Alternatives of US-based GPS satellite navigation

The usage of global satellite navigation system has become more and more important nowadays, from military to civil uses. For example, location based service (LBS) in smartphones has high level of reliance on it.

The current global satellite navigation system used by most of us are depending on the Global Positioning System (GPS) of US NAVSTAR, which has 24 to 32 satellites in operation. The actual number of operating satellites varies from time to time due to maintenance and/or replacement, but the minimum in operation in any time is 24.

GPS has been operational since 1978, and made globally available since 1994.

Due to political, and more importantly, millitary reasons, some other nations have also developed their own global satellite navigation system as alternative to the US NAVSTAR's GPS.

These include the Russian Global'naya Navigatsionnaya Sputnikovaya Sistema (Global Navigation Satellite System, GLONASS) which is currently supported in iPhone 4S. GLONASS has been operational since 1995, but fell into disrepair after the collapse of Soviet Unoin, and was later recovered and restored in 2011.

China is developing a regional navigation system called BeiDou (北斗导航系统), which has 12 satellites and will implement for Asia Pacific region by this year (2012). They have plan to further expand it into a global navigation system by 2020, under a project called Compass. By that time, BeiDou system will have 35 satellites in operation.

The European Union also developing their own Galileo positioning system, but seems like they are facing some progress delay due to financial issue.

Indian is also developing the Indian Regional Navigational Satellite System (IRNSS) with 7 satellites, mainly for their own use.