'advances in vehicular networking technologies part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 142 Advances in Vehicular Networking Technologies discover a route since the BU started broadcasting the routing information. End-to-end delays are determined using position reporting packets which are sent by the last unit . the h 1 th unit to the BU for an h-hop network where h varies from 1 to 50. Note that the h 1 th unit only starts transmitting the position reporting packets once a route is found to remove the queuing effect due to route discovery. Network Diameter Number of hops Fig. 15. Route discovery and End-to-End Packet Delay Next we will analyze the performance of the LAR route selection algorithm. For the analysis we used a star topology as shown in Fig. 16. Each unit was stationary and spaced at an equidistant of 50m from its adjacent neighbors. BU0 BU1 and BU2 initiated the route construction simultaneously by broadcasting their position packets and triggered neighboring units to transmit their positioning packets. In the star configuration the unit at the center MU0 received position packets from three different neighboring units namely DU1 DU2 and MU1 see Fig. 16. Consequently MU0 created three forward routes in its routing table. These routes are referred to as Route 1 Route 2 and Route 3 respectively as shown in Fig. 16. The hop count of Route 1 and Route 2 is three hops while Route 3 is four. Since hop count is the primary routing metric the routes with the least hop count would be selected by MU0. In this case Route 1 and Route 2 were picked by the route selection algorithm of MU0. In the simulations each unit broadcast position packets at a fixed interval of 4s. Hence the traffic load was uniformly distributed across the network. In other words none of the MUs or DUs were more congested than others. Therefore the route 143 An Ultra-Wideband UWB Ad Hoc Sensor Network for Real-time Indoor Localization of Emergency Responders selection algorithm would arbitrarily choose between Route 1 and Route 2. The MU0 was set to transmit position .
