Casualties due to traffic accidents are increasing day by day. Think of this message being displayed on your computer screen while you were driving "there's a possibility of collision with a car in the next few minutes if you go on driving with this speed and direction". Our research is intended towards developing collision avoidance architecture for the latest Intelligent Transport System. The exchange of safety messages among vehicles and with infrastructure devices poses major challenges. Specially, safety messages have to be adaptively distributed within a certain range of a basically unbounded system. These messages are to be well coordinated and processed via different algorithms. The purpose of the paper is to discuss the ITWS (intelligent transportation warning system), we have discussed the Assisted Global Positioning System(AGPS) system providing additional positioning information at variable conditions. We have also discussed study the Data fusion and kalaman filter in details. The performance of kalman filter and output are discussed. Hardware realization of this model is achieved through software defined radio (SDR).