October 16, 2016
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Galaxy-S6-Speedtest-1

4G LTE is without a doubt the de facto standard for most carriers across the globe at this stage, and 5G is already in pretty far-along talks across a variety of carriers and regulatory boards. However, the middle ground between these techs is something called LTE Advanced (LTE-A) networks. LTE-A has been available in Europe and Asia for a while now, but the technology has only recently started seeing its big push in the United States with Verizon and other carriers looking to dramatically boost their network speeds.

So what exactly is LTE-A? In this piece we take a closer look at how the technology works and what it means for consumers.

How does it work?

The new functionalities introduced in LTE Advanced are Carrier Aggregation (CA,) enhanced use of multi-antenna techniques, and support for Relay Nodes. All of these are designed to increase the stability, bandwidth, and speed of LTE networks and connections.

Carrier aggregation

Probably the key behind LTE Advanced is carrier aggregation. Essentially this technology is designed to multiply the bandwidth of LTE connections by allowing you to download data from multiple network bands simultaneously. LTE component carriers, or bands, are split up into data carrying parts that can have a bandwidth of 1.4, 3, 5, 10, 15 or 20 MHz. Up to five component carriers can be aggregated together. Carrier Aggregation combines signals from these different carriers, allowing for bandwidth to increase up to 100 MHz for a single connection. This applies for both FDD and TDD network types, as well as both download and upload connections.

Carrier aggregation can work with contiguous component carriers that are located within the same operating frequency band, or with non-continuous carriers from different bands across different operating frequencies. The image below helps to explain this:

intra-band carrier aggregation Source: 3gpp

In terms of data speeds this technique can provide extremely high peak data rates, theoretically up to 1Gbps when utilizing the maximum available bandwidth from 5 carriers. Although commercial solutions only support up to 3 carriers with peak data rates up to 600 Mbps. However, in reality carriers, hardware, and network coverage will fall short of this theoretical maximum, for example peaking at around 150Mbps download speeds with two 20MHz carriers enabled.

Qualcomm LTE Carrier Aggregation Qualcomm

Another major benefit of Carrier Aggregation is that is allows for full backwards and forwards compatibility between existing LTE networks and LTE Advanced compatible devices. LTE Advanced connections will be provided through existing LTE bands, so standard LTE users will continue to use LTE as normal, whereas Advanced connections will make use of multiple LTE carriers.

MIMO

Multiple Input Multiple Output technology (MIMO) is another technology required for LTE Advanced to work. MIMO increases the overall transfer bitrate by combining data-streams from two or more antennas and allows for carrier aggregation to work.

Rather than sending a single piece of information from one sender to one receiver, you can send the same single piece of information from multiple senders to multiple receivers. It’s a parallel process, which substantially increases the amount of data you can send and receive each second (bits per hertz,) providing you have a receiver modem which can sort all the information out into the correct order.

MIMO Telecomhall

See also:

Are you on the fastest LTE network in the U.S.?

February 2, 2016

Although MIMO is already used in current LTE networks, LTE Advanced requires that chips increase the number of inputs and outputs used simultaneously. LTE Advanced will support up to eight transmitters and receivers whilst downloading and four by four when uploading. The increased MIMO arrangement will also improve the speed and connection quality of legacy connections such as CDMA, GSM, and WCDMA.

Cell hardware

The final piece of technology introduced with LTE Advanced is a piece of carrier hardware called a relay node. Whilst relay nodes aren’t an integral part of improving your data speeds, they will improve the availability of LTE connections, and offer you more connections to choose from when sending a receiving data.

Simply put, a relay node is a low powered base station used to boost network coverage at the ends of and beyond the connection radius of the main station. These relay nodes connect wirelessly to the main station, and should help boost your signal when wondering close to the edge of your LTE network. Of course access to improved connectivity will be entirely dependent on whether carriers bother to invest in building these nodes.

4G_LTE_WEB_en

Peak theoretical and user speeds see a big boost with 4G LTE Advanced.

Teliasonera

Modem hardware

To function correctly, carrier aggregation and MIMO requires both telecommunications and device hardware implementations. You will find that many smartphone SoCs and external modems support these faster data rates these days. LTA Advanced hardware details were introduced with the Release 10 specifications. Any LTE Category 4 device or higher supports carrier aggregation and the larger MIMO configurations, each to varying degrees.

For example, Qualcomm’s Snapdragon 810 features a the company’s own 450Mbit/s Cat 9 X10 LTE modem, while the Snapdragon 820 comes with a faster X12 modem with Category 12 support, which both support up to 3 band carrier aggregation in the download link. MediaTek’s top-end Helio X20 features a LTE-A 300Mbit/s Cat 6 modem, as does the Samsung built Exynos 7420 found inside its Galaxy S6 range of smartphones. However, it is important to note that your carrier will need to keep up with your modem technology before you can hope to reach these maximum speeds, so don’t take the handset spec sheet figures too seriously.

LTE ClassSpeedsAggregation Options
Category 12600 Mbps download
100 Mbps upload
3 x 20MHz download
2 x 20MHz upload
Category 10450 Mbps download
100 Mbps upload
3 x 20MHz download
2 x 20MHz upload
Category 9450 Mbps download
50 Mbps upload
3 x 20MHz download
Category 7300 Mbps download
100 Mbps download
2 x 20MHz download
2 x 20MHz upload
Category 4150 Mbps download
50 Mbps upload
2 x 10MHz download

In the future, high-end smartphone modems will support an even wider range of aggregation technologies. WiFi and LTE Unlicenses spectrums will be thrown into the mix with LTE-A Pro and additional carrier bands with the eventually roll-out of the first 5G networks some time down the line.

Global rollout

 

While LTE-A certainly isn’t as available as standard LTE at this stage, it continues to grow across the globe and has a presence in just about every major market at this stage. This ramp-up will likely continue full speed over the next several years, as 5G still is a bit off. For those that have LTE-A access, what do you think of the speed gains? Was standard 4G LTE already ‘good enough’? Let us know your thoughts in the comments.

Robert Triggs
Lead Technical Writer at Android Authority, covering the latest trends in consumer electronics and hardware. In his spare moments, you'll probably find him tinkering with audio electronics and programming.
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