Massive MIMO technology will almost certainly be a core component of the super-fast 5G networks of the future. Indeed, several mobile network operators around the world have already begun rolling it out ahead of 5G’s arrival in 2020. But what exactly is Massive MIMO, and why is it so important to 5G?
What is Massive MIMO?
MIMO stands for Multiple-input multiple-output. While it involves multiple technologies, MIMO can essentially be boiled down to this single principle: a wireless network that allows the transmitting and receiving of more than one data signal simultaneously over the same radio channel, typically using a separate antenna for the transmitting and receiving of each data signal.
Standard MIMO networks tend to use two or four antennas to transmit data and the same number to receive it. Massive MIMO, on the other hand, is a MIMO system with an especially high number of antennas.
There’s no set figure for what constitutes a Massive MIMO set-up, but the description tends to be applied to systems with tens or even hundreds of antennas. For example, Huawei, ZTE, and Facebook have demonstrated Massive MIMO systems with as many as 96 to 128 antennas.
Because MIMO systems need to physically pack more antennas into a small area, they require the use of higher frequencies (and hence shorter wavelengths) than current mobile network standards.
What are the advantages of Massive MIMO?
The advantage of a MIMO network over a regular one is that it can multiply the capacity of a wireless connection without requiring more spectrum. Reports point to considerable capacity improvements, and could potentially yield as much as a 50-fold increase in future.
The more antennas the transmitter/receiver is equipped with, the more possible signal paths and the better the performance in terms of data rate and link reliability.
A Massive MIMO network will also be more responsive to devices transmitting in higher frequency bands, which will improve coverage. In particular, this will have considerable benefits for obtaining a strong signal indoors.
The greater number of antennas in a Massive MIMO network will also make it far more resistant to interference and intentional jamming than current systems that only utilise a handful of antennas.
It should be noted, too, that Massive MIMO networks will utilise beamforming technology, enabling the targeted use of spectrum. Current mobile networks are rather dumb in the way they apportion a single pool of spectrum between all users in the vicinity, which results in a performance bottleneck in densely populated areas.
With Massive MIMO and beamforming such a process is handled far more smartly and efficiently, so data speeds and latency will be far more uniform across the network.
MIMO and 5G
While standard MIMO principles are already in use across multiple Wi-Fi and 4G standards, Massive MIMO will really come into play once 5G arrives. Indeed, it’s widely expected that Massive MIMO will be a key enabler and foundational component of 5G.
One of the key roles of any 5G network will be to handle the huge increase in data usage that’s around the corner. Cisco estimates that by 2020 - when 5G is set to roll out in the UK - there will be 5.5 billion mobile users around the world, each consuming 20GB of data per month on average. That’s not even factoring in the huge impact the Internet of Things is predicted to have on our mobile networks.
Massive MIMO’s ability to serve multiple users - and multiple devices - simultaneously within a condensed area while maintaining fast data rates and consistent performance makes it the perfect technology to address the needs of the forthcoming 5G era.
Who is employing Massive MIMO?
Massive MIMO technology is already live commercially in China and Japan within a 4G LTE context. The latter country’s Softbank network deployed the first ever commercial Massive MIMO network towards the end of 2016.
In early September 2017, Ericsson announced the launch of a new FDD (Frequency Division Duplexing) radio with support for 5G and Massive MIMO. It claimed that this would bridge the gap between 4G and 5G, boosting the capacity of existing 4G LTE while forming the foundation for 5G.
Chinese network technology companies ZTE and Huawei both announced new European Massive MIMO tests in October 2017.
Also in 2017, Vodafone and Huawei teamed up in Australia to show off Massive MIMO technology within a real-world setting. They managed to use Vodafone's existing frequency spectrum, along with Huawei’s 5G active antenna unit (featuring 32 internal transmitters and receivers), to hit transfer speeds of 717Mbps across eight devices.
Over in the US, mobile networks Sprint and T-Mobile have followed the lead of rivals AT&T and Verizon in conducting their own ambitious Massive MIMO tests.
Early in 2018, Nokia took a step towards refining Massive MIMO antenna technology itself with the production of its ReefShark chipset. By being smaller, lighter and more power efficient than its predecessors, Nokia has claimed that ReefShark reduces the massive MIMO antenna size by half and cuts the energy consumption in baseband units by 64%.
Korean tech giant Samsung has also been busy with Massive MIMO technology. At its headquarters in Suwon, Korea, the company recently created a so-called '5G City' to provide some insight into what life might be like when 5G is rolled out.
One major element of this 5G City was a so-called '5G Stadium,’ which specifically demonstrated how massive MIMO technology can enable crowds of people to simultaneously stream HD video without any delays or interruptions.
What are UK mobile networks doing with Massive MIMO?
Vodafone became the first European mobile network to deploy Massive MIMO when it commenced upgrading a number of its UK sites in June 2017. The operator targeted UK hotspots where MIMO’s key attributes could be best exploited, such as cities and sports stadiums.
Almost a year later, in April 2018, Vodafone conducted the UK’s first 3.4 GHz spectrum trial using Massive MIMO technology.
UK network EE has also been working with massive MIMO technology. In November 2017 it used Massive MIMO to demonstrate download speeds of 2.8Gbps across an end-to-end 5G test network. More recently, parent company BT has confirmed that it is working with Nokia to implement the aforementioned ReefShark chipset into its network.
Elsewhere, O2 claims that it is "investing over £600m per year in innovations like Massive MIMO and 5G".
Can current phones use Massive MIMO?
While Massive MIMO is predominantly a 5G technology, there are a number of current smartphones that can take advantage of it on current 4G networks - where available, of course.
These devices include the iPhone 8 and iPhone X, the HTC 10 and U11, the Huawei P9 and P10, the LG G5 and G6, the Samsung Galaxy S7 and S8, and the Sony Xperia X and XZ.
However, it’s worth noting that even older or less capable phones that don’t support MIMO will be able to benefit from the more stable, more sensitive network environment that Massive MIMO will produce.
That said, the first 5G phone may well have been announced in August 2018. Smartphone manufacturer LG says that it will launch a 5G-ready handset on US network Sprint during the first half of 2019. The switch will be flipped on Sprint’s fledgling 5G network across a handful of US cities during the same period.
Just prior to that, Motorola announced that there would be a 5G Moto Mod peripheral that would grant its Moto Z3 smartphone 5G connectivity some time towards the end of 2018. The catch is that network partner Verizon’s limited 5G service won’t start rolling out in the US until sometime in 2019.
Image credit: Linkoping University