How much faster is 4G compared to 3G and what applications run better on 4G?
3G and 4G are standards for mobile communication. Standards specify how the airwaves must be used for transmitting information (voice and data). 3G (or 3rd Generation) was launched in Japan in 2001. As recently as mid-2010, the networks for most wireless carriers in the U.S. were 3G. 3G networks were a significant improvement over 2G networks, offering higher speeds for data transfer. The improvement that 4G offers over 3G is often less pronounced. Analysts use the analogy of standard vs Hi-Def TV to describe the difference between 3G and 4G.
|Data Throughput||Up to 3.1Mbps with an average speed range between 0.5 to 1.5 Mbps||Practically speaking, 2 to 12 Mbps (Telstra in Australia claims up to 40 Mbps) but potential estimated at a range of 100 to 300 Mbps.|
|Peak Upload Rate||5 Mbps||500 Mbps|
|Switching Technique||packet switching||packet switching, message switching|
|Network Architecture||Wide Area Cell Based||Integration of wireless LAN and Wide area.|
|Services And Applications||CDMA 2000, UMTS, EDGE etc||Wimax2 and LTE-Advance|
|Forward error correction (FEC)||3G uses Turbo codes for error correction.||Concatenated codes are used for error corrections in 4G.|
|Peak Download Rate||100 Mbps||1 Gbps|
|Frequency Band||1.8 – 2.5 GHz||2 – 8 GHz|
What is 4G?
The definition of 4G has changed over the years. Current commercially available technologies LTE (Long-Term Evolution) and WiMax claimed that they are sufficiently advanced from 3G and thus claimed the right to call their technology 4G. However, in October 2010, the global standards group International Telecommunication Union declared that after long study, it had determined which technologies truly qualified for its IMT-Advanced label i.e. 4G (fourth-generation). The target speed was at least 100 Mbps to qualify for the 4G label. Only two systems made the list: LTE-Advanced, an emerging version of LTE technology, and Wireless MAN-Advanced, the next version of WiMax, also called WiMax 2. Neither is commercially available yet.
But in December 2010, the standards body softened its stance. In a press release, the ITU stated:
As the most advanced technologies currently defined for global wireless mobile broadband communications, IMT-Advanced is considered as '4G,' although it is recognized that this term, while undefined, may also be applied to the forerunners of these technologies, LTE and WiMax, and to other evolved 3G technologies providing a substantial level of improvement in performance and capabilities with respect to the initial third generation systems now deployed.
This opened the door for LTE, WiMax and HSPA+ to be designated 4G because these technologies can all deliver multiple megabits per second upstream and downstream, far more than most existing 3G networks. 
The following video explains some of the concepts behind 2G, 3G and 4G terminology for wireless network generations:
4G Speed vs. 3G
How much faster is 4G compared to 3G? Unfortunately for consumers, the answer to this question is more nuanced than one would like. The speed of a 3G network depends upon how it is implemented. In the US, by 2010 Sprint and Verizon (both CDMA networks) had reached the limits of how fast they could make their 3G networks. Upgrading to 4G networks allowed them to offer data transmission speeds up to four times faster than their 3G networks. However, the 3G networks of GSM carriers AT&T and T-Mobile were designed such that there was room to upgrade 3G speeds. As of mid-2010, it is anticipated that when AT&T and T-Mobile upgrade their 3G networks, their speeds will become comparable to 4G from Sprint and Verizon.
Speed Test Results
Results from a speed test comparing Sprint's 4G and 3G networks (using a Samsung Epic 4G phone) and AT&T's 3G network (using a Dell Streak) show that Sprint 4G is considerably faster than both Sprint 3G and AT&T 3G. These test results were posted in October 2010. You can watch a video of the speed test on YouTube here.
Design Principle and Applications
Both 2G and 3G networks were designed primarily for voice communications rather than data. On the other hand, 4G is designed especially for data transmission rather than voice. So 4G offers faster access to data using mobile phones. For example, streaming video works better with 4G, with less stuttering and a higher resolution. Similarly, video conferencing and multi-player online games work better with the faster data transmission offered by 4G.
MIT engineer Keith Winstein wrote an illuminating blog post about how the speed you ultimately experience on your mobile phone depends much more on other factors than 3G or 4G. In theory, newer technologies offer performance improvements. However, 3G and 4G refer to the communication protocol between the mobile handset and the cell phone tower. So it's only one piece of the puzzle. The throughput rate and browsing speed also depend upon factors such as:
- how many cell phone towers are in the vicinity
- how many users are sharing these towers
- the bandwidth available to to these cellphone towers to connect to the Internet or the carrier's network.
Marketing 3G or 4G is easier for wireless carriers than promising (and providing) a minimum throughput rate for data transfer.