What is 3.75G?

With the recent launch of 3.75G data services in Sri Lanka, there is a lot of discussion about the different numbers associated with the G's.

Almost from the day on which Marconi made the first telephone call the telecom industry has been evolving and the evolution of this is tracked in generations. The voice service was the major focus during the initial stages and a network with the ability to offer only voice service is deemed to be a 1st Generation (1G) network. Then in the second generation (2G) primary data services were introduced. The 3rd Generation was more a standardized procedure and 3GPP maintain the standards.  The 3G specification has evolved and each revision has been named in order, starting from R99 (first version is denoted by the year) , following once in the sequence starting from R4, R5 and currently you could find revisions up to R10.

In the process of commercialization the 3GPP revisions had been marked as 3.5G, 3.75G, 3.9G. I had tried to tabulate the releases, commercial terms, and the features which would make the comparisons easier I guess. Its not complete, will try to update with more details,

Tag	release	Important Feature additions	Data rates
1G		Voice
2G		SMS and Circuit Switched data services	9.6kbps peak data rate
2.5G		General Packet Radio Services (GPRS)
3G	R99	Circuit and Packet Switched MMS Services Location Services
	R4	Enhancements
3.5G	R5	HSPDA High-Speed Downlink Packet Access	14Mbps peak data rate
3.75G	R6	High-Speed Uplink Packet Access (HSUPA) HSPA = HSPDA (from R5) + HSUPA Multimedia Broadcast Multicast Services (MBMS) Enables multimedia broadcast services like Mobile TV	14 Mbps peak data rate (HSPDA) + 5.74 Mbps peak data rate (HSUPA)
3.9G	R7	HSPA Evolution/HSPA+	28 Mbps Download peak data rate 11 Mbps Upload peak data rate
4G	R8, R9, R10	Long Term Evolution (LTE) System Architecture Evolution (SAE) Focused on Cell Edge User Through put, Average User Throughput, Coverage.

references:

[1] 3G Evolution HSPA and LTE for Mobile Broadband by Erik Dahlman, Stefan Parkvall, Johan Sköld and Per Beming
[2] http://www.3gpp.org/HSPA
[3] http://www.3gpp.org/LTE