Cellular phones have evolved over the years and are continuously being developed for better performance. 1G or the first generation of mobile technology used analog radio signals for communication; likewise 2G technology meant digital phones. Today 3G is widely used and 4G is soon catching up. New generations bring a new base technology, more network capacity so that more data per user is available, better voice quality and faster internet speed.
The major difference between 3G and 4G is with regard to the data speed. 4G is all about high speed and taking mobile internet browsing experience to the next level. 3G uses packet as well as circuit switching. Circuit switching is a very old method and it ties up resources as long as connection is kept up. 4G uses only packet switching where resources are used only when information is to be sent. Even voice and video calls are packet switched, and thus more conversations are squeezed into the same bandwidth.
What is 3G (IMT-2000)
The 3G standard for mobile technology was defined by the 3rd generation partnership project (3GPP) and later standardized by International Telecommunication Union (ITU). International Mobile Telecommunications-2000 are the requirements set by ITU that must be adhered to for marketing mobile phones as 3G. The minimum internet speed in order for a technology to be called a 3G network must be 384 kbps in a moving vehicle and 2Mbps when stationary. The third generation of mobile technology was developed in late 1990s and 2000s. It was introduced commercially in 2001 in Japan and in 2002 in the US. The goal of 3G was to improve data capability and speed. 3G uses the spectrum between 400 MHz and 3 GHz.
Most 3G technology standards have been successfully developed by using the Code Division Multiple Access (CDMA) method as a backbone for radio transmissions. CDMA technique allows multiple wireless devices to transmit simultaneously on the same radio frequency. Each CDMA device is assigned a unique mathematical signature. The transmitter adds the signature of the transmitting device with the original message and transmits it to the intended recipient. The receiver of the recipient's device performs reverse mathematical operation to decode the original message.
The following technologies meet the requirements stipulated for 3G:
Universal Mobile Telecommunication System (UMTS) uses wideband code division multiple access (WCDMA) which has a 5MHz bandwidth and a downlink speed of 384 kbps. In certain instances, the downlink speed can go up to 2 Mbps. Advantage of UMTS is that it is less vulnerable to interception and jamming.
CDMA2000, developed by Qualcomm, has a bandwidth of 1.25MHz and downlink speed of up to 2 Mbps.
EVDO is another 3G standard, also developed by Qualcomm. It was developed in 1999 and the acronym stands for 'Evolution, Data Only' or 'Evolution, Data Optimized' indicating that it is the next evolution of the CDMA2000 standard. However, the official name of EVDO as defined by the telecommunication industry association is CDMA2000, high rate packet data air interface. EVDO works by dividing data into packets and each packet is sent independent of the other. One of the advantages of EVDO is that a cell phone can itself become a hotspot and share its internet connection with other devices. The original EVDO, called Revision 0, had a data speed of 2.4 Mbps. The first upgrade to EVDO, Revision A, has a speed of 3.1 Mbps and Revision B, which is not fully deployed, can have download speed of up to 14.7 Mbps.
There were many improvements made to the existing 3G technologies to obtain faster data rates. WCDMA was added with high speed packet access (HSPA) which has higher level Quadrature Amplitude Modulation (QAM) modulation. Downlink speeds of 21 or 42 Mbps and uplink speeds of 7 or 14 Mbps were obtained. AT&T and T-mobile use this technology in the US.
4G (IMT-Advanced)
4G is expected to provide faster data access, enhanced roaming capabilities, unified messaging and broadband multimedia. In October 2010, ITU-R (ITU-Radiocommunication Sector) set the target internet speed to be 100 Mbps for a device to be called 4G. Only LTE-A (Advanced version of LTE with wider bandwidth channels and more MIMO antennas) and Wireless MAN-Advanced (WiMAX2) adhere to this strict requirement but both are not commercially available yet. In October 2012, Russian operator Yota and its partner Huawei announced the successful launch of the first ever commercial LTE-A test network in Moscow. The service is expected to be available to users in second half of 2013 or in 2014.
While 100 Mbps is the expected speed when the mobile is moving, speed as high as 1 Gbps is expected when the device is stationary which is as of now possible only by wired LAN. However, these requirements were ignored by carriers and the ITU eventually backed down and softened its stand. In a December 2010 press release, the ITU stated that:
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.
Thus, for all practical purposes, service providers market their technologies like LTE, WiMAX and HSPA+ as 4G. However, these technologies are often referred to as advanced 3G or 3.9G (since they are not as fast as expected of true 4G systems like LTE-A and WiMAX2). They are completely different technologically from WCDMA and CDMA2000.
