Beamforming and Massive MIMO in 5G Technology
By Safi Khan
January 14, 2025
Estimated reading time: 5 minutes
The first (3GPP Release 15) and second (3GPP Release 16) waves of ultralow-latency, high-speed 5G have already arrived. 5G stand-alone (SA) network tests were successful in Asia and Europe. U.S. carriers are launching SA networks while having already deployed 5G non-stand-alone (NSA) 5G in cities nationwide.
In addition, carriers finished implementing the infrastructure needed to support technologies like beamforming and massive multiple-input and multiple-output (MIMO). These technologies are critical in creating stable 5G networks that connect millions of mobile and IoT devices.
5G networks will carve new paths for mobile. It will tap into previously unusable frequencies at the high end of the radio frequency (RF) spectrum (FR2). Earlier wireless standards could not operate in these higher bands. However, 5G solves the problem of overcrowding at the middle and lower frequencies (FR1).
At first, operators leveraged millimeter wave (mmWave) and thousands of miniature base stations called small cells. These enabled 5G to operate at frequencies up to 300 GHz compared to bands below 6 GHz used by current mobile standards.
However, operators realized how expensive it would be to deploy MIMO beamforming in IoT use cases (including the distance and line of sight limitations). They shifted their focus to the mid-band spectrum, spending billions of dollars to acquire it.
The mid-band or C-band spectrum auction was crucial for closing the gap between the low spectrum and the ultrahigh (and more expensive) mmWave spectrum.
mmWave is appropriate in densely populated and high-capacity areas. It’s also suitable for premium smartphones. Still, it is not ideal for:
Sub-6 GHz is more cost-efficient for these scenarios. It does not require manufacturers to insert special mmWave active array antennas into an IoT device. Getting a mmWave capable device certified by the Federal Communications Commission (FCC) is an involved process.
5G requires a new network structure to enable more targeted bandwidth use. However, it will require innovative technologies to compensate for:
Two technologies, beamforming and massive MIMO, help direct and amplify signals, reducing interference and traffic jams. Analog, digital and hybrid beamforming are like traffic-signaling systems that conduct wireless signals in the right direction.
Beamforming and massive MIMO increase network capacity and improve performance. These technologies are ideal for densely populated, high-capacity areas (e.g., airports and stadiums) with many wireless devices. They prevent these locations from running out of network resources.
Beamforming and massive MIMO have also increased the network capacity in zones where the network infrastructure (e.g., small cells or mmWave antennas and base stations) are close to the receiver. This means the line of sight is available, and no obstructions inhibit transmission.
In addition, the latest industry advancements in antenna technology, chipsets and software continue to enhance massive MIMO and beamforming. For example, electronic manufacturing, silicon processing and electronics miniaturization allow antennas to be packed into compact form factors. As a result, even small, battery-constrained devices can perform tremendous processing without overheating or exhausting their battery life.
Cellular signals, especially those carried by millimeter waves, can be blocked by objects easily and weaken over longer distances. Beamforming shapes signals and turns them into concentrated beams aimed at the receiver or bounced off obstacles like a billiard ball. Sending signals in several directions at once increases signal loss. Instead, beamforming applies relative amplitude and phase shifts to antenna elements to cancel out interference and create streamlined signal paths.
Beamforming applies processing to signals at the transmission end. In analog beamforming, those signals are summed up and receive analog-to-digital conversion (ADC) at the receiving end. In digital beamforming, amplitude and phase variation are reversed at reception by ADC and digital down converters (DDC). Beamforming transceivers are integrated into massive MIMO arrays at the device and cell site.
Massive MIMO employs these advanced beamforming techniques. It enhances the performance of wireless communication systems like 5G networks.
According to a report from Signals Research Group, T-Mobile’s 5G multi-user MIMO increased network capacity by 50%. Many telecommunications equipment manufacturers today have incorporated massive MIMO technology into their 5G infrastructure. This enables user-specific data channel beamforming, which boosts throughput and capacity. Massive MIMO solutions are pivotal in meeting network requirements for 5G mid-band deployments.
Massive MIMO is like a traffic routing system that multiplies available network connections by a factor of 20 or more. Since higher band signals can use smaller antennas, many mmWave antenna elements can fit into a fingernail-sized pad on the device side.
4G base stations have around a dozen antenna ports, whereas 5G base stations have around a hundred antennas directing cell signals. Beamforming separates those signals and keeps them from interfering with each other.
Smaller base stations with more ports mean more transceivers can replace one transceiver on a typical cell tower. One array can have up to 64 transmitters and 64 receivers (hence the word “massive”). Among other processes, maximum ratio filtering can maximize the signal-to-noise ratio to amplify signals in dense urban areas.
Massive MIMO arrays increased LTE speeds and improved latency. However, massive MIMO and beamforming technologies work together to achieve 5G’s promised scale:
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Editor’s Note: This blog was originally published on 5 June 2020 and has since been updated.