What is LTE? Everything you need to know

by: Team AAJanuary 22, 2016
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5G TD FDD TDE LTE 4G Connectivity Carrier Network Tower Radio MBB Connected City IoT -8

Social media, video streaming and even online gaming, you name it, our smartphones are better connected than ever and we’re consuming more and more data as a result. 4G LTE is the current generation of wireless technology making all of this a reality, and at much faster speeds than the older 3G and 2G standards.

In this article, we’ll be taking a look at some of the technical aspects of how LTE works and the hardware associated with it, along with the benefits and how it all relates to the smartphone in your pocket.

How 4G LTE works

The most notable differences from LTE’s predecessors is the change in frequency and bandwidth usage. There are a wide number of 4G LTE bands defined by the standard, the usage of which will vary depending on your country and even your specific carrier’s technology.

These frequencies are split into Frequency Division Duplexing (FDD) and Time Division Duplexing (TDD) types. FDD spectrum requires pair bands, one for uplink and one for downlink. TDD uses a single band as uplink and downlink on the same frequency, but these are time separated instead. There are 31 pairs of LTE bands that operate between 452MHz and 3600MHz and an additional 12 TDD bands between 703MHz and 3800MHz. Higher frequencies allow for faster transmission in built up areas, while lower frequencies offer additional coverage distance, but more limited bandwidth. These bands typically offer between 10 and 20MHz of bandwidth for data transfer, although they are also commonly split up into smaller 1.4, 3 and 5MHz chunks too.

3G vs 4G frequencies TheVillager

FDD is the LTE variation that is regularly seen in North American, European, and some Asian markets. TDD has been implemented in China and India as the wider bandwidth allows for more users per Mhz. This is why you should always be careful to double check LTE bands and carrier compatibility when importing phones from other countries.

LTE uses two different radio links for downlink and uplink, that is, from tower to device, and vice versa. For the downlink, LTE uses an OFDMA (orthogonal frequency division multiple access), which requires MIMO. MIMO, which stands for Multiple Input, Multiple Output, uses two or more antennas to reduce latency significantly and boost speeds within a given channel. Standard LTE can accommodate up to a 4×4 arrangement (the first digit is the number of transmit antennas, and the second, the number of receive antennas).

For the uplink (from device to tower), LTE uses a SC-FDMA (single carrier frequency division multiple access) signal. SC-FDMA is better for uplink because it has a better peak-to-average power ratio.

Speeds and LTE-A

With that jargon out of the way, the major benefit for consumers with 4G LTE is faster download speeds. Although the quality and speed for your connection will clearly vary based on the number of users and the strength of the signal, most LTE networks provide between 10 and 20 Mbps download speeds, according to the latest OpenSignal research. The fastest 4G LTE countries boasts up to 50Mbps download speeds, although in reality these top out somewhere around 35Mbps.

For comparison, older 3G networks can vary quite widely in their actual results. HSPA networks can peak at around 14Mbps download and 6Mbps upload, but rarely come close to this. Typically, a good LTE network is at least 3 to 5 times faster than the best 3G coverage.

Qualcomm LTE Carrier Aggregation Qualcomm LTE theoretical speeds can peak at 100 Mbps download and around 50 Mbps upload. If we are to achieve higher speeds, we need to increase the amount of available bandwidth. LTE-Advanced introduces 8×8 MIMO in the Downlink and 4×4 in the Uplink, which allows for multiple carrier bands to be aggregated together, to improve signal strength and bandwidth. Each LTE band has a bandwidth of either 1.4, 3, 5, 10, 15 or 20 MHz, giving us a maximum bandwidth of 100MHz with five combined, although this will vary depending on the bandwidth available in your particular area.

Theoretically, these provide a maximum download speed of approximately 3.3Gbps and 1.5 Gbps upload. However, the hardware modem found inside your smartphone probably isn’t quite that fast and network coverage certainly isn’t good enough to meet that criteria yet.

From the perspective of a network carrier, the network architecture for LTE is greatly simplified from its predecessors because LTE is an Internet Protocol (IP) based packet-switched network only. The early trade-off was that these networks didn’t have the capability to handle voice calls and text messages natively, but the introduction of VoIP and LTE-A services has begun bringing these features to customers.

4G LTE network coverage 2020

The tech inside your phone

As you have probably figured out, 4G LTE has been an evolving standard and it continues to change as we move towards a future with 5G technology. As such, the hardware inside our smartphones has changed over the years to keep pace with faster LTE networks.

To keep things relatively simple, user equipment is split into a number of different categories, each designed to offer a set of features and speeds based on a specification release. This is often the number that you’ll see listed on a smartphone specification sheet. Release 10 introduced the speed and MIMO improvements that come with LTE-Advanced, but there are a number of newer Release 12 categories on the way too. Here’s a comparison of how some of them break down.

