4G: what is LTE?
The fourth generation (or 4G abbreviated by abbreviationfinder.org) of mobile telephony begins with LTE technology, short for Long Term Evolution (something like “Long Term Evolution”). This is yet another proposal submitted by 3GPP. Although, in the view of the ITU (International Telecommunication Union), an entity linked to the United Nations , LTE does not comply with all the technical requirements necessary to be considered a 4G standard, commercially, the technology is accepted as such.
Like HSPA + technology, the LTE standard draws attention due to the speeds with which it can work: depending on the combination of resources implemented in the network and the user’s device, you can reach rates of 300 Mb / s for download and 75 Mb / s for upload.
To facilitate assimilation of the aspect of speed, the level of compatibility of devices with LTE is determined in categories:
- Category 1: download up to 10 Mb / s; upload up to 5 Mb / s;
- Category 2: download up to 50 Mb / s; upload up to 25 Mb / s;
- Category 3: download up to 100 Mb / s; upload up to 50 Mb / s;
- Category 4: download up to 150 Mb / s; upload up to 50 Mb / s;
- Category 5: download up to 300 Mb / s; upload up to 75 Mb / s.
It is clear that these speeds are hardly reached in their entirety, not least because there are a number of factors that determine the rates that an LTE network can achieve. The number of antennas in use simultaneously is one of them – yes, like HSPA +, LTE technology can also use MIMO techniques.
Another important factor is the frequency of the channel, which can be 1.4 MHz, 3.5 MHz, 15 MHz or 20 MHz. Theoretically, the higher the frequency available, the higher the data transfer rate.
LTE also differs in terms of access. While UMTS and HSPA technologies are based on the W-CDMA standard, LTE uses the OFDMA specifications (Orthogonal Frequency Division Multiple Access – something like ” Orthogonal Frequency Division Multiple Access “), which distributes transmission information among several parallel subsets of carriers, this being another aspect that favors higher speeds for the downlink (download).
Regarding uplink (upload), the scheme used is SC-FDMA (Single Carrier Frequency Division Multiple Access – something like “Single Carrier FDMA”), which is a specification similar to OFDMA, but which manages to reduce power consumption , causing energy use by connected devices to also decrease. Despite its name, SC-FDMA can also use subsets of carriers.
Although LTE presents itself as a very advanced standard, there are already works in favor of an improved version, LTE Advanced , which is fully compatible with ITU requirements for 4G technology. The expectation is that this variation can offer rates of up to 1 Gb / s (gigabit per second) for download and 500 Mb / s for upload.
LTE can work with several frequency bands. In Brazil, for example, the technology, when in operation, should work with the 2.5 GHz band.
What is HSPA +?
Also called Evolved HSPA (“HSPA Evolved”) and “3.75G” technology, HSPA + is one of the most impressive updates for mobile communication: theoretically, it is capable of working with rates of up to 168 Mb / s for download and 22 Mb / s for upload. A future revision can cause the reception of data to reach an incredible speed of 672 Mb / s.
It is clear that such high levels are hardly offered in their entirety (as is the case with the “original” HSPA): in Brazil, for example, the operator Vivo started offering plans with HSPA + in 2012 with a maximum limit of 6 Mb / s.
In addition to higher data transfer rates, HSPA + also offers other advantages, such as shorter call set-up times, ability to use voice considerably extended thanks to the use of VoIP , better support for applications that require large amounts of information and, as it is an evolution of HSPA, taking advantage of the network structure of the latter type.
Among the factors that contribute to HSPA + speeds is the use of MIMO (Multiple Input Multiple Output – something like “Multiple Inputs and Multiple Outputs”), a technique that uses more than one antenna for transmission on the same channel, maintaining the use of 5 MHz carriers.
Another characteristic that influences the aspect of speed is the use of modulation (roughly speaking, a process that transforms data and voice into signals for traffic in radio frequency waves) 64-QAM (Quadrature Amplified Modulation – ” Quadrature Amplified Modulation “) for download and 16-QAM for upload, which favor higher transfer rates, especially on mobile devices that are closer to the base.
Conclusion
If you read this text from start to finish (parts 1 and 2), you may have been amazed at the amount of technologies related to mobile telephony. It is a market that involves the interest of several companies and governments and that, consequently, evolves rapidly, which may justify such complexity.
Despite so many acronyms and technical names, you will now be able to better understand what the operators offer and, thus, find a plan that is more suited to your needs and expectations, for example.
Your mobile device also offers ways to help you understand how the cell phone network you are currently using is working: your device may, for example, display a symbol with the letter ‘G’ to inform you that it is using GPRS, ‘E ‘for EDGE,’ 3G ‘for W-CDMA,’ H ‘for HSPA, and so on (see your device manual for details).