This report provides a detailed overview of the Intelligent Transportation System (ITS) narrowband digital communicator project. The project is the building and fiel~dte sting of a high performance modem architecture on the 220MHz radio channels allocatied to ITS. This architecture will provide greater than 12kbitsls transmission rate by using state of the art techniques to develop a new paradigm in bandwidth efficient land mobile communications. The main goals; are to develop a recursive model based optimum demodulator and to implement the architecture necessary for actual field tests. The modulation scheme optimizes the use of transmitter antenna diversity, forward error control coding, pilot symbol assisted modulation, and the statistical characteristics of the received signal. An overview of the entire communication system as well as a discussion of every subsystem is included in this report. Theoretical issues such as error correction coding, niodulation format, transmitter diversity, and pilot symbol assisted demodulation are investigated. Implementation issues such as the frame structure, synchronization, link budgets, and the radio frequency transmitter and receiver are also addressed. The resulting system will achieve 3 bits/Hz bandwidth efficiency with a bit error probability of 10-5 using wireless land mobile radio communication. The design is very flexible and can accommodlate a wide variety of digitally modulated signals for many applications. The architectur(2 will provide the framework for testing this and future algorithms in an actual urban environment.
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