Here is a brief description of these advanced 3G technologies:
Long Term Evolution (LTE): LTE uses Orthogonal Frequency Division Multiplexing (OFDM) and OFDM access. It divides a channel usually 5, 10 or 20 MHz wide into smaller sub-channels each 15 kHz wide. Each is modulated with part of the data. The fast data is divided into slower streams that modulate the subcarriers with one of several modulation schemes like Quadrature Phase Shift Keying (QPSK) or 16QAM. It also has multiple inputs and multiple outputs (MIMO). Thus, there are many transmitter and receiver antennas. The data stream is divided between antennas to boost speed and make link more reliable. OFDM and MIMO together can achieve speeds of up to 100 Mbps on the downlink and 50 Mbps uplink.
The first country to launch LTE networks and also have the fastest 4G with download speed as high as 22.1 Mbps is Sweden. The US was the second country to introduce LTE. Verizon and AT&T use LTE in the US. Today, LTE signals can be found in over 60 countries of the world.
Worldwide interoperability for Microwave Access (WiMAX): It is an IP based technology that can provide Broadband Wireless Access (BWA) of about 50 km for fixed stations and 5-15 km for mobile stations. There is very little interference in WiMAX systems. In the US, WiMAX is used by Sprint and Clearwire. But Sprint is now switching from WiMAX to LTE. In India, BSNL launched WiMAX 4G service in June 2011 in Kochi, Kerala.
HSPA+: It has been standardized by 3GPP. HSPA+ provides improved support and performance for picture and video sharing and video and voice over IP (VoIP). It has features like MIMO antennas, continuous packet connectivity (CPC) and higher order modulations. Telstra in Australia, Starhub in Singapore, CSL in Hongkong and Mobilkom Austria in Central and Eastern Europe were among the first to commercially launch HSPA+ in early 2009 with peak download rate of 21 Mbps. T-mobile in the US upgraded their HSPA+ technology to have speed of 42 Mbps. AT&T also uses HSPA+.
Advantages of 4G
If mobile internet means the world to you, then 4G is just the right technology. The fast data speed in 4G makes quality of applications involving huge amount of data transfer so much better and faster. You can surf the web and stream videos with less stuttering and higher resolution. Video conferencing is better and so are multi player online games. Laptop can be connected to the mobile link to take advantage of 4G internet speed. 4G technology also ensures that you get a less trafficked network for internet data; hence browsing on 4G can be a hassle free experience.
Disadvantages of 4G
With 4G, it is very easy to use up a lot of data due to the high speed, leading to higher bill amount owing to internet usage. Also, 4G won't solve dropped call problems since all calls will be made over 3G until service providers switch to voice over LTE.
There is not much use buying a 4G phone if there is no 4G coverage in your area or city (Verizon and T-mobile have broadest 4G coverage in the US). If you don't disable the 4G LTE in an area where there is no coverage, then battery life is greatly reduced because the antenna uses up the energy in continuously searching for a non-existent signal. If you value battery life more than speed of internet, then 3G phones are a better option over 4G; at least until 4G coverage becomes more widespread.
Difference between 4G and 3G
The differences between the third and fourth generations of wireless mobile technology can be summarized as follows:
|
|
3G |
4G |
|
Peak transmission rate for a stationary device |
384 kbps |
100 Mbps |
|
Peak transmission rate for a moving device |
2 Mbps |
1 Gbps |
|
Applications |
Mobile videoconferencing Video Phone/Mail Remote Medical Diagnosis Remote Education Mobile TV/Video Player Advanced Car Navigation/ City Guides Digital Catalogue Shopping Digital Audio/Video Delivery |
Mobile IPTV |
|
Where they are used |
3G services are available in over 155 countries of the world |
Strictly speaking, LTE-A and WiMAX2 are not yet commercial. But LTE, WiMAX and HSPA+ technologies can be found in many countries of the world |
|
Price/Cost |
While 3G services naturally come at a higher price than 2G services, the actual cost incurred by a user hugely depends on how much data they use |
4G services will be costlier than 3G. This may discourage users from switching to 4G where they will have to pay extra just for faster internet, especially if they don’t really make use of all the features that come with it |
|
Penetration |
According to a study by Ericsson, although it may have taken 3G technology 12 years since its inception at the turn of the century to reach half the global population, by 2017 it is expected that 85% of the world will be covered by 3G |
50% of the world population is likely to be covered by LTE by 2017 as per the study by Ericsson |
|
Technology |
UMTS, WCDMA, CDMA2000, EVDO, HSPA |
LTE-A, WiMAX2 |
|
Switching Technique |
Uses both circuit and packet switching |
Uses only packet switching |