What Makes 5G So Fast? mmWaves, MIMO, and Beamforming, and MoreDecember 02, 2020 by John Koon
With 5G rolling out more quickly as we approach 2021, it may be helpful to touch on the key technologies that make 5G such a speedy success.
In a recent article, we discussed the basics of 5G technology—a discussion that is no longer in the realm of the hypothetical with 5G now being deployed in practice. One of the key talking points of 5G, at least from the consumer perspective, is its blazing-fast speeds. But what exactly makes 5G so fast?
While the hardware-level details of 5G speed are extensive, this article will briefly discuss the basic building blocks that bump 5G speeds from 4G and LTE rates.
The Goals of 5G Point to Speed
As the name suggests, the 5G new radio (NR) requires a new kind of radio technology, antenna, and carrier tower design to achieve speeds of one gigabit per second with latency less than 10 milliseconds. The actual performance would depend on the design of the 5G products and the environment in which they operate.
The three main goals of 5G include enhanced mobile broadband (eMBB), massive machine-type communications (mMTC), and ultra-reliable low-latency communications (uRLLC).
Comparative speed of 5G. Image used courtesy of Thales Group
- eMBB enables more subscribers with higher performance of downlink speed data rate of 10 Gbps.
- mMTC enables massive IoT connections globally. This is important for smart cities and autonomous vehicles to function properly without delay.
- uRLLC provide a latency of less than 10 milliseconds.
While these are theoretical goals to achieve, Verizon was able to demonstrate peak speeds close to 1 Gbps in its 5G ultra-wideband network in Chicago and Minneapolis. The company also charted latencies of less than 30 milliseconds—faster than the average 4G speed by 23 milliseconds.
Achieving this level of 5G performance requires a new 5G architecture and cellular wireless technology, which include mmWave/spectrum and frequencies, smaller cell towers with MIMO, and beamforming. On the device side, including 5G mobile phones, developers must include new antenna and modem designs.
Operating in the mmWave Ranges
Data transmission capacity is directly proportional to frequencies. To achieve a high data rate, 5G operates in the millimeter-wave (mmWave) range between 30 GHz and 300 GHz compared to 700 MHz to 2500 MHz for 4G.
Note that the frequencies used in the US are 28 GHz while some countries have below 6 GHz. The sub-6 GHz range can travel further and requires fewer cellular towers but its bandwidth is also lower. Some countries may choose to use this frequency to reduce the cost of infrastructure, despite less efficient performance.
Depiction of what a heterogenous 5G mobile network might look like. Image used courtesy of Aqeel Hussain Naqvi and Sungjoon Lim
mmWave can transmit about 6 gigabits per second for a short distance of around 1,000 feet. Therefore, 5G requires many cellular towers to make it work. 5G will create a very large M2M network. Because of its super speed, 5G can support a million IoT devices within 0.38 square miles (1 square kilometer) while 4G can only support 2,000. That's a 500 thousand times improvement.
Latency refers to response time to a request; the lower the latency, the faster the response. 5G has a latency of fewer than 10 milliseconds and eventually goes down to one millisecond. It is a two- to three-fold improvement over 4G.
MIMO Increases Antenna Performance
Compared with 4G, 5G cellular towers are much smaller and come in an array. Multiple-input, multiple-output antenna systems (MIMO) are used to send data over one radio channel instead of a single antenna used by 4G.
Depending on the application, a radio channel may use 6 x 2 MIMO ("6T2R"): six for receiving and downloading and two for transmitting and uploading (or other combinations). A maximum MIMO of 8T8R is possible. The 5G cellular tower consists of an antenna array of 100 or more. Similarly, the user device including mobile phones has similar antenna design to support the mmWave frequencies.
Beamforming Boosts Signal Strength
Borrowed from the military radar “phased arrays” technology, 5G is able to create beamforming based on panels of small antenna elements. In the mmWave bands, beamforming is a process used to produce narrow beams that can be controlled to point in a specific direction.
Block diagram of a phased-array receiver. Image used courtesy of Aqeel Hussain Naqvi and Sungjoon Lim
Adjusting the amplitude and phase-out of each antenna, beamforming can produce strong beams that can penetrate through buildings. This will maximize signal strength.
While the inner workings of 5G, especially as it pertains to speed, are complex, hopefully, this article gave you an idea of the basic building blocks of 5G speed. Do you have hands-on design experience with 5G technology as it pertains to latency? Share your experiences in the comments below.