The Importance of Carrier Aggregation in 5G

When businesses and consumers envision 5G they think of fast speeds and low latency associated with mmWave frequencies. But in production, mmWave is sensitive to man-made and natural obstructions (e.g. rain, building materials, vegetation) and does not travel far enough without an abundance supporting wireless infrastructure to be economically viable.

As a result, wireless carriers rely on various methods to help mid-band and low-band achieve comparable performance akin to mmWave. One of these methods is carrier aggregation and it’s crucial to bridging 5G expectations with reality. Carrier aggregation has been demonstrated to reduce overall power consumption levels while increasing throughput and maintaining high service level, which is critical to consistently meet consumer demands.

How does it work?

Carrier aggregation works by combining multiple channels of a frequency band to widen the pipe and create higher throughput. It does not improve latency but it allows more data to pass from one end point to another at one time. This increases overall performance to meet the requirements of high data usage applications in various industries, such as augmented and virtual reality services or autonomous factory robots and massive IoT. T-Mobile has demonstrated incredible recent success with carrier aggregation, achieving 3Gbps network speeds by combining three channels of mid-band spectrum on its 5G network. Verizon also has used carrier aggregation back in 2020 to achieve 4.2Gbps as well.

How is it different for 5G than previous generations?

The concept and use of carrier aggregation hasn’t changed since the 4G/LTE wireless era, but the availability of spectrum to allow for more aggregation has changed. Primarily this is because more 5G frequency bands such as C-band and 2.5GHz use time division duplexing (TDD) transmission technique instead of frequency division duplex (FDD). FDD transmits data using two separate streams for uplink and downlink, while TDD uses a single stream for both—effectively cutting the bandwidth usage in half. That extra bandwidth can be used towards increasing the use of carrier aggregation over more channels. There is also a desire to aggregate FDD/TDD bands together as FDD is generally thought to be better for coverage and TDD for capacity. Additional information on the spectral efficiency benefits for 5G can be found here. 

As mobile carriers look to maximize the use of available spectrum assets in different FDD and TDD bands, carrier aggregation is the key to reaching extended coverage range. It improves mobile user experience with a consistent level of service across the network. It’s not enough for the carriers just to be able to perform carrier aggregation. Devices must be able to support it as well. Mid band and low band carrier aggregation requires the absolute latest in 5G technology and as it matures and devices become capable of handling it we will begin to see 5G speeds meet the expectations of consumers.