 Max DownloadMax UploadMIMO Config.Release #
Category 4150Mbps51Mbps28
Category 6300Mbps51Mbps2 or 410
Category 9450Mbps51Mbps2 or 411
Cateogy 10450Mbps102Mbps2 or 412
Cateogy 12600Mbps102Mbps2 or 412
Cateogy 153.9Gbps1.5Gbps812

While not necessary, mobile SoC manufacturers often bundle 4G LTE modems alongside their processing components into the main chip, as it is such an essential technology. This helps save on development time and costs. For example, Qualcomm’s Snapdragon 810 features a the company’s own Cat 9 X10 LTE modem, while the Snapdragon 820 comes with a faster X12 modem with Category 12 support, both with 3 band carrier aggregation.

MediaTek’s top-end Helio X20 features a LTE-A Cat 6 modem, as does the Samsung built Exynos 7420 found inside its Galaxy S6 range of smartphones. While supporting higher speeds is clearly better, remember that most LTE networks aren’t close to pushing these peak speeds yet, so there’s no rush to be right on the cutting edge of modem technology in order to enjoy faster data speeds.

The road to 5G

The roll-out of fast 4G LTE networks isn’t over yet, there are still many more customers to bring online and infrastructure to improve across the globe. Even legacy technologies are set to stick around for a good while yet. 4G adoption is expected to grow from around 7 billion connections in 2015 to almost 9 billion by 2020.

4G LTE network connections 2020

However, that hasn’t stopped us looking forward to the future and the even faster 5G connection standard is already under development. 5G networks will be required to offer sub-1ms latency and downlink speeds greater than 1Gbps in the real world, not just theoretical maximums. The 5G standard is also being designed to accommodate a huge number of smaller IoT connected devices, while simultaneously attempting to address concerns over growing energy consumption.

We’re still a way off from consumer deployment of 5G, but the testing of networks capable of meeting these targets have already begun in South Korea and US carrier Verzion has its own tests planned for later this year.

  • jeddo45

    “What is LTE?” -Sprint

  • Balraj

    Main question
    How to find out if network provider has put data cap on the plan ?
    Even if speed is 4g.. if data is capped at 10mbps then what’s the point of 4g…
    Many Indian network provider do it :-(

    • Iskandar

      data cap is the limit of “fast speed” you can use where after reaching the limit speed gets reduced to 2G (depend on network)

      • Balraj

        No if 4g speed is capped at 10mbps
        Then what’s the difference between 4g n 3g ?
        In India all network provider do that in the name of fair usage policy :-(

        • Ankit Banerjee

          Data cap isn’t an upper limit for the download speed, but the amount of data you’re able to use. For example, if you have a 2GB plan, you can use up to 2GB of data at 4G speeds (in India, between 10 Mbps and 30 Mbps). After the data limit is reached, the speed will reduce to 2G speeds.

          Right now in India you get 4g lte speeds of around 10 (on average) and 30 (on a good day) while 3g speeds come to maximum of 4 Mbps. The numbers may be different for other people but these are what I’ve seen from my personal use. (Airtel 4G dongle and Aircel 3G for smartphone in Bangalore)

          • Balraj

            Exactly.. 2gb data at 4g speed but 10mbpsor ssometimes 30mbpsiis not 4g !!!

  • makesNOsense

    wtf is the point of super fast connection when were data capped to a pathetic 4gigs?

    • dodz

      agreed,
      maybe some people need to update their facebook statuses very fast lol.

    • Balraj

      for us with data cap we even have speed capped !!!!

  • Groud Frank

    This global LTE revolution that you speak of will not happen any time in the near future. Two many important markets like Europe still use GSM 3G that are capable of decent speeds. I actually don’t see a rush to adopt the technology.

    • TuckandRoll84

      Ask RIM how it feels to not pursue future technology because the current technology is working just fine.

  • Android Developer

    I would also like to know about what it means for the device itself.
    For example, Do devices with LTE use more battery? Do they produce more SAR (radiation) ?

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  • raffr

    Very informative, thank you. So few tech articles these days go in depth on the actual tech. Mostly it’s just about new gadgets which while fun at times, gets pretty boring.

    • Christopher Sidharta

      Unfortunately part of the information in this article were wrong.

      • Милен Стефанов

        Only if you call 60% “part”…

        • Christopher Sidharta

          I’m trying to be nice and not throw stone.

  • https://echln.bandcamp.com Kwetsima Maluleke

    Glad I read this as they are pushing LTE-A in my country at the moment

  • Милен Стефанов

    This article is full of shits… Does anyone here ever heard about DC-HSDPA? In other words- 3,5G… In theory max speed for DC-HSDPA (or 3,5G) is 42,2Mbps- in reality, in 90% of time I can count on 30+Mbps…
    Who the fuck needs a 4G network if they can’t give me a steady 75Mbps… And I don’t want fast speeds only in cities- I want 60+Mbps when driving on highway…

    • balcobomber25

      What city do you live in?

