Abstract: We present a Lightweight GNSS (Global Navigation Satellite System) Support Protocol (LGSP), which has been devised at Monash University. LGSP aims to comprehensively address limitations in the traditional GNSS model, such as low signal availability in urban environments, receiver initialisation delays and bandwidth restrictions, by offering an alternative secure distribution channel for GNSS data. This gives compatible receivers an alternate means for acquiring GNSS data, resulting in enhanced robustness, efficiency and availability of GNSS systems. Development of LGSP is nearing completion, and a protocol specification has been released as an Internet Draft to the IETF. This paper presents the rationale behind the development of LGSP and discusses the protocol's architecture, message formats and definitions.