The antenna technology MIMO-Multiple Input Multiple Output has been part of mobile communications for many years. The MIMO technology was first introduced in the 3G UMTS (Universal Mobile Telecommunication System) networks as part of the HSPA (High-Speed Packet Access) evolution. However, it gained more popularity when 4G LTE (Long Term Evolution) networks were launched. The latest generation of mobile networks, 5G New Radio (NR), also employs the MIMO technology.
MIMO is an antenna technology that uses multiple antenna elements at the transmitter and the receiver to improve radio signal link and data rates; Massive MIMO is a type of MIMO technology in 5G New Radio (NR) networks that employs tens of antenna elements to serve multiple users simultaneously.
MIMO uses up to eight antenna elements
MIMO has been part of the 4G LTE radio networks since the first LTE launch in 2009 based on 3GPP Release 8. In mobile networks, there are two kinds of communication links, downlink and uplink. Downlink is the communication from the cellular base station to the mobile phone, and it helps with the downloads. Uplink is the communication from the mobile device to the base station, and it helps with the uploads. The basic scheme of MIMO relies on multiple antenna elements at the transmitter and the receiver. In simple terms, the transmitter and receiver antennas are made of various smaller antennas called the antenna elements. The MIMO configuration needs to be defined separately for both communication links, downlink and uplink.
The original LTE networks use a MIMO configuration of 4×4 in the downlink and 2×2 in the uplink. So, for example, if you download something on your phone when connected to LTE (as per 3GPP release 8), the base station can use multiple antennas (up to four) to transmit the data. Likewise, at the receiving end, your phone can use multiple antennas (up to four) to receive the data sent by the base station. If you upload something, the transmitter of your phone can use up to two antenna elements to send the data, and the base station can use up to two antenna elements to receive what you send. LTE Advanced and LTE-Advanced Pro networks use MIMO configurations of 8×8 for the downlink and 4×4 for the uplink.
For MIMO to work correctly, both the base station and the user device must be compatible with the latest MIMO configurations. There are various categories of LTE mobile devices, and each new category has devices (e.g. phones, dongles, MiFi routers, smartwatches etc.) of higher specs. It means that not every LTE phone is the same, and if you use a phone of an older category, it may not support the full MIMO capabilities.
Massive MIMO can use hundreds of antenna elements
5G networks take the MIMO technology to another level and use a variant of MIMO called Massive MIMO. As the name suggests, it means a MIMO system that is bigger than the earlier MIMO. Massive MIMO in 5G employs a much higher configuration than the MIMO in 4G LTE networks. With Massive MIMO, the antenna configuration involves tens or even hundreds of antenna elements in a single antenna. For example, it is already possible today to have a Massive MIMO system with a configuration of 64 x 64 in the downlink. Another critical aspect of Massive MIMO is the multi-user capability to support multiple mobile users simultaneously. Thus, massive MIMO is used to improve the data rates and increase the overall network capacity by supporting multiple 5G users simultaneously.
MIMO (Multiple Input Multiple Output) technology is used in modern mobile networks including 4G LTE and 5G NR. It makes use of multiple antennas within the antenna panels of transmitter and receiver in downlink and uplink to create multiple layers of communication between a mobile phone and a base station. Due to spatial multiplexing and diversity features within MIMO, the radio link quality and data rates can both improve. Generally, the standard MIMO technology can use up to eight (8) antenna elements. Massive MIMO is a type of MIMO technology used by the 5G networks that employs tens or even hundreds of antenna elements within a single antenna panel to serve multiple users simultaneously.
Here are some helpful downloads
Thank you for reading this post, I hope it helped you in developing a better understanding of cellular networks. Sometimes, we need some extra support, especially when preparing for a new job, studying a new topic, or maybe just buying a new phone. Whatever you are trying to do, here are some downloads that can help you:
Students & fresh graduates: If you are just starting, the complexity of the cellular industry can be a bit overwhelming. But don’t worry, I have created this FREE ebook so you can familiarise yourself with the basics like 3G, 4G etc. As a next step, check out the latest edition of the same ebook with more details on 4G & 5G networks with diagrams. You can then read Mobile Networks Made Easy, which explains the network nodes, e.g., BTS, MSC, GGSN etc.
Professionals: If you are an experienced professional but new to mobile communications, it may seem hard to compete with someone who has a decade of experience in the cellular industry. But not everyone who works in this industry is always up to date on the bigger picture and the challenges considering how quickly the industry evolves. The bigger picture comes from experience, which is why I’ve carefully put together a few slides to get you started in no time. So if you work in sales, marketing, product, project or any other area of business where you need a high-level view, Introduction to Mobile Communications can give you a quick start. Also, here are some templates to help you prepare your own slides on the product overview and product roadmap.