China today said its homegrown navigation system, deemed as rival to the US' Global Positioning System (GPS), is expected to serve global users by 2020 and will provide open satellite navigation services "free of charge". Currently, B1I and B2I open service signals are being broadcast by the operating BeiDou Navigation Satellite System (BDS) BDS-2 to provide open services to the Asia-Pacific region free of charge, an official white paper on BDS issued by the China's cabinet said. Also Read:\u00a0China launches 23rd navigation satellite By 2020, BDS is expected to serve global users and it will "provide open satellite navigation services free of charge," the report said. The services cover an area between 55 degrees north latitude and 55 degrees south latitude and between 55 and 180 degrees east longitude, with positioning accuracy less than 10 meters, velocity measurement accuracy less than 0.2 meter per second, and timing accuracy less than 50 nanoseconds. On June 13 China sent 23rd Satellite into orbit for the BDS development. The BDS satellite system is being developed as an alternative to America's GPS. China will publish BDS documents related to open services and signals to facilitate global BDS product development efforts, the report said. It will also work to protect the radio-navigation satellite frequency spectrum according to law and firmly reject harmful interference, it said. China prohibits the production, sale and use of illegal interference devices, investigates and punishes in accordance with the law any hostile interference actions which affect the system operations and services, the report said.