Design of the signal and data format for wide area augmentation of the Global Positioning System

The wide area augmentation system (WAAS) is being deployed by the Federal Aviation Administration (FAA) to augment the Global Positioning System (GPS) with additional ranging signals and a supporting ground network. The augmented system can be used as the primary position sensor for enroute through precision approach air navigation. Specifically, the WAAS provides the following three services: integrity monitoring to improve safety; a ranging function to improve time availability and continuity of service; and differential GPS corrections to improve accuracy. This paper describes the design of the WAAS signal and data format. It states the design objectives and describes the basic approach. Then, it analyzes the correction update rates, message duration, messaging rates and the use of forward error correction. This paper does not: give a basic description of the WAAS, analyze the non-interference properties of the signal, or give a description of the data fields