4G Cellular, OFDM and LTE – the "GSM vs. CDMA" Standards War Ends!

This tutorial is part of the most recent update to Course 101, Chapter 6, October 2008.

After more than 20 years, it appears that an almost universally-accepted standard for mobile radio may finally be implemented, bringing to an end the standards war between carriers that deployed TDMA/GSM for second generation and carriers that deployed CDMA for second generation. Those two factions continued the standards war for the third generation (UMTS and 1X respectively); but now carriers from both of the factions are supporting the GSM/UMTS faction’s Third Generation Partnership Project (3GPP) release 8, known as Universal Terrestrial Radio Access Network Long Term Evolution (LTE). Continue reading 4G Cellular, OFDM and LTE – the "GSM vs. CDMA" Standards War Ends!

Soft Switches

The term soft switch is not defined in a standard… meaning that marketing departments at different equipment and software manufacturers use the same term to describe different things.

A switch, in its simplest form, is a device that causes communications to happen from one point to one other particular point, often when there are multiple “other” points to choose from.

A traditional Central Office (CO) telephone switch might be called a “hard” switch, since it has physical line cards that terminate loops. The switching software running on the computer which is the CO switch directs traffic between a line card and a trunk or between two line cards during a phone call.

The term soft switch is used to mean a computer running switching software that does not have telephone line cards – the communications are instead directed to the correct destination by routers routing packets, a software function.

softswitch diagram

Continue reading Soft Switches