      • Милен Стефанов

        Put these in Google: 43.226439, 27.884299

        • balcobomber25

          That makes sense then, Bulgaria is known to have some of the fastest 3G speeds in the world. Consider yourself lucky, in most cities here in the US you never even come close to 10mb on HSDPA, which is why LTE is so popular.

          • Милен Стефанов

            I know that speeds in US are shitty, but article is not for US citizens only… Only idiot can advertise 4G with “you can achieve something around 35-40Mbps”- these speeds are LOW for a 4G network…
            Bonus- 35Mbps are possible in 3,5G network.
            Another bonus- when you go for higher Mhz you loose on penetrating obstacles. In my office, behind 3 walls 4G network disappears and my phone (Note 4) moves on 3G network… Carriers base station is not very far- no more than 300-350 yards…

            This article is paid by some of your carriers- GUARANTEED.

          • Karly Johnston

            I average 24mb on Tmob H+, it is just as fast as the band 4 LTE.

  • Christopher Sidharta

    There’s many mistake in this article. I will point out several BIG mistake only.

    Mistake #1.
    “3G work in a single frequency of 2100 MHz and gives speed up to 7.2Mbps (21.6 and some cases 42.2Mbps), but mainly urban due to small radius.”

    There were many frequency that can be use for 3G, such as 900MHz or 1800MHz. The carrier use small radius for 3G in crowded area to make sure that their Base Station (BS) is not overloaded by too many user to maintain high-speed internet. In the uncrowded area, the carrier will adjust the radius.

    Mistake #2
    “TDD has been implemented in China and India as the wider bandwidth allows for more users per Mhz.”

    This is TOTALLY wrong!!!! The bandwidth width of TDD LTE is in the same 5MHz block as FDD LTE.

    In FDD, the up & down frequency is the same i.e. 5Mhz/5Mhz, 10MHz/10MHz, and so on. So, i.e. if we watch youtube, and use 99% download, that means the up frequency is idle.

    In TDD, because the same frequency were used for up and down, the carrier can adjust the width of bandwidth. For example, 95% for download, 5% for upload. So, the word “TDD has wider bandwidth” is wrong!! It should be TDD provide more efficient bandwidth usage.

    Mistake #3
    “LTE uses two different radio links for downlink and uplink”

    FDD LTE use two different…..

    Mistake #4
    “Although the quality and speed for your connection will clearly vary
    based on the number of users and the strength of the signal, most LTE
    networks provide between 10 and 20 Mbps download speeds, according to
    the latest OpenSignal research. The fastest 4G LTE countries boasts up to 50Mbps download speeds, although in reality these top out somewhere around 35Mbps.”

    The first statement “your connection will clearly vary
    based on the number of users and the strength of the signal” is true and self explaining. But the statement after that were misleading.

    There were a max speed for certain 4G tech/category. i.e. cat 4 = 150mbps, cat 6 = 300mbps, and so on. The reason we can only archive 10mbps or 20mbps or 35mbps or 50mbps because the network in that area were congested. The trick here for carrier to know which area is crowded and put a smaller coverage, but more antenna/BS. So, let say if in some area, let say Manhattan. Carrier A put 100 Base Station (BS), and Carrier B put 200 BS, and both carrier have the same amount of user in that area. Then carrier B LTE speed will be faster. But more BS per area means more cost, so carrier need to adjust the number of BS.

    Mistake #5
    “For comparison, older 3G networks can vary quite widely in their actual
    results. HSPA networks can peak at around 14Mbps download and 6Mbps
    upload, but rarely come close to this.”

    Same as mistake #4. The speed in 3G is about how many BS a carrier want to put in certain area.

    Mistake #6
    “LTE theoretical speeds can peak at 100 Mbps download and around 50 Mbps
    upload. If we are to achieve higher speeds, we need to increase the
    amount of available bandwidth. LTE-Advanced introduces 8×8 MIMO in the
    Downlink and 4×4 in the Uplink, which allows for multiple carrier bands
    to be aggregated together, to improve signal strength and bandwidth.
    Each LTE band has a bandwidth of either 1.4, 3, 5, 10, 15 or 20 MHz,
    giving us a maximum bandwidth of 100MHz with five combined, although
    this will vary depending on the bandwidth available in your particular
    area.”

    This is only half true. While it is true that if carrier have more frequency/bandwidth it can have higher speed. It’s not the only way to do it. The carrier can make the area of each BS smaller. The only reason the carrier wants more bandwith/frequency is because having less BS point will make them easier to maintain (less cost).

    Furthermore, for 100MBps speed, it only require 10MHz band!!!! Not 100MHz!!! and no one use LTE with 1.4MHz or 3MHz bandwidth.

  • http://www.t-mobile.com Big-Myke Kanuri

    Maybe people who know it all need to have their own website and forums set up then? Please direct us to where the correct information is posted on your website?