Data rate requirements for relay links in vehicular locator systems

For the effective and efficient utilization of mobile vehicles, a vehicle locator and tracking system is necessary. Possible users of the system include the police, municipal bus systems, taxicabs, utilities, and others. One often suggested approach employs a network of distributed sensors, which sense and identify vehicles in the immediate vicinity. The sensors which receive transmissions from the vehicles then pass the vehicle identity, together with the sensor identity, to a central facility via a relay link. For the relay link, message-loss probability and time-delay statistics have been evaluated as a function of message traffic offered. By utilizing the dual criteria for acceptable performance as one of low message-loss probability and small time delays, data requirements for uniform vehicular traffic have been obtained. An extension to nonuniform vehicular traffic is suggested. Engineering estimates of data rate requirements for different system configurations can be made by using the figures presented.